Department of Animal Science, Michigan State University, East Lansing 48824.
Department of Animal Science, Michigan State University, East Lansing 48824.
J Dairy Sci. 2018 Jan;101(1):172-185. doi: 10.3168/jds.2017-13460. Epub 2017 Nov 8.
The objective of this study was to evaluate the effects of varying the ratio of dietary palmitic (C16:0), stearic (C18:0), and oleic (cis-9 C18:1) acids in basal diets containing soyhulls or whole cottonseed on nutrient digestibility, energy partitioning, and production response of lactating dairy cows. Twenty-four mid-lactation multiparous Holstein cows were used in a split-plot Latin square design. Cows were allocated to a main plot receiving either a basal diet with soyhulls (SH, n = 12) or a basal diet with whole cottonseed (CS, n = 12) that was fed throughout the experiment. Within each plot a 4 × 4 Latin square arrangement of treatments was used in 4 consecutive 21-d periods. Treatments were (1) control (CON; no supplemental fat), (2) high C16:0 supplement [PA; fatty acid (FA) supplement blend provided ∼80% C16:0], (3) C16:0 and C18:0 supplement (PA+SA; FA supplement blend provided ∼40% C16:0 + ∼40% C18:0), and (4) C16:0 and cis-9 C18:1 supplement (PA+OA; FA supplement blend provided ∼45% C16:0 + ∼35% cis-9 C18:1). Interactions between basal diets and FA treatments were observed for dry matter intake (DMI) and milk yield. Among the SH diets, PA and PA+SA increased DMI compared with CON and PA+OA treatments, whereas in the CS diets PA+OA decreased DMI compared with CON. The PA, PA+SA, and PA+OA treatments increased milk yield compared with CON in the SH diets. The CS diets increased milk fat yield compared with the SH diets due to the greater yield of de novo and preformed milk FA. The PA treatment increased milk fat yield compared with CON, PA+SA, and PA+OA due to the greater yield of mixed-source (16-carbon) milk FA. The PA treatment increased 3.5% fat-corrected milk compared with CON and tended to increase it compared with PA+SA and PA+OA. The CS diets increased body weight (BW) change compared with the SH diets. Additionally, PA+OA tended to increase BW change compared with CON and PA and increased it in comparison with PA+SA. The PA and PA+OA treatments increased dry matter and neutral detergent fiber digestibility compared with PA+SA and tended to increase them compared with CON. The PA+SA treatment reduced 16-carbon, 18-carbon, and total FA digestibility compared with the other treatments. The CS diets increased energy partitioning toward body reserves compared with the SH diets. The PA treatment increased energy partitioning toward milk compared with CON and PA+OA and tended to increase it compared with PA+SA. In contrast, PA+OA increased energy partitioned to body reserves compared with PA and PA+SA and tended to increase it compared with CON. In conclusion, milk yield responses to different combinations of FA were affected by the addition of whole cottonseed in the diet. Among the combinations of C16:0, C18:0, and cis-9 C18:1 evaluated, fat supplements with more C16:0 increased energy output in milk, whereas fat supplements with more cis-9 C18:1 increased energy storage in BW. The combination of C16:0 and C18:0 reduced nutrient digestibility, which most likely explains the lower performance observed compared with other treatments.
本研究旨在评估在含有大豆皮或全棉籽的基础日粮中，不同比例的饮食棕榈酸（C16:0）、硬脂酸（C18:0）和油酸（顺式-9 C18:1）对泌乳奶牛的养分消化率、能量分配和生产性能的影响。将 24 头泌乳中期的荷斯坦奶牛采用裂区拉丁方设计进行分组。将奶牛分配到主区，接受含有大豆皮（SH，n=12）或全棉籽（CS，n=12）的基础日粮，这些日粮在整个实验中均被投喂。在每个区中，4 个处理的 4×4 拉丁方排列在 4 个连续的 21 天周期中进行。处理分别为（1）对照（CON；无补充脂肪）、（2）高 C16:0 补充[PA；脂肪酸（FA）补充混合物提供约 80% C16:0]、（3）C16:0 和 C18:0 补充（PA+SA；FA 补充混合物提供约 40% C16:0+约 40% C18:0）和（4）C16:0 和顺式-9 C18:1 补充（PA+OA；FA 补充混合物提供约 45% C16:0+约 35%顺式-9 C18:1）。在干物质采食量（DMI）和产奶量方面观察到基础日粮和 FA 处理之间存在相互作用。在 SH 日粮中，与 CON 和 PA+OA 处理相比，PA 和 PA+SA 增加了 DMI，而在 CS 日粮中，PA+OA 降低了 DMI。与 CON 相比，SH 日粮中的 PA、PA+SA 和 PA+OA 处理增加了产奶量。CS 日粮由于新生成和预形成乳 FA 的产量增加，增加了乳脂产量。与 CON、PA+SA 和 PA+OA 相比，PA 处理增加了乳脂产量，这是由于混合来源（16 碳）乳 FA 的产量增加。PA 处理与 CON 相比增加了 3.5%校正乳脂，与 PA+SA 和 PA+OA 相比也有增加的趋势。CS 日粮增加了体重（BW）变化，与 SH 日粮相比。此外，PA+OA 与 CON 和 PA 相比，有增加 BW 变化的趋势，与 PA+SA 相比，增加了 BW 变化。与 PA+SA 和 CON 相比，PA 和 PA+OA 处理增加了干物质和中性洗涤纤维消化率。PA+SA 处理与其他处理相比降低了 16 碳、18 碳和总 FA 消化率。CS 日粮增加了能量向体储备的分配，与 SH 日粮相比。与 CON 和 PA+OA 相比，PA 处理增加了向乳的能量分配，与 PA+SA 相比，有增加的趋势。相反，与 PA 和 PA+SA 相比，PA+OA 增加了向 BW 储备的能量分配，与 CON 相比，有增加的趋势。总之，不同 FA 组合对产奶量的反应受到日粮中全棉籽添加的影响。在所评估的 C16:0、C18:0 和顺式-9 C18:1 的组合中，含有更多 C16:0 的脂肪补充剂增加了牛奶中的能量输出，而含有更多顺式-9 C18:1 的脂肪补充剂增加了 BW 的能量储存。C16:0 和 C18:0 的组合降低了养分消化率，这很可能解释了与其他处理相比，性能较低的原因。
