The present study was carried out to investigate the effect of different seasons on length and duration of estrus as well as to observe the behavioral changes and physiological peculiarities during estrus period. Three climatic seasons and age groups were considered: summer (March-June), rainy (July-October) and winter (November-February); A (6-9 month), B (9-12 month) and C (>12 month). Estrus behavior was monitored twice a day, using a teaser buck. The estrus were quantified within each season and classified as short (25 days). In case of seasonal effect, the length of estrous cycle did not differ significantly (P>0.05). The higher length of estrous cycle was found in summer (23.50±1.57 days) followed by winter (21.33±1.01 days) and rainy season (20.79±0.61 days), respectively. On the other hand, duration of estrus showed significant (P≤0.05) differences among the three different seasons. The longer duration was observed in winter (44.00±1.95 hours) followed by summer (36.00±0.70 hours) and rainy season (35.54±0.80 hours), respectively. Higher percentage of normal estrus was observed during rainy season (79.31%) when compared to winter (72.73%) and summer (53.33%). On the other hand, a greater percentage of short and long estrous cycle was reported in summer followed by winter and rainy season. Moreover, length of estrus and its duration did not differ significantly (P>0.05) with age. The mean of rectal and vaginal temperature during estrus were recorded as 39.30±0.05 °C and 39.60±0.03 °C, respectively. However, seasonal variation on post-partum heat period did not differ significantly (P>0.05). The mean post-partum heat period of Black Bengal does among the seasons was observed as 84.56±3.28 days. The present result on estrus behavior of Black Bengal goat could help to boost up effective artificial insemination of goat population for optimizing productivity under intensive condition. پرونده مقاله

Milk urea nitrogen (MUN) of dairy cows was determined in relation to breed. A total of forty (40) Pabna and red Chittagong dairy cattle each of twenty (20) were selected to know the milk composition, nutritional status and milk urea nitrogen. Live weight of Pabna Cattle (187±14 kg) was higher than that of red Chittagong cattle (174±4 kg). In Pabna cattle milk yield (4.94 kg), minerals (0.15%) and lactose (5.38%) is more than red Chittagong cattle milk yield (3.62 kg), minerals (0.12%) and lactose (5.37%) but fat (5.04%), protein (3.7%) and solid not fat (SNF) content (9.92%) was more in red Chittagong cattle than Pabna cattle fat (4.03%), protein (3.64%) and SNF (9.87%). The metabolic energy 74.93 MJ/day, dry matter 9.47 kg, crude protein 0.84 kg , ash 1.24 kg, crude fiber 2.18 kg and true digestible nutrient 5.43 kg was required for Pabna cattle and in red Chittagong cattle metabolic energy 72.60 MJ/day, dry matter 9.14 kg, crude protein 0.660kg , ash 1.16 kg, crude fiber 1.93 kg and true digestible nutrient 5.19 kg was required. Milk urea nitrogen (MUN) concentration was higher under in Pabna cattle (38.15 mg/dL) than red Chittagong cattle (RCC) (29.30 mg/dL). Milk urea nitrogen (MUN) differ Pabna cows and red Chittagong cows. پرونده مقاله