Bales A M, de Souza J, Lock A L
Department of Animal Science, Michigan State University, East Lansing, MI 48824.
Perdue Agribusiness, Salisbury, MD 21804.
JDS Commun. 2023 Nov 17;5(2):96-101. doi: 10.3168/jdsc.2023-0415. eCollection 2024 Mar.
We evaluated the effects of fatty acid (FA) supplements with different ratios of palmitic acid (C16:0) and oleic acid (-9 C18:1) in low- and high-FA basal diets on production responses of lactating dairy cows. Thirty-six multiparous Holstein cows (50.2 ± 5.8 kg/d of milk; 160 ± 36 d in milk) were used in a split-plot Latin square design balanced for carryover effects. Cows were blocked by milk yield and allocated to a main plot receiving either a low-FA (LF; 1.93% FA content) basal diet (n = 18) containing cottonseed meal and cottonseed hulls or a high-FA (HF; 3.15% FA content) basal diet (n = 18) containing whole cottonseed. Within each plot, a 3 × 3 Latin square arrangement of treatments was used in 3 consecutive 21-d periods. Treatments were (1) control (CON; no FA supplementation), (2) FA supplement containing 80% C16:0 + 10% C18:1 (PA), and (3) FA supplement containing 60% C16:0 + 30% -9 C18:1 (PA+OA). The FA supplements were fed at 1.5% of dry matter and replaced soyhulls in CON. Preplanned contrasts were (1) overall effect of FA supplementation {CON vs. the average of the FA treatments [1/2 (PA + PA+OA)]}, and (2) the effect of the PA treatment versus the PA+OA treatment (PA vs. PA+OA). Treatment by basal diet interactions were observed for yields of milk and lactose, where FA treatments increased yields of milk and milk lactose in LF but not in HF. Basal diet had no effect on dry matter intake (DMI) or milk yield. Compared with LF, HF increased milk fat yield and 3.5% fat-corrected milk (FCM) and tended to increase milk fat content and energy-corrected milk (ECM) yield. The FA treatments decreased DMI but increased the yields of milk fat, 3.5% FCM, and ECM, compared with CON, due to increases in mixed and preformed milk FA yields. The PA+OA treatment decreased DMI and milk protein yield compared with PA. In conclusion, a high-fat basal diet increased milk fat production, and the addition of FA supplements to a low-fat basal diet increased milk lactose yield and tended to increase milk yield. Additionally, regardless of basal diet fat level, FA supplements increased production responses compared with the non-FA-supplemented control diet.
我们评估了在低脂肪酸（FA）和高脂肪酸基础日粮中，不同棕榈酸（C16:0）与油酸（-9 C18:1）比例的脂肪酸（FA）补充剂对泌乳奶牛生产性能的影响。采用裂区拉丁方设计，选用36头经产荷斯坦奶牛（日产奶量50.2±5.8千克；泌乳天数160±36天），以平衡残留效应。奶牛按产奶量进行分组，分别分配到接受低脂肪酸（LF；FA含量1.93%）基础日粮（n = 18）的主区，该基础日粮含有棉籽粕和棉籽壳，或接受高脂肪酸（HF；FA含量3.15%）基础日粮（n = 18）的主区，该基础日粮含有全棉籽。在每个主区内，在连续3个21天的周期中采用3×3拉丁方排列处理。处理方式为：（1）对照组（CON；不补充FA），（2）含有80% C16:0 + 10% C18:1的FA补充剂（PA），以及（3）含有60% C16:0 + 30% -9 C18:1的FA补充剂（PA+OA）。FA补充剂按干物质的1.5%投喂，并替代对照组中的大豆壳。预先计划的对比为：（1）FA补充剂的总体效应{CON与FA处理组平均值[1/2（PA + PA+OA）]对比}，以及（2）PA处理组与PA+OA处理组的效应对比（PA vs. PA+OA）。观察到在牛奶和乳糖产量方面存在基础日粮与处理方式的交互作用，其中FA处理提高了LF组的牛奶和牛奶乳糖产量，但在HF组中未提高。基础日粮对干物质采食量（DMI）或牛奶产量无影响。与LF相比，HF提高了乳脂产量和3.5%乳脂校正乳（FCM）产量，并倾向于提高乳脂含量和能量校正乳（ECM）产量。与CON相比，FA处理降低了DMI，但由于混合和预制乳FA产量增加，提高了乳脂、3.5% FCM和ECM的产量。与PA相比，PA+OA处理降低了DMI和牛奶蛋白产量。总之，高脂肪基础日粮提高了乳脂产量，向低脂肪基础日粮中添加FA补充剂提高了牛奶乳糖产量，并倾向于提高牛奶产量。此外，无论基础日粮脂肪水平如何，与不添加FA的对照日粮相比，FA补充剂均提高了生产性能。
