Abstract
The study was conducted to characterize and investigate the genetic improvement of Black
Bengal goat in-situ through a community based breeding program under a low input
production system. Data on a total of 657 individuals from three villages; Gangatia, Borochala
and Pachpai at Bhaluka upazila in Mymensingh district from 2009 to 2015 with three progressive
generations were considered in this study. Three breeding strategies viz. mating within superior
bucks and superior does, within superior bucks and existing does and within existing bucks
ear
All
and does were applied. Phenotypic characterization for body weight, growth and reproduction
and genetic characterization were studied. Data were analyzed by SPSS 17.0 and genetic
parameters were estimated by VCE 4.2.5. Among the studied population, black coat color were
found highest about 53%, brown bezoar (16%), silver bezoar (15%), black with toggenburg
pattern 9%, dutch belt pattern 5% and solid brown 3% and others (1%). The average body
weight, body length, chest girth, wither height, head length, head width, ear length and
breadth were 1.36±0.03 kg, 19.40±0.10, 23.72±0.08, 22.88±0.04, 8.42±0.02, 6.41±0.01, 6.64±0.04 and
3.61±0.01cm, respectively at birth. The body weight, body length, chest girth and wither height
of male kids were significantly (p<0.05-p<0.001) higher than those of female kids at birth.
the parameters were linearly increased with progressing ages and at 12 month age those traits
averaged as 14.38±0.13 kg, 47.51±0.17, 56.94±0.13, 47.17±0.29, 17.42±0.09, 10.77±0.07, 14.42±0.08
and 6.06±0.03 cm, respectively. At six month and onward, all the body measurements in males
were significantly (p<0.05-p<0.001) higher than those of females. Strong positive correlations
were found among body weight, body length, chest girth and wither height (ranging from 0.88
to 0.99). The average body weight at birth, 3-month, 6-month, sexual maturity, 9-month, and 12-
month were 1.42±0.03, 5.14±0.07, 8.48±0.17, 9.88±0.16, 11.75±0.16 and 15.19±0.16 kg, respectively,
having significant effect for sex (p<0.05-p<0.001), generation (p<0.001) and breeding strategy
(p<0.001). The average growth rates from birth to 3-month, 3 to 6-month, 6 to 9-month, 9 to
month and birth to 12-month were 43.05±0.78, 21.27±0.48, 21.42±0.37, 19.42±0.46 and
36.17±0.28g/d, respectively. Growth rates at different stages differed significantly (p<0.001) for
sex, except at birth to 3-month Generation and breeding strategy influenced growth rates at all
stages significantly (p<0.01; p<0.001). The average age at sexual maturity, age at first kidding,
services per conception, litter size, post partum heat period and kidding interval were
233.09±2.71d, 383.01±2.61d, 1.13±0.03 no, 1.90±0.05no, 42.41±0.84d and 186.44±0.95d,
respectively. Sex, generation, breeding strategy and flock had significant (p<0.01; p<0.001) effect
on age at sexual maturity. Age at first kidding differed significantly (p<0.001) for the effects of
12-
generation and breeding strategy. Generation, breeding strategy and flock had significant
(p<0.05-p<0.001) influences on litter size, post-partum heat period and kidding interval, but
service per conception differed significantly (p<0.05) among flocks. The heritability estimates
for body weights, growth rates and reproductive traits were medium ranging from 0.32 to 0.57.
The genetic and phenotypic correlations for body weight traits were positive with low to high
(0.02 to 0.99 for rg and 0.17** to 0.99** for rp) relationships. Genetic and phenotypic correlations
for growth rates were also ranged from low to high (0.02 to 0.87). Genetic and phenotypic
correlations among productive and reproductive traits were low to medium (-0.03 to 0.37). The
average responses due to selection in three progressive generations for body weight traits
varied from 0.123 to 0.480 kg and that for growth rates from 2.31 to 4.52g/d per generation. The
average responses for age at sexual maturity, litter size, post-partum heat period and kidding
interval were -15.59d, 0.12no, -6.14d and -7.66d per generation, respectively. 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 performance of progressive
generations. However, estimates of heritability and genetic correlations indicated scope for
rigorous culling of inferior does and bucks in breeding program.