Centre for Dairy Research, Sustainable Agriculture and Food Systems Division, School of Agriculture, Policy and Development, University of Reading, Reading, United Kingdom, RG6 6AR; Institute for Food, Nutrition and Health, University of Reading, Reading, United Kingdom, RG6 6AR.
Centre for Dairy Research, Sustainable Agriculture and Food Systems Division, School of Agriculture, Policy and Development, University of Reading, Reading, United Kingdom, RG6 6AR.
J Dairy Sci. 2019 Jan;102(1):288-300. doi: 10.3168/jds.2018-15247. Epub 2018 Nov 15.
Isoenergetic replacement of dietary saturated fatty acids (SFA) with cis-monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) can reduce cardiovascular disease risk. Supplementing dairy cow diets with plant oils lowers milk fat SFA concentrations. However, this feeding strategy can also increase milk fat trans fatty acids (FA) and negatively affect rumen fermentation. Protection of oil supplements from the rumen environment is therefore needed. In the present study a whey protein gel (WPG) of rapeseed oil (RO) was produced for feeding to dairy cows, in 2 experiments. In experiment 1, four multiparous Holstein-Friesian cows in mid-lactation were used in a change-over experiment, with 8-d treatment periods separated by a 5-d washout period. Total mixed ration diets containing 420 g of RO or WPG providing 420 g of RO were fed and the effects on milk production, composition, and FA concentration were measured. Experiment 2 involved 4 multiparous mid-lactation Holstein-Friesian cows in a 4 × 4 Latin square design experiment, with 28-d periods, to investigate the effect of incremental dietary inclusion (0, 271, 617, and 814 g/d supplemental oil) of WPG on milk production, composition, and FA concentration in the last week of each period. Whey protein gel had minimal effects on milk FA profile in experiment 1, but trans-18:1 and total trans-MUFA were higher after 8 d of supplementation with RO than with WPG. Incremental diet inclusion of WPG in experiment 2 resulted in linear increases in milk yield, cis- and trans-MUFA and PUFA, and linear decreases in SFA (from 73 to 58 g/100 g of FA) and milk fat concentration. The WPG supplement was effective at decreasing milk SFA concentration by replacement with MUFA and PUFA in experiment 2, but the increase in trans FA suggested that protection was incomplete.
用顺式单不饱和脂肪酸（MUFA）和多不饱和脂肪酸（PUFA）替代膳食饱和脂肪酸（SFA）可降低心血管疾病风险。在奶牛日粮中添加植物油可降低乳脂 SFA 浓度。然而，这种饲养策略也会增加乳脂反式脂肪酸（FA）并对瘤胃发酵产生负面影响。因此，需要保护油补充剂免受瘤胃环境的影响。在本研究中，通过 2 项实验，用乳清蛋白凝胶（WPG）包被菜籽油（RO），用于奶牛饲养。在实验 1 中，使用 4 头处于泌乳中期的荷斯坦奶牛进行交叉试验，每个处理期 8d，每个处理期之间用 5d 的清洗期隔开。在含有 420g RO 或 WPG 的全混合日粮中添加 420g RO 或 WPG，并测量对产奶量、组成和 FA 浓度的影响。实验 2 涉及 4 头处于泌乳中期的荷斯坦奶牛，采用 4×4 拉丁方设计实验，每个周期 28d，以研究 WPG 补充剂的日粮添加量（0、271、617 和 814g/d）对最后一周产奶量、组成和 FA 浓度的影响。在实验 1 中，乳清蛋白凝胶对乳脂 FA 谱的影响很小，但 RO 组在补充 8d 后反式-18:1 和总反式 MUFA 高于 WPG 组。在实验 2 中，随着 WPG 日粮添加量的增加，产奶量、顺式和反式 MUFA 和 PUFA 线性增加，SFA（从 73g/100g FA 降至 58g/100g FA）和乳脂浓度线性降低。在实验 2 中，WPG 补充剂通过用 MUFA 和 PUFA 替代 SFA 有效降低了乳脂 SFA 浓度，但反式 FA 的增加表明保护不完全。
