Heritability and genetic correlation estimates of semen production traits with litter traits and pork production traits in purebred Duroc pigs

We estimated heritabilities of semen production traits and their genetic correlations with litter traits and pork production traits in purebred Duroc pigs. Semen production traits were semen volume, sperm concentration, proportion of morphologically normal sperms, total number of sperm, and total number of morphologically normal sperm. Litter traits at farrowing were total number born, number born alive, number stillborn, total litter weight at birth, mean litter weight at birth, and piglet survival rate at birth. Litter traits at weaning were litter size at weaning, total litter weight at weaning, mean litter weight at weaning, and piglet survival rate from birth to weaning. Pork production traits were average daily gain, backfat thickness, and loin muscle area. We analyzed 45,913 semen collection records of 896 boars, 6,950 farrowing performance records of 1,400 sows, 2,237 weaning performance records of 586 sows, and individual growth performance records of 9,550 animals measured at approximately 5 mo of age. Heritabilities were estimated using a single-trait animal model. Genetic correlations were estimated using a 2-trait animal model. Estimated heritabilities of semen production traits ranged from 0.20 for sperm concentration to 0.29 for semen volume and were equal to or higher than those of litter traits, ranging from 0.06 for number stillborn and piglet survival rate at birth to 0.25 for mean litter weight at birth, but lower than those of pork production traits, ranging from 0.50 for average daily gain to 0.63 for backfat thickness. In many cases, the absolute values of estimated genetic correlations between semen production traits and other traits were smaller than 0.3. These estimated genetic parameters provide useful information for establishing a comprehensive pig breeding scheme.     

科尔沁细毛羊主要经济性状间遗传相关的估计

为了研究科尔沁细毛羊群体遗传趋势,试验采用父系半同胞组内相关法估算科尔沁细毛羊的体重性状、抓毛性状间的遗传相关和表型相关。结果表明:初生重与断奶重、1周龄体重、2周龄体重、3周龄体重间存在极显著的遗传相关(P<0.01),相关系数分别为0.690 1,0.593 1,0.581 2,0.210 2;断奶重与1周龄体重、2周龄体重、3周龄体重间也存在极显著的遗传相关(P<0.01),相关系数分别为0.373 3,0.274 1,0.268 2;1周龄毛细度与2周龄毛细度、1周龄毛细度与3周龄毛细度、1周龄毛长与1周龄剪毛量、1周龄毛长与3周龄毛长、1周龄剪毛量与3周龄毛细度、2周龄毛细度与3周龄毛细度、2周龄毛细度与3周龄剪毛量、2周龄剪毛量与3周龄剪毛量间存在极显著的高等遗传相关(P<0.01),相关系数分别为0.712 0,0.805 0,0.717 1,0.701 9,0.531 6,0.719 0,0.681 3,0.521 3,表型相关普遍低于遗传相关。     

海拔与黄花苜蓿表型性状的相关性研究

黄花苜蓿表型性状具有丰富的多态性,受生境影响较大,尤其是经纬度、海拔,研究黄花苜蓿表型性状与海拔的相关性对揭示黄花苜蓿遗传变异规律具有重要的意义。试验以新疆黄花苜蓿为材料,通过测量同一经纬度(N 43°43',E 86°94')不同海拔(2100~2350 m)下株高、分枝数、叶、茎、花等18个表型性状,探索其变化规律,为进一步开展黄花苜蓿遗传多样性及种质创新研究提供基础数据。研究表明:海拔对表型性状的影响较大,随着海拔降低,株高、叶长、叶宽、节间长、茎粗、小花长等数值总体呈现“降-升-降”的趋势,均在海拔2150 m时有明显升高,随后降低;表型指标的变异范围为1.30%~22.83%,平均变异系数为8.49%;海拔与株高、花序长、花柄长、龙骨瓣宽等相关性显著,相关系数分别为0.490、0.601、-0.449、-0.421,与其他指标间的相关性不显著。综合分析认为,黄花苜蓿适宜生长在海拔为2150 m左右的区域。     

Stability of genetic parameter estimates for production traits in pigs

Changes in variance component estimates in growing sets of performance data in two pig breeds were investigated. Data was used from the field and station test of Czech Landrace (LA: 75 099 observations) and the Slovakian breed, White Meaty swine (WM: 32 203 observations). In LA the traits analysed were estimated lean meat content (LM) and average daily gain (ADGF) on field test and average daily gain (ADGS) and weight of valuable cuts (VCW) on station test. In WM the traits analysed were backfat thickness on field and station test (BFF, BFS, respectively), proportion of valuable cuts (VCP) on station test, ADGF and ADGS. Covariance components were estimated from four- and five-trait animal models using the VCE software. Omitting data from factor levels with a low number of records led to 4.2% of LA records and 21.7% of WM records being deleted. Changes in genetic and residual variance estimates were less than 5% for all traits in LA and less than 12% for all traits except ADGS in WM. The changes in estimated genetic variances caused by 18 months (LA) or 24 months (WM) of new data were 2–25% and the changes in estimated residual variances were less than 5% in LA and less than 20% in WM. In both breeds, changes in heritability estimates did not exceed 0.06 in absolute value. In LA, it is reasonable to use genetic parameter estimates for 3 years before re-estimation. In WM the time interval should be shorter because of changes in the estimates caused by their lower accuracy arising from the smaller size of the data-set and smaller frequency of station testing.     

Genetic parameter estimates for semen production traits and growth rate of a paternal rabbit line

Variance components of sperm production traits (volume in ml, V; concentration in ×10⁶ sperm/ml, CN; sperm production in ×10⁶ sperm, PROD) were estimated in a paternal line of rabbit selected for 25 generations based on daily weight gain (DG, g/day) between 28 and 63 days of age. Features of the marginal posterior distributions for ratios of genetic variance, variance owing to non‐additive plus environmental permanent male effects and variance owing to common litter of birth effects with respect to phenotypic variance are reported. The correlations between sperm production traits and the selection criteria were also estimated. Three sets of two‐trait analyses were performed, involving 12908 records of DG, 2329 ejaculates corresponding to 412 bucks and 14700 animals in pedigree file. The heritabilities (h²) of the semen traits were 0.13 ± 0.05, 0.08 ± 0.04 and 0.07 ± 0.03 for V, CN and PROD, respectively. The permanent environmental effects were lower than the corresponding values of h² and varied between 0.06 and 0.11. A favourable and moderate genetic correlation was observed between V and DG (0.36 ± 0.34; p > 0: 0.83), together with a non‐favourable and moderate correlation between permanent environmental effects owing to common litter of birth for both traits (?0.35 ± 0.35; p < 0: 0.85). On the other hand, the correlation between male permanent environmental effects for semen traits and DG was moderate and non‐favourable (?0.51 ± 0.29 with p < 0: 0.95 for DG‐CN, and ?0.31 ± 0.37 with p < 0: 0.79 for DG‐PROD).     

Estimation of heritability of feeding behaviour traits and their correlation with production traits in Finnish Yorkshire pigs

A major proportion of the costs of pork production is related to feed. The feed conversion rate (FCR) or residual feed intake (RFI) is thus commonly included in breeding programmes. Feeding behaviour traits do not directly have economic value but, if correlated with production traits, can be used as auxiliary traits. The aim of this study was to estimate the heritability of feeding behaviour traits and their genetic correlations with production traits in the Finnish Yorkshire pig population. The data were available from 3,235 pigs. Feeding behaviour was measured as the number of visits per day (NVD), time spent in feeding per day (TPD), daily feed intake (DFI), time spent feeding per visit (TPV), feed intake per visit (FPV) and feed intake rate (FR). The test station phase was divided into five periods. Estimates of heritabilities of feeding behaviour traits varied from 0.17 to 0.47. Strong genetic correlations were obtained between behaviour traits in all periods. However, only DFI was strongly correlated with the production traits. Interestingly, a moderate positive genetic correlation was obtained between FR and backfat thickness (0.1–0.5) and between FR and average daily gain (0.3–0.4), depending on the period. Based on the results, there is no additional benefit from including feeding‐related traits other than those commonly used (FCR and RFI) in the breeding programme. However, if correlated with animal welfare, the feeding behaviour traits could be valuable in the breeding programme.     

Genetic correlations between reproduction and production traits in swine

Genetic correlations between reproduction and production traits were estimated in swine. Reproduction traits investigated were age at first service (AFS), number of live-born piglets in the first litter (NBA1), interval from weaning to first service after first litter (WTS1), number of live-born piglets in the second litter (NBA2), and interval from weaning to first service after the second litter (WTS2). Females generating the data were Norwegian Landrace born in nucleus herds between 1990 and 2000, and the number of records ranged from 13,792 to 56,932. Genetic correlations were estimated among the main production traits in the breeding goal: adjusted age at 100 kg live weight (A100), percentage of lean meat content (LMC), individual feed consumption from 25 to 100 kg (FC), and bacon side quality (BSQ). Average adjusted backfat thickness (BF) was included as a production trait. The A100 and BF traits were recorded on gilts on-farm with 190,454 records, whereas LMC, BSQ, and FC were recorded on-station with the number of records ranging from 12,487 to 12,992. Analyses were carried out with a multivariate animal model using average information restricted maximum likelihood procedures by first running each reproduction trait with A100 and BF, followed by each reproduction trait with LMC, BSQ, and FC. Average heritabilities for reproduction traits were as follows: AFS (0.38), NBA1 (0.11), WTS1 (0.06), NBA2 (0.12), and WTS2 (0.03); and for production traits: A100 (0.30), BF (0.44), FC (0.22), LMC (0.58), and BSQ (0.23). The highest genetic correlation was estimated between A100 and AFS (r(g)= 0.68), also resulting in a positive genetic correlation between FC and AFS. Growth (A100) was negatively (i.e., unfavorably) genetically correlated to NBA1 and NBA2 (r(g) = 0.60 and rg = 0.42 respectively), and so the genetic correlation to FC also became unfavorable (r(g)= 0.23 and r(g) = 0.20). Single-trait selection for enhanced LMC would also affect NBA1 and NBA2 unfavorably (r(g)= -0.12 and r(g)= -0.24). Correlations between BF at 100 kg live weight and reproduction traits were close to zero; however, a low genetic correlation between BF and WTS1 was obtained (r(g)= -0.12), indicating that selection toward reduced BF at 100 kg live weight may have an unfavorable impact on WTS1.     

青藏高原老芒麦落粒性及农艺性状相关性研究

为探究青藏高原地区抗落粒老芒麦种质的筛选及落粒率与农艺性状的关系,以15份采自青海不同地区的老芒麦种质资源为研究对象,对老芒麦的落粒率和农艺性状进行了变异分析、相关性分析、主成分分析、回归分析和聚类分析.结果表明:1)15份老芒麦资源自然落粒率存在明显差异,其中17-124的落粒最严重,平均落粒率为56.92％.以17...     

The evidence of associations between prion protein genotype and production, reproduction, and health traits in sheep

The EU Commission issued a regulation in 2003, which requires all member states to implement a breeding programme for resistance to transmissible spongiform encephalopathies in sheep by selecting for specific alleles of the prion protein (PrP) gene. A key concern with regard to this regulation was that the intensive selection programmes, designed to increase resistance to scrapie, may have a negative impact on a range of other economically important production, reproduction, and disease traits in sheep. Such problems could arise for a number of reasons. Firstly, a number of breeds have a low frequency of the resistant PrP allele. Secondly, there may be a negative association between the resistant allele and animal performance. Thirdly, selection for scrapie resistance may reduce the rate of improvement towards current breeding goals. The evidence concerning the relationship between PrP genotype and reproduction, production, and disease traits is the subject of this review. We conclude that there is no evidence for a negative association between PrP genotype and reproduction traits (e.g. litter size), lamb performance traits (e.g. growth rate, conformation, carcass composition) or milk production. There is, however, a distinct paucity of information on the relationship between the PrP gene and disease traits. In this context it is noted that there are a number of genes located on chromosome 13, in close proximity to the PrP gene, that are involved in intracellular cell signalling, apoptosis, phagocytosis, and immune function. Thus further direct studies of key disease traits associated with sheep production systems are warranted.     

Structural equation models to disentangle the biological relationship between microbiota and complex traits: Methane production in dairy cattle as a case of study

The advent of metagenomics in animal breeding poses the challenge of statistically modelling the relationship between the microbiome, the host genetics and relevant complex traits. A set of structural equation models (SEMs) of a recursive type within a Markov chain Monte Carlo (MCMC) framework was proposed here to jointly analyse the host–metagenome–phenotype relationship. A non-recursive bivariate model was set as benchmark to compare the recursive model. The relative abundance of rumen microbes (RA), methane concentration (CH₄) and the host genetics was used as a case of study. Data were from 337 Holstein cows from 12 herds in the north and north-west of Spain. Microbial composition from each cow was obtained from whole metagenome sequencing of ruminal content samples using a MinION device from Oxford Nanopore Technologies. Methane concentration was measured with Guardian^® NG infrared gas monitor from Edinburgh Sensors during cow's visits to the milking automated system. A quarterly average from the methane eructation peaks for each cow was computed and used as phenotype for CH₄. Heritability of CH₄ was estimated at 0.12 ± 0.01 in both the recursive and bivariate models. Likewise, heritability estimates for the relative abundance of the taxa overlapped between models and ranged between 0.08 and 0.48. Genetic correlations between the microbial composition and CH₄ ranged from −0.76 to 0.65 in the non-recursive bivariate model and from −0.68 to 0.69 in the recursive model. Regardless of the statistical model used, positive genetic correlations with methane were estimated consistently for the seven genera pertaining to the Ciliophora phylum, as well as for those genera belonging to the Euryarchaeota (Methanobrevibacter sp.), Chytridiomycota (Neocallimastix sp.) and Fibrobacteres (Fibrobacter sp.) phyla. These results suggest that rumen's whole metagenome recursively regulates methane emissions in dairy cows and that both CH₄ and the microbiota compositions are partially controlled by the host genotype.     

There is room for selection in a small local pig breed when using optimum contribution selection: a simulation study

Selection progress must be carefully balanced against the conservation of genetic variation in small populations of local breeds. Well-defined breeding programs?with specified selection traits are rare in local pig breeds. Given the small population size,?the focus is often on the management of genetic diversity. However, in local breeds, optimum contribution selection can be applied to control the rate of inbreeding and to avoid reduced performance in traits with high market value. The aim of this study was to assess the extent to which a breeding program aiming for improved product quality in a small local breed would be feasible. We used stochastic simulations to compare 25 scenarios. The scenarios differed in?size of population, selection intensity of boars, type of selection (random selection, truncation selection based on BLUP breeding values, or optimum contribution selection based on BLUP breeding values), and heritability of?the selection trait. It was assumed that the local breed is used in an extensive system for a high-meat-quality market.?The?simulations showed that in the smallest population (300 female reproducers), inbreeding increased by 0.8% when selection was performed at random. With optimum contribution selection, genetic progress can be achieved that is almost as great as that with truncation selection based on BLUP breeding values (0.2 to 0.5 vs. 0.3 to 0.5 genetic SD, P < 0.05), but at a considerably decreased rate of inbreeding (0.7 to 1.2 vs. 2.3 to 5.7%, P < 0.01). This confirmation of the potential utilization of OCS even in small populations is important in the context of sustainable management and the use of animal genetic resources.     

Heritability and genetic correlation estimates for performance,meat quality and quantitative skeletal muscle fiber traits in broiler

Broiler feed efficiency and meat quality are the primary factors considered by the poultry industry. This study was conducted to estimate heritability and genetic correlation coefficients for skeletal muscle fiber number, area and diameter and performance and meat quality traits of Pectoralis major in a single male broiler line. (Co) variance components were estimated by restricted maximum likelihood method, using the software MTDFREML. The numerator relationship matrix was composed by 77,474 individuals. Heritability coefficient estimates ranged from moderate to high for juvenile BW, breast weight, ultrasound record of pectoral muscle, lightness and thawing meat loss. Genetic correlation estimates for performance and skeletal muscle fiber traits indicated that selection for higher breast weight and juvenile BW could reduce muscle fiber number and increase muscle fiber diameter and area, which could prejudice the meat quality of this line. Selection for muscle fiber number and against muscle fiber diameter and area might improve meat water retention ability and tenderness in this broiler line, and selection programs could consider those traits as selection criteria, although this may be costly. We recommend the evaluation of the indirect selection caused by the use of the performance traits as selection criteria especially for juvenile BW and breast weight. Direct, intense selection for both traits might be unfavorable for most of the meat quality traits analyzed, which could lead to losses to both the chicken meat processing industry and consumers.     

Multivariate analysis of litter size for multiple parities with production traits in pigs: II. Response to selection for litter size and correlated response to production traits

Litter size and production trait responses to experimental selection for increased litter size in a Landrace pig population are reported. The numbers of sows and litters available for the first cycle of selection were 3,034 and 961, respectively. Selection was carried out using a BLUP repeatability animal model for number of piglets born alive (NBA). The experiment included one selection and one control line, each with three nonoverlapping generations. The selection line (H) consisted of the 160 sows with the highest breeding values and one boar from each of 25 full-sib families with the highest breeding values. The control line (C) consisted of 160 sows and 25 boars randomly chosen. The two subsequent generations in each line were obtained by random selection. A Bayesian analysis of genetic response using a multivariate model was carried out by Gibbs sampler. Marginal posterior distributions were obtained for direct response in NBA, and for correlated response in weight (WT), and backfat thickness (BT) at 175 d of age. The posterior means and posterior standard deviation (PSD) for direct genetic response of NBA ranged from 0.32 (PSD 0.08) in the first parity to 0.64 (PSD 0.08) in the fourth. The posterior means for correlated genetic response in WT and BT were -0.66 kg (PSD 0.36) and 0.20 mm (PSD 0.10), respectively. For WT and BT, the 95% highest posterior density regions (HPD) contain zero-correlated genetic response. Marginal posterior distributions of selection differentials were investigated. The posterior means for standardized selection differentials for NBA in different parities ranged from 0.70 (PSD 0.12) to 0.94 (PSD 0.06) in females for line H, from 0.22 (PSD 0.19) to 0.34 (PSD 0.10) in males for line H, and from 0.08 (PSD 0.08) to 0.13 (PSD 0.07) in females for line C. All available males were used in line C. Results from this experiment showed that selection for increased litter size is effective. Responses to selection were heterogeneous across parities, suggesting that litter size in each parity may have a different genetic background. No correlated genetic response to growth and backfat thickness was observed.     

Genome-wide association study of swine farrowing traits. Part I: Genetic and genomic parameter estimates

The primary objective of this study was to determine genetic and genomic parameters among swine (Sus scrofa) farrowing traits. Genetic parameters were obtained using MTDFREML. Genomic parameters were obtained using GENSEL. Genetic and residual variances obtained from MTDFREML were used as priors for the Bayes C analysis of GENSEL. Farrowing traits included total number born (TNB), number born alive (NBA), number born dead (NBD), number stillborn (NSB), number of mummies (MUM), litter birth weight (LBW), and average piglet birth weight (ABW). Statistically significant heritabilities included TNB (0.09, P = 0.048), NBA (0.09, P = 0.041), LBW (0.20, P = 0.002), and ABW (0.26, P < 0.0001). Statistically significant genetic correlations included TNB-NBA (0.97, P < 0.0001), TNB-LBW (0.74, P < 0.0001), NBA-LBW (0.56, P < 0.0017), NSB-LBW (0.87, P < 0.0395), and LBW-ABW (0.63, P < 0.0002). Genetic parameters are similar to others found in the literature. The proportion of phenotypic variance explained by genomic markers (GP) generated by GENSEL was TNB (0.04), NBA (0.06), NBD (0.00), NSB (0.01), MUM (0.00), LBW (0.11), and ABW (0.31). Limited information is available in the literature about genomic parameters. Only the GP estimate for NSB is significantly lower than what has been published. The GP estimate for ABW is greater than the estimate for heritability found in this study. Other traits with significant heritability had GP estimates half the value of heritability. This research indicates that significant genetic markers will be found for TNB, NBA, LBW, and ABW that will have either immediate use in industry or provide a roadmap to further research with fine mapping or sequencing of areas of significance. Furthermore, these results indicate that genomic selection implemented at an early age would have similar annual progress as traditional selection, and could be incorporated along with traditional selection procedures to improve genetic progress of litter traits.     

Comparison of models for genetic evaluation of survival traits in dairy cattle: a simulation study.

Three models for the analysis of functional survival data in dairy cattle were compared using stochastic simulation. The simulated phenotype for survival was defined as a month after the first calving (from 1 to 100) in which a cow was involuntarily removed from the herd. Parameters for simulation were based on survival data of the Canadian Jersey population. Three different levels of heritability of survival (0.100, 0.050 and 0.025) and two levels of numbers of females per generation (2000 or 4000) were considered in the simulation. Twenty generations of random mating and selection (on a second trait, uncorrelated with survival) with 20 replicates were simulated for each scenario. Sires were evaluated for survival of their daughters by three models: proportional hazard (PH), linear multiple-trait (MT), and random regression (RR) animal models. Different models gave different ranking of sires with respect to survival of their daughters. Correlations between true and estimated breeding values for survival to five different points in a cow's lifetime after the first calving (120 and 240 days in milk after first, second, third and fourth calving) favoured the PH model, followed by the RR model evaluations. Rankings of models were independent of the heritability level, female population size and sire progeny group size (20 or 100). The RR model, however, showed a slight superiority over MT and PH models in predicting the proportion of sire's daughters that survived to the five different end-points after the first calving.     

Genetic and phenotypic parameter estimates for feed intake and other traits in growing beef cattle, and opportunities for selection

Growth, feed intake, and temperament indicator data, collected over 5 yr on a total of 1,141 to 1,183 mixed-breed steers, were used to estimate genetic and phenotypic parameters. All steers had a portion of Hereford, Angus, or both as well as varying percentages of Simmental, Charolais, Limousin, Gelbvieh, Red Angus, and MARC III composite. Because the steers were slaughtered on various dates each year and the animals thus varied in days on feed, BW and feed data were adjusted to a 140-d feeding period basis. Adjustment of measures of feed efficiency [G:F or residual feed intake (RFI), intake adjusted for metabolic body size, and BW gain] for body fatness recorded at slaughter had little effect on the results of analyses. Average daily gain was less heritable (0.26) than was midtest BW (MBW; 0.35). Measures of feed intake had greater estimates of heritability, with 140-d DMI at 0.40 and RFI at 0.52; the heritability estimate for G:F was 0.27. Flight speed (FS), as an indicator of temperament, had an estimated heritability of 0.34 and a repeatability of 0.63. As expected, a strong genetic (0.86) correlation was estimated between ADG and MBW; genetic correlations were less strong between DMI and ADG or MBW (0.56 and 0.71). Residual feed intake and DMI had a genetic correlation of 0.66. Indexes for phenotypic RFI and genotypically restricted RFI (no correlation with BW gain) were compared with simple economic indexes incorporating feed intake and growth to elucidate expected selection responses under different criteria. In general, few breed differences were detected across the various measurements. Heterosis contributed to greater DMI, RFI, and MBW, but it did not significantly affect ADG, G:F, or FS. Balancing output (growth) with input costs (feed) is needed in practicing selection, and FS would not be recommended as an indicator trait for selection to change feed efficiency. An index including BW gain and RFI produced the best economic outcome.     

仙湖肉鸭B系肌内脂肪含量与屠体性能关系研究

本研究对仙湖肉鸭B系的肌内脂肪含量与屠体性状关系进行分析.结果表明:公鸭活重、屠体重、半净膛重、全净膛重与肌内脂肪含量均表现为中等正相关,其中半净膛重与肌内脂肪含量的相关关系达到显著水平(P<0.05),胸肌重、腿肌重、皮脂重、皮脂率均与肌内脂肪含量呈弱的正相关,相关关系不显著;母鸭腹脂重、腹脂率与肌内脂肪含量的相关系...     

Consequences of selection for improving production traits on the frequency of deleterious alleles for fitness

In this study the effect of artificial selection on BLUP EBV for production traits on the allele frequencies of a pleiotropic QTL affecting both production and disease susceptibility was investigated. Stochastic simulations were used to model artificial selection on a production trait that is controlled, in part, by a biallelic QTL that also controls susceptibility to disease. The QTL allele increasing production also increased susceptibility to disease. Different modes of action and proportions of variation accounted for by the QTL were assessed for the production trait. The main results indicated that alleles that confer susceptibility to the disease could be maintained in the population over a long period, depending on the mode of action of the QTL. In addition, the results of the study indicate that, under various conditions, it is possible to find pleiotropic QTL that control 2 traits despite these traits appearing to be uncorrelated. Therefore, in practice, an estimate of the genetic correlation between 2 traits may be misleading when the presence of such a QTL exists. The results of this study have implications for breeding programs. For example, if a pleiotropic QTL exists that favors heterozygotes for a production trait, it would be very difficult to remove disease susceptibility alleles via traditional selection methods.     

Genetic relationships between calving performance and beef production traits in Piemontese cattle

The aim of the study was to obtain estimates of genetic correlations between direct and maternal calving performance of heifers and cows and beef production traits in Piemontese cattle. Beef production traits were daily gain, live fleshiness, and bone thinness measured on 1,602 young bulls tested at a central station. Live fleshiness (six traits) and bone thinness were subjectively scored by classifiers using a nine-point linear grid. Data on calving performance were calving difficulty scores (five classes from unassisted to embryotomy) routinely recorded in the farms. Calving performance of heifers and cows were considered different traits. A total of 30,763 and 80,474 calving scores in first and later parities, respectively, were used to estimate covariance components with beef traits. Data were analyzed using bivariate linear animal models, including direct genetic effects for calving performance and beef traits and maternal genetic effects only for calving performance. Due to the nature of the data structure, which involved traits measured in different environments and on different animals, covariances were estimated mostly through pedigree information. Genetic correlations of daily gain were positive with direct calving performance (0.43 in heifers and 0.50 in cows) and negative with maternal calving performance (-0.23 and -0.28 for heifers and cows, respectively). Live fleshiness traits were moderately correlated with maternal calving performance in both parities, ranging from 0.06 to 0.33. Correlations between live fleshiness traits and direct calving performance were low to moderate and positive in the first parity, but trivial in later parities. Bone thinness was negatively correlated with direct calving performance (-0.17 and -0.38 in heifers and cows, respectively), but it was positively correlated to maternal calving performance (0.31 and 0.40). Estimated residual correlations were close to zero. Results indicate that, due to the existence of antagonistic relationships between the investigated traits, specific selection strategies need to be studied.     

Associations between polymorphisms in the chicken VIP gene,egg production and broody traits

1.?In this study, the vasoactive intestinal peptide (VIP) gene was screened for variations by cloning and sequencing to analyse the association with chicken egg production and broodiness traits.

2.?Sequencing revealed that 69 polymorphisms were found in a 9305-bp length of the chicken VIP gene, of which 39 were located in introns, 28 in 5′ regulatory region, 1 in exon 6 (synonymous) and 1 in 3′-UTR. The nucleotide diversity corrected for sample size was 1·96 × 10^?3.

3.?Five polymorphisms, C-3134T, “AGG” indel at ?2648 to ?2650, C + 338T, G + 780T and A + 4691G, were genotyped in 644 individuals of Ningdu Sanhuang chickens to evaluate their effects on egg production and broodiness traits. Marker-trait association analyses showed that the “AGG” indel was associated with total number of eggs from 90 to 300 d of age and total number of qualified eggs from 90 to 300 d of age. In contrast, C + 338T was associated with duration of broodiness.