Body Weight and Backfat Deposition in Swine: Curves and Correction Factors

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Abstract
Data from 387 Duroc and 390 Yorkshire pigs were used to evaluate body weight and backfat deposition curves. Weights and backfat measurements were taken at 119, 126, 133, 140, 147 and 154 days of age. Least squares procedures were used to fit second degree polynomial equations of weight on age, backfat on age and backfat on weight. Analyses were completed for breeds, sexes, breed-sex groups and the pooled data. Significant quadratic effects of age on body weight and backfat were found. Regression of backfat on weight was linear. Body weight and backfat curves were significantly different among breed, sex and breed-sex groups. Correction factors to adjust weight to 140 days of age were obtained. In all cases, factors developed from breed or sex data were more efficient than those developed from pooled data. However, the increase in accuracy was not sufficient to justify separate correction factors for breed-sex subgroups. Correction factors to adjust backfat to 140 days of age and 72.7 kg were obtained, also. The correction factor derived from the pooled data was sufficiently precise to warrant its use across breeds and sexes. The procedure developed by Lush and Kincaid (1943) was effective in developing correction factors for weight and backfat. Copyright © 1971. American Society of Animal Science. Copyright 1971 by American Society of Animal Science.

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