Response of Different Genetic Lines of Boards to Varying Levels of Dietary Calcium and Phosphorus

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Abstract
Two experiments were conducted to determine the effect of various levels of dietary calcium (Ca) and phosphorus (P) on performance, soundness and blood and bone parameters of different genetic lines of boars fed under variable environmental conditions. The first experiment compared different genetic lines of boars fed two levels of dietary Ca and P. Forty purebred (Large White) and Nebraska Gene Pool boars were allotted by breed and initial weight to two levels of dietary Ca and P (.65 Ca/.50% P and 1.3% Ca/1.0% P). The dietary levels of Ca and P had no significant effect on gains when compared by breed (.72 vs .74 kg) and treatment (.74 vs .72 kg). Also, none of the differences in feed intake (2.32 vs 2.31) and feed to gain ratio (3.09 vs 3.27) between Ca-P treatments was significant. No breed × bone interactions were found for bone-breaking parameters such as peak force (kilograms), stress (kilograms/square centimeters) and stress: strain (kilograms/square centimeters/millimeters). Peak force and stress required to break bones were higher (P<.005) for bones from pigs on the high Ca-P treatments than for those from pigs on the low Ca-P treatments (206.1 kg vs 167.8 kg and 54.39 kg/cm2 vs 42.88 kg/cm2, respectively). Stress rstrain responded in a similar fashion. Percentage ash was higher (P<.001) for boars fed the diet with 1.3% Ca and 1.0% P. No significant differences were observed in serum Ca and P levels between either breeds or treatments, but serum alkaline phosphatase levels were higher (P<.001) in boars on .65% Ca and .50% P when analyzed for differences in enzyme level between the termination of the trial and 2 days afterward. A second trial was conducted to evaluate performance and soundness scores of 180 Duroc boars fed various levels of dietary Ca and P and raised under commercial conditions. Treatments were: A, .65% Ca, .50% P; B, .975% Ca, .75% P, and C, 1.3% Ca, 1.0% P. No differences in average daily gains (.90, .90, .90 kg) were observed among the three treatments. There was a tendency for higher (P<.1) average daily feed intake (2.33, 2.33, 2.47) and (P<.01) feed to gain requirements (2.60, 2.58, 2.74) for pigs fed treatment C than for those fed treatments A and B. No differences in feet and leg scores were observed among boars fed different Ca-P treatments. Copyright © 1980. American Society of Animal Science . Copyright 1980 by American Society of Animal Science.

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