Modelling genetic improvement of Pabna cattle in Bangladesh

Abstract

In this study, individual cow performance for milk yield, fat yield, protein yield, liveweight and longevity were simulated using a stochastic approach. Additive genetic effects, permanent and temporary environmental effects, and herd and age effects were included in the model along with inclusion of Mendelian sampling. The model generated 10,000 Pabna cows distributed across 200 herds with the herd size ranging between 40 and 60 milking cows. The model ran for 20 years with bulls being selected based on daughter production (progeny testing (PT)) in one scenario and on parent average genetic merit in another. Selection of replacement cows and bulls was based on one of three following objectives: genetic merit for milk yield, milk and survival, and total genetic merit which included all five traits. Each year, 150 cows with the best predicted genetic merit were selected for the production of replacements. The breeding scheme using selection of new bulls and cows based on parent average showed higher genetic gains than the PT for all selection objectives due to the differences between generation interval, accuracy and size of the progeny group/bull. The highest genetic gain was obtained when the selection objective was for milk yield genetic merit (US$15.02/year) compared with total genetic merit (US$10.95/year). ARTICLE HISTORY

Genetic analysis of longevity and lamb survival from birth to yearling in Moghani sheep

“…Low heritability estimates for longevity and survival traits would be assigned to small additive genetic variance for these traits and the influence of nongenetic effects on them (Pryce and Veerkamp 2001;GhaderiZefrehei et al 2017). Also, low heritability estimates for traits in this study implied that improvement of longevity and survival traits could be attained by direct selection for one or more traits which have positive correlation with under study traits (Khan et al 2017). The results of a previous study (Riggio et al 2008) indicated that low heritability estimates for survival traits could be due to the composite nature of these traits with many variables causing death.…”