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

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

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.

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

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.

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

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/

Bayes factor analyses of heritability for serum and muscle lipid traits in Duroc pigs

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Concern about pork quality has increased during last decades. Given the influence of fat content and composition on sensorial, nutritional, and technological variables of pork meat, an accurate knowledge about genetic control of pig lipid metabolism is required. This study focused on providing a broad characterization for serum and meat lipid trait heritability estimates in pigs. Analyses were performed on a population of 370 Duroc barrows and measured the additive polygenic background for the serum concentrations of cholesterol, triglyceride, and low- and high-density lipoproteins at 45 and 190 d of age (at slaughter), as well as intramuscular fat, cholesterol content, and C:12 to C:22 fatty acid content in longissimus thoracis et lumborum and gluteus medius muscles at slaughter. These traits were analyzed under Bayesian univariate animal linear models, and the statistical relevance of heritability estimates was evaluated through Bayes factor (BF); the model with polygenic additive effects was favored when BF >1. All serum lipid traits showed relevant genetic determinism, but the BF reached greater values at 190 d of age. Serum lipid traits displayed moderate modal estimates for heritability that ranged from 0.18 to 0.30. On the other hand, the genetic determinism for meat quality traits showed a heterogeneous behavior with large and less-than-1 BF. In general, longissimus thoracis et lumborum and gluteus medius muscles showed a similar pattern, with strong evidence of polygenic additive effects for intramuscular fat and palmitic, stearic, and cis-vaccenic fatty acids content, whereas oleic and muscle cholesterol content showed moderate to weak BF with moderate heritabilities. Similarly, results regarding linoleic, arachidonic, n-3, and n-6 fatty acids suggested a moderate genetic determinism, but only in gluteus medius muscle. For the remaining traits (myristic and palmitoleic fatty acids in both muscles, along with linoleic, arachidonic, n-3, and n-6 fatty acids in the longissimus thoracis et lumborum muscle), no statistical evidence for genetic control was observed in this study. As a whole, these results confirm the complexity of lipid metabolism in pigs.

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

Genetics of growth in piglets and the association with homogeneity of body weight within litters

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The objective of this study was to examine the genetic basis of homogeneity in piglets and the genetic correlations with litter size and growth during lactation. Genetic parameters for variation in piglet BW within litters at birth and at 3 wk of age, and in the BW of individual piglets at 3 wk (BW3) were estimated from the Norwegian Landrace nucleus population. Data on BW3 were collected from 146,572 piglets from 14,045 litters in 58 herds. Body weight at birth and at 3 wk of age was recorded for 13,318 piglets from 5 nucleus herds. Litter data were evaluated using multivariate trait models. The heritability estimates for the SD of BW at birth and at 3 wk (SDBW3) were in agreement with the literature (0.10 and 0.08, respectively). The genetic correlation for the number of piglets born alive and the mean BW at 3 wk was negative (−0.40), and the correlation of number of piglets born alive with SDBW3 was close to zero (−0.03). The genetic correlation between the SD of BW at birth and SDBW3 was moderate (0.51). The mean BW at birth was genetically correlated with mean BW at 3 wk (0.59) but was independent of SDBW3 (0.08). The estimates of direct and maternal heritability for BW3 were 0.03 and 0.07, respectively, and the genetic correlation between the 2 components was negative (−0.43). The genetic correlation of SDBW3 with the maternal effect on BW3 was positive and strong (0.66), whereas a negative correlation was found with the direct effect on BW3 (−0.18). These results suggest that it is possible to select for mean BW at birth without an increase in within-litter heterogeneity at 3 wk of age. A more efficient strategy would be to consider both the direct and the maternal effects on BW3 in the genetic evaluation, together with SDBW3. Thus, it is possible to avoid the increase in within-litter heterogeneity that would occur as a result of selection performed at 3 wk on a litter trait such as mean BW.

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

Impact of lactation length and piglet weaning weight on long-term growth and viability of progeny

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A total of 1,034 pigs produced by breeding PIC sows to 2 different PIC terminal sires were used to create 3 distinct weaning weight populations so that post-weaning growth to 125 kg could be studied. The rearing strategies resulted in BW that ranged from 4.1 to 11.5 kg by 20 d of age. Sows and corresponding litters were allocated to 3 treatments: sow reared (SR; n = 367) for 20 d, sow reared for 14 d (14W; n = 330), and sow reared for 2 d (2W; n = 337). Sows were removed from 2W and 14W groups, but progeny remained in the crates and received milk replacer ad libitum (for 18 and 6 d, respectively) until the contemporary SR pigs were weaned at 20 d of age. The SR pigs (6.49kg) weighed 1.01 kg less than 14W pigs (7.5kg) and 2.26 kg less than 2W pigs (8.75kg). The 14W pigs weighed 1.25 kg less than 2W pigs. Nursery ADG for the 2W group (547 g/d) was 35 g/d less than 14W pigs. The 14W pigs (165 d) required 3 fewer days to reach 125 kg of BW compared with SR pigs. The SR and 14W pigs gained BW 24 and 20 g/d faster in the postnursery period when compared with 2W pigs. The SR and 2W pigs consumed 0.10 and 0.12 kg/d less during this period when compared with 14W pigs (2.32 kg/d). Gain:feed of SR was improved when compared with the 14W and 2W pigs over 167 d of age (0.44 vs. 0.42 and 0.42, respectively). Lean percentage was 0.7% greater in carcasses from SR pigs (55.0%) compared with carcasses from 2W pigs (54.3%) when adjusted to a constant HCW. A study of the effect of weaning weight on days to 125 kg was limited to SR and 14W groups because maternal deprivation compromised the 2W group postweaning growth. Six weaning-weight groups were defined using a normal distribution: 4.6, 5.5, 6.4, 7.3, 8.2, and 9.5 kg. Pigs weighing 5.5 kg at 20 d of age were able to reach 125 kg 8 d sooner (168.8 d) than those weighing 4.6 kg (176.8 d). There was a linear relationship between weaning weight and ADG in the postnursery phase of growth. We conclude that  a weaning weight of less than 5.0 kg imposes the greatest marginal loss in production output for a 20-d weaning and lactation length influences long-term growth, composition of growth, and viability of progeny.

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Selection to reduce residual feed intake in pigs produces a correlated response in juvenile insulin-like growth factor-I concentration

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Data from a selection experiment for residual feed intake (RFI) were used to estimate genetic correlations between measures of efficiency and performance traits with juvenile IGF-I, and to demonstrate direct and correlated responses to selection. The heritability of IGF-I was 0.28 and genetic correlations of IGF-I with feed intake (0.26), backfat (0.52), and feed conversion ratio (0.78) were moderate to large. The estimated and realized genetic correlations between RFI and IGF-I were 0.63 and 0.84. In contrast, genetic correlations between IGFI and lifetime or test period growth did not differ significantly from zero (0.06 and −0.19). Selection for decreased RFI produced a direct response in RFI, as expected, and was accompanied by downward correlated responses in ADFI, juvenile IGFI, backfat, and growth traits, listed in order of decreasing relative magnitude, and an increased loin muscle area. The correlated response in IGF-I to selection on RFI demonstrates that this physiological measure is genetically associated with efficiency, and is thus useful as an early information source to estimate genetic merit for efficiency before performance testing. Decreased juvenile IGF-I is associated with leaner, more efficient animals.

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Influence of benzoic acid and phytase in low-phosphorus diets on bone characteristics in growing-finishing pigs

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In 2 simultaneous experiments (Exp.1 and Exp. 2), the effects of benzoic acid (BA) and phytase (Phy) in low-P diets on bone metabolism, bone composition, and bone stability in growing and growing- finishing pigs were examined. Experiment 1 was conducted with 16 crossbred gilts in the BW range of 25 to 66 kg of BW, whereas in Exp. 2, 32 crossbred gilts (25 to 108 kg of BW) were used. All pigs were individually housed in pens and restrictively fed 1 of 4 diets throughout the experiment. Total P content of the wheat-soybean diets was 4 g/kg (all values on an as-fed basis). The experimental diets were 1) unsupplemented control diet; 2) control diet with 0.5% BA; 3) Phy diet with 750 Phy units (FTU) of Phy/kg and no BA; and 4) PhyBA, control diet with 750 FTU of Phy/kg and 0.5% BA. Blood samples were taken at the beginning of the experiment, wk 3 (only for pigs in Exp. 1), wk 6, and before slaughter to determine P and Ca in serum and concentrations of total alkaline phosphatase, serum crosslaps (marker for bone resorption), and osteocalcin (marker for bone formation). Ash, P, and Ca contents of bones and bone stability were examined using the left metatarsal bones and tibia of the pigs after slaughter. Benzoic acid did not influence any of the blood variables. The addition of Phy increased P concentration in serum from 2.71 to 3.03mmol/L at wk 3 and content of serum crosslaps from 0.39 to 0.45ng/mL at wk 6 and decreased osteocalcin at wk 6 by 160 ng/mL. No long-term effect of diets on serum mineral concentrations, alkaline phosphatase, and bone markers in serum could be detected. Benzoic acid negatively affected Ca content in bones and distal bone mineral density, especially in the younger pigs. In the control diet with 0.5% BA and the control diet with 750 FTU of Phy/kg and 0.5% BA, the CA content in bones and distal bone mineral density were reduced by 6 and 11%, respectively. Throughout the whole growing and finishing period, Phy increased ash, P, and Ca contents in bones by 29.4, 4.8, and 11.6 g/kg of DM, respectively. Bone mineral density and bone mineral content were greater in diets with Phy, as well as breaking strength of tibia (+22%) and metatarsal bones (+27%). The results of this study indicate that for a healthy skeleton, BA should not be used in low-P diets without the addition of Phy.

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