Black Bengal goat (BBG) is a potential farm animal genetic resource of Bangladesh. The aim of this study was to investigate the genetic improvement of growth parameters in-situ through a community based breeding program under a low input production system in three villages; Gangatia, Borochala and Pachpai at Bhaluka upazila in Mymensingh district. Data on a total of 451 individuals taken from 2009 to 2015 in three progressive generations were considered in this study. In the community breeding program, two breeding strategies (BS); mating among selected superior bucks and does (denoted as BS1) and mating existing does (owing to farmers) with superior selected bucks (denoted as BS2). Mating among existing bucks and does owned by the farmers (denoted as BS3) were considered as test group to compare with others. Phenotypic performance and genetic evaluation for growth rates (GR) at different ages were studied. Data were analyzed by SPSS 17.0 and VCE 4.2.5. The average GR from birth to 3-month (GR0-3), 3 to 6-month (GR3-6), 6 to 9-month (GR6-9), 9 to 12-month (GR9-12) and birth to 12-month (GR0-12) were 43.05±0.78, 21.27±0.48, 21.42±0.37, 19.42±0.46 and 36.17±0.28g/d, respectively. GR at different ages differed significantly (p<0.001) for sex, except at GR0-3. Generation and BS influenced GR at all ages significantly. Better growth rates were obtained in progeny produced from BS1 and in later generations. The heritability estimates for GR at different ages were medium ranging from 0.32 to 0.57. The genetic and phenotypic correlations for GR at different ages ranged from low to high (0.02 to 0.87). The average responses due to selection in three progressive generations for GR varied from 2.31 to 4.52g/d per generation. It may be concluded that community based breeding program with selected superior bucks and does is very rationale under low input production system, as it improved growth performance in progressive generations. However, estimates of heritability and genetic correlations indicated scope of genetic improvement for GR in BBG if rigorous culling of inferior does and bucks in breeding program can be adopted.

Keywords: Black Bengal goat, growth rate, genetic evaluation, response to selection