Kesel G A, Knight J W, Kornegay E T, Veit H P, Notter D R
J Anim Sci. 1983 Jul;57(1):82-98. doi: 10.2527/jas1983.57182x.
Eighty crossbred boars were utilized in a 2 X 2 factorial arrangement of two energy levels (ad libitum and 75% ad libitum) and two Ca/P levels (100 and 150% of National Research Council daily requirement) to determine the effect of varying growth rate and Ca/P intake on performance and bone characteristics throughout the growth phase. Boars were fed the diets beginning postweaning at 5 wk of age and continuing until necropsy at 10 +/- 2-d intervals between 80 and 220 d of age, inclusive. Body weight of limit-fed boars was 72% that of ad libitum-fed boars. Daily gain and feed per gain ratio favored boars fed the 150% Ca/P levels. Although limit-feeding enhanced the development of longer, thicker and heavier metacarpals earlier in the growth period (between 80 and 150 d of age), there was little difference between limit-fed and ad libitum-fed boars at 220 d of age when values were corrected for differences in body weight. Mechanical bone characteristics, which were greater for ad libitum-fed than for limit-fed boars at the same age, were not different when values were corrected for body weight. Boars fed 150% Ca/P levels had heavier and thicker walled metacarpals that had greater bone strength than boars fed 100% Ca/P levels, with the magnitude of the difference not as great at 220 d of age and when values were corrected for body weight. Generally, boars fed the ad libitum-150% Ca/P diet had the heaviest and strongest bones. Ether extract, ash and Ca and P content of ash were generally higher for ad libitum-fed vs limit-fed and 150 vs 100% Ca/P diets at 80 and 150 d of age, but were not different at 220 d. Metacarpal weight, size, thickness, strength and ash content increased with age with a small decline in the rate of increase. Ether extract decreased with age. There was a very small increase in the Ca content of ash and a very small decrease in the P content with age, resulting in a slightly wider Ca:P ratio in older boars.
80头杂交公猪被用于一项二因素试验，该试验采用两种能量水平（自由采食和75%自由采食）以及两种钙/磷水平（分别为美国国家研究委员会每日需求量的100%和150%）的2×2析因设计，以确定在整个生长阶段不同生长速率和钙/磷摄入量对性能和骨骼特征的影响。公猪在5周龄断奶后开始饲喂这些日粮，并持续至80至220日龄（含）之间以10±2天的间隔进行剖检。限饲公猪的体重为自由采食公猪体重的72%。日增重和料重比有利于饲喂150%钙/磷水平日粮的公猪。虽然限饲在生长早期（80至150日龄之间）促进了更长、更厚且更重的掌骨的发育，但在220日龄时，对限饲和自由采食公猪的体重差异进行校正后，两者差异不大。在相同年龄时，自由采食公猪的机械骨骼特性比限饲公猪的更强，但对体重差异进行校正后，两者并无差异。饲喂150%钙/磷水平日粮的公猪的掌骨更重、壁厚更厚，其骨骼强度也高于饲喂100%钙/磷水平日粮的公猪，不过在220日龄时以及对体重差异进行校正后，差异幅度没有那么大。总体而言，饲喂自由采食-150%钙/磷日粮的公猪的骨骼最重且最强壮。在80和150日龄时，自由采食组与限饲组相比，以及150%钙/磷日粮组与100%钙/磷日粮组相比，日粮的乙醚提取物、灰分以及灰分中的钙和磷含量通常更高，但在220日龄时并无差异。掌骨的重量、尺寸、厚度、强度和灰分含量随年龄增加，增加速率略有下降。乙醚提取物随年龄减少。随着年龄增长，灰分中的钙含量略有增加，磷含量略有减少，导致老年公猪的钙磷比略宽。
