a quantitative trait locus for a primary antibody response to keyhole limpet hemocyanin on chicken chromosome 14 confirmation and candidate gene approach

A QTL involved in the primary antibody response toward keyhole limpet hemocyanin (KLH) was detected on chicken chromosome 14 in the experimental population, which was created by crossing commercial White Leghorn and a Polish native chicken breed (green-legged partridgelike). The current QTL location is a validation of previous experiments pointing to the same genomic location for the QTL linked to a primary antibody response to KLH. An experimental population was typed with microsatellite markers distributed over the chicken chromosome 14. Titers of antibodies binding KLH were measured for all individuals by ELISA. Statistical models applied in the Grid QTL Web-based software were used to analyze the data: a half-sib model, a line-cross model, and combined analysis in a linkage disequilibrium and linkage analysis model. Candidate genes that have been proposed were genotyped with SNP located in genes exons. Statistical analyses of single SNP associations were performed pointing out 2 SNP of an axis inhibitor protein (AXIN1) gene as significantly associated with the trait of an interest

A Genome-Wide Association Study Reveals Dominance Effects on Number of Teats in Pigs

Dominance has been suggested as one of the genetic mechanisms explaining heterosis. However, using traditional quantitative genetic methods it is difficult to obtain accurate estimates of dominance effects. With the availability of dense SNP (Single Nucleotide Polymorphism) panels, we now have new opportunities for the detection and use of dominance at individual loci. Thus, the aim of this study was to detect additive and dominance effects on number of teats (NT), specifically to investigate the importance of dominance in a Landrace-based population of pigs. In total, 1,550 animals, genotyped for 32,911 SNPs, were used in single SNP analysis. SNPs with a significant genetic effect were tested for their mode of gene action being additive, dominant or a combination. In total, 21 SNPs were associated with NT, located in three regions with additive (SSC6, 7 and 12) and one region with dominant effects (SSC4). Estimates of additive effects ranged from 0.24 to 0.29 teats. The dominance effect of the QTL located on SSC4 was negative (-0.26 teats). The additive variance of the four QTLs together explained 7.37% of the total phenotypic variance. The dominance variance of the four QTLs together explained 1.82% of the total phenotypic variance, which corresponds to one-fourth of the variance explained by additive effects. The results suggest that dominance effects play a relevant role in the genetic architecture of NT. The QTL region on SSC7 contains the most promising candidate gene: VRTN. This gene has been suggested to be related to the number of vertebrae, a trait correlated with NT

Using SNP Markers to Estimate Additive, Dominance and Imprinting Genetic Variance

The contributions of additive, dominance and imprinting effects to the variance of number of teats (NT) were evaluated in two purebred pig populations using SNP markers. Three different random regression models were evaluated, accounting for the mean and: 1) additive effects (MA), 2) additive and dominance effects (MAD) and 3) additive, dominance and imprinting effects (MADI). Additive heritability estimates were 0.30, 0.28 and 0.27-0.28 in both lines using MA, MAD and MADI, respectively. Dominance heritability ranged from 0.06 to 0.08 using MAD and MADI. Imprinting heritability ranged from 0.01 to 0.02. Dominance effects make an important contribution to the genetic variation of NT in the two lines evaluated. Imprinting effects appeared less important for NT than additive and dominance effects. The SNP random regression model presented and evaluated in this study is a feasible approach to estimate additive, dominance and imprinting variance

Genomic selection for boar taint compounds and carcass traits in a commercial pig population

AbstractThis study aimed to compare two different Genome-Wide Selection (GWS) methods (Ridge Regression BLUP − RR-BLUP and Bayesian LASSO − BL) to predict the genomic estimated breeding values (GEBV) of four phenotypes, including two boar taint compounds, i.e., the concentrations of androstenone (andro) and skatole (ska), and two carcass traits, i.e., backfat thickness (fat) and loin depth (loin), which were measured in a commercial male pig line. Six hundred twenty-two boars were genotyped for 2,500 previously selected single nucleotide polymorphisms (SNPs). The accuracies of the GEBV using both methods were estimated based on Jack-knife cross-validation. The BL showed the best performance for the andro, ska and loin traits, which had accuracy values of 0.65, 0.58 and 0.33, respectively; for the fat trait, the RR-BLUP accuracy of 0.61 outperformed the BL accuracy of 0.56. Considering that BL was more accurate for the majority of the traits, this method is the most favoured for GWS under the conditions of this study. The most relevant SNPs for each trait were located in the chromosome regions that were previously indicated as QTL regions in other studies, i.e., SSC6 for andro and ska, SSC2 for fat, and SSC11, SSC15 and SSC17 for loin

Follicular development of sows at weaning in relation to estimated breeding value for within-litter variation in piglet birth weight

In this study we aimed to identify possible causes of within-litter variation in piglet birth weight (birth weight variation) by studying follicular development of sows at weaning in relation to their estimated breeding value (EBV) for birth weight variation. In total, 29 multiparous sows (parity 3 to 5) were selected on their EBV for birth weight variation (SD in grams; High-EBV: 15.8±1.6, N=14 and Low-EBV: −24.7±1.5, N=15). The two groups of sows had similar litter sizes (15.7 v. 16.9). Within 24 h after parturition, piglets were cross-fostered to ensure 13 suckling piglets per sow. Sows weaned 12.8±1.0 and 12.7±1.0 piglets, respectively, at days 26.1±0.2 of lactation. Blood and ovaries were collected within 2 h after weaning. The right ovary was immediately frozen to assess average follicle size and percentage healthy follicles of the 15 largest follicles. The left ovary was used to assess the percentage morphologically healthy cumulus-oocyte complexes (COCs) of the 15 largest follicles. To assess the metabolic state of the sows, body condition and the circulating metabolic markers insulin, IGF1, non-esterified fatty acid, creatinine, leptin, urea and fibroblast growth factor 21 were analysed at weaning. No significant differences were found in any of the measured follicular or metabolic parameters between High-EBV and Low-EBV. A higher weight loss during lactation was related to a lower percentage healthy COCs (β= −0.65, P=0.02). Serum creatinine, a marker for protein breakdown, was negatively related to average follicle size (β= −0.60, P=0.05). Backfat loss during lactation was related to a higher backfat thickness at parturition and to a higher average follicle size (β=0.36, P<0.001) at weaning. In conclusion, we hypothesise that modern hybrid sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation and could thereby spare protein reserves to support follicular development.</p

Effects of a Multi-Suckling System Combined With Enriched Housing Post-Weaning on Response and Cognitive Resilience to Isolation

Improving welfare is still a critical issue in pig husbandry. Upgrades of the housing environment seem to be a promising solution to optimise resilience as a whole, and therefore improve animal welfare. The objective of this study was to evaluate the effect of an alternative housing system to enhance cognitive resilience and also to promote the pigs' welfare. A total of 96 piglets from two contrasted housing systems [alternative housing system (AHS) vs. conventional system (CONV)] was used. The major upgrades of the alternative system were multi-litter housing during lactation, delayed weaning, extra space allowance, and environmental enrichment from birth onwards. To estimate welfare, weight, and feed intake (as a general indicator of performances), the tear staining area (as a chronic stress indicator), behavioural postures, heart rate traits, and saliva cortisol concentration were measured over a 21 h-isolation. To assess cognitive resilience, the pigs were subjected to a maze with a social reward both before and after the isolation challenge and indicators of cognitive abilities were followed. The AHS pigs showed lower cortisol levels and tear staining area before the challenge, demonstrating overall better welfare due to the alternative housing conditions. During the challenge, AHS pigs had a lower heart rate, higher heart rate variability, and higher vagal activity than the CONV pigs, which might indicate a reduced sensitivity to the stressor. AHS pigs appeared to have a better long-term memory tested in a maze. Providing social and environmental enrichments, that fit the satisfaction of the essential needs of the pigs better, appears to be beneficial for pig welfare as a whole. Its effects on cognitive resilience still need to be proven

A multi‑suckling system combined with an enriched housing environment during the growing period promotes resilience to various challenges in pigs

Little is known about the impact of social and environmental enrichment on improving livestock resilience, i.e. the ability to quickly recover from perturbations. We evaluated the effect of an alternative housing system (AHS) on resilience of pigs, as compared to conventional housing (CONV). The AHS consisted of multi-litter housing during lactation, delayed weaning, extra space allowance and environmental enrichment at all times. We assessed recovery to a 2 h-transport challenge, an LPS injection, 2 h-heat stress and a biopsy wound in 96 pigs. Additionally, indicators of long-term “wear and tear” on the body were determined. AHS pigs had better physiological recoveries with quicker returns to baseline in the transport and LPS challenges, showed lower cortisol accumulation in hairs and lower variance in weight gain over the experimental period compared to conventionally-housed (CONV) pigs. They also had higher levels of natural antibodies binding KLH than CONV pigs. Their response to heat stress revealed a different strategy compared to CONV pigs. Taken together, AHS pigs appear to be more resilient and experience less chronic stress. Enhancing welfare by provision of social and environmental enrichment that better meets the behavioural needs of pigs seems to be a promising approach to improve their resilience

Effect van fokwaarde voor berengeur op het gedrag en berengeur van beren : Effect of genetic background for boar taint on the behaviour and boar taint of boars

In opdracht van het ministerie van Economische Zaken en het Productschap Vee en Vlees is op Varkens Innovatie Centrum (VIC) Sterksel en een praktijkbedrijf onderzocht of er een relatie is tussen ongewenst gedrag van beren en berengeur. Mocht deze relatie er zijn, dan wordt bij selectie op minder berengeur mogelijk ook geselecteerd op minder ongewenst gedrag van beren. Daarnaast is op 9 praktijkbedrijven nagegaan wat het effect is op berengeur bij de inzet van eindberen met een lage fokwaarde voor berengeur