The present study aimed to determine the effects of differing nutrient levels during the far-off period on postpartum metabolism and milk production in lactating cows. Twenty-six multiparous cows were assigned to three dietary treatments in the far-off period: a low-energy diet (L, n = 9, 80% intake of the total digestible nutrients requirement), a moderate-energy diet (M, n = 8, 105%) and a high-energy diet (H, n = 9, 130%). During the close-up period, all cows were provided with 105% intake. After parturition, all cows were fed a lactation diet. The BCS recovery was slow, and low milk yield was found in the H group. In the L group, BCS recovery was favorable after parturition, and lactation persistence was increased. The L group had low rumen endotoxin activity and a high initial ovulation rate after parturition. These findings indicate that a high-energy diet during the far-off period has a deleterious effect on milk production. In contrast, the restricted diet in the far-off period increased adaptability with respect to peri-parturition metabolic changes, improved the post-parturition nutritional state, and increased milk production. Furthermore, it suggests that the nutrient levels in the far-off period affect rumen endotoxin activity and reproductive function after parturition.

To elucidate the effects of medium-chain fatty acids (MCFA) on milk production and plasma metabolite and hormone concentrations in early lactating dairy cows, 10 multiparous Holstein dairy cows were randomly assigned to two dietary treatment groups after parturition. One group was fed a diet supplemented with calcium salts of MCFA (MCFA-Ca) for 8 weeks after parturition, while the other group was fed the same diet without the supplement (control). MCFA-Ca, containing 60% caprylic acid and 40% capric acid, was added to a total mixed ration (TMR) at 1.5% of the dietary dry matter (DM). Cows were offered the TMR ad libitum. DM intake, daily gain in bodyweight, milk yield, milk fat content and milk protein content did not differ between the two treatment groups. The MCFA-Ca diet decreased plasma glucose and triglyceride concentrations (P < 0.05), while plasma concentrations of total and free cholesterols tended to increase (P < 0.10). Plasma ghrelin was maintained at a higher concentration (P < 0.05) in cows fed the MCFA-Ca diet than in the control group. Relative to the control diet, the MCFA-Ca diet decreased plasma insulin concentration (P < 0.05) and numerically increased plasma glucagon concentration, resulting in a lower insulin : glucagon ratio (P < 0.05). In conclusion, plasma metabolite and hormone concentrations were affected by the MCFA-Ca diet, suggesting that MCFA-Ca supplementation may change endocrine functions and nutrient metabolism in early lactating cows, ultimately resulting in an enhanced catabolic state.