Goat Genetics

Genetics is the study of the genotype or genetic makeup of an animal at the chromosomal level. Population genetics deals with the behavior of genes in populations and those forces that change gene frequency (Pattie & Restall, 1991). Populations tend to evolve continuously as a reaction to environmental conditions. Populations that are isolated tend to express those genetic changes faster than those populations subject to constant gene in-flow from neighboring populations. Various breeds of goats may be a result of geographic isolation and color dominance. Only DNA testing can determine if there are genetic differences between the various groups. But for the purposes of this Breeding Program, we will assume that there are no significant differences in genetic make-up between goat populations and therefore there will be no difference in their response to genetic manipulation due to differences in “breed”.

The problem with cashmere goats is that we are not dealing with simple Mendelian genetics. There are multiple alleles with multiple loci that determine the expression of many of the genetic traits we wish to control. Color, for example, may be controlled by four alleles alone. What we will be dealing with is called quantitative genetics. According to Pattie and Restall (1991), quantitative genetics is “the operational science of animal breeding; many genes, each with small effects, control traits that are completely inherited.” Their work, which spanned over 20 years from the late 70s to the late 90s, studied six thousand Australian feral and selected cashmere-bearing goats. Studies of this magnitude have not been undertaken anywhere else in the world. As a result of this research, Pattie and Restall have established specific heritabilities and correlations between the six basic cashmere characteristics: length, micron, fiber weight, yield, fleece weight and liveweight.

The effect of environment will not be a factor in the Breeding Program design. According to Pattie and Restall, at every environmental level there will be genetic differences between breeds, cross breeds and individuals. We do not need to spend resources improving management and nutrition until the animals express their genetic potential before we begin to upgrade the genetics. In other words, the effect of environment will be approximately the same upon each group so changes will still be observed after genetic manipulation is attempted. But, it is very important to limit the number of traits to be manipulated to 1 or 2 in order to maximize progress.

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