Parity Differences in Heat Expression of Dairy Cows Synchronized with GnRH, CIDR and PGF2α during Dry Season in Zambia

A study was conducted to investigate parity differences in heat expression of dairy cows heat-synchronized during the dry season when feed scarcity is common. Cyclic cows (n=65) aged 2 to 10 years with parity range of 0 to 7 were selected from small-holder dairy farms around Lusaka. Cows were divided into 3 groups of nulliparous, primiparous and pluriparous. Heat-was synchronized using gonadotrophin releasing hormone (GnRH) and controlled intra-vaginal drug releasing device (CIDR). Heat detection was observed after CIDR withdraw. The study showed a significantly (P<0.05) lower number of primiparous cows (68%) coming into heat compared to nulliparous (81.8%) and pluriparous cows (83.3%). It was concluded that parity influences estrus expression rate in dairy cows following synchronization with GnRH, CIDR and PGF2α during the dry season in the sub-tropics