Restricted energy and elevated calcium and phosphorus intake for boars during growth. 1. Feedlot performance and bone characteristics

• Published in: Journal of animal science Vol. 57; no. 1; p. 82
• Main Authors: Kesel, G A, Knight, J W, Kornegay, E T, Veit, H P, Notter, D R
• Format: Journal Article
• Language: English
• Published: United States 01.07.1983
• Subjects: Animals; Body Weight; Bone Development; Calcium - metabolism; Calcium, Dietary - administration & dosage; Diet; Energy Intake; Male; Metacarpus - growth & development; Metacarpus - metabolism; Phosphorus - administration & dosage; Phosphorus - metabolism; Swine - physiology
• ISSN: 0021-8812; 1525-3163
• 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.