Genetic Correlations Of Body Weight Research Articles

Genetic and nongenetic factors affecting body weight in Nili Ravi buffaloes

Live body weight of Nili Ravi buffaloes was studied to investigate the effect of certain environmental sources of variation such as herd, lactation number, lactation stage, season of recording and age of buffaloe at the time of recording alongwith appraisal of genetic parameters of body weight including heritabilities, genetic correlation and phenotypic correlation of body weight with mik yield. Five milking herds belonging to Nili Ravi buffaloe breed in Punjab were utilized in this study. Data recorded during 2010 to 2012 included 839 observations. Estimation of genetic parameters were carried out by Best Linear Unbiased Prediction (BLUP) procedure through ASREML set of coputer program. Least square mean for body weight was found as 523.13±81.63 with a coefficient of variation of 15.60%. Herd, stage of lactation, lactation number, recording season and buffalo’s age at the time of recording significantly affected live body weight. Univariate analysis of body weight indicated that heritability estimate for body weight was 0.33±0.07. Phenotypic correlations of body weight with milk yield in 305 days and milk yield on day of recording were found as 0.071±0.034 and 0.090±0.053 while genetic correlations were found as 0.16±0.00 and 0.20±0.00, respectively. High heritability and positive genetic correlation of body weight with milk yield suggested that body weight should be included in selection program for improved milk yield in Nili Ravi buffaloes.

Study for Some Body Weight and Egg Traits in Domyati and Khaki-Campbell Ducks

The duck industry makes an important contribution to the availability of animal protein sources in Egypt, little known about the genetic parameters, particularly the heritability and genetic correlations of body weight and egg production in ducks. Body weight is the most essential feature for genetic improvement due to its ease of selection, high heredity, and large impact on meat production costs. The target of this study was to evaluate and explain genetic parameters such as the heritability, the genetic and phenotypic correlations, and sire breeding value in Domyati (local) and Khaki-Campbell (foreign) ducks in order to improve body weight and egg traits. A total of 160 (80 Domyati and 80 Khaki-Campbell ducks utilized to measure body weight at 16 and 20 weeks g), as well as 7000 eggs (2500 Domyati and 4500 Khaki-Campbell) to measure egg traits (the egg number, egg weight, and egg mass are all measured throughout the first 90 days of laying). In Domyati and Khaki-Campbell ducks, the heritability estimated for body weight was moderate to high, ranged from 0.35 to 0.40, and 0.21 to 0.30 for egg production. The genetic correlations among body weight and egg traits were all positive and had high values, also among BW16 and BW20 were stronger (0.90); (0.99). So the genetic improvement in BW16 could be followed by an increase in BW20 weeks. It concluded that, the relatively high value of genetic heritability for body weights and egg traits in Domyati and Khaki-Campbell ducks, indicates that it is possible to genetically increase body weight and egg traits through selection and subsequently inbreeding to divide the herd into groups that are selected among themselves to keep their sons.

Genetic parameters of fillet fatty acids and fat deposition in gilthead seabream (Sparus aurata) using the novel 30 k Medfish SNP array

Lipid-related traits are important candidates for a breeding goal for gilthead seabream, because they affect both fish and human health, as well as production efficiency. However, to date there have been very few estimates of genetic parameters for these traits, and the genetic relationship between fatty acids and other important traits have never been reported for gilthead seabream. Therefore, the aim of this study was to estimate genomic heritability and genetic relationships of fat deposition traits and individual muscle fatty acids in a commercial population of gilthead seabream using the novel ~30 k MedFish SNP array.In total 967 gilthead seabream fed with a commercial feed were genotyped with the MedFish SNP chip which included ~30 K informative markers for this species. On average, the fish weighed 372 g. The mean content of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) was 822 mg per 100 g fillet. The heritability of muscle fat, viscera weight and percentage viscera were in the range of 0.34–0.46. The genetic correlation of body weight with muscle fat was 0.12, indicating that genetic variation in muscle fat is largely independent of the weight of the fish. The heritability of the product of endogenous fatty acid synthesis (n = 240), palmitoleic acid (16:1n-7), was high (0.43). The estimated heritability of EPA (%) and DHA (%) was 0.39 and 0.33, respectively. Both EPA and DHA had low, non-significant genetic correlations with body weight, and DHA had a negative genetic correlation with muscle fat (−0.53).It is possible to increase EPA and DHA content in gilthead seabream fillets by selective breeding. The high heritability of 16:1n-7, a marker of de novo lipogenesis, suggests that there is a strong genetic component to this metabolic pathway in gilthead seabream. Muscle fat deposition and body weight seem to be independent traits, and selective breeding for faster growth is not likely to influence the proportional content of EPA and DHA.

Heritability and genetic correlation of body weight and Kleiber ratio in Limousin and Charolais beef cattle breeds

Reducing the environmental impact of livestock production is now indispensable and genetic selection can be of great support for this purpose. Measures that can identify high body growth at low maintenance costs in production animals are particularly useful since resources have been increasingly limited. Therefore, the goal of this study was to estimate genetic parameters for BW and Kleiber ratio (KR) in 210-day-old and 365-day-old Charolais and Limousin breeds. A database comprising animals born from 1999 to 2018 was used in a multitrait model applying Bayesian inference. The heritability for BW is high in Charolais (0.39 and 0.42 for BW210 and BW365, respectively) and moderate in Limousin (0.22), indicating possible genetic gains for BW in both breeds. The genetic variability of KR should also allow satisfactory genetic gains. In addition, the genetic correlation between BW and KR ranged from low to moderate. Thus, selection over KR should have no effects on BW, showing that high body growth can be obtained without changes in efficiency.

Growth performance, genetic parameters and selection index of pure and crossbred populations of Red Sokoto and West African Dwarf goats

In 2008, a breeding programme was designed to develop hybrid goat suitable for the rainforest agro-ecological zone of South-Eastern, Nigeria. Two indigenous goat breeds namely, Red Sokoto (RS) and West African Dwarf (WAD) goats were utilized and mated in a main (RS x WAD), reciprocal (WAD x RS) and pure line (RS x RS and WAD x WAD) fashion. A total of 74 progenies were generated from the matings and were evaluated for 12week growth performance. As part of the ranking procedure, a selection index was constructed based on two major body components namely body weight (BWT) and heart girth (HGT) to objectively determine the genetic worth of the growing pure and crossbred progenies of Red Sokoto and West African Dwarf kids. The results showed that average body weight (BWT) of RS x RS (5.29±0.13kg) and RS x WAD (5.14±0.21kg) buck kids were similar but significantly (P< 0.05) heavier than that of their WAD x RS (4.84 + 0.17kg) and WAD x WAD (4.79 + 0.17kg) counterparts. The performance of crossbred RS x WAD compared to WAD x RS and WAD x WAD buck kids indicate that the main crossbred kids sired by Red Sokoto bucks but nursed by WAD dams received superior sets of genes from their large-sized sire. The RS x WAD buck kids in particular, had significantly longer body length (BLT), height-at-withers (HWT) and HGT than WAD x RS and WAD x WAD kids. The phenotypic and genetic correlations of BWT and HGT in both sexes for the different genotypes were high and positive which were indicative of the nature of association between these conformation traits in goats. Heritability estimates (h2) for BWT and HGT in males and females kids ranged from 0.31 – 0.36 versus 0.28 – 0.30, respectively in most of the growing kids. The relative economic values (REV) of chosen traits were generally higher for male kids compared to their female counterparts. Phenotypic variances for BWT and HGT in male and female kids ranged from 0.65 – 0.80. The selection index values were highest in male and female kids of RS x RS, followed by RS x WAD, while WAD x RS kids ranked low and WAD x WAD kids ranked the least. Thus, indicating that selection and improvement of growth traits in these pure and crossbred kids would be in favour of the RS x RS and RS x WAD individuals.

Reducing the Common Environmental Effect on Litopenaeus vannamei Body Weight by Rearing Communally at Early Developmental Stages and Using a Reconstructed Pedigree

Heritability estimates may be severely biased when a large common environmental effect on a family arises from a long-lasting separate rearing at early stages (SRES) in traditional selective breeding programs, especially when bred populations have weak genetic ties. Communal rearing at early stages (CRES) may reduce common environmental effect since all families are reared in the same environment immediately after hatching. Here, we compared the effects of CRES and SRES strategies on genetic parameter estimation for harvest body weight in a selective breeding population of Litopenaeus vannamei with a small number of half-sib families. Genetic parameters of each strategy were estimated by using animal models excluding and including the common environmental effect (Model 1 and Model 2, respectively). Heritability estimates for body weight were 0.21±0.06 (P 0.05) in Model 2. The ratio of common environmental variance to phenotypic variance was 0.002 ±0.000 and 0.071 ±0.112 for CRES and SRES, respectively. Neither strategy precisely partitioned the common environmental variance according to likelihood ratio test. Lower heritability for body weight in CRES than in SRES implied that a large common environmental variance was confounded with additive genetic variance and was not effectively partitioned in SRES. Moreover, genetic correlation of body weight between the two strategies was 0.75±0.15, indicating that family rankings truly changed. The CRES should be followed in the selective breeding program of shrimp, especially in a population with a shallow pedigree and weak genetic ties between families.

Genetic parameters and genotype by environment interactions for growth traits and survival of olive flounder (Paralichthys olivaceus) in recirculating aquaculture system and flow-through system

In recent years, intensive recirculating aquaculture systems (RAS) as an eco-responsible and more efficient aquiculture model have been emerged into practice, and have been taking place of the traditional flow-through systems (FTS). The aim of this study was to estimate genetic parameters for body weight (BW), total length (TL) and survival (SUR) reared in the both environments (i.e. RAS and FTS) in olive flounder, and investigate genotype by environment (G × E) interactions for these traits between RAS and FTS. The heritability estimates for BW and TL were moderate (0.15–0.22) in both environments. For SUR, the heritability was 0.13 ± 0.05 and 0.19 ± 0.06 for RAS and FTS respectively. The genetic correlations of BW (0.65 ± 0.13), TL (0.33 ± 0.12), and survival (0.40 ± 0.10) were relatively low between the two rearing environments. The differences in the heritabilities and the low genetic correlations between the two environments suggested that the magnitude of G × E interactions was very high, which showed evidence that there was severe re-ranking of family performance. We concluded that G × E interactions for olive flounder between the two rearing environments were of vital importance. These results will be beneficial for developing breeding programs in olive flounder because the accuracy of selection and genetic gain for growth and survival may differ between rearing environments. Hence, it is necessary to select environment-specific strains in olive flounder. Statement of relevanceThis paper offers guidelines to select breeding strategy in olive flounder when fish are reared in different aquaculture systems.

Estimating the purebred-crossbred genetic correlation of body weight in broiler chickens with pedigree or genomic relationships

BackgroundIn pig and poultry breeding programs, the breeding goal is to improve crossbred (CB) performance, whereas selection in the purebred (PB) lines is often based on PB performance. Thus, response to selection may be suboptimal, because the genetic correlation between PB and CB performance (r_{pc}) is generally lower than 1. Accurate estimates of the r_{pc} are needed, so that breeders can decide if they should collect data from CB animals. r_{pc} can be estimated either from pedigree or genomic relationships, which may produce different results. With genomic relationships, the r_{pc} estimate could be improved when relationships between purebred and crossbred animals are based only on the alleles that originate from the PB line of interest. This work presents the first comparison of estimated r_{pc} and variance components of body weight in broilers, using pedigree-based or genotype-based models, where the breed-of-origin of alleles was either ignored or considered. We used genotypes and body weight measurements of PB and CB animals that have a common sire line.ResultsOur results showed that the r_{pc} estimates depended on the relationship matrix used. Estimates were 5 to 25% larger with genotype-based models than with pedigree-based models. Moreover, r_{pc} estimates were similar (max. 7% difference) regardless of whether the model considered breed-of-origin of alleles or not. Standard errors of r_{pc} estimates were smaller with genotype-based than with pedigree-based methods, and smaller with models that ignored breed-of-origin than with models that considered breed-of-origin.ConclusionsWe conclude that genotype-based models can be useful for estimating r_{pc}, even when the PB and CB animals that have phenotypes are closely related. Considering breed-of-origin of alleles did not yield different estimates of r_{pc}, probably because the parental breeds of the CB animals were distantly related.

Genetic parameters for growth and survival in rohu carp (Labeo rohita)

Estimates of genetic parameters for growth and survival were obtained from data recorded on 16,718 rohu carp (Labeo rohita), the offspring of 311 sires and 257 dams from seven year-classes. The fish from the first five year-classes (1993 to 1997) were reared in both mono- and polyculture (together with catla and mrigal) earthen ponds, while the three remaining year-classes (1999 to 2001) were reared in monoculture ponds only. The base population year-classes (1993 and 1994) was crosses between a local farmed stock and five river strains. Body weight was recorded at tagging (6 months of age), on a sample of the fish (16 months of age) and at harvest (20 months of age). Genetic correlation between body weight at harvest in the two production systems was very high, 0.96 ± 0.07, indicating a negligible genotype by production environment interaction for growth in rohu. However, the genetic correlation between survival in these two production systems was of medium magnitude, 0.55 ± 0.24, but with a large standard error. Consequently, in a rohu breeding program, the breeding candidates can be selected for growth based on body weights recorded in monoculture ponds. The estimated heritabilities (and of the effect common to full-sibs, c2) across the two production systems were 0.22 ± 0.15 (0.66 ± 0.07), 0.38 ± 0.11 (0.28 ± 0.05), 0.34 ± 0.10 (0.23 ± 0.04) and 0.14 ± 0.05 (0.08 ± 0.02) for body weight at tagging, at sampling, at harvest and survival until harvest (on liability scale), respectively. The large c2 needs to be reduced by rearing each family until tagging size in a more controllable environment, or by pooling a random sample of fry from each family shortly after hatching. The genetic correlation between body weight at sampling and harvest was very high, 0.98 ± 0.01, whereas the genetic correlations of body weight at tagging with body weight at sampling (0.46 ± 0.25) and harvest (0.38 ± 0.27) were of medium magnitude and not significantly different from zero. The low genetic correlations of survival until harvest with body weight at tagging (0.03 ± 0.38), sampling (0.11 ± 0.23) and harvest (0.19 ± 0.22) show that genetic improvement of survival of any significance is only possible through direct selection for survival.

Estimation of genetic parameters for body weight traits in Mazandaran native breeder hens by random regression models

The primary concern of this study is to investigate appropriate random regression model for estimate genetic parameters body weight at hatch (BW1), eight (BW8), twelve (BW12) and thirty two (BW32) weeks of ages by the restricted maximum likelihood method. The body weight records set included 39872 during 16 generations of hens kept at the Mazandaran Breeding Center of Iran. Random regression were modelled using generation-hatch as a fixed effect and additive genetic and permanent environmental effects as random effects Residual variances were modeled through a step function with 1 and 3 classes. The model was considered to be the most appropriate with the highest significant log likelihood ratio test (LRT) and the lowest Akaike information criterion (AIC) and Bayesian information criterion (BIC). Heritability values increased from 0.21 for BW1, to 0.40 for BW32. Genetic correlations of body weight at different record keeping were often higher than permanent environmental correlations. Genetic correlations between pairs of body weight measures were moderate to high with a range from 0.25 to 0.97. The largest genetic correlation, as well as permanent environmental correlation, was observed between BW12and BW32. High and moderate broad sense heritability values for all studied traits shows that these traits are less influenced by residual effects which make them effectively transmitted to the progeny. Findings show that genetic improvement for body weight can be achieved by selection. The Heritability of body weight at thirty two weeks of ages and its relatively high genetic correlation with all other ages showed that it could be the most appropriate period for selection. Also, the genetic trend estimates for body weight traits showed that selection decisions made during the breeding program effectively improved the growth performance.

Multi-trait estimation of genetic parameters for body weight in a commercial broiler chicken population

Data from 54 selection rounds (SRs) for growth rate in a commercial broiler chicken line were used for analysis to estimate genetic parameters for body weight (BW) in males and females at three different ages (t-7, t-4 and t days). First BW was recorded at t days of age for 39 SRs, however, as selection continued the birds start to grow faster and attain desired body weight earlier, therefore, the weighing age was changed and BW was recorded at t − 4 and t − 7 days of age for 7 and 8 SRs, respectively. Multivariate animal model was used to estimate genetic parameters for BW in males and females with REML analysis using DMU software package. In males, heritability estimates of BW were found to be 0.37, 0.33 and 0.29 at t − 7, t − 4 and t days of age, respectively, while, in females, heritability estimates of BW at t− 7, t − 4 and t days of age were found to be 0.40, 0.38 and 0.38, respectively. The genetic correlations of BW between males and females at t − 7, t − 4 and t days of age were found to be 0.94, 0.89 and 0.89, respectively, which is significantly different from unity. Also the genetic correlations of BW between ages were significantly different from unity. The heritability and genetic correlation estimates in this study suggest that BW in males and females should be considered as two different traits. Moreover, BW in the three ages should be considered as three different traits.

Random regression analysis for growth traits in rainbow trout ( Oncorhynchus mykiss )

PDF HTML阅读 XML下载 导出引用 引用提醒 虹鳟生长性状的随机回归分析 DOI: 作者: 作者单位: 1. 上海海洋大学水产科学国家级实验教学示范中心, 上海 201306;2. 农业农村部水生动物基因组学重点实验室, 北京 100141;3. 中国水产科学研究院生物技术研究中心, 北京 100141;4. 中国水产科学研究院黑龙江水产研究所, 黑龙江 哈尔滨 150070 作者简介: 王悦玲(1994-),硕士研究生,研究方向为水产动物遗传育种.E-mail:850974565@qq.com 通讯作者: 中图分类号: S96 基金项目: 国家现代农业产业技术体系专项（CARS-46）；国家自然科学基金项目（31640087）. Random regression analysis for growth traits in rainbow trout (Oncorhynchus mykiss) Author: Affiliation: 1. National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China;2. Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Beijing 100141, China;3. Aquatic Genomics and Beijing Key Laboratory of Fishery Biotechnology, Chinese Academy of Fishery Sciences, Beijing, 100141, China;4. Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生长和抗逆是水产动物遗传育种工作中最重要的农艺性状，虹鳟的生长性状关乎虹鳟规模化养殖的生产经济效益，为了从遗传上精细解析虹鳟的生长性状，我们从渤海、丹麦、挪威、唐纳森和加利福尼亚5个虹鳟（）种系间的双列杂交开始，进行了连续4代的继代选育。本研究测量了第4代总共4368个实验个体在516日龄、608日龄、668日龄、883日龄和1036日龄5个时间点的生长数据。采用随机回归测定日模型，对虹鳟生长性状进行了动态遗传分析。根据贝叶斯信息准则，确定3阶勒让德多项式为拟合体重和体长的加性遗传效应和永久环境效应变化的最优子模型。利用双变量随机回归模型同时分析体重和体长两个生长性状。它们的遗传力在400~1000日龄之间呈现递减趋势，分别从0.288下降到0.164和从0.469下降到0.186，并且在该生长区间内体长的遗传力始终高于体重的遗传力。无论体重还是体长性状，在不同日龄之间的遗传相关都随着生长间隔的增大而降低，但是两个性状在生长初期和后期之间的遗传相关较高（遗传相关系数0.75以上），尤其是体重（遗传相关系数0.85以上），该研究结果为虹鳟早期的遗传选育提供了理论支撑。两个性状之间在相同日龄之间的遗传相关均在0.75以上，在不同日龄之间的遗传相关随着生长间隔的增大由0.83下降到0.63。以上的研究结论为虹鳟生长性状（主要是体长和体重）的遗传选育提供了理论基础，同时也为虹鳟的体长和体重两个性状的联合选育提供了精确的遗传分析结果，由于两性状在前期有较高的遗传相关，因此建议在虹鳟生长前期（400日龄）进行联合选择。 Abstract:Growth and resistance are the most important agricultural traits for genetic breeding in aquaculture animals. The growth trait of Rainbow trout is central to the economic development in scaled production. Launched from strains of Bohai, Denmark, Norway, Donaldson and California, family selection of the rainbow trout was performed for four consecutive generations based on biallele crossing design. Only data from the fourth generation was selected for this study. Dynamic genetic analysis was conducted using 19299 records repeated body weight (BW) and body length (BL) measurements, which were obtained to genetically evaluate the growth traits of 4368 samples for the fourth generation at their 516 days of age, 608 days of age, 668 days of age, 883 days of age and 1036 days of age. According to the Bayesian information criterion (BIC), Legendre polynomials of three orders were selected as the most optimized submodel to fit changes in additive genetic and permanent environmental effects on both BW and BL. With a bivariate random regression model (RRM), both traits were analysed simultaneously. The heritabilities were estimated to exhibit a downward tendency between 400 and 1000 days of age, from 0.288 to 0.164 and from 0.469 to 0.186 for BW and BL, respectively, while BL was inherited in a consistently higher manner than BW. The genetic correlation of BW and BL showed a tendency towards the decrease of heritabilities with the enlarged growth space. However, the traits in the initial and later days of age showed higher correlation for both traits which are all above 0.75, especially for BW, which is higher than 0.85. The genetic correlations in the same growth days of age for both traits are equal to or above 0.75, but decreased from 0.83 to 0.63 in different growth days of age. In summary, the genetic correlation of a single trait or both traits between paired day-ages decreased with the increasing age-interval. However, the consistent genetic correlation between paired day-ages makes the genetic selection for BW feasible at an early stage. These results provide the theoretical basis for breeding selection focused on BW and BL growth traits. At the same time, this research also provides accurate genetic analysis results which is most fitted for the combined selection. Due to the existing higher genetic correlations between early and later stage for BW and BL, the combined selection is suggested from early 400-growth-day. In addition, the big population with couple families will be artificially divided into several individual subpopulations and repeated random measurements for growth points series will be executed for every subpopulation. This technique will satisfy the requirements for an improved fitting with the growth curve and also save money, including from decreased labour costs. 参考文献 相似文献 引证文献

Heritability Estimates and Genetic Correlations Among Body Weight and Measurement Traits of Large‐size Rainbow Trout, Oncorhynchus mykiss, in China

AbstractThe variance components of additive effects and genetic correlations of body weight (BW) and body measurement traits were estimated in a freshwater strain selected for large size in a breeding program for rainbow trout, Oncorhynchus mykiss, in China. Phenotypic data were collected for BW and measurement traits from 2362 individuals with a two‐generation pedigree, and the average information‐restricted maximum likelihood method was used for the genetic analysis. The genetic parameters of BW were estimated at three time points (550, 850, and 1000 days post‐fertilization [dpf]), showing high heritability in a range from 0.33 to 0.98. However, the heritability estimates of total length (TL) showed lower values ranging from 0.05 to 0.51, with high standard errors. Genetic correlation between TL and BW was almost equal to unity at 550 dpf, and the genetic correlations between TL at 550 dpf and BW at two other time points were all positive and very high (ca. 0.95–0.99). These results indicate that BW and TL selected at 550 dpf had a direct positive effect on BW performance at 1000 dpf, which was 450 d before the date of the target trait observed.

Genetic analysis of sexual dimorphism of body weight in broilers

Variation in sexual dimorphism (SD) is particularly marked in meat-type chickens. This paper investigates the genetic basis of SD in an important economic trait, i.e. body weight (BW) at 35 days of age, in broilers by applying quantitative genetic analysis. A large dataset comprising 203,323 BW records of a commercial line of broiler chicken was used. First, a bivariate approach was employed treating BW as a sex-specific trait. During this approach, seven bivariate models were applied and variances due to direct additive genetic, maternal genetic and maternal environmental effects were estimated via the restricted maximum likelihood method. The best-fitting model included direct additive genetic, maternal genetic and maternal environmental effects with a direct-maternal genetic covariance. Differences between male and female direct heritabilities were non-significant (0.28 vs. 0.29 for males and females, respectively), implying no need for sex-specific selection strategies. The direct-maternal genetic correlation was more strongly negative in males than in females (-0.72 vs. -0.56), implying a more profound antagonism between direct additive and maternal genetic effects in this particular gender. The direct genetic correlation of BW between the two sexes was as high as 0.91, i.e. only slightly lower than unity. Second, variance components and genetic parameters of two measures of SD, i.e. the weight difference (Δ) and the weight ratio (R), between the genders were estimated. Direct heritabilities for both measures were significantly different to 0 but of low magnitude (0.04). Apart from the additive-maternal covariance, no other random effects were found to be of importance for Δ and R. The results of the present study suggest that only minimal selection responses due to the selection of Δ and/or R and a small capacity for amplifying or reducing the BW differences between the sexes are to be expected in this specific population. Furthermore, selection pressure on BW is expected to amplify SD.

Estimation of genetic parameters from longitudinal records of body weight of berkshire pigs.

Direct and maternal genetic heritabilities and their correlations with body weight at 5 stages in the life span of purebred Berkshire pigs, from birth to harvest, were estimated to scrutinize body weight development with the records for 5,088 purebred Berkshire pigs in a Korean farm, using the REML based on an animal model. Body weights were measured at birth (Birth), at weaning (Weaning: mean 22.9 d), at the beginning of a performance test (On: mean 72.7 d), at the end of a performance test (Off: mean 152.4 d), and at harvest (Finish: mean 174.3 d). Ordinary polynomials and Legendre with order 1, 2, and 3 were adopted to adjust body weight with age in the multivariate animal models. Legendre with order 3 fitted best concerning prediction error deviation (PED) and yielded the lowest AIC for multivariate analysis of longitudinal body weights. Direct genetic correlations between body weight at Birth and body weight at Weaning, On, Off, and Finish were 0.48, 0.36, 0.10, and 0.10, respectively. The estimated maternal genetic correlations of body weight at Finish with body weight at Birth, Weaning, On, and Off were 0.39, 0.49, 0.65, and 0.90, respectively. Direct genetic heritabilities progressively increased from birth to harvest and were 0.09, 0.11, 0.20, 0.31, and 0.43 for body weight at Birth, Weaning, On, Off, and Finish, respectively. Maternal genetic heritabilities generally decreased and were 0.26, 0.34, 0.15, 0.10, and 0.10 for body weight at Birth, Weaning, On, Off, and Finish, respectively. As pigs age, maternal genetic effects on growth are reduced and pigs begin to rely more on the expression of their own genes. Although maternal genetic effects on body weight may not be large, they are sustained through life.

Efeitos de ambiente e estimativas de parâmetros genéticos para características de carcaça em bovinos da raça Canchim criados em pastagem

Os objetivos neste trabalho foram estudar os efeitos de ambiente sobre a espessura de gordura subcutânea (EGS), a área de olho-de-lombo (AOL) e o peso aos 19 meses de idade e estimar parâmetros genéticos para essas características. Utilizaram-se informações obtidas de 987 bovinos da raça Canchim (5/8 Charolês + 3/8 Zebu) e do grupo genético animal MA (filhos de touros charoleses e vacas 1/2 Canchim + 1/2 Zebu) nascidos em 2003, 2004 e 2005. Os componentes de covariância foram estimados pelo método da máxima verossimilhança restrita utilizando-se um modelo animal com efeitos fixos (ano de nascimento, grupo genético, rebanho e sexo) e os efeitos aleatórios genético aditivo direto e residual. As médias de área de olho-de-lombo e peso foram mais altas nos machos que nas fêmeas. No grupo genético MA, as médias para todas as características foram mais altas que na raça Canchim e houve ainda efeitos de rebanho e de ano de nascimento. As estimativas de herdabilidade para AOL (0,33 ± 0,09), EGS (0,24 ± 0,09) e peso (0,23 ± 0,09) foram moderadas, enquanto que a estimativa de correlação genética (0,21 ± 0,24) entre EGS e AOL foi baixa, o que sugere que essas características são controladas por diferentes conjuntos de genes de ação aditiva. As correlações genéticas para peso estimadas com EGS (0,57 ± 0,23) e com AOL (0,62 ± 0,16) foram moderadas. Conclui-se que as características ao sobreano devem responder à seleção nos rebanhos estudados e que a seleção para aumento de peso também eleva EGS e AOL e vice-versa.

The genetic relationship of body weight and early-lactation health disorders in two experimental herds

The objectives of this study were to estimate genetic parameters for body weight (BW) and BW change (BWC) and genetic correlations of BW and BWC with diseases and genomic predicted transmitting abilities (PTA) of productive and conformation traits of Holsteins during the first 120 DIM. Daily BW data were from the Afiweigh cow body weighing system (SAE Afikim, Kibbutz Afikim, Israel), which records BW as a cow exits the milking parlor. Disease categories included metabolic diseases, ketosis, infectious diseases, mastitis, reproductive diseases, and other diseases. Edited data included 68,914 and 11,615 daily BW observations from 441 Pennsylvania State University and 72 Virginia Tech Holstein cows, respectively. Two-trait random regression models were used to estimate relationships between BW, BWC, and diseases at 25, 38, and 58 mo of age at calving. Fixed effects for BW were age at calving nested within lactation group, week of lactation, and herd date; random effects for BW included animal, permanent environment, and error. Fixed effects for disease were herd-year-season of calving and age at calving nested within lactation group; random effects for disease were animal, permanent environment (for mastitis only), and error. Correlations of PTA for BW and BWC with genomic PTA for productive and type traits were also estimated with data from 117 cows. Heritability estimates for daily BW ranged from 0.34 to 0.63. Greater BW and less BWC were favorably correlated with ketosis, metabolic diseases, infectious diseases, and other diseases. The genetic correlation estimate between BW and ketosis was strongest at 60 DIM (−0.51), and genetic correlation estimates at 60 DIM with metabolic diseases (−0.52), infectious diseases (−0.81), and other diseases (−0.48) followed the same trend as ketosis. The genetic correlation estimate between BWC and ketosis was strongest for the change from 5 to 20 DIM (0.70) and was similar for metabolic diseases (0.37), infectious diseases (0.74), and other diseases (0.49). Correlations of BW and BWC with reproductive diseases tended to be in the reverse direction of those reported for ketosis. A larger PTA for BW was significantly correlated with smaller genomic PTA for milk yield, dairy form, rear udder height, and udder cleft. Predicted transmitting ability for BWC was negatively correlated with genomic PTA for protein percentage, strength, and hip width (ranging from −0.26 to −0.13 across lactation) and was positively correlated with dairy form, rear udder height, and udder cleft (ranging from 0.20 to 0.37 across lactation). Selection for reduced BW loss can be implemented with automated body weighing systems and may be successful in decreasing disease incidence in the early stages of lactation.

Across flock genetic parameter estimation for yearling body weight and fleece

Accurate genetic parameter estimates are needed upon which to perform multiple-trait across flock breed analyses. Genetic parameters for yearling body weight (BW), clean fleece weight (CFW) and mean fibre diameter (MFD) were estimated using records of 107 389 individuals (the progeny of 1 530 sires and 45 178 dams) collected between 1992 and 2004 in the South African Dohne Merino population. Fixed effects included in the model were flock-year-season-sex-management group (1 594 classes), type of birth (singles, multiples), age of dam (2 - 7+ years) and age at measurement, fitted as a linear covariate (385 ± 12 days). Six different single-trait animal models were fitted, where different combinations of the following random effects were fitted: direct additive, the sire-flock interaction, the sire-flock-year-season interaction (SFYS), the dam genetic effect, the direct-maternal correlation and the dam permanent environmental effect. These analyses were followed by a three-trait analysis structured according to the log likelihood ratios obtained for the single-trait analysis. This analysis allowed the calculation of relevant correlations among traits together with their respective standard errors. Direct heritability estimates from the three-trait analysis were 0.17 for BW, 0.19 for CFW and 0.45 for MFD. Maternal heritability estimates were 0.01 for BW and 0.006 for CFW, with corresponding dam permanent environmental ratios of respectively 0.03 and 0.02. The genetic correlation between animal effects amounted to 0.48 for BW. Derived proportions of the total phenotypic variance due to SFYS were 0.02, 0.02 and 0.02, respectively. Genetic correlations of BW with CFW and MFD were 0.11 and 0.13, respectively, and of CFW with MFD 0.16. It was concluded that the inclusion of some form of a genotype by environmental interaction as part of the national evaluation is essential, although it controlled only a modest portion of the overall phenotypic variation.

Estimation of breeding value and genetic trend of Garut sheep and its crossbred

Crossing of Garut (GG) sheep with St. Croix sheep (HH) and Moulton Charollais (MM) resulting HG sheep (♂HH X ♀GG) and MG sheep (♂MM X ♀GG) was done by Indonesian Research Institute for Animal Production. The work continued by crossing MG and HG sheep to obtain HMG (♂HG X ♀MG) and MHG (♂MG X ♀HG) sheep. The study was continued by selection program based on phenotypic performance. Estimation of breeding value and genetic trends were done in order to study the effectiveness of selection program and to study the genetic progress of each breed. The breeding value was estimated by Best Linear Unbiased Prediction (BLUP) method using Variance Component Estimation (VCE4) software to calculate variance component and using Prediction and Estimation (PEST) to calculate Breeding Value. Genetic variations of composite sheep were generally higher than Garut sheep, represented by higher estimated heritability value. Genetic correlation of body weight at diffrent age is high, that makes selection at one age could also increase body weight at any level of age. In general of this population shows positive genetic trend, but fluctuated from year to year. Composite breed tend to have higher estimated breeding value than Garut sheep. Selection method that was practiced in this population showed in line with selection method using breeding value criteria. Key Word s: Breeding Value, Genetic, BLUP, Garut Sheep, St. Croix, Moulton Charollais

Genetic parameters of ascites-related traits in broilers: correlations with feed efficiency and carcase traits

1. Pulmonary hypertension syndrome followed by ascites is a metabolic disorder in broilers that occurs more often in fast-growing birds and at cool temperatures. 2. Knowledge of the genetic relationships among ascites-related traits and performance traits like carcase traits or feed efficiency traits is required to design breeding programmes that aim to improve the degree of resistance to ascites syndrome as well as production traits. The objective of this study was to estimate these genetic correlations. 3. Three different experiments were set up to measure ascites-related traits (4202 birds), feed efficiency traits (2166 birds) and carcase traits (2036 birds). The birds in different experiments originated from the same group of parents, which enabled the estimation of genetic correlations among different traits. 4. The genetic correlation of body weight (BW) measured under normal conditions and in the carcase experiment with the ascites indicator trait of right ventricle to total ventricle ratio (RV:TV) measured under cold conditions was 0·30. The estimated genetic correlation indicated that single-trait selecting for BW leads to an increase in occurrence of the ascites syndrome but that there are realistic opportunities of multi-trait selection of birds for improved BW and resistance to ascites. 5. Weak but positive genetic relationships were found between feed efficiency and ascites-related traits suggesting that more efficient birds tend to be slightly more susceptible to ascites. 6. The relatively low genetic correlation between BW measured in the carcase or in the feed efficiency experiments and BW measured in the ascites experiment (0·49) showed considerable genotype by environment interaction. These results indicate that birds with high genetic potential for growth rate under normal temperature conditions have lower growth rate under cold-stress conditions due to ascites.