Effect of Various Levels of Dietary Calcium and Phosphorus on Performance, Blood and Bone Parameters in Growing Boars

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Abstract
Ninety-six 8-kg crossbred boars were initially allotted to three dietary levels of calcium (Ca) and phosphorus (P) — (A) .65% Ca; .50% P; (B) .975% Ca; .75% P and (C) 1.3% Ca; 1.0% P — to determine the effects of the different levels on average daily gain (ADG), average daily feed intake (ADFI), feed to gain (F:G) and certain blood and bone parameters. During the initial 8-week growth period, no differences in ADG (.55, .58, .55), ADFI (1.17, 1.23, 1.16)orF:G (2.08, 2.16, 2.10) were observed for treatments A, B and C, respectively. At the beginning of the 8-week final growth period (41.5 kg), 50% of the boars fed each of the primary dietary treatments (A, B and C) were assigned to the other two treatments, while the other 50% remained on their original assigned treatments. No differences in performance were observed for the total 16-week growth period when evaulated as nine treatments. Fresh femurs and third and fourth metatarsals were evaluated for physical measurements, bone strength and percentage ash. Peak force required to break the bones of the pigs on the final period treatments increased linearly (P<.025) as the dietary level of Ca and P increased. Final period stress and stress:strain parameters of the bones responded similarly to peak force (linear component, P<.01). Also, percentage ash increased (linearly, P<.05) as dietary Ca and P levels increased. No treatment differences in subjective soundness scores were observed for any of the dietary treatments. Serum Ca levels decreased linearly at the end of the initial period, but the response was quadratic at the end of the final period. Alkaline phosphatase decreased linearly (P<.05) across treatments, with the largest decrease occurring with treatment A during the final period. The feeding of dietary Ca and P at up to twice the levels suggested by NRC (1973) for growing swine did not adversely affect performance of boars fed .65% Ca and .50% P than with those fed higher levels. Copyright © 1980. American Society of Animal Science . Copyright 1980 by American Society of Animal Science.