France T L, Juarez-Leon K S, Javaid A, Vogellus M G, Reyes D C, McFadden J W
Department of Animal Science, Cornell University, Ithaca, NY 14853.
Department of Animal Science, Cornell University, Ithaca, NY 14853.
J Dairy Sci. 2025 Sep 25. doi: 10.3168/jds.2025-27297.
Supplementing rumen-protected Met (RP-Met) during the transition period has been shown to improve DMI and increase milk production in dairy cows. Omega-3 fatty acids (FA), particularly eicosapentaenoic acid (EPA; C20:5) and docosahexaenoic acid (DHA; C22:6), are known to support immune function in nonruminants, but their effects in dairy cows remain less defined. We aimed to investigate the combined effects of RP-Met and calcium salts (CS) of FA enriched with EPA and DHA on lactation performance in periparturient Holstein cows. Seventy-nine multiparous cows were enrolled in a randomized complete block design and assigned to 1 of 4 dietary treatments (n = 18 to 19 per treatment) from 3 wk before (-21 ± 3 d) to 3 wk after calving as follows: (1) no RP-Met and CS without n-3 FA (-Met/-n3FA; CS contained 56.0% saturated FA, 35.2% oleic acid, and 8.10% linoleic acid), (2) RP-Met with CS without n-3 FA (+Met/-n3FA), (3) no RP-Met with CS enriched in n-3 FA (-Met/+n3FA; CS contained 64.5% SFA, 25.4% oleic acid, 5.10% linoleic acid, 0.60% linolenic acid, 2.60% EPA and 1.40% DHA), or 4) RP-Met and CS enriched in n-3 FA (+Met/+n3FA). All cows were fed a corn silage-based TMR pre- and postpartum. Diets were formulated to provide either ≤0.96 g Met/Mcal of ME (-Met) or ≥1.13 g Met/Mcal of ME (+Met). Calcium salts were included at 1.5% of dietary DM across all diets. Prepartum DMI, BW, and BCS were unaffected by treatment. The main effect of treatment (supplemental Met and n-3 FA) increased postpartum DMI, Met (25.2 vs. 20.1 g/d Met prepartum and 59.9 vs. 35.9 g/d Met postpartum for +Met and -Met diets, respectively) and n-3 FA intakes (1.36 vs. 0 g/d EPA and DHA prepartum and 6.61 vs. 0 g/d EPA and DHA postpartum for +n3FA and -n3FA diets, respectively). Co-supplementation increased ECM, and FCM yields, and milk fat and true protein yields, and tended to increase milk yield, relative to diets containing only RP-Met or only n-3 FA. Cows co-supplemented with RP-Met and CS enriched in n-3 FA had marginally higher plasma glucose and lower plasma triglyceride concentrations at calving, and reduced plasma total and nonessential AA concentrations during lactation. Nutrient-specific responses included increased plasma Met in cows fed +Met diets and elevated milk lactose contents and yields, along with higher n-3 FA and PUFA contents and yields in cows fed CS enriched in n-3 FA. The additive effects of co-supplementation suggest potential synergy when cows are fed Met, EPA, and DHA. Although the underlying mechanisms were not fully elucidated, the observed improvements may be linked to enhanced mammary de novo FA synthesis, altered AA utilization, and increased hepatic gluconeogenesis, collectively supporting improved metabolic function and lactation performance in early lactation dairy cows.
在过渡期补充瘤胃保护蛋氨酸（RP - Met）已被证明可提高奶牛的干物质采食量（DMI）并增加产奶量。ω-3脂肪酸（FA），特别是二十碳五烯酸（EPA；C20:5）和二十二碳六烯酸（DHA；C22:6），已知可支持非反刍动物的免疫功能，但其在奶牛中的作用仍不太明确。我们旨在研究RP - Met与富含EPA和DHA的脂肪酸钙盐（CS）对围产期荷斯坦奶牛泌乳性能的联合影响。79头经产奶牛采用随机完全区组设计，从产前3周（-21±3天）到产后3周被分配到4种日粮处理中的1种（每种处理n = 18至19头），如下：（1）不添加RP - Met且CS中不含n - 3 FA（-Met/-n3FA；CS含有56.0%的饱和脂肪酸、35.2%的油酸和8.10%的亚油酸），（2）添加RP - Met且CS中不含n - 3 FA（+Met/-n3FA），（3）不添加RP - Met但CS富含n - 3 FA（-Met/+n3FA；CS含有64.5%的饱和脂肪酸、25.4%的油酸、5.10%的亚油酸、0.60%的亚麻酸、2.60%的EPA和1.40%的DHA），或4）添加RP - Met且CS富含n - 3 FA（+Met/+n3FA）。所有奶牛在产前和产后均饲喂以玉米青贮为基础的全混合日粮（TMR）。日粮配方设计为提供≤0.96克蛋氨酸/兆卡代谢能（-Met）或≥1.13克蛋氨酸/兆卡代谢能（+Met）。所有日粮中钙盐的添加量均为日粮干物质的1.5%。产前的DMI、体重和体况评分不受处理影响。处理（补充蛋氨酸和n - 3 FA）的主要效应增加了产后DMI、蛋氨酸摄入量（+Met和 - Met日粮的产前蛋氨酸摄入量分别为25.2克/天和20.1克/天，产后分别为59.9克/天和35.9克/天）以及n - 3 FA摄入量（+n3FA和 - n3FA日粮的产前EPA和DHA摄入量分别为1.36克/天和0克/天，产后分别为6.61克/天和0克/天）。与仅含RP - Met或仅含n - 3 FA的日粮相比，联合补充增加了能量校正乳（ECM）、乳脂校正乳（FCM）产量、乳脂肪和真蛋白产量，并倾向于增加产奶量。联合补充RP - Met和富含n - 3 FA的CS的奶牛在产犊时血浆葡萄糖浓度略高，血浆甘油三酯浓度较低，并且在泌乳期间血浆总氨基酸和非必需氨基酸浓度降低。特定营养素的反应包括饲喂+Met日粮的奶牛血浆蛋氨酸增加，以及饲喂富含n - 3 FA的CS的奶牛乳乳糖含量和产量升高，同时n - 3 FA和多不饱和脂肪酸（PUFA）含量和产量也更高。联合补充的累加效应表明，给奶牛饲喂蛋氨酸、EPA和DHA时可能存在潜在协同作用。尽管潜在机制尚未完全阐明，但观察到的改善可能与乳腺脂肪酸从头合成增强、氨基酸利用改变以及肝脏糖异生增加有关，共同支持了泌乳早期奶牛代谢功能和泌乳性能的改善。
