Abstract
This study investigated the effects of rumen-protected methionine (RPM) and rumen-protected choline (RPC) on energy balance, postpartum lactation performance, antioxidant capacity and immune response in transition dairy cows. Forty-eight multiparous transition cows were matched and divided into four groups: control, 15 g/d RPC, 15 g/d RPM or 15 g/d RPC + 15 g/d RPM. Diet samples were collected daily before feeding, and blood samples were collected weekly from the jugular vein before morning feeding from 21 days prepartum to 21 days postpartum. Postpartum dry matter intake (DMI) was increased by both additives (P < 0.05), and energy balance values in supplemented cows were improved after parturition (P < 0.05). Both RPC and RPM decreased the plasma concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) (P < 0.05), but increased the plasma levels of glucose, very-low-density lipoprotein (VLDL) and apolipoprotein B100 (ApoB 100, P < 0.05). The supplements improved milk production (P < 0.05), and increased (P < 0.05) or tended to increase (0.05 < P < 0.10) the contents of milk fat and protein. The post-ruminal choline and methionine elevated the blood antioxidant status, as indicated by total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) activity and the vitamin E concentration (P < 0.05), and reduced the plasma malondialdehyde (MDA) level (P < 0.05). Furthermore, RPM and RPC elevated the plasma interleukin 2 (IL-2) concentration and the CD4+/CD8+ T lymphocyte ratio in peripheral blood (P < 0.05). Alternatively, the levels of tumor necrosis factor-α (TNF-α) and IL-6 were decreased by RPM and RPC (P < 0.05). Overall, the regulatory responses of RPC and RPM were highly correlated with time and were more effective in the postpartum cows. The results demonstrated that dietary supplementation with RPC and RPM promoted energy balance by increasing postpartal DMI and regulating hepatic lipid metabolism, improved postpartum lactation performance and enhanced antioxidant capacity and immune function of transition dairy cows.
Highlights
The transition period spans from three weeks before to three weeks after calving
The results demonstrated that dietary supplementation with rumen-protected choline (RPC) and rumen-protected methionine (RPM) promoted energy balance by increasing postpartal dry matter intake (DMI) and regulating hepatic lipid metabolism, improved postpartum lactation performance and enhanced antioxidant capacity and immune function of transition dairy cows
Nutritional strategies to reduce the adverse effects of non-esterified fatty acids (NEFA), such as mitigating the body fat mobilization and accelerating the removal of hepatic of NEFA, is urgently required to safeguard the health of transition dairy cows, and many researchers have focused their attention on this area
Summary
The transition period spans from three weeks before to three weeks after calving During this period, dairy cows are more susceptible to metabolic disorders, such as fatty liver, ketosis, retained placenta, hypocalcemia and clinical mastitis [1,2]. NEB triggers body fat mobilization to meet the increasing energy demands of the cows. An elevated NEFA concentration is a typical hallmark of transition cows, and the insufficient metabolic capability of hepatic NEFA has been demonstrated to adversely affect animal health and to impair lactation performance as well as subsequent reproductive performance [7,8]. Nutritional strategies to reduce the adverse effects of NEFA, such as mitigating the body fat mobilization and accelerating the removal of hepatic of NEFA, is urgently required to safeguard the health of transition dairy cows, and many researchers have focused their attention on this area
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