Index selection of beef cattle for growth and milk production using computer simulation modelling

Abstract

The Texas A&M University (TAMU) Beef Cattle Production model was expanded to include basic concepts of quantitative genetics. The traits simulated were birth weight, yearling weight, mature weight and milk production. The progeny inherited attributes from both the sire and the dam. The incorporation of genetic concepts into the model allowed for the introduction of variation between individuals and generations. This was achieved by interfacing the original model with stochastic genetic subroutines including a restricted selection index for desired genetic change. The index included birth weight and yearling weight. In addition, a function for estimating dystocia was also added. The model was used to simulate selection strategies for a small-to-moderate size breed of cattle and a large-size breed using a restricted selection index.There was an increase in both birth and yearling weight after 20 years of selection in the small-tomoderate size breed, and there was also an increase in dystocia. Antagonistic selection to decrease birth weight and increase yearling weight was simulated for the large breed. Birth weight and dystocia problems declined while yearling weight increased for all classes of animals. In both experiments correlated responses were recorded for mature size and milk production. It was concluded that the modified TAMU Beef Cattle Production model offers breeders an opportunity to compare different selection strategies and evaluate different breeding plans.

Investigation of the Use of Alternative Economic Indices and QTL-Assisted Selection for the Genetic Improvement of Production and Health Traits in Bangladeshi Dairy Cattle

“…This might be the cause for the fluctuations in the genetic gain with the increases of generation number. Similar causes were identified by Dzama et al [29] for stochastic simulation studies.…”

“…The higher genetic gains were obtained in generation 4 onwards might be the effects of specific sire and dam matings in those generations. That sire and dam have a positive effect on increase in genetic gain, were reported by Dzama et al [29]; Andabi and Moran [25].…”

Modelling genetic improvement of Pabna cattle in Bangladesh

“…The annual rate of genetic gain for fat and protein yield had no significant differences, between cows and bulls, but for liveweight and longevity, the breeding bulls were higher than cows in both PAT and PT breeding schemes in all selection objectives. Similar results were reported by Dzama et al (2001) for the response of liveweight.…”

“…Higher genetic gains obtained in particular years might be due to the effects of sires and dams in those years. Genetic potentiality of parents was then passed on to the progeny, leading to higher genetic gains in the upcoming generation (Dzama et al 2001). For breeding bulls, a comparatively lower rate of genetic gain was achieved compared with cows under PAT and PT breeding schemes for all three selection objectives of all the traits.…”

Herdabilidades de parâmetros de curvas de crescimento não-lineares em zebuínos, no estado de Pernambuco

“…Neste caso, os índices de seleção restritos poderiam ser utilizados com mais sucesso (Rosa et al, 1979;Atchley et al, 1997;Dzama et al, 2001). Brown et al (1976) destacaram que a taxa de maturidade (k) poderia ser o único parâmetro disponível para o trabalho da indústria.…”