The Australian meat goat industry is rapidly changing. This change is predominantly due to the value of goat meat increasing and production moving from rangeland harvesting to fenced commercial systems. The aim of the project was to determine how goat meat production can be increased through genetic improvement. A meta-analysis and sensitivity analysis in the literature review identified selection for kid survival could increase lean meat production by 12.3 kg per genetic standard deviation and became the main trait of interest for the project.
The national performance recording scheme (KIDPLAN) is a database that was made available by Sheep Genetics. This producer recorded data contained pedigree and phenotypic information on 19,711 Boer goats. The KIDPLAN system provides estimated breeding values for Australian goat breeders and is the best opportunity for genetic improvement of meat goats.
A new kid survival trait was created from the birth and rearing type information. The mean kid survival rate was 0.72, with a phenotypic variance of 0.14 and a heritability of 0.09. As the kid survival trait showed variation and was heritable, bivariate analyses with the growth and carcase traits was done to determine its suitability to be included in a selection index. Birth type had a significant effect on kid survival. Kid survival was positively genetically correlated or not different to zero with all of the production traits. The survival trait was separated into three traits based on birth type for singles, twins and multiples. A multivariate analysis showed they were different traits with genetic correlations of between 0.46 and 0.72. More work and accurate data is needed for them to be included in an index as separate traits and so kid survival should currently be treated as a single trait with birth type fitted as a fixed effect.
The current KIDPLAN index is based on modified sheep parameter estimates and economic values. Surveys were conducted nationally and were used to calculate economic values for the goat production traits. The results from the parameter estimates and surveys showed that goat genetic parameters are different to sheep and the current index is not representative of the industry. Three breeding objectives were created and simulated with six different recording practices. The key finding and recommendation for industry was to adopt a new index based on goat parameter estimates and economic values, also to include reproductive traits such as kid survival as it would lead to a faster rate of gain in reproductive rate than just focusing on number of kids weaned. It was estimates that this would lead to a $6.75 improvement per doe joined per year compared to the current index.Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 201
