Department of Nutritional Physiology and Feeding, Agricultural University of Athens, Iera Odos 75, GR-11855 Athens, Greece.
J Dairy Res. 2012 May;79(2):192-200. doi: 10.1017/S0022029912000039. Epub 2012 Feb 17.
Since sheep's milk is mainly used for cheese making and milk chemical composition and fatty acids (FA) profile affect cheese yield and quality, the objective of this study was to determine the effects of different feeding levels on milk chemical composition and FA profile, as well as on plasma FA profile, and on insulin and leptin concentrations. Twenty-four sheep were assigned to three homogeneous sub-groups. Throughout the experimental period each group was fed the same diet but in quantities which met 70% (under-feeding), 100% (control) and 130% (over-feeding) of their respective energy and crude protein requirements. The results showed that the underfed sheep had higher milk fat content compared with overfed. In blood plasma the concentrations of C18:0 and C18:1 in the underfed sheep were significantly higher compared with control and overfed sheep. The concentrations of leptin and insulin were significantly higher in overfed compared with underfed sheep. Underfeeding reduced the concentrations of short chain FA (SCFA) and medium chain FA (MCFA) and increased that of C18:0 and mono unsaturated FA (MUFA) in sheep milk fat compared with controls and overfed. The concentrations of C18:0, long chain FA (LCFA) and monounsaturated FA (MUFA) in milk were significantly higher and those of SCFA, MCFA and saturated FA (SFA) significantly lower in the underfed compared with the overfed sheep. In conclusion, long term under- and over-feeding affected the sheep milk chemical composition and FA profile which consequently has an impact on milk products yield (cheese and yogurt) and quality (human health).
由于绵羊奶主要用于制作奶酪，而牛奶的化学成分和脂肪酸 (FA) 组成会影响奶酪的产量和质量，因此本研究的目的是确定不同饲养水平对牛奶化学成分和 FA 组成以及血浆 FA 组成、胰岛素和瘦素浓度的影响。将 24 只绵羊分为 3 个同质亚组。在整个实验期间，每个组都喂食相同的日粮，但数量分别满足其能量和粗蛋白需求的 70%（喂养不足）、100%（对照）和 130%（喂养过量）。结果表明，与喂养过量的绵羊相比，喂养不足的绵羊的牛奶脂肪含量更高。在血液血浆中，喂养不足的绵羊的 C18:0 和 C18:1 浓度明显高于对照和喂养过量的绵羊。与喂养不足的绵羊相比，喂养过量的绵羊的瘦素和胰岛素浓度明显更高。与对照和喂养过量的绵羊相比，喂养不足会降低绵羊乳脂肪中的短链 FA（SCFA）和中链 FA（MCFA）浓度，增加 C18:0 和单不饱和 FA（MUFA）浓度。与喂养过量的绵羊相比，喂养不足的绵羊乳中 C18:0、长链 FA（LCFA）和单不饱和 FA（MUFA）的浓度明显更高，而 SCFA、MCFA 和饱和 FA（SFA）的浓度明显更低。总之，长期的喂养不足和过量会影响绵羊奶的化学成分和 FA 组成，从而影响牛奶产品的产量（奶酪和酸奶）和质量（人类健康）。
