author(s)
Ani S Das, Metilda Joseph, Shibu Simon, K Shyama, MK Muhammad Aslam and E Niyas

abstract
Infertility due to negative energy balance is a major problem among the high producing cows, resulting huge economic loss. This study aimed to assess the effect of pre- and post-partum bypass fat supplementation on the reproduction and production parameters of high yielding crossbred cows. The trial was conducted with five groups of six cows each (GI – control, GII- Supplemented with 200 g bypass fat daily pre-partum during last 30 days of pregnancy, GIII – 200 g bypass fat daily up to 90 days post-partum, G IV - Supplemented with -200 g bypass fat daily from 30 days pre-partum to 90 days post-partum), GV- Cows without any bypass fat supplementation and under Ovsynch protocol. The animals in GIII and GIV were observed to be superior in milk production parameters viz. peak yield (P<0.05), and day of attaining peak yield (P<0.01). There was a significant increase in conception rate in GIII and GIV compared to GI, G II and GIV (p<0.05). But there is no significant increase in conception rate in GIV compared to G III (p<0.05) the calving to conception interval was significantly reduced in those animals fed with bypass fat post-partum and pre post-partum combined. Calving to conception interval is significantly lower in GIV compared to GIII. The relative economic benefit in animals supplemented with bypass fat (GIII and GIV) were higher compared to others. But relative economic benefit is not significant in GIV compared to GIII. It was observed that bypass fat feeding post-partum is an economically viable and environment-friendly recommendation for improving the productive and reproductive performance of crossbred cows. On comparison post-partum feeding is a more viable recommendation compared to pre partum feeding and combined pre and post-partum feeding.