Milk production and composition, food consumption, and energy balance of postpartum crossbred Holstein-Gir dairy cows fed two diets of different energy levels

The objective of this study was to evaluate the production, consumption, and energy balance parameters of primiparous 3/4 and 7/8 Holstein x Gir (HG) dairy cows fed two diets of differing energy levels during the postpartum period. At the beginning of the study, 28days prepartum, the average weight of both genetic groups was 498 +/- 12kg and body condition score (BCS) was 3.5 +/- 0.05. At the end of the study, 61days postpartum, the 3/4 HG cows had higher weight and body condition scores than the 7/8 HG (456 +/- 8 and 429 +/- 8kg and 3.13 +/- 0.03 and 2.94 +/- 0.03 BCS for 3/4 HG and 7/8 HG, respectively). Milk from cows fed the high-energy diet had higher percentages of fat, protein, lactose, and total dry extract than cows fed the low-energy diet. Cows fed the high-energy diet had higher net energy intake (95.3 +/- 1.9 vs. 88.1 +/- 2.1MJ/day) and higher energy balance (3.64 +/- 2.13 vs -6.02 +/- 2.30MJ/day). The 3/4 HG cows displayed higher energy for maintenance (33.1 +/- 0.4MJ/day) than the 7/8 HG (31.5 +/- 0.5MJ /day). In conclusion, although the primiparous 3/4 HG were heavier than the 7/8 HG and had a higher body condition score, no differences in milk produced up to 60days postpartum were observed. The higher energy diet during the postpartum period increased energy balance, resulting in higher production of milk fat, protein, and lactose.