Heritability Estimates For Body Weight Research Articles

Estimates of genetic parameters for indicator traits of resistance to gastrointestinal nematodes and growth traits in Santa Inês sheep

Infections by gastrointestinal nematodes is a major problem in the sheep industry worldwide. Therefore, this study aimed: (1) to estimate genetic parameters for indicator traits of resistance to gastrointestinal nematodes such as packed cell volume (PCV), total plasma protein (TPP), color of the ocular conjunctiva by Famacha© method (FAM), and fecal egg count (FEC); (2) to estimate genetic parameters for growth traits such as body weight (BW), body condition score (BCS) and chest girth (CG); and (3) evaluate the FAM as an indicator trait of resistance to gastrointestinal nematodes in Santa Inês sheep. The dataset contained 3524 observations from 1176 animals and the pedigree presented 2011 animals. The genetic parameters were estimated by the animal model, in single- and multi-trait Bayesian analyses, using the THRGIBBS1F90 program. Stochastic Markov Chain Monte Carlo Simulation (MCMC) was used to obtain estimates of the parameters of interest, using Gibbs sampling. The a posteriori estimates were obtained with the POSTGIBBSF90 program. The sensitivity and specificity of the FAM were 66.7 % and 75.8 %, respectively. In general, the sensitivity and specificity values found herein do not invalidate the use of FAM. In the single-trait model, the heritability estimates for BW, CG, BCS, PCV, TPP, FAM, and FEC were 0.51 ± 0.02, 0.61 ± 0.03, 0.40 ± 0.04, 0.38 ± 0.03, 0.29 ± 0.03, 0.19 ± 0.05 and 0.15 ± 0.03, respectively. In the multi-trait model, the heritability observed for these traits were 0.73 ± 0.02, 0.64 ± 0.02, 0.35 ± 0.05, 0.38 ± 0.03, 0.29 ± 0.03, 0.20 ± 0.05 and 0.13 ± 0.04, respectively. Genetic correlations between growth traits (BW, BCS, and CG) were positive with high magnitude. In addition, growth traits exhibited positive genetic correlations with PCV and TPP, and negative correlations with FAM. The genetic correlation between PCV and FAM, and between FEC and BW were negative and favorable. The genetic parameters suggest that it is possible to obtain genetic gains for the evaluated traits by the response to direct selection. Unfavorable genetic correlations were not found between growth traits and indicator traits of resistance to gastrointestinal nematodes. The heritability of FAM was moderate, and genetic correlations were considered favorable between FAM and PCV. In addition, FAM is easy-to-measure and has a low cost. Therefore, FAM can be an alternative secondary selection criterion associated with body weight (main selection criterion), to increase resistance to gastrointestinal nematodes.

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.

Genetic Comparisons of Body Weight, Average Daily Gain, and Breast Circumference between Slow-Growing Thai Native Chickens (Pradu Hang dum) Raised On-Site Farm and On-Station.

To ensure that any new technology developed within an experimental station is appropriate to the community’s needs and compatible with the existing systems, on-site farm research is an important component in examining the effectiveness of agricultural research. The present study examined the growth performance and genetics of Thai native chickens under conditions typically experienced by farmers on smallholder farms (on-site farms) compared with at an experimental unit (on-station). There were 1694 Thai native chickens (Pradu Hang dum) used in this experiment, and they were divided into 613 chickens for the on-station and 1081 chickens for the on-site farm experiments. The individual chicken data included the birth weight (BW0) and body weight at 4, 8, 12, and 16 weeks of age (BW4, BW8, BW12, and BW16, respectively), ADG from 0−4, 4−8, 8−12, 12−16 weeks of age (ADG0−4, ADG4−8, ADG8−12, ADG12−16, respectively), and breast circumference at 8, 12, and 16 weeks of age (BrC8, BrC12, BrC16, respectively). A multiple traits animal model and a selection index were used to estimate the variance components, genetic parameters, and breeding values of growth traits. The results showed that the body weight, average daily gain, and breast circumference at 8, 12, and 16 weeks of age of Thai native chickens raised on-station were higher than those raised on-site at the farm among mixed-sex and sex-segregated chickens, while the birth weight and body weight at four weeks of age (BW0 and BW4) and ADG from 0−4 weeks of age (ADG0−4) were not significantly different (p > 0.05). The heritability estimates of body weight, average daily gain, and breast circumference in the chickens raised at the on-site farm and on-station were moderate to high, with on-station values slightly higher than on-site farm values. The heritability estimates of body weight were 0.236 to 0.499 for the on-site farm, and 0.291 to 0.499 for on-station. For average daily gain, the heritability estimates were 0.274 to 0.283 for the on-site farm and 0.298 to 0.313 for on-station; meanwhile, and for breast circumference, the heritability estimates were 0.204 to 0.268 for the on-site farm and 0.278 to 0.296 for on-station. Both phenotypic and genetic correlations among and between growth traits were positive and ranged from low to high values. The top 20% of the estimated breeding values and selection indices in the on-site farm and on-station experiments showed that the body weight at eight weeks of age (BW8), ADG from 4−8 weeks of age (ADG4−8), and breast circumference at eight weeks of age (BrC8) should be used as selection criteria for Thai native chicken breeding programs. In conclusion, the genetic parameters and breeding values in on-station experiments showed that the breeding program by selection index for improving growth performance is valid. Therefore, to implement such a breeding program in an on-site farm, an intensive or semi-intensive farm system should be considered to minimize the effect of genotype-environment interaction.

Insight into selective breeding for robustness based on field survival records: New genetic evaluation of survival traits in pacific white shrimp (Penaeus vannamei) breeding line.

Survival can be considered a relatively ‘old’ trait in animal breeding, yet commonly neglected in aquaculture breeding because of the simple binary records and generally low heritability estimates. Developing routine genetic evaluation systems for survival traits however, will be important for breeding robust strains based on valuable field survival data. In the current study, linear multivariate animal model (LMA) was used for the genetic analysis of survival records from 2-year classes (BL2019 and BL2020) of pacific white shrimp (Penaeus vannamei) breeding lines with data collection of 52, 248 individuals from 481 fullsib families. During grow-out test period, 10 days intervals of survival data were considered as separate traits. Two survival definitions, binary survivability (S) and continuous survival in days (SL), were used for the genetic analysis of survival records to investigate; 1) whether adding more survival time information could improve estimation of genetic parameters; 2) the trajectory of survival heritability across time, and 3) patterns of genetic correlations of survival traits across time. Levels of heritability estimates for both S and SL were low (0.005–0.076), while heritability for survival day number was found to be similar with that of binary records at each observation time and were highly genetically correlated (r g > 0.8). Heritability estimates of body weight (BW) for BL2019 and BL2020 were 0.486 and 0.373, respectively. Trajectories of survival heritability showed a gradual increase across the grow-out test period but slowed or reached a plateau during the later grow-out test period. Genetic correlations among survival traits in the grow-out tests were moderate to high, and the closer the times were between estimates, the higher were their genetic correlations. In contrast, genetic correlations between both survival traits and body weight were low but positive. Here we provide the first report on the trajectory of heritability estimates for survival traits across grow-out stage in aquaculture. Results will be useful for developing robust improved pacific white shrimp culture strains in selective breeding programs based on field survival data.

Estimates of heritability and genetic correlation for growth traits at harvest in redclaw crayfish, Cherax quadricarinatus

The current study assessed genetic parameters of three growth traits in redclaw crayfish Cherax quadricarinatus, including body weight (BW), body length (BL) and carapace length (CL), and explored how the number of families affected the heritability estimates of these traits. A total of 350 families were produced, and seven family levels containing 50, 100, 150, 200, 250, 300 and 350 families respectively were designed. After a 170 d communally rearing period for 350 families, males had significantly higher BW and BL averages (P < 0.001), but significantly lower CL average than females (P < 0.001). Heritability estimates of BW, BL and CL based on 350 families were 0.138 ± 0.051, 0.123 ± 0.048 and 0.073 ± 0.035, with common environmental effects of 0.049 ± 0.024, 0.053 ± 0.023 and 0.039 ± 0.017, respectively. There were strong positive genetic correlations (0.863 ± 0.089–0.970 ± 0.028) between these growth traits. Among different family levels, heritability estimates ranged from 0.030 ± 0.090 to 0.138 ± 0.051, 0.010 ± 0.091 to 0.123 ± 0.048, and 0 to 0.073 ± 0.035, and common environmental effects ranged from 0.045 ± 0.101 to 0.092 ± 0.046, 0.053 ± 0.023 to 0.100 ± 0.047, and 0.038 ± 0.043 to 0.062 ± 0.033, for BW, BL and CL, respectively. Only heritability estimates of BW and BL based on 300 and 350 families, and that of CL based on 350 families, were significantly different from zero (P < 0.05), which suggested that larger numbers of families could contribute to more accurate estimation of heritability. The results indicate that there exists some genetic variation for our selection population to improve growth in C. quadricarinatus. However, the future program for redclaw crayfish needs to include crossing with outside stocks to replenish genetic variation of selection population.

Genetic Evaluation of Growth and Survival-Related Traits in Yesso Scallop Patinopecten yessoensis in Sea-Based Culture System

Worldwide, the bivalve aquaculture industry has realized or recognized the potential gains from selective breeding programs using phenotypic and pedigree data. Yesso scallop Patinopecten yessoensis are among the most important commercial shellfish in China. A family-based breeding program to investigate the genetic variations for growth and survival-related traits at suspended and bottom environments of sea-based culture systems was reported in this study. We proposed and conducted a novel phenotyping technique to longitudinally evaluate the shell heights in the yesso scallop. At harvest after rearing for 20 months, the individual shell heights at 6, 10, 16, and 20 months were simultaneously obtained by the growth rings in the outer shells of the animals. Meanwhile, the body weight (BW) of the survived individuals at harvest was also recorded. Variance components and genetic parameters for growth and survival-related traits were estimated using an animal and threshold model, respectively. In the suspended environment, the heritability estimates for BW and shell heights at specific ages ranged from moderate to high (0.328–0.853). The estimated correlations between shell heights at contiguous ages were consistently high, ranging from 0.890 to 0.958 but decreased with increasing intervals between ages (0.496–0.828). The estimated correlations between shell heights at contiguous ages and BW at harvest were similar, ranging from 0.535 to 0.983. The heritability estimates for individual survival at harvest were at a low level of 0.128 by the probit-threshold model. While at the bottom environment, estimates of heritability for growth and survival-related traits were similar but slightly lower than those at the suspended environment. Furthermore, the genetic correlation for BW between the two environments was very small, which probably indicates genotype-by-environment interaction effects for growth in the yesso scallop. The study can provide prior information, which might develop a new idea for selection in this species. The results are discussed concerning selection work with yesso scallop, and solutions for accurate estimation of genetic parameters and increasing genetic gain are also outlined.

On the trail of detecting genetic (co)variation between resistance to parasite infections (Diplectanum aequans and Lernanthropus kroyeri) and growth in European seabass (Dicentrarchus labrax)

The European seabass is one of the main commercial fish produced in Mediterranean marine aquaculture. Recently, its production has been negatively affected by losses due to frequent and recurring outbreaks of parasitic, bacterial and viral diseases. In recent years, the gill parasites Diplectanum aequans and Lernanthropus kroyeri are increasingly becoming more dominant and contributing more significantly to the observed losses. Genetic improvement for disease resistance represents an important strategy for controlling infectious diseases in farmed fish by increasing their robustness. In order to determine the possibility of including such trait in selective breeding programs, we need to comprehend whether additive genetic variation for resistance against Diplectanum aequans and Lernanthropus kroyeri exists. For this purpose, two open-sea parasite cohabitation trials (for two consecutive years) were performed in the commercial production sites of a private company (Nireus S.A), that had high infestation with Diplectanum aequans and Lernanthropus kroyeri. Juvenile European seabass (9425 offspring from 91 full-sib and half-sib families per year), originating from the company's breeding program were equally divided into two groups and transferred to two commercial farming sites located in the areas of Nafpactos and Sagiada, in western Greece, for the intended cohabitation studies. The parasite numbers on all the gill arches were counted and recorded at the end of the trials for the infestation levels. A third site (Palairos) without any parasite infestation was used as a control site. A multi-trait animal model was used to estimate the variance-covariance components and to evaluate the genetic parameters for Parasite Counts, recorded from all the gill arches of the fish, and their corresponding growth in sea cages. The estimated heritabilities for parasite count, using untransformed data, were 0.20 (D. aequans) and 0.28 (L. kroyeri) and for transformed data 0.29 and 0.26, respectively. The heritability estimates for body weight were 0.42−0.51 for D. aequans and 0.28−0.51 for L. kroyeri trials. Similarly, estimated heritabilities for the growth in sea cages were 0.43 and 0.29, respectively. Although parasite count has a low to medium unfavorable genetic correlation with body weight and growth (0.09−0.37), it seems that it is not significantly impairing selection for growth. Furthermore, the results of this study are very promising in terms of the existing potential for genetic improvement of parasite resistance, and provides a good basis for further genetic analysis using molecular markers.

Estimation of genetic parameters for body areas in Nile tilapia measured by digital image analysis.

Digital image analysis is a practical, non-invasive, and relatively low-cost tool that may assist in the evaluation of body traits in Nile tilapia, being particularly useful for assessing difficult-to-measure variables, such as body areas. In this study, we aimed to estimate variance components and genetic parameters for body areas of Nile tilapia obtained by digital images. The data set comprised body weight (BW) records of 1,917 pond-reared fish at 366days of age. Of this total, 656 animals were photographed and subjected to image analysis of trunk area (TA), head area (HA), caudal fin area (CFA) and fillet area (FA). Heritabilities and genetic correlations were estimated through multiple-trait models based on Bayesian inference. Heritability estimates for BW, TA, HA, CFA and FA were 0.25, 0.23, 0.26, 0.21 and 0.25, respectively. Genetic correlations between the traits were high and positive, ranging from 0.70 to 0.98. We highlight the genetic correlation between BW and TA (rG =0.98) and FA (rG =0.97). In view of the observed results, it can be concluded that trunk and fillet areas obtained by digital image analysis can lead to indirect genetic gains in weight and other body areas. In addition, the areas studied have potential as a selection criterion and may assist in studies on changes in the body shape in Nile tilapia.

Genetic parameters for growth and fillet traits in Asian seabass (Lates calcarifer, Bloch 1790) population from Thailand

This study aimed to estimate genetic parameters for growth and fillet traits of Asian seabass using REML method and Bayesian approach via Gibbs sampling. Seabass fry were produced by mass spawning of 20 males and 24 females and reared as mixed families. At 120 days post hatch (dph) 3000 fish were measured, fin-clipped and marked with PIT tags in the body cavity and distributed equally into two earthen ponds. During grow-out, fish were measured at 270 dph. At 390 dph, fish were harvested, measured and filleted by skilled processors. Pedigrees were reconstructed using eleven microsatellite loci. A total of 1750 fish used in the analysis were progeny of 16 sires and 18 dams. A multivariate animal model with the fixed effect of earthen pond was used to estimate variance components. Heritability estimates for body weight (BW) were low to moderate and increased with age. The REML (and Gibbs sampling) estimates were 0.06 (0.26), 0.16 (0.31) and 0.45 (0.48) for BW120, BW270 and BW390, respectively. Heritability for total length (TL) followed the same trend, with REML (and Gibbs sampling) estimates of 0.07 (0.26), 0.11 (0.28) and 0.37 (0.40) for TL120, TL270 and TL390, respectively. The REML and Gibbs sampling estimates for fillet weight were high (0.50 and 0.52) and low to moderate for fillet yield (0.16 and 0.31). Genetic correlations were high and close to unity between BW at different ages and fillet weight (0.85–0.98). Results indicate a selection potential in this Asian seabass population and that use of weight at younger age (120 dph) as a selection criterion would result in increased body weight at harvest (390 dph) along with increased fillet weight.

Variation in growth performance of pure and crossed meat type chickens

Genetic variation from a combination of four breeds of chickens (Anak Titan, Alpha, Giriraja and Normal indigenous chickens) were examined for importance of sire, dam, season and sex on growth traits using a Mixed-model Least-Squares and Maximum LIkelihood computer program. The results show that sire and dam genotypes significantly (P&lt;0.05) affected growth. Anak Titan cocks and hens performed best in body weight (BW) with values ranging from 38.45±0.74g and 40.21±0.66g at day old to 1135.93 35.67g and 953.38 35.38g at week 12 respectively. Normal indigenous and Alpha improved indigenous performed better in linear body parameters. Genetic correlation coefficients among parameters for all the breeds were generally high. Positive estimates ranged from 0.15 for breast girth (BG) and keel length (KL) at week four to 0.99 for BG-KL at week tweve while negative values ranged from -0.783 for body weight (BW) and wing length (WL) at week four to -0.99 for BW-BG at week twelve. Heritability estimates for body weight ranged from 0.14 at week one to 0.63 at week four. It can be concluded that appreciable variation exists for growth traits among the strains of chickens. Such variations can be utilized for improvement in the present emvironment.

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 evaluation and selection correlated response of growth traits in Japanese quail

Objectives of the current study were to i) investigate effects of selection for bodyweight at four weeks old on bodyweight (BW) and bodyweight gain (BWG) across four generations; ii) estimate correlated response to selection for BW and BWG at different ages; and iii) document best linear unbiased prediction (BLUP) of genetic trends for BW and BWG across four generations of selection. A total of 3540 chicks from 444 sires and 885 dams were used to estimate heritabilities, and genetic and phenotypic correlations for growth traits, including BW at 0, 2, 4, and 6 weeks, and BWG between 0 and 2, 2 and 4, 4 and 6, and 0 and 6 weeks. The selection effects, correlated responses and genetic trend for BW and BWG across generations were quantified by applying the animal model. Estimates of heritability for BW and BWG ranged from 0.22 to 0.42 and from 0.18 to 0.23, respectively. Ranges of genetic and phenotypic correlations for BW varied from 0.31 to 0.92 and 0.05 to 0.65, respectively. Moreover, estimates of genetic and phenotypic correlations for BWG at different ages were from 0.12 to 0.72 and 0.17 to 0.60, respectively. Bodyweight and BWG estimates after four generations of selection were significantly higher than those of the base generation. Moreover, contrasts of generation means were significant across the four generations. The genetic trends across the generations clarified that BLUP estimates for BW and BWG gradually increased with the advance of generations until the fourth generation.&#x0D; Keywords: best linear unbiased prediction, bodyweight, heritability, selection, genetic trend

Variance component analysis of growth and production traits in Vanaraja male line chickens using animal model.

ObjectiveA comprehensive study was conducted to study the effects of partition of variance on accuracy of genetic parameters and genetic trends of economic traits in Vanaraja male line/project directorate-1 (PD-1) chicken.MethodsVariance component analysis utilizing restricted maximum likelihood animal model was carried out with five generations data to delineate the population status, direct additive, maternal genetic, permanent environmental effects, besides genetic trends and performance of economic traits in PD-1 chickens. Genetic trend was estimated by regression of the estimated average breeding values (BV) on generations.ResultsThe body weight (BW) and shank length (SL) varied significantly (p≤0.01) among the generations, hatches and sexes. The least squares mean of SL at six weeks, the primary trait was 77.44±0.05 mm. All the production traits, viz., BWs, age at sexual maturity, egg production (EP) and egg weight were significantly influenced by generation. Model four with additive, maternal permanent environmental and residual effects was the best model for juvenile growth traits, except for zero-day BW. The heritability estimates for BW and SL at six weeks (SL6) were 0.20±0.03 and 0.17±0.03, respectively. The BV of SL6 in the population increased linearly from 0.03 to 3.62 mm due to selection. Genetic trend was significant (p≤0.05) for SL6, BW6, and production traits. The average genetic gain of EP40 for each generation was significant (p≤0.05) with an average increase of 0.38 eggs per generation. The average inbreeding coefficient was 0.02 in PD-1 line.ConclusionThe population was in ideal condition with negligible inbreeding and the selection was quite effective with significant genetic gains in each generation for primary trait of selection. The animal model minimized the over-estimation of genetic parameters and improved the accuracy of the BV, thus enabling the breeder to select the suitable breeding strategy for genetic improvement.

Selection response and genetic parameter estimation of feeding behavior traits in Pekin ducks

Body weight–related traits and feeding behavior traits are important in poultry breeding and production. To investigate the heritability of feeding behavior and their genetic correlation with body weight–related traits in Pekin ducks, 5,594 Pekin ducks were selected. The information about body weight–related traits and feeding behavior from 3 to 6 wk of age were recorded by automatic electronic feeders. The heritability estimates for body weight, residual feed intake, and feeding behavior traits are relatively high (ranging from 0.29 to 0.65). We observed that total feed intake, meal feed intake, body weight at the age of 3 wk, and daily body weight gain had strong positive genetic correlations with body weight at the age of 6 wk. Moreover, body weight at the age of 3 wk also showed a positive genetic correlation with the feed conversion ratio (0.33). Total feeding time, daily feed intake, and feeding rate had significant positive phenotypic correlations with feed efficiency. However, the average interval between meals, the number of daily visits, and the number of meals all had a low genetic or phenotypic relationship with body weight and feed efficiency. In conclusion, our study revealed that body weight, residual feed intake, and feeding behavior traits were all highly heritable traits, and the selection for certain feeding behaviors could improve feed efficiency in Pekin ducks. This study is the first report about genetic parameter estimates about feeding behaviors in ducks based on large datasets and provides solid data for genetic study in ducks.

Genetic variation in growth pattern within a population of farmed Atlantic salmon (Salmo salar) during a standard production cycle

Selection for faster growth to market size has a long history in selective breeding programs for aquaculture species. In Atlantic salmon, selection for faster growth has been carried out for more than four decades, i.e. about ten generations. Genetic improvement of growth rate is indicated as favourable correlated to improved feed utilization and, from an economic perspective, it can be argued that improved feed utilization is the main breeding objective: improved fish production per unit of nutrients (protein or energy) provided. However, also reduced production time in challenging grow-out environments, i.e. reduced exposure to sea lice and other disease agents, may be highly valuable from an animal welfare and environmental perspective. Reduced production time in challenging grow-out environments may also be economically favourable by reducing the need for mechanical or chemical treatments of the fish.Body weights at stocking and harvest are commonly recorded in breeding programs for Atlantic salmon. Selection for faster growth rate is usually based on recorded harvest weights, which represent the accumulated growth during the entire production cycle. Alternatively, selection could be based on other growth parameters, i.e. Thermal Growth Coefficient (TGC), which specify growth in specific production periods. Production of Atlantic salmon in open sea cages entails large variation of environmental parameters, i.e. water temperature, water quality, salinity, day light etc., that influences the growth.In this study, growth of individual Atlantic salmon in an open sea cage were investigated (as a part of the project BEHAVEGENES, NFR 2014–2017) to describe potential GxE for growth in different production periods. Test fish were transported to sea in autumn, 8 months after first feeding, and harvested after 16 months at a mean harvest weight of 5.5 kg. Individual body weights were recorded at five different time points allowing estimation of growth during a total of four subsequent production periods. Sexual growth dimorphism was discovered well before onset of sexual maturation; already 4 months after sea transfer, at average population body weight ~500 g, males were measured on average 2.8% heavier than females. Heritability estimates for body weight were all high (0.42–0.72), while heritability estimates expressed by growth calculated as TGC were mediate to high (0.35–0.56). Genetic correlations between growth (TGC) in different production periods varied between −0.20 and 0.82. The correlation between growth during an 8-month summer period (average body weights increase from 500 g to 3.9 kg) and a 4.5-month winter period (average body weight increased from 3.9 kg to 5.8 kg) was not significant (rg 0.16 ± 0.17), suggesting genetic variation for growth pattern and that different genes are involved in different growth periods.

Random regression models for genetic analysis of body weight in crossbred pigs

Body weight of an animal is represented by a continuous function of time (longitudinal trait) and can be characterized by a trajectory with number of measurements. The present study was carried out to determine heritability estimates of body weight in crossbred pigs (75% Landrace + 25% Bareilly local) using random regression model with Legendre polynomials of quadratic power. Data of 9044 records of 1,292 crossbred piglets, progeny of 86 boars and 98 sows; born in 184 parities between 5 years from 2013–17 was used for the study. Records on weight at birth and at 1 week interval up to 6 week were used. Model included sex, year of birth, season of birth and parity as fixed effect, age of dam at farrowing as co-variable and direct additive genetic effect and maternal permanent environmental effect as random regression. There was a steady increase in body weight over the age from birth (0.96 kg) to 6th week (9.0 kg). Direct additive genetic (0.006 to 7.37 kg2), maternal permanent environment (0.053 to 70.07 kg2) and total phenotypic (0.18 to 77.56 kg2) variance increased continuously from birth to 6 week of age. In general, heritability estimates of body weight at different ages of pre-weaning stage were low ranging from 0.031 to 0.12. The estimate increased up to 1st week (0.119±0.025) with very low value at birth (0.031±0.015) and decreased thereafter to 0.095±0.022 at 6 week. Relative importance of each order of Legendre polynomials showed that quadratic Legendre polynomials with three regression coefficients were enough to capture almost all variability in the model to explain all additive genetic and maternal permanent environment variability. Hence, use of random regression model with quadratic Legendre polynomials was suggested for genetic analysis of pig data for growth.

Phenotype and Genetic Analysis of Growth Characteristics of Sabu and Semau Chickens Which are Conserved Ex-Situ

Sabu and Semau chickens are originated from Sabu and Semau islands, East Nusa Tenggara. The aim of this study was to analyze the phenotypic and genetic of growth characteristics of Sabu and Semau chickens which were conserved ex-situ. Four mating groups as treatments and each using 4 males and 24 females, produced 144 chicks as research material. Mating was by artificial insemination. Observations include data on body weight from the age of 0 - 12 weeks. Nested design analysis were used to obtain the variance components used to estimate the heritability. Heritability was estimated based on male, female, and total variance. The results showed that the body weight resulting from the interse mating (SS) was better than other crosses. The estimation of heritability based on male variance (h2S), SS, MM, and SM showed positive values, while MS are more negative, except 8 weeks of age. Likewise based on females (h2D) and the total variance (h2S+D). Heritability estimates of body weight were low to hight (-2.31 to 2.33) due to small data or sample size. It can be concluded that Sabu and Semau chickens can be conserved ex-situ.

Genetic parameters of egg production trait in Alabio and Mojosari ducks under selection

Genetic parameters for egg production traits in Alabio and Mojosari ducks were estimated. Egg production data were collected from 530 Alabio and 461 Mojosari ducks. The ducks were 6th generation of selection program for egg production trait at the BPTU-HPT Pelaihari. Heritability values were estimated using paternal half-sib correlation method in a one-way analysis of variance. The result showed that heritability estimates for body weight at 16 weeks of age were high, in Alabio ducks (0.63±0.242) and in Mojosari duck (0.88±0.269). Heritability for body weight at first egg was 0.55±0.23 in Alabio duck and 0.44±0.222 in Mojosari duck. The heritability estimates for number of eggs from months 1-3 (EN3) and 1-6 (EN6), ranging from 0.30 to 0.46. The heritability for number of eggs from months 1-12 (EN12) was high in Alabio duck (0.62) and moderate in Mojosari duck (0.46). The EN12 had high genetic correlation with EN3 and EN6 (ranging from 0.80 to 0.99). EN12 had a negative genetic correlation with body weight and age at first egg (between -0.81 and -0.21). This finding indicates that EN3 could be used as a selection criteria to increase EN12 in Alabio and Mojosari ducks.

Genetic and Non-Genetic Factors Affecting Post-Weaning Growth and Morphometric Traits in Assam Hill Goat

The present work was conducted to evaluate the performance in respect of post-weaning growth and morphometric traits of Assam Hill goat. Data on 960 animals belonging to 3 populations of Assam Hill goat maintained at three field units viz., Batabari, Nahira and Tetelia under All India Coordinated Research Project on Goat Improvement were utilized. The least-squares means for body weight, height at withers, heart girth and body length were 7.557 ± 0.049 kg, 41.231 ± 0.121 cm, 44.621 ± 0.115 cm and 50.778 ± 0.172 cm at 6 months; 9.934 ± 0.044 kg, 43.902 ± 0.120 cm, 48.890 ± 0.099 cm and 55.552 ± 0.170 cm at 9 months and 12.549 ± 0.046 kg, 46.791 ± 0.112 cm, 52.765 ± 0.090 cm and 58.392 ± 0.207 cm at 12 months of age, respectively. Location had significant effect on body weight and height at withers at all age groups; on heart girth at 6, 9 and 12 months and on body length at 6 and 12 months of age. Season of birth exerted significant effect on body weight at 9 and 12 months; on height at withers at 12 months and on body length at 6, 9 and 12 months of age. Significant effect of sex was observed on body weight at 9 and 12 months, on height at withers at 6, 9 and 12 months and on heart girth and body length at 9 and 12 months of age. The heritability estimates for body weight and body measurements were moderate indicating scope of selection. The phenotypic and genetic correlation among body weights and body measurements at 6, 9 and 12 months of age were positive in direction and high in magnitude.

Non-genetic factors affecting pre-weaning growth and morphometric traits in Assam Hill goat.

Aim:This study aimed to determine the genetic and non-genetic factors affecting pre-weaning body weight (BW) and morphometry in Assam Hill goat along with the genetic parameters.Materials and Methods:The detailed information in respect of BW and body measurements of 960 animals at birth and 3 months of age belonging to three different populations of Assam Hill goat maintained at field units, namely, Batabari, Nahira, and Tetelia under “All India Coordinated Research Project on Goat Improvement” were utilized in the present study. The data were analyzed using least squares technique.Results:The least squares means for BW, height at withers (HW), heart girth (HG), and body length (BL) were 1.166±0.008 kg, 26.198±0.070 cm, 26.695±0.096 cm, and 29.482±0.119 cm at birth and 4.590±0.083 kg, 36.850±0.105 cm, 40.741±0.115 cm, and 39.703±0.108 cm at 3 months of age, respectively. Location had a significant effect on BW, HW, and BL at both birth and 3 months and on HG at 3 months of age. Season of birth exerted significant effect only on BL at birth, whereas the significant effect of sex was observed on HG and BL at 3 months of age. The heritability estimates for BW and body measurements were moderate indicating the scope of selection. The phenotypic and genetic correlations among BWs and body measurements at birth and 3 months of age were positive in direction and high in magnitude.Conclusion:On the basis of the present findings, it could be concluded that the weaning weight of kids can be considered for the selection of parent stock to increase productivity and eventually the economic efficiency. Further, animals with higher body measurements at initial phases of growth will perform better with respect to even BW at later stages of growth.