Estrus Synchronization and Conception Rate of Crossbred Cows Using Hormones

The present cattle population of Bangladesh is 24.17 million (DLS, 2009). More than 80 percent of this cattle population is indigenous and rests of them are purebreds and crossbreds of different exotic breeds (Friesian, Jersey and Shahiwal) cattle, which is contributing a major share of livestock sub-sector and playing multi-functional roles (supply of milk, meat, skin, manure, carting etc.) in the subsistence production system of Bangladesh. Although the cattle population is large, however the present livestock industry can support less than 20% of national requirements of milk, meat and their value added products. Low genetic potential along with low nutrition and other management limitations is the key factor for the low productivity of these cattle. Generally, the Deshi cattle produce only 1.5 liter milk per day (Hossain et al. 2002) and the temperate and tropical crossbred produces 3 to 5 liter milk per day per cow (Khan et al. 2005). Moreover, the demand of livestock products is increasing with the population growth and socio-economic changes. However, the productivity of livestock is not increasing for meeting the requirements of the country (Huque et al. 2011). In this circumstance, development of specialized cattle breeds for milk and meat production is an emergent issue in Bangladesh. For programmed breeding, it is essential to bring all the animals The study was conducted to know the effect of flushed feeding on estrus synchronization and conception rate of Holstein  Local crossbred cow’s after using the GnRH (fertagyl) and PGF2α hormone. As a representative sample 20 Holstein  Local crossbred cows were chosen from Chittagong Cantonment Military Dairy Farm in Bangladesh and the experimental work was carried out for 60 days. Ten cows were flushed with high energy feed (10.5 mega Joule metabolisable energy/kg feed dry matter) and considered as treated group and 10 cows was allowed for normal feeding. Both the control and treated group cows were injected intramuscularly by the GnRH and PGF2α hormone. After injection of these hormones, 100% cows from both groups showed estrus. Fixed time artificial insemination (AI) was done and the cows were diagnosed in pregnancy after 60 days of AI. It was observed that 20% cows were conceived after AI from control group, but treated group cows showed more conception / pregnancy rate (40%). After using the hormones, age of the cow did not influences for estrus synchronization, but for conception rate it was observed that younger cows showed more than older one.