The objective of this study was to select Black Bengal Buck Based on some reproductive performance of their progeny. The least-squares means for overall reproductive performances of age of first kidding (AFK), weight at first kidding (WFK), gestation length (GL), kidding interval (KI), post-partum heat (PPT), litter size at birth (LS) and litter weight at birth were 465.6 days, 13.22 kg, 145.34 days, 302.5 days, 123.84 days, 1.61 and 1.66 kg, respectively. The effect of flock and generation were significant (p<0.05) for AFK, WFK, KI, PPT, LS and LWB. The effect of parity of doe was significant (p<0.01) for LSB and LWB. The effect of season was significant (p<0.05) for KI, PPT and LWB. The heritability value for these traits was ranges from 0.17 to 0.24 and predicted breeding value from -0.003 to 0.445. According to the genetic worth of the buck the highest breeding value of reproductive traits were found in the progeny of Buck No. 32, followed by Buck No. 52, 54, 81 and 87. This progeny tested bucks may be used for the improvement of the reproductive potentials of Black Bengal goat through Artificial Insemination (A.I). The lowest breeding value of reproductive traits was found from the progeny of Buck No. 3 followed by Buck No. 11. The low estimates of heritability obtained for reproductive traits indicated that selection based on the doe's own performance may result in slow genetic improvement therefore; the progeny testing program will be beneficial to the farmers and fulfill their need by supplying superior sires of high genetic merit.

Accumulated five years data on 197 kids of 15 Black Bengal bucks in the nucleus breeding flock of Black Bengal goats were analyzed for the study of production traits. The traits considered were birth weight, weight at every 3-month interval up to 12-month, semen characteristics and milk yield. Semen parameters were evaluated from 450 ejaculates of 15 Black Bengal bucks collected twice a week by artificial vagina method and daily milk yield of Black Bengal goats were estimated from the analysis of 57 lactation records of 30 does. The significance of fixed effects sex of kid, parity, litter size, season, age, body weight and scrotal circumferance were analyzed using least-squares analyses of variance of the general linear model (GLM) procedure of the Statistical Analysis System (SAS, 1998). Least-squares means for body weights at birth, 3, 6, 9 and 12-month of age were 1.3, 4.8, 8.0, 11.1 and 14.0 kg, respectively. Body weights at 3, 6, 9 and 12-month of age except at birth were affected by the sex of kids (p<0.05). Type of birth and parity of dam had the significant affect (p<0.05) on birth weight, whereas season of birth had significant (p<0.05) effect on the body weight. The least-squares means of semen volume (ml/ejaculate), sperm concentration (10 9 /ml), mass motility (%), live spermatozoa (%) and normal spermatozoa (%) were 0.5, 2.4, 80.0, 86.5 and 89.3, respectively. Age of bucks had significant (p<0.01) affect on semen volume, sperm concentration. Body weight had a significant (p<0.05) effect on semen volume only. Least-squares mean of daily milk yield was 379.9 lit.. Milk yields was significantly (p<0.01) affected by litter size and season of kidding. It is suggested that nongenetic factors should be adopted as a technique for improving the productive traits.

The study was conducted at Sylhet Govt. dairy farm to evaluate the productive and reproductive performance of Jersey× Frisian (J×F), Jersey × Local (J×L) and Sahiwal × Local (SL×L.) crossbred during the period of April 2007 to August 2009. Data on milk yield and different reproductive traits like lactation length, milk yield, length of dry period, service per conception, gestation length and post-partum heat period were evaluated. Results indicated that milk yield, length of dry period, service per conception and post-partum heat period were significantly affected (P<0.01) by different crossbred. However, lactation length and service per conception were significantly affected (P<0.01) by parity and interaction of breed × parity. The highest lactation length was observed for the genotype Jersey × Friesian (J×F) and the lowest was Jersey × Local (J×L) in the first and second lactation. The highest milk yield was observed for the genotype J×F and the lowest was J×L. The highest length of dry period was observed in SL× L and lowest was J×F. Furthermore maximum services were required for J×F. The highest gestation length was observed for genotype SL×L. The highest post-partum heat period was observed J×F. The overall reproductive performance of different crossbreds were varied.

The present study was conducted to investigate the seasonal effect on milk production and milk qualities of crossbred dairy cows at DGDF, Sylhet. For these purposes, the data of milk production and milk samples were collected from bulk milk tank at District Govt. Dairy Farm, Sylhet and their qualities were measured by physico-chemical and microbiological tests. The season has a significant effect (p<0.05) on the milk yield and milk quality. The total milk production was highest during the rainy season 3354.00 kg followed by summer 3116.70 kg while the lowest milk production was obtained in winter 2925.50kg. The chemical composition of milk was the lowest in summer 4.27% fat, 3.20% protein, 4.46% lactose and 8.55% SNF and in rainy 3.96% fat, 3.24% protein, 4.49% lactose and 8.53% SNF respectively and the highest in winter 5.30% fat, 3.18% protein, 4.46% lactose and 8.59% SNF. The season had a significant influence on the density and freezing point of the milk (p<0.05). The temperature of the milk varied widely from one season to another season. The temperature was maximum in rainy season 28.77oC while the minimum was 25.80 oC in the winter season. The salt percentage of the milk varied within a small range from one season to another season. During the winter season the average SPC bacteria count was lower compared with the other season, 38.02 ×105 cfu/ml. The highest value was obtained in rainy season 40.50×105 cfu/ml. Coliform bacteria count was on average 4.5×105 cfu/ml in winter, 4.91×105 cfu/ml in summer and 5.46×105 cfu/ml in rainy season. There was no significant difference compared to the value found during the other season. From this study it was found that season had a significant effect on the milk quantity and quality, except for protein, lactose, SNF, SPC and coliforms count.Bang. J. Anim. Sci. 2016. 45 (3): 52-57

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