Genetic parameters for fleece uniformity in alpacas

Alpaca breeding programs can use a single sample of fiber diameter to indirectly select fleece uniformity. Fiber diameter is the main selection objective and criterion in alpaca breeding programs, but it can vary across anatomic regions of the animal. As fiber diameter is usually registered from a unique sample from the mid side of the body, fiber diameter variability within fleece is never addressed and phenotypic and genetic differences may exist for fleece uniformity in alpaca populations. The objective of this work was to estimate the genetic parameters of fleece uniformity in an alpaca population. Fiber diameters measured in three different locations were used as repeated records of the same animal and studied for fitting a model that considers heterogeneous the residual variance of the model. Also, the logarithm of the standard deviation of the three measures was used as a measure of the fleece variability. Estimate of the additive genetic variance of the environmental variability was 0.43 +/- 0.14, enough high to suggest the existence of wide room to select for fleece uniformity. Genetic correlation of the trait with its environmental variability was 0.76 +/- 0.13 showing that fleece uniformity will be indirectly selected when aiming to reduce the fiber diameter. In the light of these parameters, and due to the cost of registering and the cost of opportunity, it looks no worthy to include uniformity as a selection criterion in alpaca breeding programs. Lay Summary The quality of alpaca fiber is mainly assessed by a low fiber diameter. However, the fiber diameter can greatly vary along the different body locations of the animal, the industry demands not only the fineness of the fiber but also the fleece uniformity. This work studied the genetic parameters related to fleece uniformity by analyzing the diameter of three samples from different body locations (mid side, shoulder, and thigh) under two different models of analysis. The results showed variability between sampling locations and the existence of important genetic variability susceptible to being used in alpaca selection. Nevertheless, selection based on a single measurement could be used as the high correlations between locations and between the trait and its variability, saving the cost of sample analyses, being the fleece uniformity indirectly selected.