Abstract
A research plan was undertaken to study the factors affecting the post-partum reproduction in local and crossbred dairy cows of Bangladesh. The entire programme was splitted into three experiments as (i) effect of nutrition and management on post- partum reproduction in dairy cows, (ii) evaluation of artificial insemination in relation to fertility in the selected areas of Bangladesh and (iii) infertility problems of dairy cattle and response to various treatments in different selected areas of Bangladesh.
In experiment I, different reproductive parameters were studied in both local cows and their crosses. The effects of improved nutrition, restricted suckling and extended weaning of calves were studied. The age at puberty and age at first calving was significantly earlier in crossbred cows specially the local x Jersey crosses than the local zebu cows. The local x Shahiwal crosses had longest age at puberty and age at first calving even longer than the local cows. The post-partum reproductive performance such as calving to uterine involution, oestrus, ovulation, conception, conception rate and number of services per conception were better in crossbred cows than the local cows. Again, in local X Jersey crosses uterine involution was sooner, exhibition of oestrus and ovulation were earlier, conception interval were shorter, conception rate was higher and less number of services per conception was required than the local and other crosses.
The lower blood biochemical parameters were related with low reproductive performance due to repeat breeding and post-partum anoestrus. The better performance in crossbred animals might be due to adequate nutritional supplementation, better management practices, involving restricted suckling, early weaning of calves and genetic potentiality and better health care.
In experiment II, the reproductive traits of 980 cows from different areas of Dhaka, Rangpur and Rajshahi of which 288 cows were served naturally (NS) and 692 cows by artificial insemination (AI) were analyzed.