Bayesian approach for genetic analysis of production and reproduction traits in Jersey crossbred cattle

Bayesian approach to estimate variance components and genetic parameters of average daily gains and Kleiber ratios in crossbred cattle

The present study aimed to estimate variance components and genetic parameters of the average daily gains from birth to 3-months (ADG1), 3- to 6-months (ADG2), 6- to 9-months (ADG3) and 9- to 12-months (ADG4) of age and corresponding Kleiber ratios (KR1, KR2, KR3 and KR4, respectively) in Jersey crossbred calves. Data for this study were collected from National Dairy Research Institute, Eastern Regional Station, Kalyani, West Bengal, India during 2013 to 2021. Genetic parameters for the traits were estimated using Bayesian procedure through Gibbs sampling by fitting six animal models. The deviance information criterion (DIC) was employed to determine the most appropriate model for each trait under investigation. Direct heritability estimates for ADGs and KRs ranged from 0.19 (ADG3) to 0.59 (ADG2) and 0.14 (KR3) to 0.72 (KR1), respectively. Significant maternal heritability (m 2 ) was observed for average daily gains (17-24%) and Kleiber ratios (13-18%) at different age intervals under the best model. Estimates of permanent environmental effects (c 2 ) of dam for ADG1, ADG2, KR2 and KR4 were only 1-4% of the total phenotypic variance in this study. Large negative estimates of correlations, ranging from -0.87 to -0.98, between direct and maternal( r a , m ) effects for ADGs and KRs (except KR3) at different age intervals were observed. Total heritability ( h t 2 ) and maternal repeatability( t m ) of the studied traits ranged 0.05-0.28 and 0.01-0.14, respectively. The moderate to high heritability estimates for all traits in this study indicate the possibility of genetic progress for these traits through selective breeding program.

Bayesian approach for assessment of co-variances and genetic parameters of production and reproduction traits in Sahiwal cattle

Precise as well as unbiased estimates of genetic parameters of economically important traits is important for framing breeding programmes meant for genetic progress of dairy animals. Present work was carried out to assess the co-variances along with genetic parameters of production and reproduction traits in Sahiwal cattle with Bayesian approach. Records of Sahiwal cattle kept at ICAR-National Dairy Research Institute, Karnal, Haryana for the period 1988-2016 were used. Heritability estimates ± posterior standard deviation for 305 days' milk yield (305DMY), lactation milk yield (LMY), lactation length (LL), peak yield (PY), days to attain peak yield (DPY), dry period (DP), gestation period (GP), calving to first insemination interval (CFI), days open (DO) and calving interval (CI) as obtained were 0.23 ± 0.03, 0.26 ± 0.03, 0.18 ± 0.03, 0.18 ± 0.03, 0.07 ± 0.02, 0.08 ± 0.02, 0.08 ± 0.02, 0.07 ± 0.02, 0.09 ± 0.02 and 0.02 ± 0.02, respectively and estimates of repeatability for the corresponding traits were 0.23 ± 0.03, 0.26 ± 0.03, 0.21 ± 0.03, 0.21 ± 0.03, 0.12 ± 0.02, 0.14 ± 0.03, 0.16 ± 0.03, 0.16 ± 0.03, 0.17 ± 0.03 and 0.17 ± 0.03. Moderate heritability values for 305DMY and LMY implies that sufficient additive genetic variability is available to obtain selection response. Repeatability estimates for 305DMY, LMY and PY were moderate, pointing towards the possibility of early appraisal of Sahiwal cattle for selection. Antagonistic genetic associations were observed between reproduction and production traits suggesting that reproduction traits need due attention while selecting high producing Sahiwal animals.

Genetic analysis of milk and milk composition traits in Murrah buffaloes using Bayesian inference

Accurate and unbiased assessment of genetic parameters of milk and milk composition traits play an important role in formulating breeding program for genetic improvement of Murrah buffaloes. In this study, data spread over 28 years were utilized to estimate genetic parameters of traits viz., 305 d milk yield (305MY), 305 d fat yield (305FY), 305 d solid not fat yield (305SNFY), milk fat percentage (fat%) and solid not fat percentage (SNF) percentage (SNF%) in Murrah buffaloes kept at ICAR-National Dairy Research Institute, Karnal. Bayesian multiple-trait analysis was done using animal model and Gibbs sampling to estimate (co)variance components. Posterior means of heritability and posterior standard deviation for 305MY, 305FY, 305SNFY, fat% and SNF% were 0.18 ± 0.05, 0.17 ± 0.05, 0.18 ± 0.05, 0.07 ± 0.03 and 0.15 ± 0.06 and posterior means of repeatability estimates along with posterior standard deviation for corresponding traits were 0.33 ± 0.04, 0.32 ± 0.04, 0.33 ± 0.04, 0.14 ± 0.02 and 0.30 ± 0.04, respectively. Estimates of genetic correlation varied from -0.080 (305MY and fat %) to 0.999 (305MY and 305SNFY). Permanent environmental correlations varied from -0.060 (305MY and SNF%) to 0.999 (305FY and 305SNFY). This study indicated that all considered traits except fat% have ample genetic variability which can be exploited for selection and genetic improvement of Murrah buffaloes.