Improving the efficiency of turkey breeding programs through selection index design, technological advancements, and management optimization
Breeding objectives in the turkey industry are heavily weighted towards improving growth traits. This thesis focused on methods to efficiently select for other important production traits such as reproduction, feed efficiency, and meat yield. Based on bivariate and random regression modeling it was determined that egg production, fertility, and hatchability were influenced by genotype by environment interactions and, as a result, the regulation of reproductive traits is by some unique genes in the summer and winter. This may be due to changes in day length and temperature. Feed efficiency is another important consideration in a breeding objective and feed conversion ratio and residual feed intake were both moderately heritable. Residual feed intake was also more independent of production traits than feed conversion. Feed intake, body weight, and weight gain were moderately heritable and progress can be made in feed efficiency by appropriately weighting these traits in an index. Infrared measures of surface temperature were then investigated to determine if they can be used to select for feed efficiency. Temperatures of the distal metatarsus, eye, neck, and head did not show a strong relationship to feed efficiency and therefore offer limited advantages to a breeding program. Selection for breast meat yield (BMY) is important and it was determined that breast muscle depth, measured with ultrasound technology, is heritable and highly correlated to the carcass trait. As a result, ultrasound traits can compliment conformation scoring and sibling testing in a breeding program to increase the accuracy of selection for BMY and increase response to selection. A deterministic model was also developed and could be used to determine optimum slaughter weight. This would optimise profits in an integrated system, enabling the industry to account for and capitalize on genetic gains. Overall, the population parameters and selection criteria identified for reproduction, efficiency, and meat yield traits identified in the present thesis could be used to increase selection efficiency in turkey breeding programs. Further, the developed production model can be used by the industry to slaughter turkeys at a time that maximizes profits, based on performance levels.