Kadegowda A K G, Piperova L S, Delmonte P, Erdman R A
Animal and Avian Sciences Department, University of Maryland, College Park 20742, USA.
J Dairy Sci. 2008 Jun;91(6):2370-9. doi: 10.3168/jds.2007-0894.
The objective of this study was to compare the effects of abomasal infusion of butterfat containing all fatty acids (FA) present in milk, including the short- and medium-chain FA, with infusion of only the long-chain FA (LCFA) present in milk, on the FA composition and milk fat yield in lactating dairy cows. Eight rumen-fistulated Holstein cows, in early lactation (49 +/- 20 days in milk) were used in a replicated 4 x 4 Latin square design. Treatments were abomasal infusion of the following: 1) no infusion (control), 2) 400 g/d of butterfat (butterfat), 3) 245 g/d of LCFA (blend of 59% cocoa butter, 36% olive oil, and 5% palm oil) providing 50% of the 16:0 and equivalent amounts of C18 FA as found in 400 g of butterfat, and 4) 100 g/d of conjugated linoleic acid (CLA, negative control), providing 10 g of trans-10, cis-12 CLA. Fat supplements were infused in equal portions 3 times daily at 0800, 1400, and 1800 h during the last 2 wk of each 3-wk experimental period. Daily dry matter intake and milk production were unaffected by the infusion treatments. Butterfat infusion increased milk fat percentage by 14% to 4.26% and milk fat yield by 21% to 1,421 g/d compared with controls (3.74% and 1,178 g/d). Milk fat percentage and fat yield were decreased by 43% by CLA. Milk protein percentage was higher (3.70%) in CLA-infused cows than in control (3.30%), butterfat (3.28%), or LCFA (3.27%) treatments. Although LCFA had no effect on fat synthesis, abomasal infusion of butterfat increased milk fat percentage and yield, suggesting that the availability of short- and medium-chain FA may be a limiting factor for milk fat synthesis.
本研究的目的是比较向皱胃内输注含有牛奶中所有脂肪酸（FA）（包括短链和中链FA）的乳脂肪，与仅输注牛奶中长链FA（LCFA），对泌乳奶牛的FA组成和乳脂肪产量的影响。选用8头处于泌乳早期（产奶49±20天）的瘤胃造瘘荷斯坦奶牛，采用重复4×4拉丁方设计。处理方式为向皱胃内输注以下物质：1）不输注（对照）；2）400克/天的乳脂肪（乳脂肪组）；3）245克/天的LCFA（59%可可脂、36%橄榄油和5%棕榈油的混合物），提供400克乳脂肪中50%的16:0以及等量的C18 FA；4）100克/天的共轭亚油酸（CLA，阴性对照），提供10克反式-10，顺式-12 CLA。在每个3周实验期的最后2周，每天于0800、1400和1800时将脂肪补充剂分等量输注3次。输注处理对每日干物质摄入量和产奶量无影响。与对照组（乳脂肪百分比3.74%，乳脂肪产量1178克/天）相比，输注乳脂肪使乳脂肪百分比提高了14%至4.26%，乳脂肪产量提高了21%至1421克/天。CLA使乳脂肪百分比和脂肪产量降低了43%。输注CLA的奶牛的乳蛋白百分比（3.70%）高于对照（3.30%）、乳脂肪组（3.28%）或LCFA组（3.27%）。尽管LCFA对脂肪合成无影响，但向皱胃内输注乳脂肪可提高乳脂肪百分比和产量，这表明短链和中链FA的可利用性可能是乳脂肪合成的限制因素。
