1:30 pm - 2:30 pm
410C Agriculture/Forestry Centre, Agriculture/Forestry Centre, Edmonton
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Prince Opoku. This seminar is open to the general public to attend.
Thesis Topic: Relationships among loin sub-primal, meat quality and intramuscular collagen characteristics of carcasses from crossbred swine populations
MSc with Dr. Heather Bruce.
Sub-primal and meat quality attributes are key determinants of the final economic value of animals produced. Genetic progress in these traits requires them to be measurable and of adequate heritability to enable selective breeding. Therefore, genetic parameter estimation is needed to explore the additive genetic variability in swine populations for these traits and their genetic relationships with other traits so that strategies for selective breeding to improve these traits can be developed. Collagen characteristics in pork have been reported to influence pork toughness and texture variability, however, limited knowledge is currently available regarding their heritability and genetic relationships with other pork quality traits. In the current study, phenotypic data and pedigree information of 500 crossbred pigs from Duroc sires and hybrid Large White ✕ Landrace sows were used to estimate phenotypic and genetic parameters. Fixed effects (slaughter batch, sex and animal origin) and a random additive genetic effect were fitted in bivariate animal models to estimate phenotypic and genetic parameters in ASReml software. Moderate heritabilities were obtained for loin sub-primal traits ranging from 0.21±0.10 for bone weight to 0.44±0.11 for loin eye weight. However, low estimates of 0.09±0.08, 0.19±0.08, 0.13±0.09 were obtained for bone percent, loin weight and fat trim weight, respectively. Meat quality traits were low to moderately heritable with the highest estimate being that of intramuscular fat (0.42±0.13). Heritability estimates for percentages of heat soluble and insoluble collagen were 0.12±0.09 and 0.15±0.09, respectively, while 0.33±0.12 was the estimate for total collagen, suggesting a reasonable potential for improving these traits through selective breeding. Muscle lightness (L*) was highly positively (0.68±0.30) correlated with soluble collagen and highly negatively (-0.71±0.35) correlated with insoluble collagen. Warner-Bratzler shear force had moderate genetic correlations with insoluble collagen (0.42±0.16) and soluble collagen (-0.38±0.10). These correlations suggest similarity in the genetic background of the traits; hence such relationships should be considered when designing breeding programs for traits to ensure desired improvements in both correlated traits.
Additionally, investigations into the contributions of animal origin, sex and sub-primal and collagen characteristics to pork carcass and meat quality indicated that there was no significant effect (p>0.05) of sex on sub-primal and meat quality traits, although animal origin influenced (p<0.01) sub-primal, pH, drip loss (%), cooking loss (%) and collagen characteristics. Multiple regression analysis revealed intramuscular collagen characteristics could predict variations in cooking loss, but showed pH not to be a reliable sole predictor of meat quality. Cooked pork tenderness appeared to be driven by denaturation of myofibrillar protein native structure rather than by intramuscular fat content. The results from this study indicated that collagen characteristics are heritable and selection against insoluble collagen and for soluble collagen has the potential to decrease toughness as measured by Warner-Bratzler shear force.