Factors affecting the quantity and quality of porcine muscle and fat
Abstract
Continued selection pressures have been most successful at creating genetic populations of swine that contain higher percentages of carcass lean. Unfortunately, such genetic populations also tend to produce carcasses of lesser quality. Carcass leanness may be further enhanced by the presence of the halothane (HAL) gene, which is also associated with lower pork quality. The impact of myosin heavy chain isoforms on pork composition and quality traits of HAL-negative (NN) and HAL-carrier (Nn) gilts was investigated. Phenotypic correlations between fiber type composition and carcass composition or pork quality traits tend to be higher when the HAL gene is present. Regression analyses demonstrated that fiber type composition accounted for 53% vs. 18% of the variation in drip loss and 97 vs. 9% of the variation in 24-h pH for Nn and NN gilts, respectively. Overall, fiber type composition accounted for a larger proportion of variation in the quality traits of Nn compared to NN gilts. In another study, the effects of conjugated linoleic acid (CLA) on the composition and quality of lean pigs were investigated. CLA did not affect 24-h pH, drip loss, or subjective quality evaluations of the longissimus. Gilts fed CLA tended to have less backfat. Bellies of CLA-fed gilts contained greater (P < .001) levels of saturated fatty acids and were subjectively evaluated to be firmer (P < .01) than controls. The effect of CLA to improve belly firmness may provide a nutritional solution to fat quality problems, thereby enhancing the overall value of extremely lean carcasses. Continued selection against backfat thickness has also resulted in pigs that contain less intramuscular fat (IMF). The potential to select for increased IMF is dampened by difficulties in accurately measuring this trait in the live animal. Multivariate regression equations were developed using data on total and individual backfat layer thickness, thickness ratios, slaughter weight, and loin eye area for the prediction of percent IMF of the longissimus for both live animals (R 2 = .41, RMSE =.82%) and carcasses (R2 =.60, RMSE =.68%). In conclusion, information on individual backfat layer depths contributed to the accurate prediction of longissimus IMF.
Degree
Ph.D.
Advisors
Schinckel, Purdue University.
Subject Area
Livestock|Food science
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