Estimates of genetic parameters among scale activity scores, growth, and fatness in pigs1,2

Posted in: Production, Welfare by admin on July 29, 2011 | No Comments

Genetic parameters for scale activity score (AS) were estimated from generations 5, 6, and 7 of a randomly selected, composite population composed of Duroc, Large White, and 2 sources of Landrace (n = 2,186). At approximately 156 d of age, pigs were weighed (BW) and ultrasound backfat measurements (BF1, BF2, and BF3) were done. While pigs were in the scale, an AS was assigned, which ranged from 1 (calm) to 5 (highly excited), where 58.1, 28.5, 8.9, 4.0, and 0.5% were scored as 1, 2, 3, 4, and 5, respectively. Statistical model effects were year-week of measurement, sex, covariates of age for AS and BW or BW for BF1, BF2, and BF3, and an animal direct genetic effect. A 5-trait linear mixed model was used. Estimated heritabilities were 0.23, 0.54, 0.56, 0.52, and 0.48 for AS, BW, BF1, BF2, and BF3, respectively. Estimated genetic correlations between AS and BW, AS and BF1, AS and BF2, and AS and BF3 were −0.38, −0.11, −0.12, and −0.16 respectively. Results indicated AS had a heritable genetic component and was genetically correlated with performance traits. Estimated genetic correlations between AS and backfat measurements adjusted to a common BW were negative, as was the genetic correlation of AS with BW. Therefore, selection for more docile animals would be expected to result in fatter, faster growing pigs.

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Maternal responses to daily maternal porcine somatotropin injections during early-mid pregnancy or early-late pregnancy in sows and gilts

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Piglet neonatal survival and postnatal growth and efficiency are positively related to birth weight. In gilts, daily maternal porcine ST (pST) injections from d 25 to 100 (term approximately 115 d), but not d 25 to 50, of pregnancy increase progeny birth weight. Daily maternal pST injections from d 25 to 50 increase fetal weight at d 50 in gilts and sows. We therefore hypothesized that daily pST injections from d 25 to 100, but not d 25 to 50, of pregnancy would increase birth weight similarly in both parities. Landrace × Large White gilts and sows were uninjected (controls) or were injected daily with pST (gilts: 2.5 mg/d; sows: 4.0 mg/d, each approximately 15 μg of pST/kg per day) from d 25 to 50 or 100 of pregnancy. Litter size and BW were recorded at birth, midlactation, and weaning. Dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 25 to 100, but not d 25 to 50, increased mean piglet birth weight by 11.6% in sows and by 5.6% in gilts. Both pST treatments decreased litter size by approximately 0.6 live-born piglets. In sows, maternal pST treatment from d 25 to 100 increased culls at weaning. In remated dams, prior treatments did not affect the weaning-remating interval, conception rate, or subsequent litter size. Greater pST-induced birth weight increases in sows than in gilts may mean that underlying metabolic or placental mechanisms for pST action are constrained by maternal competition for nutrients in rapidly growing gilts.

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The insulin-like growth factor 2 ( IGF2 ) gene intron3-g.3072G>A polymorphism is not the only Sus scrofa chromosome 2p mutation affecting meat production and carcass traits in pigs: Evidence from the effects of a cathepsin D ( CTSD ) gene polymorphism

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The objective of this study was to evaluate the effects of mutations in 2 genes [IGF2 and cathepsin D (CTSD)] that map on the telomeric end of the p arm of SSC2. In this region, an imprinted QTL affecting muscle mass and fat deposition was reported, and the IGF2 intron3-g.3072G>. A substitution was identified as the causative mutation. In the same chromosome region, we assigned, by linkage mapping, the CTSD gene, a lysosomal proteinase, for which we previously identified an SNP in the 3′-untranslated region (AM933484, g.70G>A). We have already shown strong effects of this CTSD mutation on several production traits in Italian Large White pigs, suggesting a possible independent role of this marker in fatness and meat deposition in pigs. To evaluate this hypothesis, after having refined the map position of the CTSD gene by radiation hybrid mapping, we analyzed the IGF2 and the CTSD polymorphisms in 270 Italian Large White and 311 Italian Duroc pigs, for which EBV and random residuals from fixed models were calculated for several traits. Different association analyses were carried out to distinguish the effects of the 2 close markers. In the Italian Large White pigs, the results for IGF2 were highly significant for all traits when using either EBV or random residuals (e.g., using EBV: lean cuts, P = 2.2 × 10−18; ADG, P = 2.6 × 10−16; backfat thickness, P = 2.2 × 10−9; feed:gain ratio, P = 2.3 × 10−9; ham weight, P = 1.5 × 10−6). No effect was observed for meat quality traits. The IGF2 intron3-g.3072G>A mutation did not show any association in the Italian Duroc pigs, probably because of the small variability at this polymorphic site for this breed. However, a significant association was evident for the CTSD marker with EBV of all carcass and production traits in Italian Duroc pigs (lean content, ADG, backfat thickness, feed:gain ratio) after excluding possible confounding effects of the IGF2 mutation. The effects of the CTSD g.70G>A mutation were also confirmed in a subset of Italian Large White animals carrying the homozygous genotype IGF2 intron3-g.3072GG, and by haplotype analysis between the markers of the 2 considered genes in the complete data set. Overall, these results indicate that the IGF2 intron3-g.3072G>A mutation is not the only polymorphism affecting fatness and muscle deposition on SSC2p. Therefore, the CTSD g.70G>A polymorphism could be used to increase selection efficiency in marker-assisted selection programs that already use the IGF2 mutation. However, for practical applications, because the CTSD gene should not be imprinted (we obtained this information from expression analysis in adult skeletal muscle), the different modes of inheritance of the 2 genes have to be considered.

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Relationships between colostrum production by primiparous sows and sow physiology around parturition

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Relationships between hormonal and metabolic changes around parturition and colostrum yield and composition were investigated in 16 Landrace × Large White primiparous sows. Blood samples were taken daily from d 105 of pregnancy to d 2 postpartum (with d 0 being the day of parturition). Colostrum samples were taken at the onset of parturition (T0), and then 3, 6, and 24 h later (T3, T6, and T24, respectively). Colostrum yield was calculated from the beginning of parturition until 24 h later by adding colostrum intake of individual piglets, which was estimated from their BW gain. Colostrum yield averaged 3.22kg. Four sows had very low colostrum production (1.10kg; n = 4), whereas the others produced between 2.83 and 4.64 kg of colostrum (3.93kg; n = 12). Compared with the high-colostrum-producing sows, the low-colostrum-producing sows tended to have greater plasma concentrations of progesterone during the 20-h prepartum and tended to have smaller plasma concentrations of prolactin 40 and 30 h before parturition. Sows with a low colostrum yield had greater plasma concentrations of glucose than sows with a high colostrum yield from d −9 to −2. At the onset of parturition, colostrum from lowproducing sows had greater percentages of DM, lipids, and GE, but less lactose, than that from high-producing sows. The Na:K ratio in colostrum during the 6 h postpartum was greater in low-producing sows than in high-producing sows, indicating that cellular junctions between epithelial mammary cells were less tightly closed. Concentrations of IgG in colostrum varied greatly between sows and decreased by approximately 80% between T0 and T24. Within high-producing sows, concentrations of IgG in colostrum at T0, T3, and T6 were negatively correlated with lactose concentrations in colostrum at the same times and were positively correlated with plasma concentrations of IGF-I measured from d −9 to 0. In contrast, no correlation was found between IgG concentrations in colostrum at any time and prolactin, estradiol-17β, progesterone, or cortisol. In conclusion, sows that produced a low yield of colostrum were characterized by a leaky mammary epithelium and reduced synthesis of lactose, related to delayed hormonal changes before parturition.

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Altrenogest treatment during late pregnancy did not reduce colostrum yield in primiparous sows

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The decrease in circulating concentrations of progesterone is the lactogenic trigger in many species. The aim of the present study was to determine the effect of an orally active progestogen, altrenogest, administered in late gestation, on lactogenesis in sows. Gilts were treated with altrenogest (20 mg/d) from d 109 to 112 of gestation (ALT112, n = 6) or d 113 (ALT113, n = 8) or were not treated (control, n = 9). Colostrum production, estimated from the BW gains of the piglets, was measured during 24 h starting at the onset of parturition. Colostrum samples were collected at the onset of parturition until 48 h later. Jugular blood samples were taken from d −8 prepartum until d 3 postpartum. Altrenogest treatment extended the gestation length of ALT113 sows in comparison with control sows (116.3 vs. 114.7d). Litter size and litter weight at birth did not differ between groups. Estimated colostrum yield was not reduced in altrenogest-treated sows compared with control sows (4.20 kg) and tended to be greater in ALT112 (4.73 kg) than in ALT113 sows (3.74 kg). Altrenogest reduced endogenous progesterone concentrations during the 2 d prepartum in ALT113 relative to control sows, likely because luteolysis occurred earlier in relation to parturition in ALT113 sows. Altrenogest reduced estradiol-17β concentrations during the 2 d prepartum in ALT113 and ALT112 sows. Altrenogest treatment did not influence the timing of the prepartum peak of prolactin in relation to parturition. The ALT113 sows had lesser concentrations of lactose in plasma and a lesser Na:K ratio in colostrum after parturition than Control and ALT112 sows, indicating that the junctions between their mammary epithelial cells were tighter. Concentrations of colostral IgG in sows that received altrenogest tended to be less than in control sows. In conclusion, altrenogest administered from d 109 to 112 or 113 of pregnancy did not affect lactogenesis in sows, possibly because the treatment delayed farrowing and main hormonal changes without affecting the relative chronology of these changes.

For more information the full article can be found at http://jas.fass.org/

Fumonisin B1 and implications in nursery swine productivity: A quantitative exposure assessment

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This study estimated the long-term exposure of fumonisin B1 (FB1) in nursery swine diets and associated toxicological adverse effects on negative productivity potential using quantitative exposure assessment. Fumonisin B1 is a mycotoxin produced by Fusarium verticillioides and Fusarium proliferatum and is a common biological contaminant of corn (Zea mays L.) and other grains. Acute effects from FB1 exposures are well recognized and managed in the swine industry, but practices to limit prolonged low-dose exposures to FB1 have been less fully considered and may negatively affect production efficiency. Deterministic (single-point estimates) and stochastic (probabilistic) modeling were performed for comparative analyses of FB1 exposures originating from genetically engineered Bacillus thuringiensis (Bt)-corn, conventional non-Bt corn, and distillers dried grains with solubles (DDGS). Six feeding scenarios differing in the source of corn in diets were modeled to assess variation in FB1 exposure representing a mixture of Bt and non-Bt grain and DDGS (blended); Bt grain and Bt DDGS; non- Bt grain and non-Bt DDGS; Bt and non-Bt grain; Bt grain; and non-Bt grain. Long-term exposure estimates (49-d duration) were compared with chronic levels of concern (LOC). The first LOC (LOC1; 1 mg of FB1/kg of diet, least observed adverse effects concentration) represents a decrease in ADG. Concentrations of 5 mg of FB1/kg of diet represent the second LOC (LOC2), which showed pulmonary pathological alterations and a significant dose-dependent increase in pulmonary weight. Estimates indicated LOC1 was frequently exceeded regardless of feeding scenario, but LOC2 was not attained. Diets where the corn fraction was entirely from Bt-corn showed the least FB1 exposure (exceeding LOC1 in 35% of occasions), whereas a blended diet or diets using non-Bt grain and DDGS sources more commonly exceeded this threshold (95% of occasions). Based on these estimates, under blended corn source feeding conditions, swine populations in nursery facilities may frequently exhibit incipient effects (i.e., LOC1) of FB1 toxicity; however, impacts on production efficiency remain uncertain.

For more information the full article can be found at http://jas.fass.org/

Oral inoculation with Salmonella enterica serovar Typhimurium or Choleraesuis promotes divergent responses in the somatotropic growth axis of swine

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Enteric disease and immune challenge are processes that have detrimental effects on the growth performance of young swine. The current study tested the hypothesis that salmonella-induced enteric disease would perturb the endocrine growth axis in a serovar-dependent fashion. Specifically, we evaluated the effects of Salmonella enterica serovar Typhimurium (Typhimurium) and serovar Choleraesuis (Choleraesuis) on critical regulatory components of growth in young swine. Weaned pigs were housed 2 per pen with ad libitum access to feed and water in a 14-d experiment. Pigs were then repeatedly fed 108 cfu of either Choleraesuis or Typhimurium in dough balls, with control pigs receiving dough without bacteria. Bacteria were re fed twice weekly. Rectal temperatures were monitored daily from d 0 to 7 and ADFI was measured through d 14. Pigs were weighed and samples of serum were obtained for circulating IGF-I on d 0, 7, and 14. At the conclusion of the study, samples of semitendinosus muscle and liver were obtained and subsequently assayed for IGF-I, IGFBP-3, and IGFBP-5 mRNA. Rectal temperatures were elevated in pigs given Choleraesuis from d 2 through 7 when compared with control pigs and pigs fed Typhimurium. Pigs receiving Choleraesuis had a substantially decreased feed intake on d 2, 3, 4, 7, 8, 9, and 10, with a trend for a reduction on d 5, and they experienced an approximately 25% reduction in BW compared with control pigs and pigs given Typhimurium by the conclusion of the study. Pigs given Choleraesuis also experienced marked reductions in circulating IGFI on d 7, with reductions of lesser magnitude on d 14. Inoculation tended to affect liver IGFBP-3 mRNA, for which expression tended to be elevated in pigs given Typhimurium and Choleraesuis. In contrast, IGFBP-3 mRNA relative abundance was increased in pigs given Typhimurium compared with control pigs. Muscle IGF-I mRNA was reduced in pigs given Choleraesuis compared with control pigs and pigs given Typhimurium. Treatment tended to affect muscle IGFBP-3 mRNA. Oral inoculation of growing pigs with Choleraesuis disrupted feed intake and BW gain, and this was accompanied by decreases in circulating IGF-I and reduced muscle expression of mRNA for IGF-I and IGFBP-3.

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The relevance of purebred information for predicting genetic merit of survival at birth of crossbred piglets

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The objective of this study was to infer (co)variance components for piglet survival at birth in purebred and crossbred pigs. Data were from 13,643 (1,213 litters) crossbred and 30,919 (3,162 litters) purebred pigs, produced by mating the same 168 purebred boars to 460 Large White-derived crossbred females and 1,413 purebred sows, respectively. The outcome variable was piglet survival at birth as a binary trait. A Bayesian bivariate threshold model was implemented via Gibbs sampling. Flat priors were assigned to the effects of sex, parity of the dam, litter size, and year month of birth. Gaussian priors were assigned to litter, dam, and sire effects. Marginal posterior means of the sire and dam variances for liability of piglet survival in purebred were 0.018 and 0.077, respectively. For crossbred, sire and dam variance estimates were 0.030 and 0.120, respectively. The posterior means of the heritability of liability of survival in purebred and crossbred and of the genetic correlation between these traits were 0.049, 0.091, and 0.248, respectively. The greatest 95% confidence region (−0.406, 0.821) for the genetic correlation between purebred and crossbred liabilities of piglet survival included zero. Results suggest that the expected genetic progress for piglet survival in crossbreds when selection is based on purebred information may be nil.

A comparison between different survival and threshold models with an application to piglet pre-weaning survival in a dry-cured ham-producing crossbred line

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Different approaches for predicting genetic merit of piglet pre-weaning survival were compared using proportional hazard, threshold (TM), and sequential threshold (STM) models. Data were from 13,924 crossbred piglets (1,347 litters), born from 2000 to 2006, and originated by mating 189 Large White C21 Gorzagri boars to 328 Large White-derived crossbred sows. A frailty proportional hazard model was fitted assuming 2 different baseline hazard functions (Cox and Weibull time-dependent model) and including sire and nursed litter as random effects. The TM and STM included the same effects as considered in the proportional hazard model. Model fitting was evaluated in terms of goodness of fit and predictive ability. The goodness-of-fit was evaluated using the local weighted regression and the mean squared error, whereas the predictive ability was assessed by using a cross-validation procedure. Estimated sire variances for piglet preweaning mortality were low, and heritability ranged from 0.04 to 0.06. All 4 models led to similar ranking of sires. Results suggest that STM may be preferred to the other models for genetic evaluation of piglet preweaning survival, both for its better predictive ability and its easier interpretation. Further, STM is computationally less demanding than survival models and allows for estimating different variance components from birth up to weaning.

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Effect of dietary n-3 fatty acids (fish oils) on boar reproduction and semen quality

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The aim of this study was to evaluate the effects of dietary supplementation with different fish oils (rich in PUFA) vs. hydrogenated animal fat (SFA) on semen production and quality, fatty acid composition, and preservation properties in boars under controlled and commercial conditions. In Exp. 1 (in a research station), 44 boars, allocated to 4 dietary treatments, received daily 2.5 kg of basal diet with a supplement of 62 g of hydrogenated animal fat (AF, n = 12); 60 g of menhaden oil containing 18% docosahexanoic acid (DHA) and 15% eicosapentanoic acid(EPA; MO, n = 11); 60 g of tuna oil containing 33% DHA and 6.5% EPA (TO, n = 11); and 60 g of menhaden oil and 2 mg/kg of biotin (MO+B, n = 10). Biotin is a critical factor in the elongation of PUFA. Semen was collected according to 3 successive phases: phase 1 (twice per week for 4 wk); phase 2 (daily collection for 2 wk); and phase 3 (twice per week for 10 wk). Experiment 2 was conducted in commercial conditions; 222 boars were randomly allocated to AF, MO, and TO treatments. Semen was collected twice weekly over a 6-mo period. All diets were balanced to be iso-energetic and provided an equivalent of 989 mg of vitamin E per day. Classical measurements of sperm quantity and quality were done for both experiments. Experiment 1 showed, after 28 wk of supplementation, a massive transfer of n-3 PUFA into sperm from boars fed fish oil diets (MO and TO). No differences were observed among dietary treatments for libido, sperm production, or percentage of motile cell. Unexpectedly, MO+B diet reduced the percentage of normal sperm compared with the other treatments. In conclusion, although it modified the fatty acid composition of sperm, supplementation of boars with dietary fish oils, rich in long chain n-3 fatty acids, did not influence semen production or quality post ejaculation.

For more information the full article can be found at http://jas.fass.org/