本试验旨在研究饲喂不同钙、磷水平饲粮对泌乳期伊犁马乳成分、乳脂脂肪酸组成及马驹生长发育、血浆生理生化指标的影响，为进一步探讨伊犁马钙、磷营养提供参考。选取年龄、体重和胎次接近的处于第2泌乳月末的伊犁马25匹，根据母马体重和马驹体重随机分为5组，每组5匹。5组马匹饲粮钙、磷水平分别设为45．0、30．0 g／d（Ⅰ组），48．5、32．0 g／d（Ⅱ组）， 52．0、34．0 g／d（Ⅲ组），55．5、36．0 g／d（Ⅳ组），59．0、38．0 g／d（Ⅴ组）。试验为期90 d，每30 d为1个试验周期。结果显示：饲粮钙、磷水平显著影响每次平均挤奶量及估计日产奶量（ P＜0．05），对乳中乳脂率、乳蛋白率、乳糖率和乳总固形物含量无显著影响（ P＞0．05）。Ⅲ组每次平均挤奶量分别比Ⅰ和Ⅳ组提高了20．65％（P＜0．05）和15．22％（P＜0．05），而Ⅲ组乳中钙含量比Ⅰ组低21．54％（ P＜0．05）。不同钙、磷水平饲粮对乳脂中肉豆蔻脑酸（ C14∶1）、棕榈油酸（ C16∶1）、亚油酸（ C18∶2n6c）、花生酸（ C20∶0）、顺－11－二十碳烯酸（ C20∶1）和α－亚麻酸（ C18∶3n3）的含量均有显著影响（ P＜0．05）；随着饲粮钙、磷水平的增加，乳脂中饱和脂肪酸含量增加而不饱和脂肪酸含量下降。母马饲喂不同钙、磷水平饲粮对马驹体重、体长、体高和管围等生长发育指标以及血浆钙、磷、甲状旁腺素、骨钙素含量均无显著影响（P＞0．05），而胸围则随着饲粮钙、磷水平的增加有不同程度的下降。Ⅰ组马驹血浆降钙素含量显著高于Ⅱ、Ⅲ和Ⅳ组（P＜0．05），分别增加34．24％、24．89％和23．64％。由此得出，增加饲粮钙、磷水平可提高伊犁马的产奶量，但使乳中钙含量降低；饲粮钙、磷水平不影响乳成分，但增加乳脂中饱和脂肪酸的含量，减少不饱和脂肪酸的含量；由于乳中钙含量降低，导致马驹血浆降钙素含量下降、胸围发育较慢。%The objective of this study was to evaluate the effects of feeding different levels of calcium ( Ca) and phosphorus ( P) diets to Yili mares during lactation period on milk composition and fatty acid composition of milk fat, and growth development and plasma physiological⁃biochemical indices of foals, in order to provide references for further understand nutrition of Ca and P for Yili mares. Twenty⁃five Yili mares in their end of sec⁃ond lactation month with similar age, body weight ( BW ) and parity were selected, and divided into five groups randomly according to the BW of mares and foals, each group with 5 mares. Dietary Ca and P levels of the five groups were 45. 0 and 30. 0 g/d ( group Ⅰ) , 48. 5 and 32. 0 g/d ( group Ⅱ) , 52. 0 and 34. 0 g/d ( groupⅢ) , 55.5 and 36.0 g/d ( groupⅣ) , 59.0 and 38.0 g/d ( groupⅤ) , respectively. The trial lasted for 90 days, and every 30 days for a test cycle. The results showed as follows:dietary Ca and P levels significant⁃ly affected the average milking volume each time and estimated daily milk yield ( P<0.05) , but there were no significant differences among groups for milk fat percentage, milk protein percentage, lactose percentage and milk total solid content (P>0.05). Compared with groups Ⅰ and Ⅳ, average milking volume each time of group Ⅲ was significantly increased by 20.65% (P<0.05) and 15.22% (P<0.05). Subsequently, milk Ca content of group Ⅲwas 21.54% lower than that of groupⅠ( P<0.05) . Meanwhile, the contents of some fat⁃ty acids, such as myristoleic acid ( C14∶1 ) , palmitoleate ( C16∶1 ) , linoleate ( C18∶2n6c ) , arachidate ( C20∶0) , cis⁃11⁃eicosenoate ( C20∶1) and linolenate ( C18∶3n3) in milk fat, were significantly affected by different levels of dietary Ca and P ( P<0.05) . Along with the increase of dietary Ca and P levels, the content of saturated fatty acid ( SFA) in milk fat was increased while the content of unsaturated fatty acid ( USFA) was decreased. Growth development indices ( BW, body length, body height and circumference of cannon) and the contents of plasma Ca, P, parathyroid hormone ( PTH) and bone Gla protein ( BGP) of foals showed no sig⁃nificant differences when mares were fed different levels of dietary Ca and P diets ( P>0.05) . With the increase of dietary Ca and P levels, chest girth of foals declined by a certain extent. Moreover, plasma calcitonin con⁃tent of foals in the group Ⅰ was significantly higher than that of groupsⅡ,Ⅲ andⅣ with an increase of 34. 24%, 24.89% and 23.64% ( P<0.05) , respectively. In conclusion, increasing dietary Ca and P levels can im⁃prove the milk yield of Yili mares, but reduce the milk Ca content. Dietary Ca and P levels do not affect the milk composition, but increase saturated fatty acids and reduce unsaturated fatty acids contents in milk fat. Lower milk Ca content may decrease plasma calcitonin content of foals, and hence slow the chest girth devel⁃opment of foals.
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