Background: The Bachaur is a medium sized draft purpose breed mostly present in Madhubani, Darbhanga and Sitamarhi districts of Bihar and presently the breed is at the verge of extinction. Since no data is presently available regarding the estrus pattern in these cows therefore, present study was designed to document the oestrus intensity, estrus cycle length, estrus behaviour and duration of estrus in these animals. 
 
Methods: The total of nine healthy breeding Bachaur cows aged 3 to 5 years were maintained under identical managemental conditions.The estrous cycles of nine animals was synchronized using Cloprostenol Sodium @ 500 mg I/M (Pragma&reg;, Intas, India) in cycling Bachaur cows. Estrus was detected in the morning and evening for external signs of estrus, estrus behavior, intensity of estrus, estrus duration and estrous cycle length.&nbsp; 
 
Result: In the present study, mounting or&nbsp; mounted by other animals was observed in&nbsp; more than 70% and sniffing, tried to lick and Flehmen&rsquo;s reaction was&nbsp; observed in about 66.67% of treated cows. The other parameters like&nbsp; bellowing, restlessness, milk yield reduction, frequent micturition and Flehmen&rsquo;s reaction were recorded in 44.44%, 55.56%, 44.44%, 55.56% and 66.67%, of animals, respectively. The most appreciable physical sign of estrus recorded was intense swelling of vulva (in 88.89%) however hyperaemia of vulva, copious estrual mucous discharge, pronounced tonicity of uterus, completely dilated os cervix and presence of large palpable follicle on the ovary was observed in&nbsp; 44.44%, 55.56%, 66.67%, 77.78% and 66.67%,&nbsp; of cows respectively.

Reproductive Performance of Estrus Pattern in Bachaur Cows of Bihar