Parity Differences in Heat Expression of Dairy
Cows Synchronized with GnRH, CIDR and PGF2α during Dry Season in Zambia
E. S. Mwaanga*, K. Choongo, H. Simukoko and C.
Chama1
University of Zambia, School of Veterinary
Medicine, Department of Biomedical Sciences, P. O. Box 32379,
Lusaka, Zambia; 1Makeni Dairy Small-holder, Lusaka,
Zambia
* Corresponding author: e.mwaanga@unza.zm; mweenzu@yahoo.com
Abstract
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 on 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.