Estimation of genetic trends in French Large White pigs from 1977 to 1998 for growth and carcass traits using frozen semen

Posted in: Meat Quality, Production by admin on August 8, 2011 | No Comments

Genetic trends for growth, feed efficiency, composition, and morphometry of carcasses were estimated in a French Large White (LW) pig population using frozen semen. Two groups of pigs were produced by inseminating LW sows with either stored, frozen semen from 17 LW boars born in 1977 or with semen from 23 LW boars born in 1998. In each group, 15 males and 90 females were randomly chosen and mated to produce approximately 1,000 pigs/group. These pigs were performance tested with individual ADFI and serial BW and backfat thickness measurements, slaughtered at 105 kg of BW, and measured for carcass traits. The data were analyzed using mixed linear animal models, including the fixed effect of the experimental group (offspring of 1977 or 1998 boars), the random effect of the additive genetic value of each animal, and, when significant, the fixed effects of sex, fattening batch, and slaughterhouse, the linear regression on BW, and the random effect of the common environment of birth litter. For each trait, the genetic trend was estimated as twice the difference between the 2 experimental groups. Results showed moderately favorable trends for on-test ADG (3.7 g/d per year) and feed conversion ratio (−0.014kg/ kg per year) in spite of a tendency toward an increase in ADFI (7.6g/yr). A strong reduction in carcass fatness (−0.35mm/yr for carcass average backfat thickness) and a large improvement in carcass leanness (0.31mm2/yr and 0.41%/yr for loin eye area and carcass muscle content, respectively) were observed. Carcass shape measurements (back and leg length, back width, muscle thickness of hind limbs) were not affected by selection. Serial measurements of BW and backfat thickness showed that the major part of the genetic gains occurred during late growth and that the reduction in the backfat layer was more pronounced in the rear than in the front part of the carcass. The use of frozen semen appears to be a powerful practice to thoroughly investigate changes attributable to selection.

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Genetic parameters for preweaning and early growth traits in Berkshire pigs when creep feeding is used

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The objective of this study was to find optimal traits for inclusion in selection criteria by estimating genetic parameters for direct genetic, maternal genetic, and common environmental effects for growth traits before 60 d of age and for the number of teats under an open breeding population, and to evaluate genetic relationships for traits at 60 d of age. Records of 2,344 male and 2,204 female purebred Berkshire pigs were analyzed. For BW at 14 d of age and for weaning weight, the heritabilities of a direct genetic effect were greater than those of a maternal genetic effect. This result is contrary to previous results showing a gradual decrease in the maternal genetic effect and an increase in the direct genetic effect up to weaning. The positive genetic correlations between direct and maternal genetic effects for BW at 14 d of age and weaning weight are clearly contrary to other reports. This phenomenon seems to be caused by creep feeding begun just after the birth of the piglets and maintained throughout the preweaning period in this Berkshire population.

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Effects of varying creep feeding duration on the proportion of pigs consuming creep feed and neonatal pig performance

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In Exp. 1, 54 sows (PIC Line 1050) and their litters were used to determine the effects of creep feeding duration on the proportion of pigs consuming creep feed and preweaning performance. Two groups of sows were blocked according to parity and date of farrowing and allotted to 3 experimental treatments in a randomized complete block design. Creep feeding was initiated at d 7, 14, and 18 from birth for durations of 13, 6, and 2 d of creep feeding. A creep diet (3,495 kcal of ME/kg, 1.56% standardized ileal digestible Lys) with 1.0% chromium oxide was offered for ad libitum intake until weaning (d 20) in a rotary creep feeder with hopper. Fecal samples from all piglets were taken with sterile swabs on d 14, 18, and 20 for treatment 1, d 18 and 20 for treatment 2, and d 20 for treatment 3. Piglets were categorized as eaters when the fecal sample was colored green at least once on any of the sampling days. In Exp. 1, there were no differences in weaning weights, total BW gain, and daily BW gain among pigs fed creep for 13, 6, or 2 d. Total creep feed intake of litters fed creep for 13 and 6 d was greater than that for litters fed creep feed for 2 d. Litters provided with creep feed for 13 d produced 10% more (80 vs. 70%) eaters than litters fed creep for 6 or 2 d. In Exp. 2, all 273 pigs weaned from 1 of the 2 groups used in Exp. 1 (averaging 5.67 kg of BW and 20d) were randomly allotted to 2 treatment categories (non-eater or eater of creep feed) in a completely randomized design to determine whether there were any differences in nursery growth performance between creep feed consumption categories. There were 10 and 33 replications (pens) with 5 to 7 pigs per pen for the non-eater and eater treatment categories, respectively. Non-eaters were heavier than eaters at d 0, but eaters had greater ADG and ADFI than non-eaters from d 0 to 3 postweaning. Overall (d 0 to 28), there were no differences in ADG, ADFI, and G:F of eaters and non-eaters. In conclusion, longer durations of creep feeding increased the proportion of eaters in whole litters, but did not affect preweaning performance. Eaters had greater postweaning feed intake than non-eaters, which resulted in greater initial daily BW gains.

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A multilevel nonlinear mixed-effects approach to model growth in pigs

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Growth functions have been used to predict market weight of pigs and maximize return over feed costs. This study was undertaken to compare 4 growth functions and methods of analyzing data, particularly one that considers nonlinear repeated measures. Data were collected from an experiment with 40 pigs maintained from birth to maturity and their BW measured weekly or every 2 wk up to 1,007 d. Gompertz, logistic, Bridges, and Lopez functions were fitted to the data and compared using information criteria. For each function, a multilevel nonlinear mixed effects model was employed because it allowed for estimation of all growth profiles simultaneously, and different sources of variation (i.e., sex, pig, and litter effects) were incorporated directly into the parameters. Furthermore, variance in-homogeneity and within-pig correlation were introduced to the functions. Inclusion of a variance of power function and a continuous autoregressive process of first order rendered a substantially improved fit to data for all 4 growth functions. The Lopez function provided the best fit to the data set and was used for characterizing mean growth curves for the 3 sexes (barrows, boars, and gilts). It was estimated that the maximum growth rate occurs at 117, 134, and 96 kg of BW for barrows, boars, and gilts, respectively. Hence, the gilts reached their maximum growth rate at an earlier stage in life compared with boars. Mature size of pigs varied systematically with sex and was estimated to be 466, 537, and 382 kg of BW for the barrows, boars, and gilts, respectively. These estimates are significantly affected by the duration of the experimental period, and it is recommended that future studies looking at estimating the mature size in animals are conducted long enough so that the BW visually stabilizes. Furthermore, studies should consider adding continuous autoregressive process when analyzing nonlinear mixed models with repeated measures.

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A multivariate nonlinear mixed effects method for analyzing energy partitioning in growing pigs

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Simultaneous equations have become increasingly popular for describing the effects of nutrition on the utilization of ME for protein (PD) and lipid deposition (LD) in animals. The study developed a multivariate nonlinear mixed effects (MNLME) framework and compared it with an alternative method for estimating parameters in simultaneous equations that described energy metabolism in growing pigs, and then proposed new PD and LD equations. The general statistical framework was implemented in the NLMIXED procedure in SAS. Alternative PD and LD equations were also developed, which assumed that the instantaneous response curve of an animal to varying energy supply followed the law of diminishing returns behavior. The Michaelis-Menten function was adopted to represent a biological relationship in which the affinity constant (k) represented the sensitivity of PD to ME above maintenance. The approach accommodated inclusion of a PD potential (PDPotential) concept. This was described by a Gompertz function, which was parameterized in terms of the maximum rate of PD (PDMax) and corresponding BW (BWPDMax) at that point. Metabolizable energy for LD was equated to the difference between ME intake and the sum of ME used for maintenance and PD. Metabolizable energy designated for PD and LD was used, with efficiencies kp and kf, respectively. The new equations were compared with the van Milgen and Noblet (1999) equations using 2 comprehensive data sets on energy metabolism in growing pigs. The 2 equation sets were evaluated using information criteria, which showed that the new equations performed best for data set II, whereas the reverse was true for the first. For the data set I population, estimates for kp and kf were 0.57 and 0.84, respectively. Maintenance was quantified as 1.10 MJ/d∙kg0.55. The animal variation in the parameter kp was estimated to be 6% CV. The animal variation in PDMax and kf was estimated to be 9 and 10% of the population estimates, respectively. It was conclude that application of the MNLME framework was superior to the multivariate nonlinear regression model because the MNLME method accounted for correlated errors associated with PD and LD measurements and could also include the random effect of animal. It is recommended that multivariate models used to quantify energy metabolism in growing pigs should account for animal variability and correlated measurement errors.

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Effect of virginiamycin on the apparent ileal digestibility of amino acids by growing pigs

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The objective of this experiment was to measure the influence of virginiamycin on the apparent ileal digestibility (AID) of AA by growing pigs. Fifteen barrows were surgically equipped with a T-cannula in the distal ileum and used in the experiment (initial BW = 35.0 kg). Animals were randomly allotted to 3 dietary treatments with 5 pigs per treatment during a 6-wk experiment. Dietary treatments included 1) a basal corn-soybean meal diet, 2) the basal diet supplemented with 11 mg/kg of virginiamycin, and 3) the basal diet supplemented with 22 mg/kg of virginiamycin. Pigs were fed their respective treatment diets during wk 2, 3, and 4, but during wk 1, 5, and 6, all pigs were fed the basal diet. Ileal samples were collected on d 6 and 7 of each week. Results showed that the AID of all indispensable AA, except Arg, His, and Ile, increased during wk 2, 3, and 4 compared with wk 1 in pigs fed the diet containing 11 mg/kg of virginiamycin. Pigs fed 22 mg/kg of virginiamycin during wk 2, 3, and 4 had increased AID of Trp and Val during these weeks compared with the AID in wk 1. However, the increased AID of AA did not carry over to wk 5 and 6, when virginiamycin was withdrawn from the diet, regardless of the inclusion rate. In pooled data from wk 2, 3, and 4, the AID of CP, the mean of all indispensable AA, and Ile, Leu, Met, Phe, Trp, and Val increased (linear) as virginiamycin was added to the diets, whereas a tendency for a linear or quadratic increase was observed for His, Lys, and Thr. These results indicate that addition of virginiamycin to corn-soybean meal diets fed to growing pigs increases the AID of AA, but this effect is not maintained after the removal of virginiamycin from the diet.

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Dietary effects of distillers dried grains with solubles on performance and milk composition of lactating sows

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A study was conducted to evaluate the dietary effect of adding increasing concentrations of distillers dried grains with solubles (DDGS) to cornand soybean meal-based sow lactation diets on sow and litter performance, energy and N digestibility, plasma urea N (PUN), and milk fat and protein concentrations. Mixed-parity sows [n = 307; 221 kg of BW, 4.54 parities, litter size of 10.6, and litter weight at birth (alive) of 15.14 kg] were assigned randomly to 1 of 5 dietary treatments: control (CON; corn-soybean meal); 10, 20, and 30% DDGS; and 30% DDGS high-protein (HP) diets. Sows were moved to farrowing rooms on d 109 of gestation and were fed the dietary treatments until weaning. Within each treatment group, feces and urine for energy and N digestibility analysis (from d 10 to 12 of lactation) and blood for PUN analysis and milk fat and protein concentrations (on d 0 and 19 of lactation) were collected from 6 randomly chosen parity 3 to 5 sows. There were no dietary effects of DDGS on ADFI of sows and sow backfat change. However, sows fed 30% DDGS HP lost more BW compared with sows fed CON. There were no dietary effects of DDGS on preweaning mortality of piglets, litter weight gain, and piglet ADG. Dietary treatments did not affect DE, ME, N retention, or N digestibility of the diets. There were no differences in the concentrations of fat and protein in milk at weaning (d 19) among dietary treatments. Sows fed 20 and 30% DDGS had less PUN at weaning (d 19) than sows fed CON and 30% DDGS HP. Inclusion of up to 30% DDGS in a lactation diet did not affect sow and litter performance, DE and ME contents of the diets, N retention and digestibility, and milk composition compared with sows fed a cornsoybean meal CON diet. It was concluded that addition of up to 30% DDGS in a lactation diet will support satisfactory sow and litter performance.

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Effect of polymorphisms in candidate genes on reproduction traits in Finnish pig populations

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Reproduction traits play an important role in economically viable piglet production and are closely related to the quality and length of the productive life of the sow. A increased removal rate of young sows is undesirable not only because of the associated financial penalties incurred, but also because of ethical concerns. Candidate genes and gene pathways have been identified for fertility in model species, and recent studies have provided evidence that polymorphisms within these genes are associated with reproduction traits in American Yorkshire/Large White and Landrace populations. In this study we evaluated the impact of single polymorphisms (n = 7) in 7 candidate genes on reproductive efficiency in Finnish Yorkshire (n = 280) and Landrace (n = 271) populations: IGFBP1, IGFBP2, IGFBP3, IGFBP5, CPTIA (carnitine O-palmitoyltransferase I), COX2 (PG-endoperoxide synthase 2, also known as cyclooxgenase-2), and SLC22A5 [organic cation/carnitine transporter 2 (solute carrier family member I), OCTN2]. In the Finnish Yorkshire population, only 4 of the analyzed markers were polymorphic. Significant effects on farrowing time were detected from the Yorkshire data, with polymorphisms within the genes CPT1A [a (allele substitution effect of allele A) = 2.97 d for age at first farrowing)], IGFBP3 (a = 0.54 d for farrowing interval of parities >1), and IGFBP5 (a = 3.22, 1.27, and 0.85 d for age at first farrowing and farrowing interval in the first and later parities, respectively). For the Landrace population, 6 markers were polymorphic, and significant effects were detected for traits affecting litter size. The polymorphism within the COX2 gene had an additive effect of 0.3 piglets for litter size in parities >1, and the IGFBP1 gene had an additive effect of 0.21, 0.26, and 0.11 piglets for litter size in the first parity, parities >1, and stillborn in parities >1, respectively. The additive effect of the SNP within the IGFBP2 gene was 0.16, 0.09, and 0.09 piglets for litter size in parities >1 and stillborn in the first and later parities, respectively. Finally, the IGFBP5 gene had an additive effect of 0.18, 0.07, and 0.07 piglets for litter size in the first parity, stillborn in parities >1, and mortality between farrowing and weaning in the first parity, respectively. These results support the suitability of the candidate gene approach for identification of markers to improve the reproductive performance of sows and to provide potential markers for marker-assisted selection.

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Determination of Optimal True Digestible Calcium (Ca) to Phosphorus (P) Ratio in Grower-Finishing Pigs for Minimizing Phosphorus Excretion

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Phosphorus is an expensive ingredient in pigs diets, despite this it is often given to pigs in excess and therefore is not digested and then spread in fields as manure. The objective of this study was to determine the effect of changes in dietary true digestible calcium (Ca) to true digestible phosphorus (P) ratio on growth performance, efficiency of P utilization and manure P excretion. The first experiment involved a small group of pigs put on one of two diets, each was based on corn and soybean meal and two levels of Ca and P with the lower nutritional diet having 25.5% corn starch. There was also a digestible marker in each diet. Pigs who were on the low nutrient diet had reduced ADG, and had a decreased feed conversion ratio. The second experiment involved six diets, which were all corn and soybean meal based but each with a different ratio of Ca and P. Some results from the second experiment were that changes in the Ca and P ratio had no effect on the average daily feed intake. Changes did have an effect on ADG and feed conversion ratio with positive responses in diets 2-4 which had ratios of 0.74-0.81:1 (Ca:P). It was concluded that changes in dietary Ca to P ratio have significant effects on growth performance. Dietary true digestible Ca to true digestible P ratio of 0.90:1 to 1.10:1 equivalent to total Ca to total P ratio of 0.70:100 to 1.20:1:00 may be optimal for feeding grower pigs.

Effect of β-glucans contained in barley- and oat-based diets and exogenous enzyme supplementation on gastrointestinal fermentation of finisher pigs and subsequent manure odor and ammonia emissions

Posted in: Environment, Production by admin on August 5, 2011 | No Comments

The objective of the current experiment was to evaluate the influence of dietary cereal sources of β(1,3)(1,4)-d-glucan (β-glucan) and enzyme supplementation on indices of environmental pollution from finisher pigs. An experiment with a 2 × 2 factorial arrangement of treatments was initiated to investigate the effect of dietary source of β-glucan (barley vs. oats) and enzyme supplementation (no vs. yes) on nutrient digestibility, N utilization, intestinal fermentation, and manure odor and ammonia emissions from finisher boars (n = 4; BW = 73.9 kg; SD = 4.7). Sixteen boars were assigned to 1 of 4 dietary treatments (n = 4/treatment): 1) barley-based diet, 2) barleybased diet + exogenous enzyme, 3) oat-based diet, and 4) oat-based diet + enzyme. The enzyme supplement used contained endo-1,3(4)-β-glucanase and endo-1,4- β-xylanase. Experimental diets were formulated to contain similar concentrations of DE (13.5 MJ/kg) and digestible lysine (8.8 g/kg). Pigs offered oat-based diets had reduced digestibility of DM (0.795 vs. 0.849), OM (0.808 vs. 0.865), GE (0.806 vs. 0.845), and NDF (0.233 vs. 0.423) compared with those offered barley-based diets. Oat-based diets increased populations of Bifidobacterium spp. (7.26 vs. 6.38 log cfu/g of digesta) and Lactobacillus spp. (6.99 vs. 6.18 log cfu/g of digesta) in the proximal colon and decreased manure odor emissions [2,179.6 vs. 4,984.6 OuE/m3 (where OuE refers to European odor units)] compared with barleybased diets. There was an interaction between cereal type and enzyme inclusion on manure ammonia emissions from 0 to 96 h. Pigs offered barley- based diets containing an enzyme supplement had increased manure ammonia emissions compared with those offered unsupplemented barley-based diets. However, there was no effect of enzyme inclusion on oatbased diets. In conclusion, pigs offered oat-based diets harbored increased Bifidobacterium spp. and Lactobacillus spp. populations in the proximal colon and had decreased manure odor emissions compared with those offered barley-based diets. Enzyme inclusion had no effect on manure ammonia emissions from pigs offered oat-based diets.

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