Department of Animal Science, Federal University of Bahia, Salvador, Brazil, 0170-110.
Department of Animal Nutrition and Animal Production, University of São Paulo, Pirassununga, Brazil, 13635-900.
J Dairy Sci. 2018 Sep;101(9):7881-7891. doi: 10.3168/jds.2017-13666. Epub 2018 Jul 13.
Ruminants have a unique metabolism and digestion of unsaturated fatty acids (UFA). Unlike monogastric animals, the fatty acid (FA) profile ingested by ruminants is not the same as that reaching the small intestine. The objective of this study was to evaluate whole raw soybeans (WS) in diets as a replacer for calcium salts of fatty acids (CSFA) in terms of UFA profile in the abomasal digesta of early- to mid-lactation cows. Eight Holstein cows (80 ± 20 d in milk, 22.9 ± 0.69 kg/d of milk yield, and 580 ± 20 kg of body weight; mean ± standard deviation) with ruminal and abomasal cannulas were used in a 4 × 4 Latin square experiment with 22-d periods. The experiment evaluated different fat sources rich in linoleic acid on ruminal kinetics, ruminal fermentation, FA abomasal flow, and milk FA profile of cows assigned to treatment sequences containing a control (CON), with no fat source; soybean oil, added at 2.68% of diet dry matter (DM); WS, addition of WS at 14.3% of diet DM; and CSFA, addition of CSFA at 2.68% of diet DM. Dietary fat supplementation had no effect on nutrient intake and digestibility, with the exception of ether extract. Cows fed fat sources tended to have lower milk fat concentration than those fed CON. In general, diets containing fat sources tended to decrease ruminal neutral detergent fiber digestibility in relation to CON. Cows fed WS had lower ruminal digestibility of DM and higher abomasal flow of DM in comparison to cows fed CSFA. As expected, diets containing fat supplements increased FA abomasal flow of C18:0 and total FA. Cows fed WS tended to present a higher concentration of UFA in milk when compared with those fed CSFA. This study suggests that under some circumstances, abomasal flow of UFA in early lactation cows can be increased by supplementing their diet with fat supplements rich in linoleic acid, regardless of rumen protection, with small effects on ruminal DM digestibility.
反刍动物具有独特的不饱和脂肪酸（UFA）代谢和消化方式。与单胃动物不同，反刍动物摄入的脂肪酸（FA）谱与到达小肠的 FA 谱并不相同。本研究旨在评估生大豆（WS）在日粮中作为钙盐脂肪酸（CSFA）的替代品，从 UFA 谱的角度评估其对泌乳早期至中期奶牛皱胃消化物的影响。8 头荷斯坦奶牛（泌乳 80±20d，产奶量 22.9±0.69kg/d，体重 580±20kg；平均值±标准差）具有瘤胃和真胃套管，采用 4×4 拉丁方试验，22d 期。试验评估了富含亚油酸的不同脂肪源对瘤胃动力学、瘤胃发酵、FA 真胃流量和奶牛乳 FA 谱的影响，这些奶牛被分配到含有对照（CON）的处理序列中，CON 组日粮不含脂肪源；添加 2.68%日粮干物质（DM）的大豆油；添加 14.3%日粮 DM 的 WS；添加 2.68%日粮 DM 的 CSFA。日粮脂肪补充对养分摄入量和消化率没有影响，但乙醚提取物除外。与 CON 相比，饲喂脂肪源的奶牛乳脂浓度降低。一般来说，与 CON 相比，添加脂肪源的日粮降低了瘤胃中性洗涤纤维的消化率。与 CSFA 相比，饲喂 WS 的奶牛瘤胃 DM 消化率较低，DM 真胃流量较高。如预期的那样，添加脂肪补充剂增加了 FA 十八碳烯酸和总 FA 的真胃流量。与 CSFA 相比，饲喂 WS 的奶牛乳中 UFA 浓度较高。本研究表明，在某些情况下，通过在日粮中添加富含亚油酸的脂肪补充剂来增加泌乳早期奶牛的 UFA 真胃流量，而无需瘤胃保护，对瘤胃 DM 消化率的影响较小。
