Detection of a quantitative trait locus for ham weight with polar over-dominance near the ortholog of the callipyge locus in an experimental pig F2 population

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

 The distal part of SSC7, which contains the ortholog to the ovine region encompassing the callipyge locus, was analyzed in a Pietrain F2 resource population comprising more than 2,700 offspring. The aim of the study was to map QTL affecting carcass traits comparable with the callipyge phenotype in sheep. We applied an interval mapping approach using 14 microsatellite markers and detected 3 QTL with small effects. The first QTL affects fat thickness on the middle of the back, with no detectable impact on fat sizes at other places on the back, whereas the second QTL affects side fat thickness. The third QTL influences the ham weight and shows a clear parent-of-origin dependent effect in the form of maternal polar over-dominance. It is not located at the position of the imprinting cluster including the callipyge locus, but 7 cM proximal.

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

Maternal and social genetic effects on average daily gain of piglets from birth until weaning

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The aim of this study was to investigate whether there is heritable social variation in ADG from birth until weaning in piglets. Nursing and the establishment of teat order are sources of social interaction among suckling piglets nursed by the same sow. If a heritable social effect is present, but ignored, the selected animals might be the most competitive ones with negative effects on growth of their group mates, resulting in less response to selection than expected. The social interaction model was extended with a maternal component to estimate genetic maternal and social effects. Four different animal models were compared: a basic model with a direct heritable effect only; a social model accounting for direct and social heritable effects; a maternal model with a heritable maternal effect in addition to the basic model; and a social-maternal model accounting for direct, social, and maternal heritable effects. Estimates of direct, maternal, and social heritability were 0.07, 0.06, and around 0.0007, respectively. Total heritable variance, including direct, social, and maternal heritable variance and their covariances ranged from 0.07 to 0.15 of the phenotypic variation. Both maternal models were significantly better than equivalent nonmaternal models. The social model was not significantly better than the basic model, and the social-maternal model was also not significantly better than the maternal model. There was no evidence for heritable social effects among piglets in a group. The generally used maternal model fit the data as well as the social-maternal model. Sufficient cross-fostering is needed to partition social and maternal variation.

Intrauterine crowding decreases average birth weight and affects muscle fiber hyperplasia in piglets

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High prolificacy of sows and increased fetal survival lead to greater incidence of intrauterine crowding (IUC), which may then affect pre- and postnatal development of the progeny. The aim of the study was to assess the impact of IUC, using unilaterally hysterectomized- ovariectomized gilts (UHO), on organ and muscle development of their progeny at birth. In the study, 7 UHO and 7 intact control (Con) Swiss Large White gilts were used. At farrowing, if available, 3 male and 3 female progeny with a low (>0.8 and <1.2 kg), medium (>1.2 and <1.4 kg), and high (>1.6 kg) birth weight (BtW) were killed. Internal organs and brain were weighed, and semitendinosus (STN), psoas major (PM), and rhomboideus (RH) muscles were collected. Histological analyses were performed in PM, RH, and STN (dark and light portion) using myofibrillar ATPase staining after preincubation at pH 10.3. Myosin heavy chain (MyHC) polymorphism was determined in the PM using SDS-PAGE gel electrophoresis. Despite that only one-half of the uterine space was available, litter size was smaller only by 35% inUHO compared with Con gilts. However, UHO progeny tended to be lighter than Con progeny. Theaverage BtW of the selected piglets did not differ between the 2 sow groups, whereas PM and kidneys tended to be lighter in UHO than in Con progeny. Compared with Con progeny, the PM and the STNdark of UHO progeny had fewer secondary and total myofibers as well as fewer primary myofibers in the PM. In the RH, the secondary-to-primary myofiber ratio was smaller in UHO than in Con progeny, whereas the total number of myofibers did not differ. The relative abundance of fetal MyHC was less and that of type I MyHC tended to be greater in UHO than in Con offspring. With increasing BtW, organ and brain weights increased. Muscle cross-sectional area and total number of myofibers in the light portion of the STN were greater in high and medium than in low piglets. In conclusion, IUC reduced hyperplasia of secondary and total myofibers in the STNdark and PM. These effects were independent of the BtW and sex.

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

Interaction of Bacillus species and Salmonella enterica serovar Typhimurium in immune or inflammatory signaling from swine intestinal epithelial cells

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Previous research evaluated a laboratory strain of Bacillus licheniformis (BL) in a model swine epithelium and found it exerted anti-inflammatory effects on Salmonella enterica serovar Typhimurium (Sal)-induced secretion of IL-8. The current investigation evaluated the antiinflammatory actions of Bacillus bacteria available commercially as feed additives for the swine industry. Three isolates were obtained from the product, 2 Bacillus subtilis (BS1 and BS3) and 1 BL (BL2). Swine jejunal epithelial IPEC-J2 cells were seeded into wells on permeable membrane supports and allowed to form confluent monolayers. Treatments included apical pretreatment with BL, BS1, BL2, or BS3 for 17 h without Sal, and the same Bacillus treatments but with 108 cfu of Sal added in the final hour of Bacillus incubation. Two additional treatments included negative control wells receiving no bacteria (control) and positive control wells receiving only Sal (10 total treatments). After bacterial incubation, wells were washed and fresh medium containing gentamicin was added. Cells were incubated for an additional 5 h, after which apical and basolateral media were recovered for determination of IL-8 and bacitracin. In addition, inserts with epithelial cells that had received Sal were lysed and lysates were cultured to determine treatment effects on Sal invasion. Exposure to Sal alone provoked an increase in IL-8 secretion from IPEC-J2 cells compared with control wells. Pretreatment with each Bacillus isolate followed by challenge with Sal reduced Sal-induced IL-8 secretion in both the apical and basolateral compartments compared with wells receiving only Sal. The residual presence of bacitracin could be detected only in BL2 and BL2+Sal. Fewer Sal colonies could be cultured from lysates of BL2+Sal than from the Sal, BS1+Sal, and BS3+Sal treatments. Results indicate that B. subtilis and BL have the ability to intervene in secretion of the neutrophil chemoattractant IL-8 from swine intestinal epithelial cells. This effect on chemokine secretion by gastrointestinal epithelial cells in vitro could not be explained solely by reduced invasion of epithelial cells by Sal.

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

Impact of piglet birth weight, birth order, and litter size on subsequent growth performance, carcass quality, muscle composition, and eating quality of pork

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The objective of this study was to investigate the relationships among birth weight, birth order, or litter size on growth performance, carcass quality, and eating quality of the ultimate pork product. Data were collected from 98 pig litters and, with the addition of recording birth weight and birth order, farrowing and piglet management were according to normal barn practices. In the nursery and during growout, the pigs received the normal feeding program for the barn and, with the addition of individual tattooing, were marketed as per standard procedure. From 24 litters, selected because they had at least 12 pigs born alive and represented a range of birth weights, 4 piglets were chosen (for a total of 96 piglets) and sent to Agriculture and Agri-Food Canada–Lacombe Research Centre when they reached 120 kg for extensive meat quality and sensory analysis. Individual BW was measured at birth, on the day of weaning, 5 wk after weaning, at nursery exit, at first pull, and at the time of marketing. Litter sizes were divided into 3 categories: small (3 to 10 piglets), medium (11 to 13 piglets), and large (14 to 19 piglets). There were 4 birth-weight quartiles: 0.80 to 1.20, 1.25 to 1.45, 1.50 to 1.70, and 1.75 to 2.50 kg. Increased litter size resulted in reduced mean birth weight, but had no effect on within litter variability or carcass quality when slaughtered at the same endpoint. Lighter birth-weight pigs had reduced BW at weaning, 5 and 7 wk postweaning, and at first pull and had increased days to market. Birth weight had limited effects on carcass quality, weight of primal cuts, objective quality, and overall palatability of the meat at the same slaughter weight. In conclusion, increased litter size resulted in decreased mean birth weight but no change in days to market. Lighter birthweight pigs took longer to reach market. Despite some differences in histological properties, birth weight had limited effects on carcass composition or final eating quality of the pork when slaughtered at the same BW and large litter size resulted in more pigs weaned and marketed compared with the smaller litters. We concluded that based on the conditions of this study, other than increased days to market, there is no reason based on pig performance or pork quality to slow down the goal of the pork industry to increase sow productivity as a means to increase efficiency.

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

Expression profiling of IGFs and IGF receptors in piglets with intrauterine growth restriction

Posted in: Production by admin on July 26, 2011 | No Comments

Intrauterine growth restriction (IUGR), defined as impaired growth and development of the mammalian fetus or its organs during pregnancy because of inadequate food intake, disease, environmental stress, or the dysfunction of the placenta, endometrium, or uterus is a major problem in human medicine and animal production. In order to test the hypothesis that expression levels of insulin-like growth factor system is altered in piglets with IUGR, the present study was conducted to compare the expression levels of IGF-I, IGF-II, IGFR1, IGFR2 and IGFBP5 in m. longissimus, liver and kidney in 21-day-old IUGR piglets with normal birth weight (NBW) piglets. Our results showed that the expression level of insulin-like growth factor 1 was significantly lower in m. longissimus, liver and kidney of the IUGR piglets compared with the NBW piglets. However, there were no differences in the expression levels of IGF2, IGF1R, IGF2R and IGFBP5 in all tissues tested between NBW and IUGR piglets.In the previous studies, higher levels of liver or serum IGF-I, IGF-II, IGFBP2 and IGFBP3 were observed in spontaneously arising IUGR fetal piglets. This demonstrates that the expression level is different in insulin-like growth factor system genes between IUGR fetal pigs and piglets of 21 days. Our results suggested that it is possible to cure or prevent IUGR in piglets through injection of IGF1.

For more information the full article can be found at http://www.journals.elsevierhealth.com/periodicals/livsci

Group housing of sows in early pregnancy: A review of success and risk factors

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A recent telephone survey of 735 Dutch farmers with group housing of sows in early pregnancy suggested a wide variation in reproductive success, irrespective of husbandry system. The reason for these differences between farms is not known, but of great importance to the pig industry which is moving worldwide from individual to group housing systems, mainly for animal welfare reasons. Therefore, the aim of this review is to list the most likely success and risk factors for group housing of sows in early pregnancy, in relation to reproduction (such as pregnancy rate) and animal welfare (such as aggression and health). The review first considers a limited number of group housing comparisons and finds that the results of the few studies performed are not very conclusive, neither on fertility nor on leg problems, longevity and welfare of sows. As a consequence, it is hard to draw any significant practical conclusions, and the review proceeds to look at studies in which single factors were addressed. For the effects on fertility it is concluded that especially factors causing chronic stress (e.g. due to unfavourable social, management or climatic conditions) and a low feed intake may impact reproductive performance. The vulnerable period lies in weeks 2 and 3 of pregnancy. On leg problems and longevity an important factor seems to be the quality of the floor, regardless of other aspects of the housing system. The use of straw seems to be advantageous. Finally, on aggression it is argued that this will never be eliminated from systems in which sows are housed as a group. However, it can be properly managed and key factors in this are a gradual familiarisation of unfamiliar animals, sufficient space and pen structure during initial mixing, minimizing opportunities for dominant sows to steal food from subordinates, the provision of a good quality floor and the use of straw bedding. The review concludes with a series of practical recommendations to improve welfare and reproduction in group housed sows.

For more information the full article can be found at http://www.journals.elsevierhealth.com/periodicals/livsci

Obstetric and fetal outcomes in dystocic and eutocic sows to an injection of exogenous oxytocin during farrowing

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Sixty hybrid Yorkshire-Landrace penned sows, 30 with eutocic farrowing and 30 experiencing a dystocic parturition, were studied to evaluate the obstetric and neonatal outcomes to low doses of oxytocin administered at advanced stages of parturition. Animals in each group were randomly subdivided into 2 subgroups: 15 eutocic and 15 dystocic sows received oxytocin 0.083 IU/kg (equivalent to 1 IU/12 kg body weight), administered intramuscularly after the delivery of the 5th piglet; the other 15 eutocic and 15 dystocic sows received saline solution intramuscularly at the same time. Oxytocin decreased the number of intrapartum deaths by approximately 50% (P = 0.002). No piglet was born dead from the saline- and oxytocin-treated eutocic sows. The highest viability score was observed among piglets born to eutocic sows treated with oxytocin. In summary, this dose schedule would help to decrease the number of stillbirths in both eutocic and dystocic farrowing sows.

Management factors associated with farrowing rate in commercial sow herds in Ontario

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The objectives of this study were to determine associations between low farrowing rate and various management factors in sow herds. In 30 sow herds, a management survey, breeding observations, semen evaluation, and semen storage temperature monitoring were completed. Herds with an average farrowing rate of, 85% were classified as low farrowing rate herds while those with an average farrowing rate of $ 85% were classified as good farrowing rate herds. Low farrowing rate herds were more likely than good farrowing rate herds to move boars into gilt pens for estrus detection, breed a high proportion of sows by artificial insemination (AI) only, start heat detection 3 d post-weaning, wipe the vulva prior to breeding, and use “hands-free” AI devices.

Results from six generations of selection for intramuscular fat in Duroc swine using real-time ultrasound. I. Direct and correlated phenotypic responses to selection

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A study was conducted to evaluate the efficacy of selection for intramuscular fat (IMF) in a population of purebred Duroc swine using real-time ultrasound. Forty gilts were purchased from US breeders and randomly mated for 2 generations to boars available in regional boar studs, resulting in a base population of 56 litters. Littermate pairs of gilts from this population were randomly assigned to a select line (SL) or control line (CL) and mated to the same sire to establish genetic ties between lines. At an average BW of 114 kg, a minimum of 4 longitudinal ultrasound images were collected 7 cm off-midline across the 10th to 13th ribs of all pigs for the prediction of IMF (UIMF). At least 1 barrow or gilt was slaughtered from each litter, and carcass data were collected. A sample of the LM from the 10th to 11th rib interface was analyzed for carcass IMF (CIMF). Breeding values for IMF were estimated by fitting a 2-trait (UIMF and CIMF) animal model in MATVEC. In the SL, selection in each subsequent generation was based on EBV for IMF with the top 10 boars and top 75 gilts used to produce the next generation. One boar from each sire family and 50 to 60 gilts representing all sire families were randomly selected to maintain the CL. Through 6 generations of selection, an 88% improvement in IMF has been realized (4.53% in SL vs. 2.41% in CL). Results of this study revealed no significant correlated responses in measures of growth performance. However, 6 generations of selection for IMF have yielded correlated effects of decreased loin muscle area and increased backfat. Additionally, the SL obtained more desirable objective measures of tenderness and sensory evaluations of flavor and off-flavor. Meat quality characteristics of pH, water holding capacity, and percent cooking loss were not significantly affected by selection for IMF. Selection for IMF using real-time ultrasound is effective but may be associated with genetic ramifications for carcass composition traits. Intramuscular fat may be used in purebred Duroc swine breeding programs as an indicator trait for sensory traits that influence consumer acceptance; however, rapid improvement should not be expected when simultaneous improvement in other trait categories is also pursued. 

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