- 2009 -
Temporal changes in hepatic gene expression during the periparturient period of spring-calving beef cows on grazing conditions
A.L. Astessiano1, R. Perez-Clariget1, G. Quintans2, P. Soca1, B.A. Crooker3, and M. Carriquiry1
Primiparous crossbred (Hereford/Angus; n=10) were used in a randomized block design, to study effects of day postpartum (DPP) on hepatic gene expression during the periparturient period. Cows grazed together on a native pasture paddock (60 ha) with an average forage mass available of 453 kg DM/ha (13.2% CP and 24.4% ADF). Milk yield was measured at 14 and 35±4 DPP and liver biopsies obtained at -11, 7, 31, and 52 DPP. The amount of mRNA for growth hormone receptor (GHR), GHR-1A, insulin-like growth factor-I (IGF-I), IGF binding proteins-2 (BP2),-3 (BP3), and an endogenous control (hypoxanthine phospho-ribosyltransferase;(HPRT) were measured by real time RT-PCR. Means from a repeated measures analysis differed when P<0.05. Cows lost 1.25 units of body condition score (BCS,scale 1-8) during the last 60 d of gestation, calved with a BCS of 3.7 ±0.08 units, and lost only 0.25 units during the first 60 DPP. Milk yield tended (P=0.07) to decrease from 6.3 to 5.5±0.4 kg/d from 14 to 35 DPP, but this decrease was evident only in cows that calved with BCS≤3.5. Abundance of HPRT mRNA was not affected by DPP or BCS at calving. Relative amounts of GHR mRNA reached nadir at 7 DPP, and increased thereafter until 52 DPP, but there was no effect of DPP on amounts GHR-1A pr IGF-I mRNA amounts. However, when BCS at calving was considered in the analysis, mRNA expression of GHR1A and IGF-I tended (P<0.10) to increase for cows with BCS≤3.5 but tended to decrease for cows with BCS>3.5 from -11 to 52 DPP. Although BP2 and BP3 mRNA relative amounts were not affected by DPP, BP2/BP3 mRNA ratio tended (P=0.11) to decrease from -11 to 52 DPP and BP2 mRNA was greater for cows with BCS≤3.5 at calving. Hepatic expression of genes associated with GH-IGF the axis were affected during the periparturient period in spring-calving beef cows under grazing conditions and tended to be modulated by BCS at calving.
(J. Dairy Sci. 2009.92:E-Suppl. 1. Page 76.)
1School of Agronomy, UDELAR, Uruguay
2INIA, Treinta y Tres, Uruguay
3Department of Animal Science, University of Minnesota, St. Paul
Effect of bovine somatotropin (bST), dietary fat, and day in milk (DIM) on hepatic mineral concentrations in Holstein cows
M. Carriquiry1, W.J. Weber1, W.A. House2, and B.A. Crooker1
Multiparous cows (n=59) were blocked by expected calving date and previous milk yield and assigned randomly to treatments to determine effects of bST, dietary fat, and DIM on hepatic minerals (Ca, P, Mg, Na, K, Fe, Mn, Zn, Cu, Cd, Mo). Dietary n-6 or n-3 fatty acids were
provided from calving as whole, high-oil sunflower seeds (SS; 10% of diet DM) or as a mixture of Alifet-High Energy® and Alifet-Repro® (AF; 3.4 and 1.5% of diet DM). Cows received 0 (N) or 500 (Y) mg bST (POSILAC®) every 10 d from 12 to 70 DIM and at 14-d intervals thereafter. Treatments from the factorial combination were designated SSN, SSY, AFN, and AFY. Biopsies were collected at -12, 10, 24, and 136 DIM and mineral content (μg/g DM) determined by inductively coupled plasma atomic emission spectrometry. Means from a repeated measures analysis differed when P< 0.05. Liver DM decreased from -12 to 136 DIM (27.6 ± 1.1% vs. 23.9 ± 1.3%) and was not affected by bST or diet. Hepatic P, K, Zn, Cu, Mo, and Cd decreased and Ca tended (P<0.09) to decrease after calving, reached nadir at 10 or 24 DIM, and returned to or exceeded prepartum values by 136 DIM. The Mg values at -14 DIM were intermediate and values at 10 and 24 DIM less than at 136 DIM. Hepatic Fe increased from -12 to 10 DIM and decreased from 10 to 136 DIM. Hepatic Mn increased 50% from -12 to 136 DIM but Na was not affected by DIM. Hepatic Zn (100 vs. 90 ± 3.3 μ/g) and Fe (213 vs. 188 ± 7 μ/g) were reduced in bST treated cows. Hepatic Zn (101 vs. 89 ± 3.3 μ/g), Mn (7.6 vs. 6.7 ± 0.3 μ/g), and Fe (210 vs. 192 ± 7 μ/g) decreased in cows fed AF. There was an interaction of bST, diet, and DIM on K and Mo as their concentrations were less at 24 and 136 DIM in AFY cows than in SSN, SSY, and AFN cows. Hepatic concentration of several minerals decreased with initiation of lactation, bST and AF but no signs of deficiency were detected.
(J. Dairy Sci. 2009.92:E-Suppl. 1. Page 77.)
1Department Animal Science, University of Minnesota, St. Paul
2USDA-ARS, Ithaca, NY
Serum metabolomics of multiparous Holstein cows during the transition period
C. Chen, W.J. Weber, M. Carriquiry, S.C. Fahrenkrug, and B.A. Crooker
Department of Animal Science, University of Minnesota, St Paul
Transition from pregnancy to lactation is associated with dramatic alterations in metabolism that can significantly impact health, milk yield and reproductive performance. Advances in metabolomic techniques have improved the ability to monitor metabolic profiles and flux of small molecules in serum to define changes in metabolism on a global scale. Cows from control (stable milk yield since 1964; CL; n=5) and select (contemporary; SL; n=6) lines that differed in milk yield (6,200 and 11,100 kg milk/305 d) were fed ad libitum quantities of the same diets, milked 2X/d, and exposed to the same environment. Diets were fed as TMR composed primarily of legume-grass hay, corn silage, ground corn, and soybean meal, and were formulated to meet or exceed requirements. A dry cow diet (15.5% CP, 1.60 Mcal NEL/kg DM) was fed until calving and an early lactation diet (18.2% CP, 1.67 Mcal NEL/kg DM) was fed thereafter. Production results were analyzed by repeated measures analysis and means differed if P<0.05. Deproteinized serum samples collected at -14, -7, 3, 14, 28 and 38 DIM were separated by ultra-performance liquid chromatography and ionized chemical components detected by a time-of-flight mass spectrometer. Mass, retention time, and intensity of serum ions was extracted from chromatograms and spectra and used to construct a multivariate model by principal components analysis. Chemical structures of serum ions were determined by accurate mass measurement and MS/MS fragmentation. The SL cows produced more FCM (29.5 vs. 45.6 ± 2.1 kg/d) during the first 42 DIM. Differences between pre- and postpartum serum samples were due mainly to dramatic postpartum increases in several lipid species, especially lysophosphatidylcholines. Differences between CL and SL cows were less striking. Overall, this study demonstrated that serum metabolomics can serve as a useful tool to investigate the underlying mechanisms of lactation-induced metabolic changes.
(J. Dairy Sci. 2009.92:E-Suppl. 1. Page 71.)
Animal welfare in cross-ventilated and naturally ventilated
dairy barns in the upper Midwest USA
K.M. Lobeck, M.I. Endres,
E.M. Shane, S.M. Godden, and J. Fetrow
University of Minnesota,
St. Paul
The objective of this observational study was to describe animal welfare
in low profile cross-ventilated freestall barns (CV) compared to
conventional naturally ventilated freestall barns (NV) in the Upper
Midwest. The study was conducted on 12 commercial dairy farms in
Minnesota and eastern South Dakota with herd sizes ranging from 400
to 1600 lactating cows. All herds had stalls bedded with sand. Farms
were visited once seasonally between January and November 2008 and
approximately ninety percent of the lactating herd was scored on each
visit for body condition, hygiene, hock lesion and locomotion. DHIA
records were collected monthly. Body condition scores (1=emaciated,
5=severely obese) for winter, spring, summer, and fall, respectively,
were (mean±SD): 3.07±0.27, 3.06±0.30, 2.97±0.36, 3.00±0.32 for NV
herds; 3.10±0.29, 3.10±0.31, 3.04±0.36, and 3.04±0.37 for CV herds.
Hygiene scores (1=clean, 5=dirty) were: 2.6±0.6, 2.5±0.5, 2.8±0.6,
and 2.7±0.6 for NV herds; 2.6±0.6, 2.7±0.6, 3.0±0.6, and 2.9±0.5 for
CV herds. Hock lesion percent prevalence for winter, spring, summer
and fall (mild or severe lesion, respectively) was: 18.9, 6.7; 22.0, 9.3;
25.3, 8.7; 20.2, 6.0 for NV herds; 19.7, 8.9; 19.6, 12.0; 27.9, 11.7; and
18.1, 8.6 for CV herds. Lameness percent prevalence (lame or severely
lame, respectively) determined by locomotion scoring (1=normal
locomotion, 5=severely lame) was 18.7, 5.4; 19.7, 3.5; 13.2, 2.0, and
13.2, 2.5 for NV herds; 14.1, 3.8; 13.7, 1.3; 9.2, 1.2; and 9.5, 1.9 for
CV herds. Somatic cell counts (x 1,000) were: 349±1020, 292±827,
294±827, and 269±713 for NV herds; 323±888, 280±731, 346±918,
and 288±813 for CV herds. Cow comfort quotient (%) was 83.4±13.4,
86.5±7.0, 77.3±17.2, and 83.5±15.3 for NV herds; 89.0±10.5, 89.0±7.4,
85.5±14.6, and 88.7±5.2 for CV herds. Stall usage index (%) was
70.1±19.2, 74.7±9.3, 77.3±17.2, and 71.7±15.5 for NV herds; 77.1±11.0,
75.7±9.8, 72.6±16.5, and 77.2±8.4 for CV herds. Based on these results
it appears that cross-ventilated and naturally ventilated freestall barns
can provide relatively similar animal welfare conditions, but additional
investigation and analysis are needed.
Environmental characteristics in cross-ventilated and naturally ventilated dairy barns in the upper Midwest USA
K.M. Lobeck,
M.I. Endres, E.M. Shane, and K.A. Janni
University of Minnesota,
St. Paul
The objective of this study was to characterize air quality, light intensity,
and air velocity in low-profile cross-ventilated freestall barns (CV)
compared to conventional naturally ventilated freestall barns (NV).
The study was conducted on 12 commercial dairy farms in Minnesota
and eastern South Dakota between January and November 2008.
Each farm was visited seasonally for a total of four visits for the year.
Representative measurements were taken with portable meters along
the feed bunk and inside the pen twice daily. Measurements included
ammonia and hydrogen sulfide concentrations, light intensity, and air
velocity. Ammonia concentrations (ppm, mean±SD) were 3.5±2.3 in the
NV barns and 5.2±2.3 in the CV barns. Ammonia concentrations for
winter, spring, summer, and fall, respectively were 1.9±2.19, 3.59±2.1,
5.6±1.3, and 2.9±1.5 for NV barns; 5.4±2.6, 5.0±2.4, 6.2±1.7, and
4.3±2.2 for CV barns. There were housing system and season(P≤0.001),
and system-season interaction (P=0.039) effects for ammonia concentrations.
Hydrogen sulfide concentrations (ppb) were 24±26 for NV
barns and 67±240 for CV barns. Seasonal concentrations of hydrogen
sulfide were 40±27, 14±14, 30±35, and 13±11 for NV barns; 118±418,
56±179, 69±235, and 42±54 for CV barns. There were system and
season effects (P≤0.01). Light intensity (lux) was 945.6±2200.6 for
NV barns and 158.0±129.5 for CV barns. Seasonal light intensity was
827.4±616.6, 871.1±2293.4, 931.7±923.9, and 1130.8±3545.6 for NV
barns; 214.4±193.1, 174.4±161.8, 144.6±83.4, and 131.5±80.3 for
CV barns. There was a system effect (P≤0.001) and a trend for season
effect (P=0.057). Air velocity (m/s) was 43.9±48.6 for NV barns and
56.6±50.5 for CV barns. Seasonal air velocity was 17.7±17.4, 44.1±38.5,
61.5±53.2, and 48.9±58.7 for NV barns; 15.1±10.8, 78.1±55.8,
84.7±48.5, and 39.8±35.0 for CV barns. There was no difference
between systems for air velocity. However, there was a season effect
(P≤0.001). These results indicate that there were some environmental
differences between cross-ventilated barns and conventional naturally
ventilated barns.
- 2008 -
Hyperglycaemia in day 9 of the estrous cycle did not increase ovulation rate in ewes but modified plasma IGF-I concentrations
R. Pérez-Clariget1, C. López-Mazz1, M. Regueiro1, B.A. Crooker2, and M. Carriquiry1
To evaluate the effect on ovulation rate of increased glycaemia during 24 h in the luteal phase of cycling ewes, thirty-four non-lactating adult Corriedale ewes (44.6±4.5 kg of body weight and 3.2±0.5 body condition, in a scale 1-5) that grazed native pastures were used. Estrus was synchronized with 2 doses of cloprostenol 8 d apart and on day 9 of the synchronized estrous cycle, ewes were randomly assigned to receive an oral administration of a neoglucogenic solution (125 ml; 70% glycerol, 20% propilenglycol, 10% distilled water; n=17; Group-G) or saline (n=17; Group-S), administrated every 6 h for a 24 h-period. All ewes were inseminated with fresh semen at the following (natural) estrus and number of corpus luteum (CL) was observed by laparoscopy at day 8 of the natural estrous cycle. Means were considered to differ when P<0.05. The interval from second injection of cloprostenol-estrus was 47±0.8 h. Plasma glucose concentrations increased for Group-G during the 24 h that treatment was applied. Administration of the neoglucogenic solution did not affect the length of the estrous cycle, and ewes ovulated at 8.3±0.4 d after treatment. Ovulation rate (1.2 and 1.1±0.09 for Group-S and Group-G, respectively) and percentage of embryo retention at first service (53 and 76 ± 10% for Group-S and Group-G, respectively) were similar for both groups. Plasma IGF-I concentrations from -24 to 96 h of initiation of treatment did not differ between groups. However, there was a trend (P=0.065) for an interaction between treatment group and sampling time, as when compared with Group-S, plasma IGF-I of Group-G was reduced during the 24 h that treatment was applied and plasma glucose was elevated, did not differ between 48 and 72 h, and was increased at 96 h. When data were normalized to day of the following estrus (-8 to -3 d), plasma IGF-I tended (P=0.058) to be greater for ewes that had 2 CL (133.6 vs 155.6±7.3 ng/ml for ewes with 1 or 2 CL, respectively), whereas were not affected by day to following estrus.
(Abstract presented at the 16th International Congress on Animal Reproduction in Budapest, July 13 to 17, 2008.)
1Department of Animal Production and Pastures, School of Agronomy, UDELAR, Uruguay
2Department of Animal Sciences, University of Minnesota, St. Paul
Bedding options for an alternative housing system for dairy cows: A descriptive study
E.M. Shane1, M.I. Endres1, D.G. Johnson2, and J.K. Reneau1
University of Minnesota, St. Paul
Availability of bedding material for compost bedded pack barns is a concern for dairy producers who use this type of alternative housing system. The material most commonly used in these barns is sawdust. The objective of this descriptive study was to evaluate different types of material that could potentially substitute or partially substitute for sawdust in these housing systems. The study was conducted at the West Central Research & Outreach Center in Morris, Minnesota from November 2006 to March 2007. Materials included: sawdust (control) (SD), corn cobs (CC), woodchip fines, and soybean straw (SS). Some of these materials were evaluated as mixtures on a 2:1 volume to volume ratio. These mixtures included: woodchips/sawdust (WC/SD), woodchips/soybean straw (WC/SS), and soybean straw/sawdust (SS/SD). Six bedded packs were used, each with one of six different materials, and 16 cows were placed on each pack for the specified time period. Replicated samples of the bedded pack material were collected biweekly and analyzed for dry matter. C:N ratios and pH were analyzed monthly. Temperatures of each pack were measured weekly at various depths (15.2, 30.5, 45.7, and 61.0 cm). Cows were scored for hygiene (1=clean, 5=dirty) biweekly. Moisture content (mean ± stdev.) of SD was 59.7 ± 8.6; CC, 44.5 ± 9.8; WC/SD, 60.6 ± 7.6; SS/SD, 58.2 ± 10.5; WC/SS, 60.7 ± 4.5; and SS, 60.6 ± 3.2. SD pH was 8.7 ± 0.28; CC, 7.7 ± 0.75; WC/SD, 8.6 ± 0.28; SS/SD, 8.6 ± 0.19; WC/SS, 8.3 ±0.37; and SS, 8.6 ± 0.14. C:N ratio of SD was 37.3 ± 8.1; CC, 29.2 ± 6.1; WC/SD, 47.5 ± 12.0; SS/SD, 25.6 ± 5.0; WC/SS, 31.0 ± 5.4; and SS, 22.8 ± 3.3. Temperatures (ºC) across depths were: SD, 31.0 ± 11.4; CC, 40.0 ± 12.2; WC/SD, 22.6 ± 13.9; SS/SD, 26.0 ± 8.8; WC/SS, 20.0 ± 10.5; and SS, 13.0 ± 11.1. Hygiene score of cows on SD was 2.4 ± 0.7; CC, 2.7 ±0.8; WC/SD, 2.5 ± 0.8; SS/SD, 2.9 ± 0.8; WC/SS, 2.6 ± 0.9; and SS, 2.8 ± 0.8. Based on these results and our observations, it appears that any of the materials evaluated in this study would potentially work in this type of housing system if proper bedding management is applied on a consistent basis.
1 Department of Animal Science, University of Minnesota, St. Paul
2 West Central Research and Outreach Center, University of Minnesota, Morris
Compost: A potential value-added product for dairy operations?
E.M. Shane11, M.I. Endres11, D.G. Johnson12, C.J. Rosen13, M.P. Russelle13
University of Minnesota, St. Paul
The objective of this study was to evaluate the composting potential of various bedding materials that were previously used in experimental compost bedded packs for dairy cows. Each material was placed in windrows (1.8m high, 9.1m long and 2.3m wide) from April 2007 to September 2007 and managed as needed to promote composting. Materials included: sawdust (SD) (control), corn cobs (CC), woodchip/sawdust mix (WC/SD), soybean straw (SS), woodchip/soybean straw mix (WC/SS), and soybean straw/sawdust mix (SS/SD). Replicated samples were taken weekly and analyzed for dry matter (DM). Carbon:nitrogen ratio (C:N ratio), pH, total C, total N, NH4-N, and NO3-N were measured once monthly. Temperature was measured twice weekly. Total P, total K, and EC were measured at initial and end of period. None of the windrows had a significant decrease in temperature from day 1 to day 141, but all materials had a major reduction in coliforms. CC, SS/WC, WC/SS and SS were the only materials that decreased (P<0.05) in moisture content from day 0 to day 138. Materials were similar when comparing day 0 and day 138 for NH4-N, NO3-N, and inorganic N concentrations. SS, SS/SD, WC/SS, and WC/SD all decreased (P<0.05) from day 0 to day 138. Some of the observed C:N ratios were slightly below 20:1, with the exception of SD and WC/SD at the end of the period. Based on these results, all materials composted during the time period and would potentially work as a soil amendment/ mulch if proper composting takes place.
1 Department of Animal Science, University of Minnesota, St. Paul
12 West Central Research and Outreach Center, University of Minnesota, Morris
13 Department of Soil, Water, Climate, University of Minnesota, St. Paul
- 2007 -
Performance and welfare of dairy cows in an alternative housing system in Minnesota
A.E. Barberg1, M.I. Endres1, J. A. Salfer2, and J.K. Reneau1
The compost bedded pack dairy barn is an alternative housing system for lactating cows that has received increased attention in the last 2 yr. No descriptive data were available about this housing system. Therefore, a study of 12 compost dairy barns in Minnesota was conducted between late June 2005 and September 2005. The objectives of this study were to describe the housing system, identify management practices used in these herds, observe cow welfare, analyze herd performance and udder health prior to and following the change in housing system, and measure producer satisfaction with the system. Producers were interviewed on various aspects related to the housing system and herd management, samples of milk were collected, and cows were scored for locomotion, body condition, hygiene, and hock lesions. In addition, historical bulk tank information and Dairy Herd Improvement Association data were collected when available. At the time of the visit, the Dairy Herd Improvement Association somatic cell count (SCC) was 325,000 ± 172,000 cells/mL, rolling herd average was 10,457 ± 1,138 kg per cow, and herd size was 73 ± 35.5 lactating cows. The body condition score was 3.04 ± 0.11, the cow hygiene score was 2.66 ± 0.19, and 7.8% of all cows were clinically lame (locomotion score 3 on a 1 to 5 scale). No hock lesions were present on 74.9% of the cows; 24.1% of cows had a mild lesion (hair loss), and 1.0% had a severe lesion (swollen hock). Historical analysis of the bulk tank SCC showed that 3 out of the 7 herds analyzed had a significant reduction in bulk tank SCC when compared with the previous housing system. Mastitis infection rates decreased significantly by 12% on 6 of the 9 farms analyzed. Reproductive performance significantly improved for 4 out of the 7 herds analyzed, with 25.9 and 34.5% improvement in heat detection rates and pregnancy rates, respectively. The main reasons producers reported for building this type of housing system were for improved cow comfort, cow health and longevity, and ease of completing daily chores. The largest concern was the cost and availability of bedding, especially as additional compost barns are built. Overall, all producers were satisfied with their decision to build a compost barn.
1Department of Animal Science, University of Minnesota, St. Paul
2University of Minnesota Extension Service, St. Cloud
In vitro examination of rumen biohydrogenation (BH) of four dietary fats
M. Carriquiry1, W.J. Weber1, L.H. Baumgard2, and B.A. Crooker1
Rumen microbial BH of unsaturated fatty acids in dietary fats (Alifet High-Energy® (AHE), Alifet-Repro® (AR), Megalac® (MG), and Energy Booster® (EB)) that differ in fatty acid content, method of protection from rumen BH, or both factors was assessed. Fats (20 mg) were incubated at 37°C with strained rumen fluid diluted 5-fold with 16 mL of medium, 0.8 mL of reducing solution buffer and 200 mg of a purified, synthetic diet. Total contents were collected after 0, 6, 24, and 36 h and change in fatty acid content used to estimate rate of BH. For oleic acid, loss after 36 h (about 60%) and rate of BH (4.0 ± 1.3 vs. 6.1 ± 1.9 %/h) did not differ between EB and AHE. For MG, rate of BH was 4-times greater for linoleic than for oleic (4.0 ± 1.3 vs. 0.9 ± 0.2 %/h) acid. Only 20% of the oleic acid but 65% of the linoleic acid disappeared from MG after 36 h. In contrast, BH of oleic, linoleic and linolenic from AR were similar (2.6 ± 1.1, 2.5 ± 1.1, and 2.4 ± 0.9 %/h, respectively) and 95, 65, and 65% of these fatty acids remained after 36 h. Only AHE and AR contained trans-18:1 but total trans-18:1 increased with time of incubation for all dietary fats. Trans-10 and trans-11 were the predominant trans-isomers in AHE and AR incubations whereas trans-9 and trans-10 were the predominant isomers in EB and MG incubations. None of the fats contained conjugated linoleic acid (CLA) but CLA was in the inoculum. Although not affected by fat source, the amount of CLA decreased with incubation time. Only AR contained eicosapentaenoic (EPA, 20:5) and docosahexaenoic (DHA, 22:6) and loss of EPA and DHA was minimal (10 and 5%, respectively). The expected increase in BH of fatty acids with degree of saturation occurred with MG but neither degree of saturation nor chain length affected BH of fatty acids in AR. Results suggest that fatty acids in AR are protected from rumen metabolism and that AR can deliver significant amounts of EPA and DHA to the ruminant intestine.
1Department of Animal Science, University of Minnesota, St. Paul
2Department of Animal Science, University of Arizona, Tucson
Hepatic gene expression in Holstein cows treated with bovine somatotropin (bST) and fed omega-3 fatty acids in early lactation
M. Carriquiry, W.J. Weber, S.C. Fahrenkrug, and B.A. Crooker
Department Animal Science, University of Minnesota, St. Paul
Multiparous cows were blocked by expected calving date and previous milk yield and assigned randomly to treatments to determine effects of bST and dietary fat on hepatic gene expression. Dietary fat was provided from calving and included whole, high-oil sunflower seeds (SS; 10% of dietary dry matter (DM); omega-6:omega-3 ratio of 4.7) as a source of linoleic acid or a mixture of Alifet-High Energy® and Alifet-Repro® (AF; 3.4 and 1.5% of dietary DM, respectively; omega-6:omega-3 ratio of 2.6) as a source of protected omega-3 fatty acids. Cows received 0 or 500 mg bST (POSILAC®) every 10 d from 12 to 70 d in milk (DIM) and at 14-d intervals thereafter. Treatments from the 2 x 2 factorial combination of diet (SS or AF) with or without bST administration were designated as SSY, SSN, AFY, and AFN, respectively. Biopsies were collected (-12, 10, 24, and 140 DIM) when cows (n=32, 8 blocks) were in positive and negative energy balance (EB). The amount of mRNA for growth hormone receptor (GHR), insulin-like growth factor-I (IGF-I), IGF-binding protein-3 (IGFBP3), peroxisome proliferator-activated receptors α (PPARα) and hepatic nuclear factor 4α (HNF4α) and an endogenous control (hypoxanthine phosphoribosyltransferase (HPRT)) were measured by quantitative realtime RT-PCR. Relative amounts of mRNA for GHR, IGF-I, and IGFBP3 were reduced after calving and increased thereafter. Abundance of PPARα mRNA increased as lactation progressed. Administration of bST increased hepatic expression of GHR, IGF-I, and IGFBP3 mRNA by 10 d (24 DIM) of treatment and the effect was still present at 140 DIM. There was interaction of bST with diet on PPARα mRNA abundance as the amount of PPARα mRNA increased in AFN cows and decreased in AFY cows. The amount of hepatic HNF4α mRNA was not affected by stage of lactation, bST, or diet. Initiation of bST at 12 DIM increased hepatic mRNA abundance for components of the somatotropic axis even when cows were in negative EB.
Evaluation of an intraruminal pH probe
B.A. Crooker1, W.J. Weber1, S.C. Denham2, and J.L. Vicini2
Studies were conducted to compare rumen pH measurements from an intraruminal pH probe (IRP) to those obtained from a standard pH meter (M). Functional life and ability of IRP to detect changes caused by alterations in diet and feeding management were evaluated. The IRP (Well Cow, LTD, Bedford, UK) were calibrated prior to insertion and the M (Thermo Electron Corp., Beverly, MA) was calibrated before each use. Frequency (1 or 10 min) of measurement and data download from IRP were controlled through software on an external computer. The IRP (n=2 or 3) were placed in the reticulum (R) or rumen of 3 lactating and 1 non-lactating cows for up to 28 d (Study 1). Measurements by M were obtained from R and ventral (V), caudal-ventral (CV) and caudal-dorsal (CD) sacs on d 0 to 5, 11, 23, and 27. Study 2 had three, 3-wk periods in which cows were fed a basal diet with sodium bicarbonate (B) 1X/d (continuous access to feed) and pH in R was compared with that of cows fed a) B with extra starch 1X/d, b) B as two discrete (3h) meals/d, or c) B without bicarbonate 1X/d. Each period had a 7 d transition (all cows fed B) and 14 d of treatment. The IRP (n=2) were placed in R of 12 lactating cows blocked (n=3) by DIM and milk yield. Results from IRP and M were compared using restricted maximum likelihood mixed model analysis. Means differed if P<0.05. Mean pH by M differed by site (6.37, 6.28, 6.19, and 6.13 ± 0.04 in R, V, CV and CD, respectively) and time with no interaction (Study 1). When IRP functioned correctly, IRP and M values differed by less than 0.1 units but this was significant. Life of IRP was shorter (24.8 ± 1.5 and 28.6 ± 3.6 d for Study 1 and 2, respectively) and overall failure (50% by 28 d) greater than expected. Daily mean pH was not altered by treatment. Mean daily decline in pH after feeding was greater in cows not fed bicarbonate (-0.57 vs -0.44 ± 0.01). The minimum pH per day was less for cows fed 1X/d than 2X/d (6.29 vs. 6.44 ± 0.07). The IRP have potential to provide accurate, prolonged measurements of pH but their functional life needs to be increased.
1Department of Animal Science, University of Minnesota, St. Paul
2Monsanto Company, St. Louis, MO
Behavior of dairy cows in an alternative bedded pack housing system
M.I. Endres and A.E. Barberg
Department of Animal Science, University of Minnesota, St. Paul
The objectives of this study were to measure lying behavior and social interactions of lactating cows housed in an alternative bedded pack system commonly referred to as a compost dairy barn, and to investigate the association between temperature-humidity index and lying behavior of these cows. The study was conducted in 12 compost dairy barns in MN between late June 2005 and September 2005. Lying, standing and walking behavior of 147 focal cows was measured using automatic activity monitors. The average daily lying time was 9.34 ± 1.94 h. The average number of daily lying bouts was 11.0 ± 3.2 and the average lying bout length was 50.8 ± 35.6 min. As days in milk increased, the total number of lying bouts increased, corresponding to an increase in total daily lying time. Cows in the compost barns lay down for less time, took more steps, and reduced the length of lying bouts as the temperature-humidity index increased. Social interactions and lying positions of all cows in the bedded pack area (total of 886 cows in the 12 dairies) were recorded using visual observations during two 4-h periods on 2 separate days. There were 43.3% of the cows lying down at any time. All 4 natural lying positions (head back, head up, flat on side, and head on ground) were observed in 9 of the bedded packs during the direct visual observation periods. A majority (84.6%) of the cows observed lying down assumed the head up position. Of all observed lying events, the head back lying position was assumed 8.8% of the time, the head on ground 5.4% of the time, and flat on the side 0.8% of the time. Observations of social interactions on the bedded pack area showed that 0.94 incidents of chasing away, 0.94 ± 1.8 of pushing, 1.4 ± 1.6 of head butting, and 2.3 ± 2.9 of allogrooming (social licking) occurred per hour. Observations of lying behavior, social interactions, and natural lying positions indicated that compost dairy barns can be an adequate housing system for dairy cows.
Feeding management and characteristics of rations for high producing dairy cows in freestall herds
M.I. Endres and L.A. Espejo
Department of Animal Science, University of Minnesota, St. Paul
The objectives of this cross-sectional observational study were to describe the feeding management and characteristics of rations for high producing Holstein cows housed in freestall barns in Minnesota, evaluate ration particle size change throughout the day, and investigate herd-level risk factors for particle size change. Each of 50 randomly selected freestall dairy herds was visited once during the study. Samples of TMR were collected from the high group feed bunk to represent the initial ration as delivered to the cows, three other samples collected every 2-3 hours, and the accumulated orts cleaned out of the bunk. Feeding management practices and TMR formulation were also collected at that time. The most common frequency of feeding was 1x/day (70%) followed by 2x/day (22%) and 3x/day (8%). Frequency of feed push-up was 5.4 ± 2.3 x/day. Linear feed bunk space per cow was 0.45 ± 0.11 m. Sixty-two percent of the farms had 3-row pens and 38% had 2-row pens. Linear feed bunk space per cow was greater in 2-row pens (0.56 m/cow) than 3-row pens (0.39 m/cow). Post and rail was the most common type of feed barrier (60%), followed by headlocks (28%), combination of post and rail with headlocks (8%), and diagonal bars (4%). Water was provided mainly on water troughs with an average linear space of 4.6 ± 2.1 cm/cow. The forage content of the formulated ration was 52% of the ration DM, with an estimated DMI of 24.3 kg/cow/day. Corn silage was the most commonly used forage on the formulation of the TMR. The NDF content of the analyzed ration was greater than the estimated NDF content of the formulated ration (30.6% and 29.8%, respectively). In contrast, the CP content was lower (17.5% and 17.9%, respectively). The average particle size of the initial TMR was 6.4 mm and it increased to 9.2 mm in the orts. Initial particle size and initial dry matter of the ration, time after feed delivery, linear feed bunk space per cow, and frequency of feed push-up were associated with particle size change throughout the day.
Herd-level risk factors for lameness in high-producing Holstein cows housed in freestall barns
L.A. Espejo and M.I. Endres
Department of Animal Science, University of Minnesota, St. Paul
The objective of this study was to investigate the association of some herd-level factors with the prevalence of lameness in 53 high-production groups of Holstein cows housed on 50 commercial dairy farms having freestall barns in Minnesota. Cows in the high-production group (n=5,626) were scored for locomotion (score of 1 to 5, where 1=normal and 5=severely lame) to estimate prevalence of lameness (locomotion score 3) in the group. Herd-level variables were used to explain the variation in prevalence among groups. Among the variables tested, herd size, pen space per cow, type and size of milking parlor, total mixed ration content of crude protein and neutral detergent fiber, feeding frequency, linear feedbunk space per cow, type of feed barrier, and use of footbath did not show any association with the prevalence of lameness in the univariate analysis screening test and were not included in the multivariate model. Pen stocking density (cows per 100 stalls), total daily distance between pen and milking parlor, number of cows per full-time employee equivalent, cud chewing index, and pen type were eliminated from the multivariate model in the backwards stepwise procedure. Daily time away from the pen for milking was positively associated with the prevalence of lameness, whereas cow comfort quotient was negatively associated with prevalence of lameness. Prevalence of lameness was greater when farms performed hoof trimming only when the manager decided cows needed it because of hoof overgrowth or lameness compared with farms on which the feet of all cows were trimmed on a maintenance schedule once or twice annually. Brisket board height of more than 15.24 cm and presence of the area behind the brisket board filled with concrete were associated with greater prevalence of lameness. Most of these herd-level factors could be managed to reduce lameness prevalence in commercial dairy farms.
Evaluation of the fermentation dynamics of the soluble protein fraction of three protein sources in continuous culture fermenters
M. Ruiz Moreno1, A. Bach2,3, M. Thrune1, and M.D. Stern1
Six dual-flow continuous culture fermenters were used to assess differences in degradation pattern and ability to promote bacterial growth from the soluble CP fractions of canola meal (CM), soybean meal (SBM) and fish meal (FM) using a completely randomized design with two 9-d experimental periods. All fermenters received the same basal diet (58% ground corn, 40% canary grass hay, 0.4% vitamin-mineral premix, 1% CaCO3, 0.6% salt on a DM basis). During sampling on the last 3-d of each period, 90-mL doses containing soluble proteins were infused into fermenters 30 min after the beginning of the first and last feedings of the day at a rate of 3 mL/min, using a constant-infusion pump. These doses were prepared from samples of FM, SBM and CM that were ground and soaked in distilled water (1:4 wt/vol, 38C, 1h) under continuous stirring. The solutions were centrifuged and the supernatant vacuum-filtered through a N-free filter paper. Equal N concentrations were achieved by diluting filtrates with the higher N content to match the one with the lowest N content using distilled water. Normalized filtrates (1.8% CP as is) were frozen in 90-mL doses and were gently thawed prior to infusions into the fermenters. The total amount of soluble CP supplied by the infusions of FM, CM and SBM was 3.2 g/d, representing 27% of daily dietary CP intake. Each sampling day, at 0, 0.5, 1, 3, and 6 h following the morning infusion of soluble CP fractions, a 10-mL aliquot from each fermenter flask was collected to determine NH3-N concentrations. Infusion of FM resulted in the greatest NH3-N concentrations (4.5 ± 0.08 mg/dL) compared with the other treatments (0.42 ± 0.08 mg/dL). Bacterial N flow (g/d) was also greatest (P<0.05) with FM (1.47 ± 0.07) compared with the other soluble CP fractions (1.09 ± 0.07). Results indicate that microbial degradation of the soluble CP fraction of FM is much higher than the soluble CP fractions of CM or SBM.
1Department of Animal Science, University of Minnesota, St. Paul
2ICREA, Barcelona, Spain
3IRTA-Unitat de Remugants, Barcelona, Spain
- 2006 -
Bovine somatotropin and dietary fat enriched with omega-3 fatty acids in dairy cows: I. Lactation performance<
M. Carriquiry1, W.J. Weber1, C.R. Dahlen2, G.C. Lamb3, and B.A. Crooker1
Multiparous cows (n=59) were blocked by expected calving date and previous 305ME and assigned randomly to a 2x2 factorial design to determine effects of bST (POSILAC ®) and dietary fat during 280 DIM. Diets (1.98 Mcal NEL1x, 184 g CP, and 185 g ADF per kg DM) included whole, high-oil sunflower seeds (10% of dietary DM, SS) or a mixture of Alifet-High Energy® and Alifet-Repro® (3.4 and 1.5% of dietary DM, AF) and were provided from calving. Cows received 0 or 500 mg bST (N,Y) every 10 d from 12 to 70 DIM and at 14 d-intervals thereafter. Blood was collected weekly through 150 DIM. Means from a repeated measures analysis differed when P<0.05. Daily 4%FCM yield was 4.7 kg/d greater after 23 d of bST but was not altered by diet. Peak milk was delayed (54.9 vs. 72.0 ± 3.9 DIM) and tended (P=0.07) to increase (48.9 vs. 51.1 ± 1.0 kg) with bST. Milk fat, protein, and lactose yields increased with bST but did not differ between diets. Daily DMI did not differ among treatments but BCS was reduced with bST (3.30 vs. 3.18 ± 0.06). Energy balance (EB) nadir (-11.2 ± 0.75 Mcal NEL/d) occurred at 15 DIM and did not differ among treatments. There was an interaction of bST and diet on EB as AF decreased the impact of bST on mean EB (2.04a, -2.75c, 2.00a, 0.13b ± 0.69 Mcal NEL/d for SSN, SSY, AFN, and AFY) and allowed AFY cows to reach positive EB earlier than SSY cows (70 for SSN, AFN, and AFY vs. 105 DIM for SSY). Adjusted gross efficiency was greater for bST cows (1.10 vs. 1.24 ± 0.02 kg FCM/Mcal NEL intake). Plasma NEFA and glucose were similar among treatments. The postpartum decrease in IGF-I did not differ among treatments but mean IGF-I during lactation was less for SS than AF (98.6 vs. 112.2 ± 6.7 ng/mL) and for non-bST than bST (85.7 vs. 126.1 ± 6.7 ng/mL) cows. Plasma IGF-I increased by 35 DIM for bST cows. Pre-calving concentrations of IGF-I were reached by 84 DIM for bST and after 168 DIM for non-bST cows. Initiation of bST at 12 DIM in cows fed AF increased FCM yield and plasma IGF-I by 35 DIM without detrimental effects on EB.
1University of Minnesota, St. Paul
2Northwest Research & Outreach Center, Crookston, MN
3North Central Research & Outreach Center, Grand Rapids, MN
Bovine somatotropin and dietary fat enriched with omega-3 fatty acids in dairy cows: II. Milk fatty acid composition
M. Carriquiry1, W.J. Weber1, C.R. Dahlen2, G.C. Lamb3, S.R. Sanders4,
L.H. Baumgard4, and B.A. Crooker1
Multiparous cows (n=32) were blocked by expected calving date and previous 305ME and assigned randomly to a 2x2 factorial design to determine effects of bST (POSILAC®) and dietary fat on milk fatty acid (FA) composition during the first 140 DIM. Isocaloric diets (1.98 Mcal NEL1x) that included whole, high-oil sunflower seeds (10% of dietary DM, SS) or a mixture of Alifet-High Energy® and Alifet-Repro® (3.4 and 1.5% of dietary DM, AF) were provided from calving. Alifet-Repro® contained protected omega-3 FA (15.7% 18:3, 1.3% 20:5, and 1.3% 22:6). Cows received 0 or 500 mg bST (N, Y) every 10 d from 12 to 70 DIM and at 14 d-intervals thereafter. Milk samples from wk 2, 8, and 20 of lactation were analyzed for FA composition. Means from a repeated measures analysis differed when P<0.05. Proportions of de novo synthesized FA (200 vs 185 ± 6 mg/g FA) tended to decrease (P=0.06) and preformed FA (533 vs 558 ± 5 mg/g FA) increased in milk with bST. Diet did not modify the proportions of de novo or preformed FA but 18:3, 20:5, and 22:6 FA were greater with AF. As lactation progressed, the proportion of de novo and mixed origin FA increased, while preformed FA decreased. The saturated to unsaturated FA ratio (S/U) did not differ among treatments and increased as lactation progressed. However, the increase in de novo FA, the decrease in preformed FA, and the increase in S/U ratio were detected later in lactation for bST cows (wk 8 vs. 20). The omega-6 to omega-3 FA ratio in milk was reduced in cows fed AF (8.80 vs 7.39 ± 0.29) and increased by bST as lactation progressed. The cis-9, trans-11 CLA tended (P=0.07) to be reduced by AF and increased between wk 2 and 8 of lactation despite the decrease in trans-11 18:1. The 14:1/14:0 ratio increased with wk of lactation. Alifet-Repro® induced an increase in omega-3 FA in milk and bST prolonged the mobilization period in milk FA composition.
1University of Minnesota, St. Paul
2Northwest Research & Outreach Center, Crookston, MN
3North Central Research & Outreach Center, Grand Rapids, MN
4University of Arizona, Tucson
Bovine somatotropin and dietary fat enriched with omega-3 fatty acids in dairy cows: III. Postpartum ovarian activity
M. Carriquiry1, C.R. Dahlen2, W.J. Weber1, G.C. Lamb3, and B.A. Crooker1
Multiparous cows (n=59) were blocked by expected calving date and previous 305ME and assigned randomly to a 2x2 factorial design to determine effects of bST (POSILAC®) and dietary fat on ovarian activity during the first 90 DIM. Isocaloric diets (1.98 Mcal NEL1x) that included whole, high-oil sunflower seeds (10% of dietary DM,SS) or a mixture of Alifet-High Energy® and Alifet-Repro® (3.4 and 1.5% of dietary DM, AF) were provided from calving. Cows received 0 or 500 mg bST (N, Y) every 10 d from 12 to 70 DIM and at 14 d-intervals thereafter. Follicular dynamics, luteal growth and development (transrectal ultrasonography) and plasma P4 concentrations were evaluated (3X/wk) from 15 to 90 DIM. Breeding started after 90 DIM. Means differed when P<0.05. Days to first ovulation (33.6 ± 1.4) and incidence of anovulation at 45 or 70 DIM did not differ among treatments but time to first ovulation was less variable for AFY. Intraovulatory intervals were similar among treatments (22.1 ± 0.9 d). Incidence of 2-wave cycles was greater for SSY (71.0%) and AFN (80.0%) but more 3-wave cycles occurred with AFY (83.3%). Growth rate of the ovulatory follicle was greater for AF than SS (1.9 vs. 2.2 ± 0.11 mm/d) and diameter of ovulatory follicles was larger for AFN than the other treatments (17.9 vs 15.7 ± 0.7 mm). Multiple ovulations tended (P<0.10) to increase with bST. Maximal CL volume did not differ among treatments. Area under the P4 curve was reduced for SSY (63.2a, 48.1b, 55.5ab, and 61.4a ± 5.1 dxng/mL for SSN, SSY, AFN, and AFY). The number of class 1 (2 to 5 mm; decreased), class 2 (6 to 9 mm; increased), and class 3 (10 to 15 mm; tended to increase (P=0.07)) follicles were altered by bST. Class 2 follicles were reduced with AF. Neither diet nor bST affected the number of class 4 (>15 mm) or the mean size of class 2, class 3, and class 4 follicles. Initiation of bST at 12 DIM and dietary omega-3 fatty acids enhanced ovarian activity during the first 90 DIM and could benefit reproductive performance.
1University of Minnesota, St. Paul
2Northwest Research & Outreach Center, Crookston, MN
3North Central Research & Outreach Center, Grand Rapids, MN
Effect of feed barrier design on the behavior of loose-housed lactating dairy cows
M.I. Endres1, T.J. DeVries2, M.A.G. von Keyserlingk2, and D.M. Weary2
The objective of this study was to evaluate the effects of 2 feed barrier systems on feeding and social behavior of dairy cows. Forty-eight lactating Holstein cows were subjected to each of 2 treatments in a cross-over design. The treatments were 2 types of feed-line barriers: 1) post and rail, and 2) headlock. Time-lapse video was used to quantify the feeding behavior and incidence of aggressive displacements of the cows at the feed bunk. Average daily feeding time did not differ when cows used the headlock barrier compared with the post-and rail barrier. However, there were certain changes in feeding time during periods of peak feeding activity: cows that had lower feeding times relative to group mates when using the post-and-rail barrier showed more similar feeding times to group mates when using the headlock barrier. There were 21% fewer displacements at the feed bunk when cows accessed feed by the headlock barrier compared with the post-and-rail barrier. These results suggest that using a headlock barrier reduces aggression at the feed bunk and improves access to feed for socially subordinate cows during peak feeding periods.
1University of Minnesota, St. Paul
2Animal Welfare Program, The University of British Columbia, Vancouver
Management risk factors associated with clinical lameness in freestall housed Holstein cows
M.I. Endres and L.A. Espejo
University of Minnesota, St. Paul
The objective of this study was to investigate the association of some herd-level factors with the prevalence of lameness in 53 high-production groups of Holstein cows housed in 50 commercial dairy farms having freestall barns in Minnesota. Cows in the high-production group (n=5,626) were scored for locomotion (score of 1 to 5, where 1=normal and 5=severely lame) in order to estimate prevalence of lameness (locomotion score ≥ 3) in the group. Herd-level variables were used to explain the variation in prevalence among groups. Among the variables tested, herd size, pen space per cow, type and size of milking parlor, total mixed ration (TMR) content of crude protein and neutral detergent fiber (NDF), feeding frequency, linear feedbunk space per cow, type of feed barrier, and use of footbath did not show any association with the prevalence of lameness in the univariate analysis screening test and they were not included in the multivariate model. Pen stocking density (cows per 100 stalls), total daily distance between pen and milking parlor, number of cows per full time employee equivalent, cud chewing index, and pen type were eliminated from the multivariate model in the backwards stepwise procedure. Daily time away from the pen for milking was positively associated with the prevalence of lameness, whereas cow comfort quotient was negatively associated with prevalence of lameness. Prevalence of lameness was greater when farms performed hoof trimming only when the manager decided cows needed it because of hoof overgrowth or lameness compared with all cows in which feet were trimmed on a maintenance schedule once or twice annually. Brisket board height of more than 15.24 cm and presence of the area behind the brisket board filled with concrete were associated with greater prevalence of lameness. Most of these herd-level factors could possibly be managed in order to reduce lameness prevalence in commercial dairy farms.
1University of Minnesota, St. Paul
2University of Minnesota Extension Regional Center, St. Cloud
Prevalence of lameness in high-producing Holstein cows housed in freestall barns in Minnesota
L.A. Espejo1, M.I. Endres1, and J.A. Salfer2
A cross-sectional study was conducted to estimate the prevalence of clinical lameness in high-producing Holstein cows housed in 50 freestall barns in Minnesota during summer. Locomotion and body condition scoring were performed on a total of 5,626 cows in 53 high production groups. Cow records were collected from the nearest Dairy Herd Improvement Association test date, and herd characteristics were collected at the time of the visit. The mean prevalence of clinical lameness (proportion of cows with locomotion score ≥3 on a 1-to-5 scale, where 1=normal and 5=severely lame), and its association with lactation number, month of lactation, body condition score, and type of stall surface were evaluated. The mean prevalence of clinical lameness was 24.6%, which was 3.1 times greater, on average, than the prevalence estimated by the herd managers on each farm. The prevalence of lameness in first-lactation cows was 12.8% and prevalence increased on average at a rate of 8 percentage units per lactation. There was no association between the mean prevalence of clinical lameness and month of lactation (for months 1 to 10). Underconditioned cows had a higher prevalence of clinical lameness than normal or overconditioned cows. The prevalence of lameness was lower in freestall herds with sand stalls (17.1%) than in freestall herds with mattress stall surfaces (27.9%). Data indicate that the best 10th percentile of dairy farms had a mean prevalence of lameness of 5.4% with only 1.47% of cows with locomotion score = 4 and no cows with locomotion score = 5.
1University of Minnesota, St. Paul
2University of Minnesota Extension Regional Center, St. Cloud
Farmer-driven research for developing models of successful low input dairy farms of small to medium size in the American Midwest
D.G. Johnson1, M.V. Rudstrom1, R. Imdieke2, E. Ballinger3, and G.J. Cuomo1
The dairy industry in the upper Midwest continues to evolve with a drastic reduction in the numbers of moderate-sized, conventionally managed dairy farms that have been the backbone of dairying. Many of the farms that do remain are at a critical point where facilities require renovation or replacement that is not economic. Rural communities have fewer residents engaged in agriculture to participate in the local economy and the rural landscape includes many farm sites that are abandoned. Barns that have been used to stable cows may be renovated to provide a low cost but efficient milking center. Low input farms may include grazing, outdoor housing throughout the year, crossbreeding, group housing of calves, etc. The public investment in research to evaluate has been minimal, but farmers are eager to participate when they determine the direction of research. We will describe a research project designed to answer questions determined by farmers and next steps in designing effective reduced input dairy farms.
1West Central Research & Outreach Center, Morris, MN
2New London, MN
3University of Minnesota, St. Paul
Grazing dairies can be profitable
M.V. Rudstrom
West Central Research & Outreach Center, Morris, MN
Questions about the profitability of grazing dairies are a barrier to the adoption of management intensive rotational grazing (MIRG) systems in Minnesota and other Upper Midwest dairy states. Producers understand MIRG systems tend to have lower milk production and assume lower production will translate to lower net returns. Farm financial records from grazing dairies and non-grazing (confinement) dairies in Minnesota were queried with the purpose of assessing profitability of grazing dairies relative to confinement dairies over time. Production and financial performance summary statistics were reported for 2000-2002 for both groups. Because of the relatively small number of grazing dairy farms in the database, milk production comparisons of the Minnesota grazing dairy farms were made to a larger database of grazing dairy farms to validate production results. Farm financial records show grazing operations have about 25 percent lower production per cow than confinement dairies. Lower productivity did not translate to lower net returns per cow on the grazing dairies. Grazing dairies had similar direct costs but lower overhead costs than confinement dairies. For each year, net returns per cow and per hundredweight of milk sold were greater on the grazing dairies than confinement dairies in Minnesota.
- 2005 -
Relationship between type of stall surface and prevalence and severity of hock lesions in dairy cows housed in freestall barns
M.I. Endres1, L.A. Espejo1, and J.A. Salfer2
A total of 5,538 cows in 50 randomly selected dairy farms in Minnesota were scored for hock lesions using a standardized scoring system in a scale of 0 to 3 with 0= no signs of hair loss or swelling on either hock region (no lesion), 1=evidence of hair loss (mild lesion), 2=one or more swollen hocks but no evidence of hair loss (moderate to severe lesion), 3=one or more swollen hocks with evidence of hair loss (severe lesion). Free stall surface was either deep-bedded sand or rubber-filled mattresses. Thirty-four percent of the dairies used sand and 66% used mattresses. In each dairy, cows in one or more high producing pens were scored. On the average, 90% of cows in each group were scored. Number of cows per group varied from 34 to 304 with an average group size of 118. Number of milking cows in each herd varied from 104 to 1,250 with an average milking herd size of 423 cows. Lactation number, days in milk, and milk production per cow in the scored group averaged 2.6, 169.7 days, and 38.6 kg/d, respectively. Fifty-eight percent of the cows scored had hock lesions. Stall surface was associated with the prevalence of hock lesions (P≤0.001) with 29.4% of cows in sand barns having lesions compared to 71.3% of cows in mattress barns. Severity of lesions was also greater (P ≤ 0.001) for cows in mattress herds than cows in sand herds. For the statistical analysis of severity of lesions, scores 2 and 3 were combined. In mattress herds, the percent of cows with hock lesion score of 1 was 57.2% and 2 or 3 was 14.1%. In sand herds, the percent of cows with hock lesion score of 1 was 27.6% and 2 or 3 was 1.8%. The association between lactation number (age) and DIM (stage of lactation) and the prevalence and severity of hock lesions was also investigated. Both prevalence and severity increased with age and DIM (P ≤ 0.05). There was no relationship between daily milk production and either prevalence or severity of lesions. In conclusion, the prevalence and severity of hock lesions were greater on dairy farms using mattress based stalls than on dairy farms using sand bedded stalls.
1University of Minnesota, St. Paul
2University of Minnesota Extension Regional Center, St. Cloud |
