Abstract This study evaluated the effects of feeding close-up diets differing in starch content with or without stearic acid supplementation (SA) on performance, and metabolic status of dairy cows during the transition period. Forty-six multiparous dry cows were used in a completely randomized design with a 2 × 2 factorial arrangement of starch content [(200 or 250 g/kg of dry matter (DM); L vs H)] and SA supplementation (0 or 20 g/kg of DM; NO vs SA) from 21 d before expecting calving to parturition date. After calving, all cows were fed the same postpartum diet containing 250 g/kg of DM starch and 11.9 g/kg of DM SA supplement. Results indicated that dietary starch concentration did not affect intakes during close-up period, while, stearic acid supplementation had more pronounced effect on increasing dry matter intake (DMI) in H diet than L diet (21.6% vs 5.71%, respectively; significant interaction). Also, SA feeding increased NEL intake compared to NO cows. There was an interaction between starch content and SA supplementation on body weight (BW) change, as cows fed SA diets had greater BW gain in H diets, but this response was not observed in L diets during close-up period. At the postpartum period, an interaction effect was observed between starch and SA for DMI, indicating SA increased postpartum DMI and DMI as a percentage of BW in L diet while cow received NO had more DMI in H diet. Animals fed L diets had less negative EB, and lower BW and BCS losses compared to those received H diets. Milk fat enhanced in cows fed L diets compared to those fed H diets. Interactions between starch and SA treatments were observed for insulin (HNO and LSA had highest concentrations), and aspartate aminotransferase (AST) activity (L group had highest activity) on −7 d to calving. Also, there were significant interactions among treatments for glucose, insulin, non-esterified fatty acids (NEFA) and AST activity over the postpartum period. Cows assigned to the HNO and LSA groups had higher serum glucose and insulin, lower NEFA concentration, while HSA treatment has lowest AST activity. The results from this study indicate that feeding 20 g/kg DM of fat supplement rich in stearic acid in a low starch close-up ration (200 g/kg DM), improved prepartum intake, and had positive carryover effects on postpartum performance and metabolic status compared to high starch diet (250 g/kg DM).

中文翻译：

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特写日粮中添加硬脂酸和淀粉浓度对过渡奶牛生产性能和代谢反应的影响

摘要 本研究评估了在添加或不添加硬脂酸 (SA) 的情况下饲喂不同淀粉含量的特写日粮对过渡期奶牛生产性能和代谢状态的影响。在完全随机设计中使用了 46 头经产干奶牛，其中淀粉含量 [（200 或 250 g/kg 干物质（DM）；L vs H）] 和 SA 补充（0 或 20 g/kg DM；NO vs SA）从预计产犊到分娩日期前 21 天。产犊后，所有奶牛都饲喂相同的产后日粮，其中含有 250 g/kg DM 淀粉和 11.9 g/kg DM SA 补充剂。结果表明，日粮淀粉浓度不影响特写期间的摄入量，而，与 L 饮食相比，补充硬脂酸对增加 H 饮食中干物质摄入量 (DMI) 的影响更显着（分别为 21.6% 和 5.71%；显着的相互作用）。此外，与 NO 奶牛相比，SA 喂养增加了 NEL 摄入量。淀粉含量和 SA 补充对体重 (BW) 变化之间存在相互作用，因为喂食 SA 日粮的奶牛在 H 日粮中增加了更大的 BW，但在近距离期间在 L 日粮中没有观察到这种反应。在产后阶段，观察到淀粉和 SA 之间对 DMI 的交互作用，表明 SA 增加了产后 DMI 和 DMI 作为 L 日粮中 BW 的百分比，而奶牛接受 NO 在 H 日粮中具有更多的 DMI。与接受 H 饮食的动物相比，喂养 L 饮食的动物具有较少的负 EB，以及较低的 BW 和 BCS 损失。与喂食 H 日粮的奶牛相比，喂食 L 日粮的奶牛的乳脂增加。观察到淀粉和 SA 处理之间的相互作用对于胰岛素（HNO 和 LSA 的浓度最高）和天冬氨酸转氨酶（AST）活性（L 组的活性最高）在-7 天到产犊。此外，在产后期间，葡萄糖、胰岛素、非酯化脂肪酸 (NEFA) 和 AST 活性的治疗之间存在显着的相互作用。分配到 HNO 和 LSA 组的奶牛具有较高的血清葡萄糖和胰岛素，较低的 NEFA 浓度，而 HSA 处理的 AST 活性最低。本研究的结果表明，在低淀粉特写日粮 (200 g/kg DM) 中饲喂 20 g/kg DM 富含硬脂酸的脂肪补充剂，可改善产前摄入量，并对产后性能和代谢产生积极影响与高淀粉饮食（250 g/kg DM）相比的状态。