The Effects of Age and Reproductive Status on Serum and Blood Parameters in Merino Breed Sheep

Abstract

Merino breed female sheep (225 in total) were used to study the effects of age and reproductive state on the values of 31 physiological parameters. Of these 31 parameters, 23 were affected by the age of animals, by their reproductive state, or by the interaction between these two factors. The statistical weighing of each of the factors of variability was determined. This revealed that the effects produced by them were indeed systematic. In order to demonstrate the systematic nature of the factors of variability, an attempt was made to classify each animal with respect to its reproductive state and age group, given only the set of biochemical values relating to it. The number of correct assignments to an age group achieved was 84.41%, and this rose to 92.17% with regard to reproductive state. A figure of 100% of correct assignments was reached with the adult age group and animals in oestrus. Thus, although the range of values observed for physiological parameters can, on occasions, be very large, this must be seen as a result of physiological deviations from average. These deviations are systematic and quantifiable, whether analysed in isolation or together as part of a multivariate analysis.