Cymbaluk N F, Christison G I, Leach D H
Dept. of Herd Med. and Theriogenol, University of Saskatchewan, Saskatoon, Canada.
J Anim Sci. 1989 Feb;67(2):414-25. doi: 10.2527/jas1989.672414x.
Eighteen Quarter Horse and Paint weanling colts were assigned to two treatments, either limit or ad libitum feeding. Nutrient digestibilities of diets were evaluated between 6 and 12 mo, 12 and 18 mo and 18 and 24 mo of age. From 6 to 12 mo, energy digestibility (64 to 68%) was unaffected by feed intake level. Ad libitum-fed horses had energy digestibilities 9 to 10% greater (P less than .05) than limit-fed horses between 12 and 24 mo of age, but adjustment for DM intake removed these differences. Limit-fed, mature ponies used dietary energy similarly to growing horses from 6 to 18 mo of age, but they used digested dietary energy more efficiently (P less than .05) than young horses at 24 mo of age. Ad libitum-fed horses digested more (P less than .05) dietary protein than limit-fed horses between 12 and 24 mo of age, but adjustment for DM intake removed these differences. True digestibilities of dietary Ca were estimated at 71 to 42% among periods, whereas true digestibilities of dietary P ranged from 52 to 6%. Sufficient P was absorbed by all horses between 6 and 18 of age, but by 24 mo of age horses were in negative P balance despite an apparently adequate P intake. Using regression analyses, daily endogenous fecal Ca and P were predicted to be 36 and 18 mg/kg body weight, respectively.
18匹夸特马和佩尔什马断奶小公马被分为两组进行处理，即限量饲喂或自由采食。在6至12月龄、12至18月龄以及18至24月龄期间评估日粮的养分消化率。6至12月龄时，能量消化率（64%至68%）不受采食量水平的影响。12至24月龄时，自由采食的马匹能量消化率比限量饲喂的马匹高9%至10%（P<0.05），但对干物质摄入量进行调整后消除了这些差异。6至18月龄时，限量饲喂的成年矮种马利用日粮能量的方式与生长马相似，但在24月龄时，它们比年轻马更有效地利用了消化后的日粮能量（P<0.05）。12至24月龄时，自由采食的马匹比限量饲喂的马匹消化更多的日粮蛋白质（P<0.05），但对干物质摄入量进行调整后消除了这些差异。日粮钙的真消化率在各阶段估计为71%至42%，而日粮磷的真消化率范围为52%至6%。6至18月龄的所有马匹都吸收了足够的磷，但到24月龄时，尽管磷摄入量明显充足，马匹仍处于负磷平衡状态。通过回归分析预测，每日内源性粪便钙和磷分别为36毫克/千克体重和18毫克/千克体重。
