Abstract
The study was performed in the Gurudaspur and Baraigram upazila of Natore district of Bangladesh to evaluate the productive and reproductive characteristics of pure Black Bengal goat and its crossbred with Beetal reared under semi-intensive system. Record on body weight at birth weight, weaning weight and important reproductive traits of 193 foundation stock of pure Black Bengal does, 674 Black Bengal kids and 335 crossbred kids was maintained from October 2010 to December 2013. Eighty Black Bengal goats of 9-11 months age of different sexes were also slaughtered for determining meat quantity and quality. The socio-economic study revealed that 92.40%, 7.45% and 0.51% goats were Black Bengal goats, crossbred goats and exotic goats and average number of goat per household was 2.20 at the onset of the study in the selected villages. Eighty nine per cent of those goats were reared by landless, marginal and small farmers. The average birth weight (BWT) of Black Bengal and crossbred kids was 1.25±0.01 and 1.48±0.02 kg, respectively and birth weight of two genotypes differed significantly (p<0.01). The BWT of male and female kids of Black Bengal goat differed significantly (p<0.01), but the BWT of male and female kids of crossbred did not differ significantly (p>0.05). The BWT of Black Bengal kids were 1.27±0.02, 1.26±0.03 and 1.23±0.02 kg and those of crossbred kids were 1.48±0.04, 1.43 ±0.06 and 1.51±0.04 kg in summer, rainy and winter, respectively with non-significant difference. The average weaning weight (WWT) of Black Bengal and crossbred kids were 6.38±0.35 and 7.73±0.14 kg, respectively. The differences were highly significant (p<0.01). The WWT of male and female kids of Black Bengal goat as well as crossbred goat did not differ significantly (p>0.05). The WWT of Black Bengal kids were 6.37±0.47, 5.68±0.81 and 6.61±0.45 kg and those of crossbred kids were 7.93±0.40, 7.61±0.55 and 7.60±0.31 kg in summer, rainy and winter, respectively with non-significant difference (p>0.05). The average daily gain (ADG) of Black Bengal and crossbred goat were 55.65±1.26 and 68.40±1.47g, respectively and were highly significant (p<0.01). ADG in two sexes and in three seasons of two genotypes follow the same pattern of birth weight as observed for two genotypes. The age and weight at puberty were 246.93±5.09 days and 14.11±0.21 kg for Black Bengal goat and 318.06±10.91 days and 15.73±0.50 kg for crossbred goat, respectively and difference were highly significant (p<0.01). The gestation length of Black Bengal and crossbred were 146.06±0.51 and 148.61±2.02 days, respectively. The litter size of Black Bengal and crossbred goat were 2.05±0.04 and 1.40±0.13, respectively and those differences were highly significant (p<0.01). The average post partum heat period and kidding interval of Black Bengal does were 94.94±6.40 days and 233.46±6.19 days, respectively. The hot carcass yields at 9 to 11 month of age were 8.42+0.79, 6.75±0.62 and 5.89±0.37 kg for buck, wither and doe of Black Bengal goat, respectively. The dressing percentage ranged from 39.86 to 48.18%. There was significant difference in dressing% between buck and doe (p<0.05) but there was no difference in dressing% between wither and doe (p>0.05). The dressing percentage reduced 1.5% on chilled carcass basis. The additive genetic variances for BWT, WWT and ADG were observed as 0.093 kg2, 3.929 kg2 and 503.793 g/d, respectively. The heritability estimates for BWT, WWT and ADG ranged from 0.80 to 0.90. Black Bengal goats had better reproductive efficiency and more resistance to diseases than crossbred goats. On the other hand, crossbred kids had higher growth rate than Black Bengal kids.