Faculty of Chemistry, Biotechnology and Food Science (KBM), Norwegian University of Life Sciences (NMBU), 1430 Ås, Nroway.
Faculty of Chemistry, Biotechnology and Food Science (KBM), Norwegian University of Life Sciences (NMBU), 1430 Ås, Nroway.
J Dairy Sci. 2017 Sep;100(9):7088-7105. doi: 10.3168/jds.2016-12383. Epub 2017 Jul 12.
Impaired quality due to a high content of free fatty acids (FFA) and off-flavors has caused challenges in the development of Norwegian goat milk products. The present study aimed to examine the effect of lipid-supplemented concentrates on milk fat content, fatty acid composition, FFA, lipoprotein lipase activity, sensory properties, and size of milk fat globules of goat milk. Thirty goats assigned to 3 experimental groups were fed different concentrates from 60 d in milk (DIM) until late lactation (230 DIM). The diets were (1) control concentrate (no added fat); (2) control concentrate with 8% (added on air-dry basis) hydrogenated palm oil enriched with palmitic acid (POFA); and (3) control concentrate with 8% (added on air-dry basis) rapeseed oil (RSO). The POFA group produced milk with the highest fat content, and fat content was positively correlated with the mean size of milk fat globules. Goats in the RSO group had a higher content of long-chain and unsaturated fatty acids, whereas milk from goats in the POFA group had a higher content of palmitic and palmitoleic acids (C16:0 and C16:1 cis). The control group produced milk with a higher content of short-, medium-, odd-, and branched-chain fatty acids compared with the 2 other groups. The content of FFA in milk was low in early and late lactation and peaked in mid lactation (90 DIM). A high content of FFA was correlated with poor sensory properties (tart/rancid flavor). The RSO group produced milk with lower content of FFA and off-flavors in mid lactation and a higher proportion of unsaturated fatty acids. Therefore, replacement of palm oil with rapeseed oil as a lipid source in dairy goat feed would be favorable.
由于游离脂肪酸（FFA）含量高和异味，导致挪威山羊奶产品的开发面临挑战。本研究旨在研究添加脂肪的浓缩物对羊奶脂肪含量、脂肪酸组成、FFA、脂蛋白脂肪酶活性、感官特性和乳脂肪球大小的影响。30 只山羊从泌乳 60 天（DIM）开始分配到 3 个实验组，直至泌乳后期（230 DIM），分别饲喂不同的浓缩饲料。日粮分别为：（1）对照浓缩料（未添加脂肪）；（2）对照浓缩料添加 8%（以风干基础计）富含棕榈酸的氢化棕榈油（POFA）；（3）对照浓缩料添加 8%（以风干基础计）菜籽油（RSO）。POFA 组产奶的脂肪含量最高，脂肪含量与乳脂肪球的平均大小呈正相关。RSO 组的长链和不饱和脂肪酸含量较高，而 POFA 组的乳中棕榈酸和棕榈油酸（C16:0 和 C16:1 cis）含量较高。与其他两组相比，对照组在泌乳早期和晚期的短链、中链、奇数和支链脂肪酸含量较高。FFA 在泌乳早期和晚期含量较低，在泌乳中期（90 DIM）含量最高。FFA 含量高与感官特性差（酸涩味）有关。在泌乳中期，RSO 组产奶的 FFA 和异味含量较低，不饱和脂肪酸比例较高。因此，用菜籽油替代棕榈油作为奶山羊饲料中的脂肪源是有利的。
