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Department of Animal Science
University of Minnesota
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Swine Research Abstracts

- 2009 -

Effects of low-solubles distiller′s dried grains (LS-DDG) in diets for growing-finishing pigs: Carcass characteristics and pork fat quality

R.B. Amaral¹, L.J. Johnston², J.E. Anderson³, S.K. Badoo⁴, and G.C. Shurson¹

This study was conducted to assess the effects of LS-DDG on carcass characteristics and pork fat quality when fed to growing-finishing pigs. Pigs (n=216; 18.8 ± 0.76 kg initial BW) were blocked by weight and pens were assigned randomly to one of 3 dietary treatments in a 4-phase feeding program (24 pens, 9 pigs/pen). Diets were formulated on a SID amino acid basis following NRC (1998) nutrient requirements for pigs gaining 350 g/d of lean tissue. Diets included a corn-soybean meal control (C); C containing 20% LS-DDG (L); and C containing 20% distiller′s dried grains with solubles (D). Crude fat content of LS-DDG (7.95%) was lower than typical distiller′s dried grains with solubles (8.87%). Hot carcass weight did not differ among treatments but dressing percentage was lower (P<0.01) for pigs fed L and D compared to C (C=73.8%; L=72.8%; D=72.8%; SEM=0.22). Pigs fed L displayed reduced (P=0.02) 10th-rib backfat depth (C=15.5 mm; L=14.2 mm; D=16.0 mm; SEM=0.47) and increased (P=0.02) carcass lean (C=54.1%; L=54.8%; D=53.4%; SEM=0.33) compared to pigs fed D, but similar to pigs fed C. The belly flop test revealed that bellies from pigs fed D were softer (P<0.01) than those from pigs fed C (C=17.7°; L=14.1°; D=12.9°; SEM=1.07). However, only a tendency (P=0.07) for softer bellies was observed when pigs received L compared to C. The PUFA content of belly fat was reduced (P<0.01) by L compared with D but was still elevated compared to pigs fed C (C=9.4%; L=14.0%; D=15.4%; SEM=0.34). Thus, pigs fed L tended (P=0.06) to have lower iodine value of belly fat compared to pigs fed D (C=57.8; L=63.1; D=65.0; SEM=0.53). Gilts fed L had lower (P=0.02) PUFA (13.4%) in belly fat than gilts fed D (15.9%) while there was no difference among barrows (L=14.6%; D=15.0%, SEM=0.50). In summary, inclusion of 20% LS-DDG in diets for growing-finishing swine can lessen the negative impacts of DDGS on pork fat quality; and pork fat of gilts may be more sensitive to dietary LS-DDG than that of barrows.

¹Department of Animal Science, University of Minnesota, St. Paul
²West Central Research and Outreach Center, Morris
³University of Minnesota, Morris
⁴Southern Research and Outreach Center, Waseca

Effects of low-solubles distiller′s dried grains (LS-DDG) in diets for growing-finishing pigs: Energy content and pig growth performance

R.B. Amaral¹, L.J. Johnston², J.E. Anderson³, S.K. Baidoo⁴, and G.C. Shurson¹

Two experiments were conducted to assess the energy content of LS-DDG and its effects on growth performance when fed to growing-finishing pigs. In Exp. 1, barrows (n=48; 51.9 ± 2.05 kg of BW) were assigned randomly to one of six dietary treatments in a metabolism study. The basal diet (B) was formulated on a total amino acid basis following NRC (1998) nutrient requirements for pigs gaining 350 g/d of lean tissue. The LS-DDG or distiller′s dried grains with solubles (DDGS) were combined with basal diet to yield five additional diets: L30, L40, and L50 (30, 40, and 50% LS-DDG, respectively), and D30 and D40 (30 and 40% DDGS, respectively). Crude fat content of LS-DDG (7.95%) was lower than DDGS (8.87%). Increased dietary LS-DDG level decreased DE content (DM basis) of diets (B=3,753 kcal/kg; L30=3,595 kcal/kg; L40=3,525 kcal/kg; L50=3,537 kcal/kg; PSE=27.9). The DE content of LS-DDG and DDGS used in this experiment were 3,231 ± 77 and 3,351 ± 76 kcal/kg DM, respectively. In Exp. 2, pigs (n=216; 18.8 ± 0.76 kg initial BW) were blocked by weight and pens were assigned randomly to one of three dietary treatments in a 4-phase feeding program (24 pens, 9 pigs/pen). Diets were formulated on a SID amino acid basis following NRC (1998) nutrient requirements for pigs gaining 350 g/d of lean tissue. Diets included a corn-soybean meal control (C); C containing 20% LS-DDG (L); and C containing 20% DDGS (D). Overall final BW (C=113.8 kg; L=112.1 kg; D=114.0 kg; PSE=0.90), ADG (C=0.88 kg; L=0.86 kg; D=0.88 kg; PSE=0.01), and ADFI (C=2.32 kg; L=2.35 kg; D=2.39 kg; PSE=0.04) were similar (P>0.27) among treatments. Pigs fed L exhibited similar (P=0.90) G:F compared to pigs fed D, but tended (P=0.09) to have lower G:F compared to pigs fed C (C=0.380; L=0.367; D=0.370; PSE=0.004). Inclusion of 20% LS-DDG in diets for growing-finishing pigs supports ADG and ADFI similar to that of diets containing 20% DDGS. However, gain efficiency of pigs fed 20% LS-DDG may decline slightly compared to pigs fed corn-soybean meal diets.

¹Department of Animal Science, University of Minnesota, St. Paul
²West Central Research and Outreach Center, Morris
³University of Minnesota, Morris
⁴Southern Research and Outreach Center, Waseca

Influence of rapid introduction and removal of dietary corn distillers dried grains with solubles (DDGS) on pig performance and carcass characteristics

A.M. Hilbrands¹, L.J. Johnston¹, G.C. Shurson², and I. Kim²

Due to price fluctuation the dietary inclusion of DDGS may only be economical intermittently throughout the growing-finishing period. A study was conducted to determine the effects of rapid introduction and removal of DDGS from growing-finishing pig diets on growth performance and carcass composition. Crossbred pigs (n=216; BW = 51.3 ± 3.1 kg) were blocked by weight and assigned randomly to one of 24 pens (9 pigs/pen). Pens within a block were assigned randomly to one of 4 dietary treatments fed in 3 phases. Dietary treatments consisted of a corn-soybean meal control (D0), a corn-soybean meal diet containing 20% DDGS fed throughout the study (D20), D20 and D0 diets alternated bi-weekly (D20SW), and a 40% DDGS diet alternated bi-weekly with the D0 diet (D40SW). There were 5 bi-weekly feeding periods with pigs assigned to D20SW and D40SW treatments starting and ending the trial consuming DDGS diets. There were no differences in ADG among treatments but D20SW pigs tended to have heavier final BW (P<0.09) than D40SW pigs. Pigs assigned to D40SW tended to have lower ADFI (P<0.07) than D20 pigs. Pigs assigned to D20SW had better gain efficiency (P<0.05) than D20 pigs. At harvest, D0, D20, and D20SW pigs had heavier HCW (P<0.01) than D40SW pigs but 10th rib backfat depth, loin eye area and percent carcass lean were not affected by treatment. These results suggest that the rapid inclusion and removal of 20% DDGS from growing-finishing pig diets will not adversely affect pig performance or carcass characteristics but that at 40% DDGS inclusion levels it may reduce ADFI and HCW.

¹West Central Research and Outreach Center, University of Minnesota, Morris
²University of Minnesota, St. Paul

Use of crude glycerol, a biodiesel co-product, in diets for lactating sows

S.J. Schieck¹, L.J. Johnston², B.J. Kerr³, S.K. Baidoo⁴, and G.C. Shurson¹

An experiment was conducted to evaluate the dietary effects of crude glycerol in lactating sow diets on sow and litter performance.  Mixed parity (range = 0 to 13) sows (n=345; 253 + 24 kg BW) were assigned randomly within gestation housing location and parity to 1 of 4 dietary treatments. The treatments were: a corn-soybean meal based diet (CON), CON + 3% glycerol (GLY3), CON + 6% glycerol (GLY6), or CON + 9% glycerol (GLY9). Dietary treatments were imposed on d 109 of gestation when sows moved into farrowing rooms. From d 109 of gestation until farrowing, sows received 2.25 kg/d of their assigned diet. At farrowing, sows were allowed ad libitum access to feed throughout lactation. Sows and litters were weighed on d 0 of lactation, after litter size was standardized within treatments to 10 pigs, and at weaning. Last rib backfat depth was recorded ultrasonically on d 0 and at weaning. Milk samples were collected at weaning from a randomly pre-selected group of sows (n=84; 21 sows/treatment). Dietary treatment tended (P<0.08) to influence ADFI. Inclusion of up to 9% crude glycerol had no effect on sow weight or backfat losses, wean-to-estrus interval within 10 d, litter size at weaning, or ADG of piglets. Dietary treatment had no effect on moisture, crude protein, crude fat, lactose, or ash content of sow’s milk. Results from this study suggest that lactating sows fed diets containing up to 9% crude glycerol perform similar to sows fed a standard corn-soybean meal control diet.

¹Department of Animal Science, University of Minnesota, St. Paul
²West Central Research and Outreach Center, University of Minnesota, Morris
³USDA-ARS, Ames, IA
⁴Southern Research and Outreach Center, University of Minnesota, Waseca

Evaluation of crude glycerol, a biodiesel co-product, in growing pig diets to support growth and improve pork quality

S.J. Schieck¹, L.J. Johnston², G.C Shurson¹, and B.J Kerr³

Two-hundred sixteen crossbred pigs (BW = 31.28 + 1.76 kg) were used to determine the effects of long-term and short-term feeding of glycerol on growth performance, carcass traits, and muscle quality of growing-finishing pigs. Pigs were blocked by initial BW, and pens within blocks were assigned randomly to 1 of 3 dietary treatments in a 4-phase feeding program (24 pens, 9 pigs/pen). Dietary treatments were: Control - a corn-soybean meal based diet (CON); Long-term – CON + 8% glycerol fed throughout the entire experiment (LT); and Short-term – pigs fed CON for the first 6 weeks followed by CON + 8% glycerol fed during the last 8 weeks of the experiment (ST). Pigs fed LT had higher (P<0.05) ADG and pigs fed ST tended (P=0.07) to grow faster than CON. Pigs assigned to LT but not ST expressed greater (P<0.05) ADFI compared to CON. Dressing percentage for pigs on LT and ST treatments was not different from CON fed pigs. Fat-free lean percentage tended (P<0.10) to be greater in CON pigs than LT pigs. Short-term glycerol feeding increased (P<0.05) belly firmness compared to CON, and tended (P<0.10) to have firmer bellies than LT fed pigs. Dietary treatments had no effect on total moisture loss or subjective color, marbling, and firmness scores of loins. Growing-finishing pigs fed diets containing 8% crude glycerol achieved growth performance similar to pigs fed a typical corn-soybean meal diet. Effects of crude glycerol on carcass traits appear to be limited to improvements in belly firmness with shorter-term feeding regimens.

Trait

CON

LT

ST

PSE

Initial wt., kg

31.47

31.33

31.03

0.15

Final wt., kg

126.7

128.9

128.9

0.78

ADG, kg

0.96^b

1.00^a

0.99^ab

0.01

ADFI, kg

2.78^a

2.93^b

2.86^ab

0.03

Dressing percent, %

74.5^ab

74.9^a

74.3^b

0.15

Fat-free lean, %

53.3^x

52.2^y

52.6^xy

0.34

Belly firmness, degrees

30.27^a

35.30^ab

42.26^b

2.27

Loin total drip loss, %

3.18

3.22

3.60

0.46

Loin color score

3.84

3.80

3.77

0.12

Loin marbling score

2.47

2.57

2.51

0.20

Loin firmness score

2.31

2.66

2.26

0.17

 ^abMeans with unlike superscripts differ (P<0.05).
 ^xyMeans with unlike superscripts tend to differ (P<0.10).

¹Department of Animal Science, University of Minnesota, St. Paul
²West Central Research and Outreach Center, University of Minnesota, Morris, MN
³USDA-ARS, Ames, IA

- 2008 -

Effect of reduced nocturnal temperature for early-weaned pigs on performance and energy consumption

R.C. Thaler¹, L.J. Johnston², M.C. Brumm³, and M.S. Carlson-Shannon⁴

The objective of this project was to determine the effect of a reduced nocturnal nursery temperature regimen on performance of early-weaned pigs and energy consumption during the nursery phase. A common protocol was developed and 4 universities (South Dakota State Univ., Univ. of Minnesota, Univ. of Nebraska-Lincoln, and Univ. of Missouri) each ran two trials in the fall, winter or spring months. Two nursery rooms were used and the experimental treatments were: Control (CON - 30 C at pig height at weaning lowered 2 C per week) and Reduced Nocturnal Temperature (RNT - beginning on day 7 post weaning, target temperature lowered 6 C from 1900 to 0700 h from CON, but then returned to CON from 0700 to 1900 h). Prior to day 7, CON regimen was employed in the RNT treatment as well. Performance was measured weekly in the nursery phase (35-42 d), and electrical and heating fuel usage recorded weekly. Data from SDSU were dropped from the analysis due to a confounding factor within the building. A total of 1,258 weaned pigs weighing 6.2 kg were used in the 6 trials. Nursery ADG (.43 kg/d), ADFI (.62 kg/d), and Gain/Feed (.685) were identical for the CON and RNT pigs. There were no statistical differences in BTU usage/pig (405,447  vs 334,049 ) or Kwh usage/pig (5.6 vs 5.0) between CON and RNT treatments. However, the lack of significant treatment effects on energy usage could have been due to the large standard error associated with these two variables. Heating fuel use (BTU/pig) was numerically reduced by 17.4% and Kwh/pig was reduced by 9.5% for the pigs in the RNT treatment. Assuming these results are repeatable, producers can save money through lower propane and electrical costs by reducing nocturnal temperature the second week after weaning for early-weaned pigs without affecting growth performance. This project was funded by the National Pork Checkoff.

¹South Dakota State University, Brookings
²West Central Research and Outreach Center, University of Minnesota, Morris
³University of Nebraska, Lincoln
⁴University of Missouri, Columbia

- 2007 -

RNA interference of mouse CFTR function; towards a pig model of cystic fibrosis

D.F. Carlson^1,2, A.M. Geurts², M. Palmer-Densmore¹, C. Won Park³, W. Warwick⁴, C. Steer³, C. Milla⁴, S. O'Grady¹, D.A. Largaespada², and S.C. Fahrenkrug^1,2

Although mouse models of CF have been generated that manifest some of the electrophysiologic characteristics of CF, their benign pulmonary phenotype renders these models incomplete. Pigs may provide a superior model given the importance of CFTR in the transport of chloride, bicarbonate and fluid across their pulmonary mucosa. Pigs may also represent a better model for the development of gene therapeutics given that their bronchial branching, vascular distributions, and morphologic characteristics are strikingly similar to humans. We have undertaken the development of a porcine model of CF by transpositional transgenesis (TnT) with shRNA expressing transposons. As proof of principle, mice were created by pronuclear injection of a CpG methylated and nonmethylated Sleeping Beauty (SB) transposon driving the expression of a short hairpin RNA directed against the mouse CFTR mRNA (shCFTR). Mouse transgenesis was extremely efficient using the methylated transposon (90%), and was accompanied by erasure of transgene methylation and reliable expression from both pol II and pol III promoters. Several F1 animals with distinct TnT insertions displayed phenotypes consistent with CF, including impairment of chloride transport in colonic epithelia and impairment of reproduction.

In vitro CF models in cultured pig endometrial epithelial cells by TnT with analgous transposons reduced CFTR mRNA and chloride channel transport by 90-94%. Several transgenic pig fibroblast clones were developed as nuclear donors for somatic cell nuclear transfer (SCNT) and characterized for shRNA expression by quantitative PCR. A selected fibroblast cell line was cloned at the National Swine Resource and Research Center and resulted in the birth of 7 healthy piglets harboring the same transgene insert locus. While the presence of the transposon and expression of a Pol II transcript was confirmed by PCR from ear and tail biopsy, expression of the shCFTR hairpin was not detected. Founder pigs will be sacrificed and characterized for shRNA expression and levels of CFTR mRNA in relevant tissues. Alternatively, our remarkable transgenesis rate at multiple loci and accurate recapitulation of the CF phenotype in mice provides a compelling argument for production of founder pigs by pronuclear TnT.

¹Animal Biotechnology Center and Department of Animal Science, University of Minnesota
²Arnold and Mabel Beckman Center for Transposon Research, University of Minnesota
³Department of Medicine, University of Minnesota
⁴Department of Pediatrics, University of Minnesota

A toolbox for transgenesis and functional annotation of the porcine genome

K.J. Clark^1,2, D.F. Carlson^1,2, L.K. Foster¹, A.R. Bents¹, and S.C. Fahrenkrug^1,2

The swine genome-sequencing initiative has been undertaken to aid in the annotation of a species with importance to both animal agriculture and biomedicine. Comparative information from human and model organism genomes will provide useful information for annotating the function of pig genes. However, the function of the majority of vertebrate genes remains to be determined. Transposons have historically played an important role in the annotation of invertebrate and plant genomes by transgenesis and insertional mutagenesis. For transgenesis, transposons offer an efficient and precise mechanism for the integration of DNA that avoids incorporation of CG-rich vector DNA and multi-copy transgene concatemerization that can lead to suppression of gene expression. For insertional mutagenesis, transposons tag mutated loci, facilitating the isolation and annotation of affected genes. Recently, these tools have been applied to the annotation of mouse and zebrafish gene function at the Beckman Center for Transposon Research. We have also begun to apply transposons and recombinases to the manipulation and annotation of the porcine genome. We have developed and tested a transposon toolbox (including Sleeping Beauty, Tol2, piggyBac, and a novel transposon from P. platessa) in pig cells, observing up to a 50-fold increase in the rate of transgenesis. CRE and FLP recombinases have effectively been applied to conditional gene expression and selection-cassette recycling in pig cells. Strategies for the application of transposons and recombinases to swine transgenesis and functional gene annotation will be discussed.

¹Animal Biotechnology Center and the Department of Animal Science, University of Minnesota
²Arnold and Mabel Beckman Center for Transposon Research, University of Minnesota

Selected additives do not improve flowability of dried distillers grains with solubles (DDGS) in commercial systems

L.J. Johnston¹, A.M. Hilbrands¹, G.C. Shurson², and J. Goihl³

An experiment was conducted at a commercial, dry-grind ethanol plant to determine if selected additives would improve flowability of DDGS. Experimental treatments were imposed on 4 different days in a 2 x 4 factorial arrangement. Main treatment effects were moisture content of DDGS (9 vs 12%) and flowability additive (FA). The FA treatments were: No additive (CON); a moisture migration control agent at 0.25% (DMX-7, Delst, Inc.); calcium carbonate at 2% (CA, Unical-P, ILC Resources); or a clinoptilolite zeolite at 1.25% (ZEO, St Cloud Zeolite, St. Cloud Mining Co.). The FA were added at the desired level to about 2,250 kg of DDGS using a vertical-screw feed mixer. After 3 min of mixing, batches of DDGS were weighed and loaded into one of eight compartments in an auger-equipped feed truck. After loading, the truck traveled 250 km, sat idle for at least 60 h, and traveled 250 km back to the ethanol plant. Time required to unload each compartment was recorded. Samples of each lot were collected at loading for analysis of moisture content and angle of repose (AOR). The statistical model included effects of moisture level, FA, and their interaction. There were no significant interactions between moisture level and FA for any response criteria. Mean moisture levels were 9% and 11.6% for low and high moisture treatments. Flow rate of DDGS at unloading was higher (P<0.05) for the 9% compared with 12% moisture level (620 vs. 390 kg/min). Similarly, drained AOR at loading (57.7 vs. 65.7°) and poured AOR after storage (40.9 vs. 42.0°) were lower (P<0.05) for 9% compared with 12% DDGS. Flow rates of DDGS at unloading were: 509 (CON), 441 (DMX-7), 512 (CA), and 558 (ZEO) kg/min. None of the FA created flow rates that differed significantly from CON. Drained AOR at loading was higher (P<0.05) for DMX-7 compared with CON, CA, and ZEO (65.1 vs. 61.0, 60.4, 60.3°, respectively). Poured AOR after storage was not affected by FA. In conclusion, increasing moisture content from 9 to 11.6% clearly decreased flowability of DDGS. The FA used in this experiment at the selected concentrations did not improve flowability of DDGS.

¹West Central Research and Outreach Center, University of Minnesota, Morris
²Department of Animal Science, University of Minnesota, St. Paul
³Agri-Nutrition Services, Inc., Shakopee, MN

Injectable progesterone does not reduce mid to late pregnancy failure of sows during summer infertility

L.J. Johnston¹, E. Keetelaar², and R.J. Smits²

Reproductive failure is an important cause of culling sows. Pregnancy failure due to irregular returns to oestrus and non-pregnant sows at expected farrowing can account for 14 % of non-age based culling of sows. Social stresses are related to increased rate of pregnancy failure and may be mediated through a decline in plasma progesterone (P₄). Low P₄ may occur during seasonal infertility or when sows are relocated or mixed in groups after pregnancy diagnosis. Sows may benefit from exogenous P₄ during these stressful periods. Spanish researchers supplemented lactating dairy cattle with P₄ and reduced pregnancy loss. In an earlier experiment, we observed a trend for improved farrowing rate when sows received one intramuscular (i.m.) injection of 125 mg P₄ on day 42 postcoitum. These results required verification with a statistically valid sample size.

We hypothesized that a single injection of P₄ on day 34 post-mating would increase the proportion of sows remaining pregnant to full term when subjected to stresses associated with mixing social groups and environmental conditions during seasonal infertility. Large White x Landrace F₁ sows (n=522) were selected randomly from matings conducted during late summer (Week 2 through 8) in a commercial production unit in Victoria. Sows were mated artificially and housed in individual stalls from weaning through 34 ± 1.5 days post-mating. On day 34 post-mating after positive diagnosis of pregnancy by ultrasound, sows were moved from stalls to group pens of 17-18 sows per pen (1.4 m²/sow). Treated sows received one i.m. injection of 125 mg P₄ (Jurox Progesterone) in the neck while control sows received no injection. Sows were housed in pens from day 34 post-mating until farrowing or the sow failed to farrow. Categorical data were analysed using Chi square. Treatment effects on litter size were analysed using analysis of variance with sow parity (range = 0 to 8) used as a covariate.

Progesterone injection did not affect the incidence of pregnancy failure after week five of gestation in this experiment (Table 1). Overall, 12.6 % of sows confirmed pregnant at five weeks of gestation failed to maintain pregnancy and typified seasonal infertility on this farm. There were no interactions between P₄ treatment and sow parity or week of mating for pregnancy loss. Litter size at farrowing was not affected by P₄ treatment. Distribution of litter sizes at subsequent farrowing (range = 3 to 18 live pigs) was not affected by P₄ treatment (χ2 = 3.94; P<0.42).

We conclude that one i.m. injection of P₄ at the time of moving sows from stalls to group pens at week five of gestation does not reduce pregnancy loss during a time of seasonal infertility.

¹West Central Research and Outreach Center, University of Minnesota, Morris
²QAF Meat Industries, Corowa, New South Wales

Effects of familiarity and weight variation on aggression among grow-finish pigs following regrouping

Y.Z. Li and L.J. Johnston
West Central Research and Outreach Center, University of Minnesota, Morris

An experiment was conducted to study effects of familiarity and weight variation at regrouping on aggression and growth performance of pigs. Pigs (n=180) at 8 wk of age (BW=23.0 ± 3.11 kg) from 3 group farrowing rooms where they mingled within each room from 10 d of age were used. Five groups of 9 pigs (5 males:4 females) were allotted to each of the four treatments: familiar pigs of uniform BW, familiar pigs of mixed BW, unfamiliar pigs of uniform BW and unfamiliar pigs of mixed BW. Familiar groups consisted of pigs from one farrowing room, and unfamiliar groups consisted of 3 pigs from each of the 3 farrowing rooms. Uniform groups were formed by using the middle 2 quartiles and the mixed weight groups by using the heaviest and lightest quartiles of pigs. Aggression and activity were observed directly for 4 h during the first 3 d, on d 7, and d 14 post regrouping. Skin lesions on head, shoulders and body were scored (scale 0-3 based on the number of scratches) on all pigs 48 h post regrouping. Total fighting durations were higher in unfamiliar groups during the first (48.5 vs. 0.5 s/(pig.4h), SE=15.39; P<0.001) and second day (10.8 vs. 0.4 s/(pig.4h), SE=4.58; P<0.005) post regrouping than in familiar groups. Unfamiliar pigs had higher total injury scores (6.5 vs. 1.2, SE=0.40; P<0.001) and spent less time eating during the first day (5.2 vs. 8.9%, SE=1.31 of total observation time; P<0.01) post regrouping than familiar pigs. There was an interaction (P<0.02) in injury score between familiarity and BW variation as pigs of mixed BW compared with uniform BW increased injury scores in unfamiliar groups but not in familiar groups. ADG in unfamiliar groups was lower during the initial 6 wk (809 vs. 849 g/d, SE=11.2; P<0.001) but not for the entire 15 wk (806 vs. 821 g/d, SE=9.7; P=0.11) compared with familiar groups. Familiarity did not affect ADFI or G:F. Sorting pigs by familiarity and weight at mixing could be beneficial in terms of alleviating aggression-associated injuries.     

- 2006 -

Dietary supplementation of oregano essential oils (OEO) in gestation and lactation sow diets and its effect on reproductive performance of sows, growth pattern of piglets and their immune status

C. Ariza-Nieto, S.K. Baidoo, R. Walker, M.R. Hathaway, M. Bandrick, and T.W. Molitor
University of Minnesota, St. Paul

This study involved supplementation of OEO in gestation and lactation diets on sow reproductive and suckling pig performance. Twenty four hours after breeding, 144 sows were randomly assigned to control and oregano (OEO 250ppm, Regano500®). Blood was collected via jugular from 6 randomly chosen sows per treatment and their litter at farrowing (piglets bled before and after suckling), 7, and 14 days of lactation. Colostrum and milk samples were collected on these days. T lymphocytes were phenotyped (γδ, CD8, CD4) from whole blood. Natural cytotoxicity was used to assess innate immunity in pigs. To evaluate growth rates due to OEO supplementation, 630 piglets were individually identified and weighed at 1, 5, 9, 12, 16, and 19 days of age. The number of live born piglets was higher when sows were supplemented with OEO during gestation (+1.1 piglets, P<0.05). Sows fed OEO during gestation-lactation improved litter weaning weight and litter weight gain (2.7 and 3.3 kg; P<0.05) compared to control. Wean to service interval was lower in OEO fed sows compared to control (5 v 8 days). Growth rate of piglets was higher (P<0.01) in sows fed OEO on 1-5, 9-12, and 16-19 days of lactation. The percentage of γδ lymphocytes isolated from piglets before suckling from sows fed OEO was greater (P<0.05) than control, although no differences were observed after suckling. These pigs also demonstrated greater natural killer (NK) activity throughout lactation, and significantly greater NK activity before suckling (P<0.01). OEO supplementation during gestation and lactation shows a biological growth potential on suckling piglets.

Eating sequences of gestating sows in group housing with electronic sow feeders

Y.Z. Li^1,2 and H.W. Gonyou¹

Electronic sow feeders (ESF), a sequential feeding system, have been used in group housing of gestating sows to control individual intake and aggression during feeding. However, the effect of sequential feeding on sow eating behaviour and performance is not clear. A hypothesis was that gestating sows may adapt to sequential feeding systems by establishing a feeding order. An experiment was carried out to study the feeding order of gestating sows in group housing with ESF. A total of 146 sows in parity 1 to 6 were studied in seven static groups. Each of the three pens used was equipped with an ESF and accommodated 36±2.1 (SD) sows. Space allowance was 2.1 m2 per sow. Sows from two breeding groups were simultaneously moved into each pen, one group at 5 d (pre-implantation) and another at 40 d (post implantation) post breeding. All sows were limited fed according to their nutritional requirements. Feeding cycle started at 3 pm daily. Feeding order was recorded at d 3 and d 56 (wk 8) post mixing by the computer which controlled the feeding system. Feeding order score was calculated for each individual sow (Feeding order score = (p–1) / (n-1); where p = sow’s numerical position within the feeding order, n = total number of sows ate in the feeder). Weight gain during gestation and farrowing data (total born, live born, dead born) were collected. The results showed that 80-90% of sows entered ESF and ate their ration voluntarily on d 3 post mixing. Pre-implantation sows ate earlier than post-implantation (P<0.01) and mature sows (parities 3 to 6) ate before sows in parity 1 and 2 (P<0.05) in feeding order on d 3. On wk 8, neither sow parity nor gestation stage affected feeding order. There was not correlation in feeding order scores between day 3 and wk 8. Higher feeding order scores (ate later) did not affect farrowing performance and weight gain during gestation. These results suggest that gestating sows can not adapt to sequential feeding systems by establishing and maintaining a feeding order. Although reproduction performance was not affected by feeding order, sow competition for the feeder raised welfare concerns in sequential feeding systems.

¹Prairie Swine Centre, Saskatoon, Canada
²West Central Research & Outreach Center, University of Minnesota, Morris

Factors related to piglet pre-weaning mortality in a bedded group farrowing system

Y.Z. Li, L.J. Johnston, and A.M. Hilbrands
West Central Research & Outreach Center, University of Minnesota, Morris

Recently there has been increased interest in loose farrowing systems in North America due to sow welfare concerns. However, piglet mortalities of 25 to 33% have been reported in these systems. We investigated factors related to piglet mortality in a group farrowing system. A total of 156 sows (Landrace x Yorkshire) in parity 0 to 5 and their litters were studied in three farrowing rooms. All sows were group housed during gestation, and moved to the farrowing room one wk before expected farrowing dates.  Each farrowing room (9.6 x 10.8 m) was equipped with eight straw-bedded, ‘get-away’ pens (2.4 x 3.0 m) to accommodate eight sows and their litters. A communal eating/drinking/dunging area was provided in each room.  The pens were removed about d 10 post farrowing, so sows and their litters mingled in a group.  Minimal cross fostering was conducted within 2 d of farrowing. Piglets were weaned at 28 to 36 d of age. The PROC MIXED procedure of SAS was used to analyze effects of sire breed (Yorkshire vs Landrace) of the sows, sire breed (Duroc, Yorkshire vs Landrace) of the litter, birth location of the sows (group vs crate), previous farrowing location (group vs crate), and sow parity on total born, live born, number of piglets nursed and weaned, and piglet mortality. Overall pre-weaning mortality of piglets was 27%. Piglet mortality increased with increasing sow parity (from Parity 0=22.5% to Parity 3~5=34.0%; SE=3.87%, P=0.06), which was coincident with increasing litter size (from Parity 0=11.1 to Parity 3~5=13.5 total piglets born/litter; SE=0.61, P=0.01). Piglet mortality was greater for Landrace-sired sows compared with Yorkshire-sired sows (30.8 vs 23.4 ±2.37 %; SE=3.15%, P=0.05), possibly due to the larger litter size of Landrace-sired sows (P=0.05). There was a positive correlation (R2=0.75, P<0.01) between litter size and average pre-weaning mortality of piglets. Sire breed of the litter, sow birth place, and previous farrowing location did not affect piglet mortality. In the current study litter size at farrowing appeared to be the primary factor influencing piglet mortality in a bedded, group farrowing system. 

Evaluation of regional differences in nutrient composition and physical characteristics among six U.S. soybean meal sources

P.E. Urriola¹, M.H. Whitney², N.S. Muley¹, and G.S. Shurson¹

A total of 86 soybean meal (SBM) samples were collected monthly from July 2003 to December 2004 from 6 soybean processing plants (SPP) located in two regions (R): North Carolina (n=13), South Carolina (n=13), and Alabama (n=12) in the southern region (SR), and two Minnesota (n=14, respectively) and one South Dakota SPP (n=20) in the Northern region (NR). Subsamples were sent to Iowa Testing Laboratory (Eagle Grove, IA) for proximate and mineral analysis, and to the University of Missouri for amino acid analysis. Additional sub-samples were analyzed for bulk density and particle size. All nutrient values were expressed on a DM (%) basis. Total content of CP (55.23 ± 0.14) and ash (7.02 ± 0.05) content were influenced by year, R, and SPP (P<0.01). However, crude fat (1.68 ± 0.05) was affected only by SPP (P<0.01), while crude fiber (3.77 ± 0.03) was affected only by year (P=0.01). Samples from SR were higher (P=0.05) in lys (3.45 ± 0.02), met (0.77 ± 0.01), thr (2.08 ± 0.01), and trp (0.76 ± 0.01) than NR (3.38 ±0.01, 0.74 ± 0.01, 2.00 ± 0.01, and 0.73 ± 0.01, respectively). Total AA content and total non-essential AA were higher (P<0.01) for SR compared to NR. Total CP in SBM was poorly correlated with total lysine content (r2=0.39, P<0.01). Concentrations of P, K and Mn were higher (P<0.01) in samples from SR than NR. However, Ca, Mg, Na, S and Zn content was similar (P=0.35) between R. Average particle size (µm) was higher (P>0.01) in NR (851 ± 33) compared to SR (731 ± 31). Bulk density (kg/m3) was similar (P=0.41) between R (532 ± 3). Mean particle size and bulk density values were different (P>0.01) between SPP. Although there were significant differences in nutrient content and physical characteristics of soybean meal samples among regions, year, and SPP, these differences were small and of minimal consequence when formulating practical animal diets.

¹Department of Animal Science, University of Minnesota, St Paul
²University of Minnesota Extension Regional Center, Mankato