AL-KAHTANE, Abdullah Ali (2002)
Advisors: El Halawani, Mohamed E. and Kannan, Mathur Sriniva
Transcriptional regulation of prolactin gene by vasoactive intestinal peptide and dopamine in cultured turkey pituitary cells: Role of calcium(2+)/PKC signaling pathway
Abstract
It has been established that prolactin (PRL) secretion in birds is under the tonic stimulatory control of hypothalamic vasoactive intestinal peptide (VIP). Dopamine (DA) has been shown to stimulate (at the hypothalamic level) and inhibit (at the pituitary level) VIP-stimulated PRL secretion. Little is known about the signal transduction mechanism(s) mediating VIPergic and DAergic effects on PRL gene expression and release. This study was designed to examine: (1) the role of VIP and DA in the transcriptional regulation of PRL gene, and (2) the involvement of the Ca2+/PKC signal transduction pathway in mediating VIPergic and DAergic effects on PRL gene expression and PRL release. Run-on transcription assay analysis showed that VIP increased the rate of PRL gene transcription, an effect abolished completely by DA, via D2 DA receptors. Moreover, the measurement of PRL mRNA steady state level by semi-quantitative RT-PCR, indicated that DA, via D2 DA receptors, also inhibited the stimulatory effects VIP on PRL mRNA level and PRL mRNA half-life. Moreover, VIP-stimulated PRL release was inhibited by DA. In cultured turkey anterior pituitary cells, VIP treatment (10-2 to 10-5 M) increased intracellular Ca 2+ ([Ca2+]i), as using the fluorescent Ca 2+ indicator Fura-2/AM. This VIP stimulation was inhibited by a D 2, but not by a D1 DA receptor agonist. VIP-stimulated PRL expression and release were blocked by the L-type Ca2+ channel blocker, verapamil, and mimicked by the L-type Ca2+ channel agonist, Bay K-8644, suggesting that Ca2+ influx through L-type Ca2+ channels is required for the VIP stimulatory effect on PRL synthesis, and that DA may antagonize these VIP-stimulatory by inhibiting Ca2+ influx. The protein kinase C (PKC) activator, phorbol-12-mysterate-13-acetate (PMA) significantly increased PRL expression and release, an effect inhibited by verapamil. Bisindolylmaleimide I, a PKC inhibitor, significantly reduced VIP-stimulated PRL expression and release. These results indicate the involvement of PKC in mediating VIP effects on PRL synthesis. Taken together, these findings strongly demonstrate that the DAergic system inhibits PRL synthesis at the transcriptional and post-transcriptional levels by antagonizing VIP at the pituitary level via D2 DA receptors, and that the Ca2+/PKC pathway plays a major role in mediating these effects.
AL-ZAILAIE, Khaled A. (2003)
Advisor: El Halawani, Mohamed E.
Neuroanatomical relationship between hypothalamic dopamine and vasoactive intestinal peptide in the regulation of prolactin: Immunocytochemical and tract-tracing studies
Abstract
Dopamine (DA) acts centrally through the vasoactive intestinal peptide (VIP) system to stimulate turkey prolactin (PRL) secretion. DA also modulates LH/FSH secretion through gonadotropin-releasing hormone I (GnRH-I) neurons. The distribution of DAergic, VIPergic, and GnRHergic-immunoreactive cells and fibers were mapped in the turkey hypothalamus. The DAergic system overlapped the VIPergic system in the medial preoptic nucleus (POM), anterior hypothalamus (AM), infundibular nuclear area (INF) and median eminence (ME), and the GnRHergic system in the POM and ME. Changes in DA immunoreactivity were associated with changes in VIP/PRL across the reproductive cycle. This neuroanatomical evidence indicates a close association between these systems in regulating turkey reproduction. The retrograde tracer DiI, combined with tyrosine hydroxylase (TH), VIP, and GnRH-I immunocytochemistry, was used to identify neurons projecting to the POM, INF, and ME. DiI/TH double-labeled neurons were found in the POM and AM after DiI injections into the INF. This reinforces the hypothesis that DA neurons in the POM project to the PRL-releasing area in the INF and may be involved in the regulation of PRL. DiI/TH labeled neurons were also found mainly in the POM after DiI injections into the ME. These DAergic projections may have some influence on PRL regulation at the pituitary level. GnRH neurons were shown to project directly to the ME, while the only VIP projection to the ME was from the INF. The immediate early gene c-fos was used as an indicator of neural activation to identify hypothalamic neurons that participate in the secretion of PRL and LH that results from electrical stimulation in the POM (ES/POM). The double-labeling procedure of in situ hybridization (c-fos) and (VIP/GnRH-I) immunocytochemistry revealed that ES/POM induced c-fos expression in VIP neurons in the INF only. This indicates a neural connection exists between POM and INF that is involved in PRL release, and suggests that c-fos mRNA is involved in the regulation of VIP gene expression. The regulation of GnRH-I gene expression and LH secretion may also be facilitated by c-fos mRNA, since c-fos mRNA was expressed in GnRH-I neurons.
ALLEN, Dana Marie (2001)
Advisor: Linn, James G.
Dry matter intake and neutral detergent fiber intake of dairy cattle
Abstract
Accurately determining feed intake of dairy cattle is essential to formulate cost effective, nutritionally balanced diets. Understanding factors such as neutral detergent fiber (NDF) and how they affect feed intake is needed. Alfalfa leaf meal (ALM) was included at 0, 12.5 or 25% of pelleted calf starters fed to Holstein calves from 4 to 60 days of age. Calved fed starter with 12.5 and 25% ALM had similar average daily gains and feed intake to calves fed a commercial (0% ALM) calf starter. When ALM partially replaced either by-products (30% NDF) or forages (34% NDF) in diets fed to lactating dairy cows, changes in milk production and dry matter intake (DMI) indicated ALM was not a profitable alternative to by-products or forages. A two year study was conducted to investigate the optimum feeding level of a leafy corn silage hybrid (17, 18, 20, 22, 24, and 26% NDF from forage) in diets for lactating Holstein cows. As NDF from corn silage increased, DMI decreased and milk production increased for multiparous cows. Level of NDF from corn silage did not affect milk production or feed intake of primiparous cows. Previously developed DMI prediction equations were evaluated for their accuracy in predicting the average pen DMI of lactating dairy cows on three commercial dairy farms. The most accurate equations were developed by the National Research Council (2001) and May (1994). Accurate determination of average milk production, days in milk, and body weight for a pen of lactating Holstein cows on a specific day is needed to attain an accurate prediction of DMI using these equations. Equations were developed to predict the average per cow DMI per day of lactating Holstein cows grouped in freestall barns. Variables included in the equations were easily attainable from on-farm data and accounted for 77 to 82% of the variation in actual DMI. Climate accounted for more variation in DMI than previously reported in published equations while milk production and composition accounted for less.
ARIZA-NIETO, Claudia Janeth (2006)
Advisor: Baidoo, Samuel Kofi
Evaluation of oregano (Origanum vulgare) essential oils in swine production systems
Abstract
The general objective of this thesis was to provide a scientific basis for the use of oregano essential oils (OEO) in swine production systems. One hundred fifty sows were fed a control (Corn-SBM) or oregano (Regano500®) diet during gestation and/or lactation. Sows supplemented with OEO during gestation farrowed on average 1.1 more piglets per litter. Breeding value sow productivity and sow productivity indices were higher in OEO-fed sows (104 vs. 99 and 115 vs. 98, respectively). Colostrum from OEO-fed sows contained 26% more IGF-1 and 50% more T-lymphocytes. Piglets from OEO-fed sows had a significantly higher percentage of γδ and NK activity before suckling than controls (+6% and +2.2%, respectively). Growth rate (g/day) of piglets between 16-19 days of age increased 9.7% relative to controls. The COUNT growth model demonstrated a difference between OEO and control sow lactation diets on velocity of growth (+10%). Three hundred eighty-four weaned pigs from sows fed control or oregano diets were randomly assigned to one of four treatments: control, antibiotic, oregano and oregano+antibiotic. OEO supplementation may have physiological properties that improved intestinal mucosal area of pigs. Nursery growth rate (g/day) of pigs from OEO-fed sows increased 9% and villus to crypt ratio (VCR) of pigs increased by 8.5% compared to control, and VCR in pigs fed OEO increased 42.5% relative to control. Pigs supplemented with OEO increased the metabolizability of the diet by 4% compared to control. Pigs from OEO-fed grew faster (28 g/d) and ate more feed (65 g/d) than pigs from sows without supplementation during the wean-to-finish period. OEO supplementation in pig diets showed overall average daily gain increase of 20 g/d. Pigs from OEO-fed sows had increased loin depth (0.10 mm), percent lean (0.4%) and carcass value ($4.90) compared to controls. Dietary supplementation of OEO adjusted nutrient partitioning in sows to essential functions enhancing reproductive efficiency with economical implications. Sows fed OEO earned on average $57.30 more per litter than sows with no supplementation. Furthermore, finished pigs from sows fed OEO earned $3.20 more than control.
BAILEY, Michael Thomas (2000)
Advisor: Wheaton, Jonathan E.
Inhibin production and secretion in mares with granulosa-theca cell tumors
Abstract
The hormone "inhibin" has been shown to be an important factor associated with reproductive health and disease. Inhibin has been used as a diagnostic marker of ovarian granulosa cell tumors in humans. Similar tumors, termed granulosa-theca cell tumors (GTCT), are also present in some farm species and represent the most common ovarian tumor reported in mares. Goals of the research conducted were to investigate inhibin production and secretion by equine GTCT and assess its potential in diagnosis of these tumors in mares. Studies were conducted to determine the cell types within the GTCT that produce inhibin and whether inhibin forms produced by the GTCT were different in mares with GTCT than in control mares. Additional studies investigated the secretion of different forms of inhibin (α-inhibin and inhibin A) in mares with GTCT. Measurement of the different forms of inhibin was accomplished using specific assays developed in our laboratory. Immunohistochemical examination of GTCT tissue revealed positive α- and βA-subunit staining in granulosa cells and theca-epithelioid cells, while theca cells were negative for both subunits. Characterization of inhibin forms in GTCT fluid and equine follicular fluid (eFF) showed that low molecular weight forms of the α-subunit were less abundant in GTCT fluid than in eFF, while βA-subunit forms were similar in GTCT fluid and eFF. Studies investigating α-inhibin and inhibin A secretion showed that mares with GTCT oversecreted both forms of inhibin as compared to control mares. The oversecreted inhibin in these mares was a product of the GTCT as concentrations were undetectable after GTCT removal. α-inhibin levels were more consistently elevated and more constant over time than inhibin A levels in mares with GTCT. In conclusion, the equine GTCT overproduces and oversecretes α-inhibin and inhibin A. α-inhibin appears to be the predominant form produced and its measurement is a more reliable indicator of GTCT in mares. Forms of the inhibin α-subunit secreted by the GTCT have less abundant low molecular weight forms of the α-subunit and may be involved in the formation of these tumors in mares.
CARRIQUIRY, Mariana (2006)
Advisor: Crooker, Brian A.
Dietary fat and bovine somatotropin (bST) initiated in early lactation in dairy cows
Abstract
Objectives of this study were to examine the role of supplemental dietary fat and administration of bST initiated in early lactation on production responses, milk fatty acid composition, postpartum ovarian activity, and hepatic gene expression of dairy cows. Multiparous cows blocked by expected calving date and previous milk production were assigned randomly to one of four treatments in a 2 x 2 factorial arrangement of dietary fat enriched with omega-3 fatty acids (FA) and bST treatment. Administration of bST (POSILAC®, 500 mg) was initiated at 12 DIM and continued at 10-d intervals through 70 DIM and at 14-d intervals thereafter. Feeding dietary fat was initiated at calving and dietary ratio of omega-6 to omega-3 FA varied by inclusion of whole sunflower seeds (10% dietary DM, omega-6/omega-3 FA ratio = 4.6) or a mixture of Alifet-High Energy® and Alifet-Repro® (3.5 and 1.5% of dietary DM, omega-6/omega-3 FA = 2.6). Initiation of bST administration at 12 DIM increased milk, 3.5%-FCM, and 4.0%-SCM yields and plasma IGF-I. In addition, bST did not exacerbate the moment or magnitude of energy balance nadir but did prolong the postpartum delay in onset of tissue replenishment and partitioning of dietary FA into milk fat, and interacted with dietary fat to alter Δ9-desaturase index in the mammary gland. Feeding dietary fat enriched with omega-3 FA increased plasma IGF-I, decreased the impact of bST on overall energy balance, increased omega-3 FA in milk, and reduced the omega-6 to omega-3 FA ratio in milk. Results indicate diets enriched with omega-3 FA increased size of ovulatory follicles and corpus luteum development during the early luteal phase and that bST interacts with dietary omega-3 FA to increase the incidence of estrous cycles with 3-follicular waves. Our results suggest: IGFBP3 mRNA expression may be involved in molecular mechanisms that regulate the GH- IGF-I axis, administration of bST increased hepatic mRNA abundance of GH receptor, IGF-I, and IGFBP3 even when cows were in negative energy balance, and PPARα could mediate, at a molecular level, the interaction of bST and dietary fat on some productive and reproductive responses.
CHAHINE, Mireille (2005)
Advisor: Crooker, Brian A.
Induction of lactation in non-pregnant reproductive cull Holstein cows
Abstract
This research was conducted to examine effects of season, estrous stage, somatotropin, and mammary massage on success and subsequent milk production by non-pregnant reproductive cull Holstein cows induced to lactate. The basic treatment used to induce lactation was initiated 14 d prior to initiation of milking and consisted of twice daily injections of 17β-estradiol (0.1 mg/kg BW/d) and progesterone (0.25 mg/kg BW/d) for 7 d and an injection of dexamethasone (0.05 mg/kg BW/d) 1 d prior to milking. In study 1, cows were induced in February or June and received POSILAC 1 STEP (500 mg bST) on day -13, -3, 6, and 16 of lactation and at 14 d intervals thereafter. Udders were massaged twice daily (2 to 3 min) on d -6 to 0 of lactation. Induction was successful (≥13.6 kg/d in wk 7 of lactation) in 87% of the cows and milk yield (25.0 ± 1.9 kg/d) and composition were not affected by season. Cows in Study 2 were synchronized to be between 0 to 5 d or 10 to 15 d of their estrous cycle when treatments to induce lactation were initiated. The basic protocol either with or without bST (500 mg on d -13 and -3 of lactation) was used to induce lactation. Cows that were not at the desired stage of estrous also received bST on d -13 and -3 of lactation. All cows received bST on d 6 and 16 of lactation and at 14 d intervals thereafter. Overall success (52%) and milk yield (23.5 ± 2.9 kg/d) did not differ among treatments but tended to be greater when cows were in late rather than early estrous (58.3 vs. 33.3%). Cows (n = 30) not induced successfully in Study 2 were synchronized to be at 10 to 15 d of their estrous cycle, induced with the basic protocol and bST, and either received or did not receive mammary stimulation on d -6 to 0 of lactation (Study 3). Success (32.0%) was poor but milk yield (17.5 ± 2.8 kg/d) and composition were similar to that of Study 1 and 2.
CHRISTMAN, Shelly Ann (2004)
Advisor: Foster, Douglas N.
Involvement of p53 and p15(INK4b) in the spontaneous immortalization of two chicken embryo fibroblast cell lines
Abstract
Two spontaneously immortalized reverse transcriptase-negative chicken embryo fibroblast (CEF) cell lines, SC-1 and SC-2, were established. Both cell lines have been in culture for over three years, and continue to increase their growth rate, albeit slowly. Levels of various cell cycle regulatory genes were analyzed in the SC-1 and SC-2 cell lines and compared to primary CEF cells and to the other spontaneously immortalized CEF cell line (DF-1). Early passage SC-1 cells possessed normal levels of p53, while later passage SC-1 cells had significantly decreased levels of p53 mRNA compared to primary CEF cells. Treatment of SC-1 cells with the protein synthesis inhibitor cycloheximide increased the expression of p53 in passage 120 SC-1 cells to the levels found in primary CEF cells, suggesting the possibility of p53 suppressor activity. The functional activity of p53 in the SC-1 cells was decreased slightly in early passages and significantly decreased in later passage cells. Since p53 mRNA and functional activity were down-regulated in later passage SC-1 cells, short-interfering RNA-p53 constructs were transfected into early passage SC-1 cells. Results indicated that silencing of p53 in early passage SC-1 cells was not sufficient to accelerate the conversion from a life-span extended population of cells into a fully immortal cell line. It appeared that other genetic alterations may be required to attain full immortality. In the SC-2 cells, mRNA expression levels of p53 were undetectable at passage 45, but by passage 95 were greater than the levels in primary CEF cells. The high level of p53 mRNA detected in passage 95 SC-2 cells did not correlate to functional protein activity. In all passages of SC-2 cells examined, the mRNA levels of p21WAF1 were undetectable. Together, these studies indicate that alterations in the p53 and Rb pathways cause fluctuations in expression levels of important cell cycle regulatory genes during crucial transition periods that may have contributed to the spontaneous immortalization of the SC-1 and SC-2 CEF cell lines.
CHRYSTAL, Mathew Anthony (2003)
Advisor: Da, Yang
Marker assisted selection in dairy cattle using a mixed model approach
Abstract
A mixed model method combining marker and phenotypic information was developed for genetic evaluation. Marker effects were treated as uncorrelated random effects, providing a convenient framework for marker assisted selection using best linear unbiased prediction (BLUP). It is computationally efficient because only a small number of additional equations are needed to include marker effects in the model. The total genetic merit of QTL and polygenes are obtained as the sum of the predicted marker and polygenic effects. A maximum likelihood method was developed to estimate each marker component required for the BLUP procedure. Computer simulations showed that MAS using the proposed approach may significantly improve selection accuracy, particularly in situations when traditional phenotypic selection is least effective, i.e., when heritability is low and the percentage of selected individuals is high.
DE VRIES, Albert (2001)
Advisors: Conlin, Bernard J. and Shurson, Gerald C.
Statistical process control charts applied to dairy herd reproduction
Abstract
The objective of this research was to evaluate the design and performance of statistical process control (SPC) charts when applied to dairy herd reproduction. A review of the literature involving the application of SPC charts in livestock production revealed that most papers provide an introduction to SPC charts and show examples with livestock performance data. No studies have determined the performance of SPC charts in livestock production. A stochastic dynamic simulation model of a dairy herd named DASIMO was developed to simulate the performance of SPC charts in dairy herd reproduction. This Monte Carlo model simulates daily performance of individual dairy cows and youngstock over time using functions for milk production, feed intake, disease, reproduction, and animal replacement. DASIMO realistically simulated normal variability in dairy herd reproductive performance. Various Shewhart and cusum control charts were designed for first service interval, conception interval, estrus detection index, and conception ratio. DASIMO was used to measure the average time to signal on the SPC charts using these four variables when estrus detection efficiency changed. The observed false alarm rate on the SPC charts was occasionally quite different from the target. Cusum charts typically signaled a step change faster than Shewhart charts. The estrus detection index signaled the implemented changes most quickly. Several topics related to the design of SPC charts for the estrus detection ratio variable were investigated. Equations to calculate the optimal period length for Shewhart X- and P-charts for various changes in estrus detection efficiency were derived. DASIMO was also used to study the effect of varying cusum reference values and false alarm rates on the performance of cusum charts. The economic value of SPC charts was determined with DASIMO by simulating temporary changes in estrus detection efficiency. Culling policy had a major effect on the economic cost of a temporary change in estrus detection efficiency. Small changes in estrus detection efficiency were shown to be more costly than larger changes because of the increased time to signal on SPC charts. Stochastic dynamic simulation was demonstrated to be useful for measuring the performance of SPC charts in dairy herd reproduction.
DOGAN, Soner (2004)
Advisors: Kannan, Mathur Sriniva and Walset, Timothy F.
The effects of sex steroid hormones on the CD38/cADPR signaling pathway in uterine smooth muscle
Abstract
Changes in hormonal profile lead to structural and functional changes in the uterus during different phases of reproduction. The uterine contractility increases at the end of pregnancy with an increase in the estrogen/progesterone ratio compared to that during early pregnancy. Expression of many genes changes during this transition and of particular interest include genes encoding various signaling molecules. Calcium is an important second messenger regulating muscle contraction and uterine contractile agonists act through their effects on intracellular calcium. Many signaling molecules are known to play a role in the regulation of intracellular calcium levels, including cyclic-ADP-ribose (cADPR). CD38, a bifunctional transmembrane protein, has both ADP-ribosyl cyclase and cADPR hydrolase enzyme activities which mediate the synthesis and degradation of cADPR, respectively. The studies described in this dissertation are aimed at understanding the role of cADPR mediated calcium release in the myometrium and its regulation by sex steroid hormones. Using ovariectomized rats, the studies demonstrated that estrogen increases CD38 expression and ADP-ribosyl cyclase, but not c ADPR hydrolase, activity. In uteri from term rats, the levels of CD38, cADPR and ADP-ribosyl cyclase activity were higher than those in uteri from rats at days 14-17 of pregnancy. In immortalized pregnant human myometrial cells, oxytocin, PGF2α and endothelin-1 induced intracellular calcium levels and these increases were inhibited by 8Br-cADPR, a membrane permeant cADPR antagonist. These studies demonstrate that sex steroid hormones regulate the expression and function of CD38 and the CD38/cADPR signaling has a role in intracellular calcium responses induced by contractile agonists in the myometrium.
HE, Gaofeng (2004)
Advisor: Baidoo, Samuel Kofi
Improving pig performance and nutrient utilization by manipulating dietary protein level and using fermentable fiber ingredients
Abstract
In order to evaluate the efficiency of manipulating dietary protein level and using fermentable fibers on reducing nutrient excretion, improving growth performance and carcass characteristics, five studies were conducted. The objective of Study 1 was to examine the effects of dietary protein level on growth performance, carcass characteristics and plasma metabolite concentrations in pigs fed barley and canola meal based diets from 40 kg to market BW. Feeding low protein diet resulted in poor growth performance, carcass characteristics and total tract nitrogen digestibility. Study 2 was conducted to evaluate the effect of 10 ppm ractopamine (RAC) in late finishing pigs fed two levels of total lysine (0.81% and 1.11%). Ractopamine improved growth performance and carcass characteristics at larger extent in high lysine group than in low lysine group except dressing percentage, which was increased at larger extent in low lysine group. Nitrogen retention (% of N intake) was improved by ractopamine at similar extent at the two lysine levels. Study 3 was conducted to evaluate the effect of dietary inclusion of inulin on the performance of early-weaned pigs. Nitrogen and P balance were not influenced by dietary treatments. Supplementation of inulin in water and/or feed tended to improve piglets' growth performance. Study 4 was designed to determine the performance and carcass characteristics of wean to finish pigs fed diets with different fermentable carbohydrate sources (inulin or sugar beet pulp). Continuous supplementation of inulin in water improved pig performance during the late growth stage. Sugar beet pulp supplementation reduced the dressing percentage. Study 5 was conducted to determine the effect of dietary treatments on microbial population composition in swine fecal samples with colony counting technique and direct fecal sample gas chromatography of bacterial cellular fatty acids (BCFA) profile technique. Dietary treatments were similar to those used for Study 4. Fecal bacterial population was changed by dietary treatments. Withdrawal of antibiotics caused an increase in number for most of the bacterial groups studied. Multivariate analysis of bacterial cellular fatty acids profile is an alternative method to monitor bacterial composition change in swine feces.
HEINS, Bradley J. (2006)
Advisor: Hansen, Leslie B.
Pure Holsteins compared to Normande/Holstein, Montbeliarde/Holstein, and Scandinavian Red/Holstein crossbreds for production, calving difficulty, stillbirths, fertility, and survival
Abstract 1:
Production of pure Holsteins versus crossbreds of Holstein with Normande, Montbeliarde, and Scandinavian Red
Pure Holsteins (n = 380) were compared to Normande/Holstein crossbreds (n = 245), Montbeliarde/Holstein crossbreds (n = 494), and Scandinavian Red/Holstein crossbreds (n = 328) for 305-d milk, fat, and protein production during first lactation. Scandinavian Red was a mixture of Swedish Red and Norwegian Red. Cows were housed in seven commercial dairies in California and calved from June 2002 to January 2005. All Holstein sires and all Holstein maternal grandsires were required to have a code assigned by the National Association of Animal Breeders to assure they were sired by artificial insemination (AI) bulls. Daughters of Normande, Montbeliarde, and Scandinavian Red sires were AI bulls via imported semen. Best Prediction was used to calculate actual production (milk, fat, and protein) for 305-d lactations. Adjustment was made for age at calving and milking frequency, and records less than 305 d were projected to 305 d. Herd-year-season (4-month seasons) and the genetic level of each cow’s Holstein maternal grandsire were included in the model for statistical analysis. Pure Holsteins had significantly higher milk (9757 kg) and protein (305 kg) production than all crossbred groups, but pure Holsteins (346 kg) were not significantly different than Scandinavian Red/Holstein (340 kg) crossbreds for fat production. Fat plus protein production was used to gauge the overall productivity of pure Holsteins versus crossbreds. The Scandinavian Red/Holstein (637 kg) crossbreds were not significantly different from the pure Holstein (651 kg) for fat plus protein production; however, the Normande/Holstein (596 kg) and the Montbeliarde/Holstein crossbreds (627 kg) had significantly lower fat plus protein production than pure Holsteins.
Abstract 2:
Calving difficulty and stillbirths of pure Holsteins versus crossbreds of Holstein with Normande, Montbeliarde, and Scandinavian Red
Pure Holstein cows and Normande/Holstein, Montbeliarde/Holstein, and Scandinavian Red/Holstein crossbred cows were compared for calving difficulty and stillbirth rates. Scandinavian Red was a combination of Norwegian Red and Swedish Red. All cows calved from June 2001 to August 2004 in 7 California dairies. Statistical models for analysis included effects of herd-year-season of calving and sex of calf in addition to breed of sire and breed group of dam. Male calves had significantly more calving difficulty and stillbirths than heifer calves. First-calf Holsteins bred to Holstein, Brown Swiss, Montbeliarde, and Scandinavian Red bulls were used to determine effects of breed of sire. Calves sired by Scandinavian Red bulls (5.5%) and Brown Swiss bulls (12.5%) had significantly less calving difficulty than calves sired by Holstein bulls (16.4%) from Holstein first-calf heifers. Also, fewer stillbirths resulted from use of Scandinavian Red bulls (7.7%) compared to use of Holstein bulls (15.1%) for first-calf Holstein heifers. Scandinavian Red-sired calves (2.1%) had significantly less calving difficulty than Holstein-sired calves (8.4%) for multiparous Holstein dams. Non-Holstein breeds of sire had significantly fewer stillbirths than Holstein sires when mated to multiparous Holstein dams. For the effect of breed of dam, this study utilized 676 pure Holsteins, 262 Normande/Holstein, 370 Montbeliarde/Holstein, and 264 Scandinavian Red/Holstein crossbred virgin heifers that had been bred to Brown Swiss, Montbeliarde, and Scandinavian Red bulls. All groups of crossbred cows had significantly less calving difficulty at first calving than pure Holsteins (3.7% to 11.6% versus 17.7%). Furthermore, Montbeliarde/Holstein (6.2%) and Scandinavian Red/Holstein (5.1%) crossbreds had significantly lower stillbirth rates at first calving than pure Holsteins (14.0%).
Abstract 3:
Days to first breeding, first service conception rate, days open, and survival of pure Holsteins versus crossbreds of Holstein with Normande, Montbeliarde, and Scandinavian Red
First-calf pure Holsteins and Normande/Holstein, Montbeliarde/Holstein, and Scandinavian Red/Holstein crossbreds were compared for days to first breeding, first service conception rate, days open, and survival. First-calf heifers were in 7 commercial dairies in California and calved from June 2002 to October 2004. Holsteins were required to have a recorded sire with an NAAB code to assure they were sired by AI bulls. Normande, Montbeliarde and Scandinavian Red sired crossbreds were all daughters of AI bulls via imported semen. For days open, first-calf heifers were required to be at least 250 days in milk and those with greater than 250 days open were truncated to 250 days. Least squares means for days to first breeding were 69 days for Holsteins, 62 days for Normande/Holstein, 65 days for Montbeliarde/Holstein, and 66 days for Scandinavian Red/Holstein crossbreds, and differences were significantly different than pure Holsteins for Normande/Holstein and Montbeliarde/Holstein crossbreds. First service conceptions rates were 22% for Holsteins, 35% for Normande/Holstein, 31% for Montbeliarde/Holstein, and 30% for Scandinavian Red/Holstein crossbreds and, again, differences from Holstein were significant for the Normande/Holstein and Montbeliarde/Holstein crossbreds. Least squares means for days open were 150 days for pure Holsteins, 123 days for Normande/Holstein, 131 days for Montbeliarde/Holstein, and 129 days for Scandinavian Red/ Holstein crossbreds, and all three crossbred groups had significantly fewer days open than pure Holsteins. Three measures of survival were to 30 days, 150 days, and 305 days postpartum, and all crossbred groups survived significantly longer than pure Holsteins during first lactation for all three measures of survival. Least squares means for survival to 30 days postpartum were 95% for pure Holsteins and 98% for Normande/Holstein, Montbeliarde/Holstein, and Scandinavian Red/Holstein crossbreds; for survival to 150 days postpartum were 91% for pure Holsteins and 96% for Normande/Holstein, Montbeliarde/Holstein, and Scandinavian Red/Holstein crossbreds; and for survival to 305 days postpartum were 86% for pure Holsteins, 93% for Normande/Holstein, 92% for Montbeliarde/Holstein, and 93% for Scandinavian Red/Holstein crossbreds.
KANG, Seong Wook (2002)
Advisor: El-Halawani, Mohamed E.
Molecular regulation of prolactin gene expression by vasoactive intestinal peptide (VIP) in the domestic turkey
Abstract
The present studies were designed to investigate molecular mechanisms of prolactin (PRL) gene expression by vasoactive intestinal peptide (VIP) in the domestic turkey. A new protocol for determining transfection efficiency was developed using the β-lactamase gene. Deletion analysis of PRL promoter indicated that the PRL promoter activity stimulated by VIP was controlled by three major positive regions and two negative regions. Further deletion analysis and Decoy assay revealed a 35-bp activator element in proximal PRL promoter, named the VIP response element (VRE). Moreover, three independent protein complexes were bound to VRE in an electrophoretic mobility shift assay (EMSA) using anterior pituitary extracts from laying hens. To investigate the role of cAMP second messenger system in VIP-induced PRL gene expression, we tested the effects of cAMP analog, 8-Br-cAMP, and 3-isobutyl-1-methylxanthine (IBMX) upon PRL mRNA expression. The results suggested that cAMP second messenger system maybe involved in the inhibitory action of DA upon VIP-stimulated PRL secretion and gene expression at the pituitary level. In a study of VIP immediate and long-term effects on c-fos expression in relation to PRL expression, VIP dramatically induced c-fos mRNA expression within 5 min, suggesting c-fos protein may be involved in VIP-stimulated PRL gene expression. In anterior pituitary (AP) cells from hyperprolactinemic hens (incubating), PRL promoter activity was down-regulated by VIP. It was tested that the presence of negative acting repressor(s) in the culture media and the effect of exogenous PRL on PRL gene expression at the transcriptional level in primary AP cells from laying and incubating hens. The results suggested that the secreted PRL may be a negative regulator of PRL promoter activity and VRE may be involved in the negative regulation of PRL gene expression in hyperprolactinemic AP cells. These results provide the evidence of VRE as one of the important cis-acting elements involved with VIP-stimulated PRL expression and suggest that changes in PRL promoter activity by VIP may be one of the important inductive mechanisms leading to prolactinemia and the suppression of PRL promoter activity by PRL may be one of the mechanisms for the ultra-short negative feedback regulation of PRL.
KIM, Hyunggee (2001)
Advisor: Foster, Douglas N.
Mechanisms of cellular proliferation, death, senescence and immortalization
Abstract
For senescence-associated genetic alterations, the functional activity of p53-dependent pathway was elevated in senescent human WI38 and chicken embryo fibroblast (CEF) cells. However, p53 function did not increase in senescent mouse embryo fibroblast (MEF) cells, while expression of p16INK4a dramatically increased possibly due to maximal demethylation of CpG islands in the promoter. The functional alterations of p53 and E2F1 that were found to occur through transcriptional deregulation were common genetic events in several immortalized CEF cell lines. In particular, the loss of p53 function was shown to be caused by the rapid destabilization of its mRNA in the nucleus of several immortal CEF cells and immortal MEF (10)3 and (10)7 cell lines. The ectopic expression of the catalytic subunit of human telomerase (hTERT) per se was shown to be sufficient to cause primary HME cells to become immortal accompanying by certain genetic alterations. Immortal HME cells possibly established by the clonal selection of a subset of telomerized cells exhibited telomerase activity and an intact p53-dependent regulatory pathway accompanied by a spontaneous loss of p16INK4a expression. Coupled to the deregulation of cell cycle genes, active mitochondrial function through increased de novo mitochondrial transcription and ATP generation was shown to be associated with rapid proliferation in the immortal DF-1 CEF cells. These cells were hypersensitive to cell death in response to oxidative stress that was mediated through increased intracellular levels of H2O 2 due to the unbalanced activity of antioxidant MhSOD and catalase activity. Two different clone 47 long and short isoforms were found to predominately express in the chicken gonadal tissues and encode different putative Zn-finger transcription factors. In particular, expression of C47L was shown to be downregulated in senescent fibroblast cells and regressed/atretic ovarian follicles. The novel chicken DcoHα gene was shown to play an important role in regulating the hepatocyte-specific gene expression and be specifically upregulated in immortal CEF cells. Together, these studies indicate that differential gene expression caused by various genetic and epigenetic alterations seem to be major factors involved in changing the cell's properties under a variety of cellular physiological environments.
KNOTT, Jeffrey Steven (2004)
Advisor: Shurson, Gerald C.
Evaluation of potential value-added properties of feeding diets containing dried corn distiller's solubles fractions to young pigs
Abstract
Two experiments were conducted to investigate the effects of adding three corn condensed distiller's solubles by-products to early-weaned pig diets on growth performance, nutrient balance, and health. Dietary treatments included: control diet (NC), 15% spray dried distiller's solubles (DS), 7.5% spray dried yeast cream (YC), 15% spray dried residual solubles (RS), 55 ppm carbadox (AB), 6% spray dried porcine plasma (PP), and 55 ppm carbadox + 6% spray dried porcine plasma (PC). In the first experiment, 63 barrows were fed one of seven dietary treatments during a 10-d growth performance and nutrient balance trial. Average daily gain (ADG) tended to be greater for pigs fed the PP and PC diets, but gain:feed (G:F) was not different among treatments. Fecal, urinary, and total N excretion/d and urinary and fecal energy excretion/d were not affected by treatment. In the second experiment, two trials were conducted. In the first trial, 560 barrows were used to determine the dietary treatment effects on growth performance, gut morphology, acute phase protein levels, and insulin like growth factor 1 (IGF-1) concentrations in a 6-wk trial. The experimental diets were fed for the first 10-d postweaning (phase 1) and common diets were fed during phase 2 and phase 3. Pigs fed the PC diet had higher ADG during phase 1 compared to pigs fed the NC, DS, YC, RS, and AB diets. There were no differences among treatment for ADFI or G:F during phase 1. In the upper 25% of the small intestine, pigs fed the RS and PC diets had longer villi and greater villus height:crypt depth ratio compared to pigs fed the NC, DS, YC, and AB treatments. Serum AGP and IGF-1 concentrations were not different, but pigs fed the AB and PC diets had lower Hp concentrations on d 10 compared to the other treatments. In the second study, 441 pigs were used in a 5-wk growth performance trial. During phase 1, pigs fed the PP and PC diets had higher ADG and ADFI compared to pigs fed the NC, DS, YC, and RS treatments, but overall ADG or G:F did not differ among treatment.
KONG, Byung-Whi (2005)
Advisor: Foster, Douglas N.
Establishment of an immortal turkey turbinate cell line for propagation of avian metapneumovirus
Abstract
Avian metapneumovirus (AMPV) is an upper respiratory viral pathogen that causes turkey rhinotracheitis. In most studies, the African monkey kidney derived Vero cell line has been widely used for the propagation of AMPV. Until recently, there has not been a homologous avian cellular substrate which could continuously produce high titer AMPV. Of the primary cell substrates tested of avian origin, primary turkey turbinate and kidney cells produced AMPV titers equal to or greater than Vero cells. When compared to Vero propagated AMPV, both turkey turbinate and kidney cell propagated AMPV generated larger fluorescent plaques. Furthermore, turkey turbinate propagated AMPV showed 11 amino acid differences in fusion (F) protein gene of the AMPV genome, suggesting that AMPV propagated in homologous avian cellular substrates may produce more infectious virus with possibly more effective fusion activity. Efforts to generate a continuously growing homologous cell line, resulted in the establishment of the first known spontaneously immortalized line of embryonic turkey turbinate cells, designated as the TT-1 cell line. Rapidly growing TT-1 cells propagated sufficiently high AMPV titers, suggesting that a non-tumorigenic, reverse transcriptase negative TT-1 cell line can serve as an excellent homologous cellular substrate for virus propagation. The TT-1 cell line produced an AMPV negative sense single stranded RNA genome that contains 1.8kb attachment glycoprotein (G) gene, which is a hypervariable gene that enables virus subtypes to be distinguished. Surprisingly, Vero cell propagated AMPV revealed an essentially deleted G gene in the viral genome, resulting in no G gene mRNA expression. In addition, no splicing mRNA variants of the G gene were detected from either mammalian or avian propagated AMPV. The G gene deletion might be caused by subcellular molecular mechanisms that are species-specific, suggesting that the antigenic changes together with the lack of viral gene deletions found in avian cell propagated AMPV could serve as an alternative approach for live vaccine development.
POONYACHOTI, Sutthasinee (2000)
Advisor: Brown, David R.
Characteristics and roles of delta-opioid receptor in porcine small intestine
Abstract
Natural and synthetic opioid drugs such as morphine and loperamide are important analgesic and antidiarrheal agents which act through the central and enteric nervous systems. Although the properties and functions of opioid receptors (OR) in the central nervous system are well-understood, less is known about OR in the intestinal tract. In this dissertation, delta-OR (δ-OR) were examined because they are expressed in the intestinal tracts of several animal species and there are abundant reagents and pharmacological tools to characterize these receptors. In this study, I localized and characterized δ-OR in the myenteric and submucosal plexuses of the small intestine. The porcine ileum served as the experimental model for this study because it is considered to be a homolog of the human small bowel. The colocalization of δ-OR immunoreactivity by indirect immunohistochemistry with antibodies to several enteric neurotransmitters or neurotransmitter receptors was determined in order to gain an understanding of the distribution patterns of δ-OR in the porcine ileal wall. Furthermore, the neuronal inhibitory actions of δ-OR were characterized using pharmacological approaches in preparations of ileal smooth muscle with attached myenteric plexus and mucosal sheets containing the inner submucosal plexus. Because submucosal neurons mediate aspects of intestinal host defense, I further examined the role of submucosal δ-OR in the neuromodulation of immediate hypersensitivity reactions evoked by histamine and mediators released upon chemically- or immunologically-induced mast cell degranulation. The results of these studies provide important new information concerning the novel pharmacological characteristics and modulatory roles of δ-OR in the small intestine.
RENTERIA FLORES, Jose Antonio (2003)
Advisors: Johnston, Lee J. and Shurson, Gerald C.
Effects of soluble and insoluble dietary fiber on diet digestibility and sow performance
Abstract
Three experiments were conducted to investigate the effects of feeding increased levels of dietary soluble (SF) and insoluble (ISF) fiber to gestating sows on digestibility of nutrients, ovulation rate, embryo survival, and sow performance. In experiment one 24 pregnant sows (12 nulliparous and 12 multiparous) were assigned randomly to one of four experimental diets. Experimental diets included a corn-soybean meal control (C; 1.20% SF, and 9.78% ISF); corn-soybean meal-34% oat bran which was high in SF (HS 3.02% SF, 10.11% ISF); corn-soybean meal-12% wheat straw which was high in ISF (HIS; 1.11% SF, 17.86% ISF); and corn-soybean meal-16% sugar beet pulp (HS + HIS; 2.32% SF; 16.08% ISF). Feeding high levels of dietary ISF decreased energy, nitrogen, and SF digestibility. Feeding high levels of SF increased energy, SF, and ISF digestibility, and decreased digestibility of nitrogen. Multiparous sows demonstrated greater ability to digest diets with increased levels of dietary fiber than nulliparous sows. In the second experiment, 43 gilts were assigned randomly to four experimental diets. The C, HS, and HIS diets used in this experiment had a dietary fiber profile similar to those used in the previous experiment. For the HS + HIS diet (2.46% SF, 24.55% ISF), soy hulls (21%) replaced sugar beet pulp. Feeding gilts elevated levels of dietary SF and(or) ISF did not affect ovulation rate or embryo survival. In a third experiment, 716 sows were used in three concurrent trials. Diets were similar to those used in experiment two. Sows were fed either the C or one of the high fiber diets (i.e HS, HIS, or HS + HIS) in each trial. Feeding sows increased levels of dietary SF and(or) ISF beginning two days after mating to day 106 of gestation did not affect litter size at farrowing. Feeding sows increased levels of SF and ISF from soy hulls during gestation increased feed intake and reduced weight loss of sows during lactation. Gestating sows can be fed increased levels of dietary SF and(or) ISF without compromising sow or litter performance if daily energy requirements are satisfied.
SPIEHS, Mindy Jo (2004)
Advisor: Shurson, Gerald C.
Evaluation of dietary manipulations to improve growth performance and reduce Salmonella Typhimurium prevalence and shedding in finishing swine
Abstract
Two disease challenge studies were conducted to evaluate the effect of dietary treatment on growth performance, and level and incidence of fecal Salmonella shedding and tissue colonization of Salmonella in growing-finishing pigs. In the first study, 175 pigs were used in a two-part study. Pigs were fed one of three dietary treatments: corn-soybean meal control (C), C + a polyclonal antibody (PCA), or C + 50% distiller's dried grains with solubles (DDGS). Part I was a 16-wk growth performance study to measure ADG, ADFI, and G:F (n = 135). Part II was a 6-wk disease challenge study (n = 40). Serum haptoglobin (Hp), α1-glycoprotein (AGP), IgM and IgG, fecal shedding, and prevalence of Salmonella in tissues at necropsy were measured in Part II. The results indicated that pigs fed diets containing 50% DDGS had decreased ADFI and ADG compared to pigs fed C diets or diets containing a PCA. Growth performance of pigs fed PCA was similar to pigs fed the C diet. The disease challenge model used in this study was unsuccessful in producing an acute salmonellosis infection in finishing pigs inoculated with Salmonella Typhimurium. Therefore, differences in Salmonella infection or shedding due to dietary treatment could not be determined. In the second experiment, forty finishing pigs (113 ± 2.1kg initial BW), were used in a disease challenge study to determine the effects of two direct fed microbials (DFM) on the ability of pigs to resist an infection from Salmonella Typhimurium. Pigs were fed one of three dietary treatments: a corn-soybean meal control diet (C), C + a DFM added in the water (PROBIOS), and C + 0.05% DFM included in the feed (BIOPLUS). Ten pigs were not challenged with Salmonella (NC), while the remaining 30 pigs received intranasal inoculation with S. Typhimurium. Qualitative and quantitative fecal shedding, tissue prevalence of Salmonella, and serum Hp, AGP, IgM, and IgG concentrations were measured. The results indicated a successful disease challenge model, but no differences in incidence or severity of the acute salmonellosis infection was apparent among challenged pigs fed PROBIOS or BIOPLUS compared to pigs fed the C diet.
THAYANANUPHAT, Aree (2007)
Advisor: El Halawani, Mohamed E.
Neuronal regulation of avian reproductive stages
Abstract
Dopamine (DA) has been shown to be involved in reproductive initiation by stimulating vasoactive intestinal peptide/prolactin (VIP/PRL) and gonadotrophin releasing hormone-I/ luteinizing hormone, follicle stimulating hormone (GnRH-I/FSH-LH) systems in turkeys. DA is also involved in reproductive inhibition by inhibiting both systems in turkeys. DA and oxytocin (OT) have been extensively elucidated for their involvement in the onset of maternal behavior in rat. Mesotocin (MT) is a homolog of OT in avian species. However DA and GnRH-I neuronal groups that are involved in reproductive initiation and DA group(s) that is involved in PRL inhibition are still elusive. Moreover, the role of MT in brooding behavior in avian species has never been investigated. The aim of this thesis research is to explore DA and GnRH-I neuronal groups that are responsible for reproductive initiation, DA group that inhibits PRL secretion, and the role of DA and MT in the initiation of brooding behavior. The first approach using dark interrupted photostimulation, and in situ hybridization (ISH) alone and combined with immunocytochemistry (ICC) techniques revealed that DA in the PMM and GnRH-I in the nCPa are responsible for reproductive initiation. The second approach using poult stimulation, and DA and OT antagonists prior to poult stimulation, as well as ISH and ICC techniques revealed that DA in the MPO and MT in the SON and PVN are activated during the transition to brooding behavior. D2 DA and MT receptors are required for brooding behavior initiation. The results from these studies elucidate neuronal pathways that are involved in reproductive stimulation and inhibition as well as brooding behavior in the turkey.
WHITNEY, Mark Howard (2004)
Advisor: Shurson, Gerald C.
Nutritional strategies to improve gastro-intestinal health in swine
Abstract
The objective of this dissertation was to investigate the impact of diet composition on gastro-intestinal health of swine experimentally infected with Lawsonia intracellularis, the causative organism for proliferative enteropathy, or ileitis. Two preliminary growth trials were conducted to determine maximal inclusion level of corn distiller's dried grains with solubles (DDGS) in nursery diets. Increasing level of DDGS reduced feed intake of pigs weighing less than 7 kg, while growth performance of heavier pigs was unaffected up to 25% DDGS. Three disease challenge experiments were conducted in growing pigs. Weaned pigs (17 d of age) were allotted to treatments, fed experimental diets during a 4-wk pre-challenge period, orally inoculated with L. intracellularis , and maintained on diets for three weeks. Feces were collected on d 14 and d 20 post-challenge and analyzed by PCR to determine shedding of L. intracellularis. On d 21 post-challenge, pigs were euthanized, lesions of intestinal mucosa evaluated, and ileal tissue samples analyzed by immunohistochemistry to determine presence of L. intracellularis . In the first experiment, diets contained 0, 10, or 20% DDGS. Inoculation dose was 1.5 × 109 L. intracellularis per pig. Feeding DDGS did not reduce lesion length, prevalence, proliferation of L. intracellularis, or severity of lesions, but did increase fecal shedding. The second trial evaluated diets containing 10% DDGS and/or antimicrobial therapy (33 g/tonne BMD® in the diet, while pulsing 550 g/tonne Aureomycin® from d 3 pre-challenge to d 11 post-challenge). Inoculation dose was 8.0 × 108 L. intracellularis per pig. Feeding DDGS reduced ileum and colon lesion length and prevalence and reduced severity of the lesions. Antimicrobial regimen reduced prevalence and severity of lesions in the jejunum, and tended to reduce overall lesion length. In the third experiment, dietary inclusion of 20% DDGS, 5% soybean hulls, or 5% soybean hulls sprayed with a polyclonal antibody product specific for L. intracellularis were evaluated. Inoculation dose was 8.0 × 108 L. intracellularis per pig. Diet did not affect lesion parameters. Overall, it appears that dietary inclusion of DDGS provides some benefit to growing pigs subjected to a moderate ileitis challenge, but not during a severe infection.
XI, Gang (2005)
Advisor: Hathaway, Marcia R.
The role of insulin-like growth factor binding protein-3 (IGFBP-3) in the proliferation and differentiation of L6 myogenic cells and porcine embryonic myogenic cells (PEMC)
Abstract
There are six high affinity insulin-like growth factor binding proteins (IGFBP 1-6) that regulate IGF biological activity. Among them, IGFBP-3 has been shown to suppress or stimulate proliferation of cultured cells depending upon the cell types and the assay conditions. IGFBP-3 has been shown to suppress both IGF-I and Long-R3-IGF-I-stimulated proliferation of embryonic porcine myogenic cells (PEMC). In this study, exogenous addition of recombinant porcine IGFBP-3 (rplGFBP-3) suppresses the proliferation of L6 myogenic cells via both IGF-dependent and -independent mechanisms. Our data also show that rpIGFBP-3 causes IGF-independent anti-proliferatioe actions without increasing the level of phosphosmad-2 in L6 cultures. In addition, rpIGFBP-3 has been shown to inhibit L6 cell differentiation only via an IGF-dependent pathway. Forced expression of pIGFBP-3 in L6 myogenic cells indicates that endogenous pIGFBP-3 plays a similar role to exogenous rpIGFBP-3 in regulating the proliferation and differentiation of L6 myogenic cells. Using a DNA-based RNA interference (RNAi) technique, endogenous pIGFBP-3 is suppressed in cultured PEMC, which provides an excellent model in which to conduct pIGFBP-3 loss-of-function studies. Addition of rpIGFBP-3 to the cultured PEMC inhibits cell differentiation in serum-containing medium via an IGF-I-dependent pathway. IGFBP-3 mRNA level has been found to be relatively high in PEMC at 48 h post plating, but drops by 72 h post-plating, thereafter, increasing with differentiation. The pattern of IGFBP-3 protein expression mirrors that of IGFBP-3 mRNA expression over time. Immunofluorescent staining data reveal that IGFBP-3 protein localizes in both the cytoplasm and nucleus of proliferating PEMC but is located primarily in the cytoplasm of differentiated PEMC. Furthermore, IGFBP-3 is enriched in nucleus when PEMC are treated with TGFβ1, which may contribute to the antiproliferative actions of TGFβ1. Real-time RT-PCR data reveal that the members of IGFs system, TGFβ1 and myostatin mRNA expressions are differentially regulated during the proliferation and differentiation of PEMC. The studies in this area provide new information about the role of IGFBP-3 and potential interactions of these important growth factors during porcine muscle growth and development, which will allow us to understand more about how to produce meat efficiently.
XU, Jie (2005)
Advisor: Da, Yang
Statistical analysis for mapping linked quantitative trait loci
Abstract
Three basic statistical methods: mixture model method (MM), regression on genotypic probability (RGP) and least squares method (LS) in QTL mapping were evaluated by simulation study. These results suggest that each of the three methods has its own strength. When detecting additive QTL, LS had the highest power; when detecting dominance QTL, MM and RGP had the higher power and LS had the lowest power for all heritability levels. In the estimation of location for additive QTL, LS had the best accuracy (smallest MSE), followed by RGP, with MM having the lowest accuracy. In the estimating of the location for dominance QTL, MM had the best accuracy. When estimating additive effect, LS had the best accuracy followed by RGP. For estimating dominance effect, the three methods had similar performance but the accuracy of MM decreases when heritability is low. Dominance effect is a cause of heterosis. Marker contrasts are used for the detection of dominance effects and for the estimation of QTL location and the dominance effect under the F-2 and the reciprocal backcross designs. With these marker contrasts the dominance effect not only can be estimated invariant to additive effects but also can ensure the independence of estimation from other linked QTL. Analytical formulae for recombination frequency and dominance effects were developed for three cases: single QTL, side interval and middle interval. The simulation study showed that these formulae are useful statistical tools. It also showed that with conditional markers included in the model the accuracy of estimating QTL location will be improved while the accuracy of estimation for dominance effects will decrease. In most studies the interference effect was assumed nonexistence among the loci. A simulation study showed that genetic sampling could cause false interference although there was no interference in the original population. If interference effect was considered in least square analysis the accuracy of estimating QTL location could be improved as much as half.
ZEHNDER, Chad Michael (2002)
Advisor: DiCostanzo, Alfredo
Evaluation of alfalfa leaf meal as a protein source in beef cattle diets
Abstract
A study was conducted to determine effects of using alfalfa leaf meal (ALM) as a supplemental protein source in beef cattle diets. Feeding 112.5% of recommended protein to gestating heifers increased (P < .05) pre-calving rate of gain and DM digestibility. Protein source or intake did not affect (P > .05) gestation BW change or calving traits in gestating cows or heifers. Suckling calves supplemented with a wheat middlings (MIDD) based supplement had greater (P < .05) ADG and creep feed DMI than those fed ALM based supplements, whereas nonsupplemented calves had the poorest (P < .05) ADG. Feed efficiencies for additional gain were greater (P < .05) for calves supplemented with ALM. Newly received feedlot steers fed ALM00 [supplemental protein source from ALM at 0% (ALM00), 33% (ALM33), 66% (ALM66), or 100% (ALM100)] had greater (P < .05) ADG for the entire experiment (Exp. 1) and the first 14 d (Exp. 3), and required less (P < .05) DM/kg gain (Exp. 1 and 3). In Exp. 2, protein source did not affect (P > .05) performance during the receiving or step-up period. Morbidity rate (all 3 experiments) or DMD (Exp. 2 and 3) was not significantly (P > .05) affected by supplemental protein source. Finishing steers fed ALM100 (treatments similar to all 3 receiving experiments) had greater (P < .05) ADG and DMI resulting in similar feed efficiencies across all treatments. Steers fed ALM100 had greater (P < .05) final BW and hot carcass weights. No other carcass characteristics were affected (P > .05) by treatment; but, incidence of liver abscesses in steers fed ALM100 tended to be lower (P < .10). In a continuous culture fermenter system, non ammonia nitrogen flow and total N intake were greater (P < .05) in the ALM00 treatments; crude protein degradation and total DM and OM digestion was not affected (P > .05) by treatment; however, NDF and ADF digestion, and total VFA concentration were reduced (P < .05) with ALM100 supplementation.
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