Influence of rumen bypass fat supplementation during early lactation in tropical crossbred dairy cattle.

The present study investigated the influence of rumen bypass fat-supplemented total mixed ration (TMR) on milk production of tropical crossbred, dairy cows. Twelve stall-fed, tropical crossbred, dairy cows were studied from calving to 15 weeks of lactation. The cows were 397.6 kg in body weight and produced 9.14 L/cow/day milk at the first week of lactation. The experiment was on a complete randomized design with two treatments (i.e., basal diet alone and basal diet with bypass fat supplement) each consisting six (n = 6) replicate cows. During the experimental period, while cows of both treatments were individually fed with respective basal diet (TMR), only the cows allocated for experimental dietary treatment were supplemented with rumen bypass fat (200 g/cow/day) containing calcium salts of long-chain fatty acids. Feed intake, body weight (BW), and milk yield of cows were recorded. Proximate composition of feed, milk composition, and blood metabolic profile of cows were assessed. Dry matter intake and BW of cows were not affected (P > 0.05) by supplementation of rumen bypass fat. The cows supplemented with bypass fat had recorded significantly higher (P < 0.05) milk production compared with cows that did not receive bypass fat supplements until eleventh week of the lactation. As such, bypass fat supplementation resulted 132.38 L/cow higher (P < 0.05) cumulative milk production at 15 weeks compared with their counterparts (1142 vs. 1010 L/cow). But, milk fat, solid non-fat (SNF), protein, and milk urea nitrogen (MUN) contents were not influenced (P < 0.05) by bypass fat supplementation. Bypass fat-supplemented cows had comparatively greater (P < 0.05) serum non-esterified fatty acids (NEFA) level around 6-8 weeks of lactation. However, the serum metabolites' (i.e., NEFA, betahydroxy butyric acid (BHBA), albumin, calcium, and phosphorous) contents of both treatments varied within their respective reference range throughout the experiment. Neither the fat-supplemented cows nor their counterparts experienced negative energy balance (NEB). Benefit cost ratio of bypass fat supplementation confirmed that there is a direct financial benefit of bypass fat supplementation until 12.7th week of lactation. In conclusion, bypass fat supplementation with TMR feeding during early lactation is recommended to increase the milk production of tropical crossbred dairy cows with medium production.