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Pedigree analysis of 5 swine breeds in the United States and the implications for genetic conservation

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

Globally, genetic diversity of livestock populations is contracting. Knowing the true extent of the contraction is needed to develop effective conservation strategies. Although contractions of genetic diversity have been documented at the breed level, little within breed documentation has occurred. This situation is no different for US swine breeds. Therefore, the objective of this study was to establish an inbreeding baseline for 5 pig breeds via pedigree records extracted from purebred registrations to each breed association for Berkshire (n = 116,758), Duroc (n = 878,480), Hampshire (n = 744,270), Landrace (n = 126,566), and Yorkshire (n = 727,268). For all breeds the number of registrations peaked after 1990 and declined since that time. The breeder structure was analyzed for Berkshire and Duroc; the average breeder registered pigs for 4.0 yr for both breeds. Breeders were grouped by longevity and herd size, and the inbreeding levels for the current population (pigs born 2006 and later) were evaluated. Presently, more than 99% of all pigs are inbred with the majority having inbreeding less than 10%. The range for percentage of animals that are more than 25% inbred ranged from 1.16% for Yorkshire to 6.09% for Berkshire. The greatest inbreeding for all animals within a breed ranged from 51% for Landrace and 65% for Yorkshire. Sires were grouped into 10 percentiles based on number of great-grandprogeny (GGP) produced; for all breeds, the top 10 percentile accounted for more than 75% of all GGP. Sixty percent of all sires produced less than 1% of all GGP, indicating few males are contributing to future generations. Generations ranged from 17 to 19 per breed with a generation interval ranging from 1.65 yr for Berkshire to 2.21 yr for Yorkshire. Mean inbreeding (%) at generation 17 (the most generations computed across breeds), rate of inbreeding per generation, and effective population size were 12.3, 0.0065, and 77 for Berkshire; 11.8, 0.0044, and 113 for Duroc; 6.8, 0.0046, and 109 for Hampshire; 17.9, 0.0067, and 74 for Landrace; and 8.0, 0.0044, and 113 for Yorkshire, respectively. The 2 breeds with fewest registrations, Berkshire and Landrace, had greater inbreeding rates and smaller effective population sizes, suggesting a need for more immediate conservation efforts. This analysis provides a basis for future monitoring of the genetic diversity of pig breeds and serves as a basis for planning conservation activities.

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

Evaluation of elevated dietary corn fiber from corn germ meal in growing female pigs

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To evaluate the effects of dietary hemicellulose from corn on growth and metabolic measures, female pigs (n = 48; initial BW 30.8 kg) were fed diets containing 0 to 38.6% solvent-extracted corn germ meal for 28 d. Increasing the hemicellulose level had no impact on ADG or ADFI, but resulted in a quadratic response on G:F. To investigate physiological changes that occur with increased dietary hemicellulose, blood, colon contents, and tissue samples from the liver and intestine were obtained from a subset (n = 16; 8 pigs/treatment) of pigs fed the least and greatest hemicellulose levels. The abundance of phosphoadenosine monophosphate-activated protein kinase (AMPK) and the mitochondrial respiratory protein, cytochrome C oxidase II (COXII) were determined in liver, jejunum, ileum, and colon by Western blotting. The mRNA expression levels of AMPKα1, AMPKα2, PPAR coactivator 1α (PGC1-α), PPARγ2, and sirtuin 1 (Sirt1) were determined in liver and intestinal tissues. When compared with pigs fed the control diet, pigs fed the high hemicellulose diet had increased plasma triglycerides, but there was no difference in plasma cholesterol, glucose, or insulin. Absolute and relative liver weights were decreased in pigs consuming the high hemicellulose diet. The highfiber diet led to a tendency for decreased liver triglyceride content. In pigs fed the high hemicellulose diet, ileal mucosal alkaline phosphatase activity was increased and sucrase activity tended to be increased. The high hemicellulose diet had no effect on phospho-AMPK, AMPK mRNA, or colonic VFA, but in pigs consuming the high fiber diet there was a greater abundance of COXII in colon tissue. The expression of PGC1-α, PPARγ, or Sirt1 mRNA was not altered by dietary fiber in liver, jejunum, or ileum tissue. In colon tissue from pigs fed the high fiber diet there was an increase in Sirt1 mRNA and a trend toward increased of PGC1-α mRNA. These data suggest that alterations in metabolism involved in adaptation to a diet high in hemicellulose are associated with increased colonic Sirt1 mRNA and COXII expression, indicating an increased propensity for oxidative metabolism by the intestine.

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

Effect of dry- versus wet-autoclaving of spray-dried egg albumen compared with casein as protein sources on apparent nitrogen and energy balance, plasma urea nitrogen and glucose concentrations, and growth performance of neonatal swine

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Forty crossbred neonatal pigs with an average initial age of 4 d and BW of 2.16 kg were used in a 28-d experiment to evaluate the nutritional effects of autoclaving a commercial sugar-free, spray-dried egg albumen (EA) compared with casein. Basal diet protein sources were lactic acid casein and EA. Two more dietary treatments were made by replacing the EA with dry-autoclaved EA (DAEA) or wet-autoclaved EA (WAEA, EA and water mixed in a 1.0:1.2 ratio before autoclaving). The DAEA and WAEA were autoclaved at 121°C and 1.75 kg/cm2 pressure for 30 min, and WAEA was oven-dried after autoclaving. Analyzed trypsin inhibitor units/mg of EA, DAEA, and WAEA were 535.0, 9.0, and 6.5, respectively. Pigs were fed the diets in gruel form to appetite in individual metabolism cages every 2 h during the experiment. Blood samples were taken on d 7, 14, and 21, and total urine and fecal grab-samples were collected from d 14 to 21 of the experiment. Response criteria were N and energy balance, plasma urea N (PUN) and glucose concentrations, and growth performance. The WAEA was a higher quality protein source for neonatal pigs than DAEA. Pigs fed the diet containing WAEA absorbed and retained more grams of N/d, had higher percentages of N and energy that were absorbed and retained/intake, had lower concentrations of PUN overall, and had higher ADG and G:F than pigs fed the diet containing DAEA. Most response criteria of pigs fed the diets containing DAEA or EA were not different, although pigs fed the diet containing DAEA had lower overall PUN concentrations, and pigs fed the diet containing EA had higher percentages of energy absorbed and retained/intake, and higher ADG and G:F than pigs fed the diet containing DAEA. Growth performance was not different for pigs fed the diets containing WAEA or casein. However, pigs fed the diet containing casein excreted less (P < 0.05) fecal N, retained more grams of N/d, had higher percentages of N absorbed and retained/intake, and had lower PUN concentrations overall than pigs fed the diet containing WAEA. In conclusion, WAEA was a higher quality protein source for neonatal pigs than DAEA or EA, whereas lactic casein was a higher quality protein source for neonatal pigs than EA, DAEA, or WAEA.

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

Fiber-related digestive processes in three different breeds of pigs

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The hypothesis examined in this experiment was that, because of intensive selection for greater daily BW gains and efficient utilization of concentrated low-fiber diets, modern pig breeds differ from old local breeds in their physiological ability to respond to soluble dietary fiber. Thus, the old local breeds, Schwaebisch Haellisches Schwein (SH) and Bunte Bentheimer (BB), and a modern crossbred pig (CB) were used in metabolism trials to study fiber-related digestion, including microbial hindgut fermentation, by applying a colon simulation technique (Cositec) and measuring intestinal glucose transport in Ussing chambers. A basal diet or basal plus 20% dried sugar beet pulp (SBP) as a soluble fiber source was fed to 6 pigs/breed in a 2 × 3 factorial arrangement of treatments. Four pigs of each breed per treatment were used for intestinal anatomical measurements at the end of the metabolism trials. The pigs had an initial average BW of 33.9kg. The basal diet was formulated to meet 80% of energy and 100% of nutrient requirements for pigs with 700 g of ADG. Feeding the SBP diet reduced total intestinal tract, but it increased colon length, water-holding capacity of the digesta, and fecal bulk. The digestibility of OM, CP, and ether extract decreased, whereas that of NDF and ADF increased, by SBP. Pigs receiving SBP excreted less urinary N and retained more N. The fecal proportions of undigested dietary and water soluble N increased and those of bacterial and endogenous debris N decreased in SBP-fed pigs. The SH pigs had lighter empty cecum weight, shorter colons, and less NDF digestibility than BB and CB pigs. Fecal N excretion did not differ among breeds, but SH pigs excreted more urinary N than the other breeds. In Cositec, OM, NDF, and ADF disappearance rates from cecal chyme of SBP-fed pigs increased irrespective of pig breed. Cecal chyme of SBP-fed BB pigs produced more VFA with a smaller proportion of propionate and a larger acetate to propionate ratio than chyme of SBP-fed SH and CB pigs. The intestinal epithelial glucose transport was greater for ileal than for jejunal tissues but was not influenced by diet and pig breed. In conclusion, the modern and intensely selected pig breed can utilize SBP fiber as efficiently as the old pig breeds under the present experimental conditions.

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

Effects of distillers dried grains with solubles on amino acid, energy, and fiber digestibility and on hindgut fermentation of dietary fiber in a corn-soybean meal diet fed to growing pigs

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The objective of this experiment was to measure the effect of distillers dried grains with solubles (DDGS) on the digestibility of AA, energy, and fiber, on the fermentation of fiber, and on the first appearance of digesta at the end of the ileum, in the cecum, and in the feces of growing pigs fed a cornsoybean meal-based diet. Sixteen pigs (initial BW = 38.0 kg) were prepared with a T-cannula in the distal ileum and a T-cannula in the cecum and allotted to 2 treatments. In period 1, all pigs were fed a cornsoybean meal diet. In periods 2, 3, and 4, pigs were fed the control diet or a diet containing corn, soybean meal, and 30% DDGS. First appearance of digesta at the end of the ileum, in the cecum, and over the entire intestinal tract was measured at the end of period 4. The apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of nutrients were measured, and the concentration of VFA was analyzed in ileal, cecal, and fecal samples. The AID of Lys (74.1%) in the DDGS diet was less than in the control diet (78.6%), but the AID of most other AA and GE, NDF, and total dietary fiber (TDF) were not different between the 2 diets. The ATTD of GE (81.0%), NDF (57.2%), TDF (55.5%), and DM (81.7%) were less in the DDGS diet than in the control diet (86.0, 69.3, 66.0, and 87.2%, respectively). The concentration of VFA in ileal, cecal, and fecal samples was not different between pigs fed the 2 diets. The pH of ileal and cecal digesta from pigs fed the DDGS diet (6.3 and 5.5) was greater than from pigs fed the control diet (5.8 and 5.3). The ATTD of DM, GE, ADF, NDF, and TDF did not change with collection period, but the AID of ADF, NDF, and TDF increased from period 2 to period 4. The concentration of all VFA, except isobutyrate, was greater in cecal samples from period 4 compared with period 2, and the concentration of all VFA except propionate and isovalerate were greater in fecal samples collected in period 4 compared with those collected in period 2. The first appearance of digesta at the end of the ileum, in the cecum, and in the feces was not affected by DDGS. In conclusion, pigs fed the diet containing DDGS had less digestibility of Lys, GE, ADF, NDF, and TDF than pigs fed the control diet. The digestibility of DM and GE was not influenced by collection period, but the concentration of VFA in cecal digesta and feces increased with the length of time pigs received the diets.

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

Digestibility of dietary fiber in distillers coproducts fed to growing pigs

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The objective of this work was to measure the apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of dietary fiber in different sources of distillers dried grains with solubles (DDGS) and to calculate hindgut fermentation of dietary fiber in DDGS fed to growing pigs. Diets, ileal digesta, and fecal samples from pigs fed corn or diets containing 1 of 28 sources of distillers coproducts were analyzed for fiber. Of the 28 sources of coproducts, 24 sources were corn DDGS (C-DDGS), 1 source was sorghum DDGS (S-DDGS), 1 source was DDGS from a blend of sorghum and corn (SC-DDGS), 1 source was C-DDGS from beverage production (DDGSbeverage), and a source of corn distillers dried grain (DDG) was also included in the experiment. Total dietary fiber (TDF) and DM were analyzed in all DDGS sources, ileal digesta, and fecal samples. Hindgut fermentation was calculated by subtracting values for AID from values for ATTD. In 10 sources of DDGS and in ileal and fecal samples from pigs fed those sources, crude fiber, ADF, NDF, insoluble dietary fiber (IDF), and soluble dietary fiber (SDF) were also determined. Concentrations of CP, ether extract, and ash were also analyzed in these samples, and concentrations of organic residue (OR) were calculated by subtracting the concentration of CP, ether extract, and water from OM. The AID and the ATTD of TDF differed among sources of C-DDGS. The average AID of TDF in 10 sources of C-DDGS (21.5%) was not different from the AID of TDF in corn (16.5%), but the ATTD and the hindgut fermentation of TDF in the 10 sources of C-DDGS (44.5 and 23.0%, respectively) were greater than in corn (23.1 and 6.6%, respectively). The AID of crude fiber, NDF, IDF, SDF, and TDF were not different between C-DDGS and S-DDGS, but the AID of ADF was greater (P < 0.01) in S-DDGS (57.4%) than in C-DDGS (36.8%). The ATTD of OR in S-DDGS (72.5%) and SC-DDGS (68.4%) were less than in C-DDGS (77.1%), but the ATTD of ADF, NDF, IDF, SDF, and TDF were not different among the 3 sources of DDGS. The AID, ATTD, and hindgut fermentation of TDF were not different between DDGS from an ethanol plant and DDGS from a beverage plant. The average AID, ATTD, and hindgut fermentation of TDF in the 24 sources of C-DDGS were 23.0, 47.3, and 24.4%, respectively. It is concluded that the AID and ATTD of fiber differ among sources of DDGS and those differences may contribute to differences in the digestibility of energy in DDGS.

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

The effect of dentition on feeding development in piglets and on their growth and behavior after weaning

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The objectives of this study were to determine the effects of dentition on feed-oriented behavior and feed consumption before weaning at 28 d, and whether premolar eruption or occlusion at the time of weaning influenced postweaning growth or behavior. Over 3 trials, 24 litters of Yorkshire piglets (n = 233) were provided with creep feed marked with 1% chromic oxide on d 5. Dental exams were performed on d 2, 6, 9, 13, 16, 20, 23, and 27. Fecal samples were visually assessed for feed consumption (via fecal color) on the same day as dental exams, beginning on d 6. The duration of time spent at, and frequency of visits to, the creep feeder were determined from continuous video recordings on d 7, 10, 14, 17, 21, and 24 for 6 h/d (0700 to 1000 h, 1300 to 1600 h). After weaning, behavior was recorded every 5 min for three 2-h time periods (0600 to 0800 h, 1100 to 1300 h, and 1600 to 1800 h) on d 2, 4, 6, 8, 10, and 12. Piglets younger than 17 d with their premolars erupted and occluded spent less time at the creep feeder and visited it less often than piglets without their premolars erupted and occluded [duration: p3 (premolar position 3 on maxilla), d 7; p4 (premolar position 4 on mandible), d 7, d 10; p4 (premolar position 4 on maxilla), d 17; occlusion, d 7, d 10; visits: p3, d 7; p4, d 7, d 10; p3 (premolar position 3 on mandible), d 14; p4, d 17; occlusion, d 7, d 10]. By d 21 of age, this trend reversed such that piglets with premolars erupted and occluded spent more time at the feeder and visited it more frequently [duration: p3, d 24; p4, d 24; occlusion, d 21, d 24; visits: p3, d 21, d 24; p4, d 24; occlusion, d 21, d 24]. The percentages of piglets with positive fecal scores were 0, 1.4, 4.6, 8.0, 29.0, 44.9, and 60.6% on d 7, 10, 14, 17, 21, 24, and 27, respectively between each day). No associations were found between the eruption or occlusion of premolars and feed consumption before weaning, and no dental measures influenced growth rates or behavior after weaning. A more precise method may be necessary for detecting associations between dental eruption and feed consumption. However, the behavioral results indicate that, before weaning at 28 d, younger piglets are inhibited from feeding when their premolars first erupt, whereas older piglets with a more advanced dentition are more attracted to feed.

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

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

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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.

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

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.

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

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.

To view this complete article please visit: http://jas.fass.org/

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