A multivariate approach to the diagnosis of gastrointestinal infection in ewes

Abstract

Diagnosing the effects of helminth infections is an efficient way to manage the problem in ruminant production systems. Selection of animals in a flock that are infected with Haemonchus has traditionally involved differential packed cell volume measurements (PCV), and in recent years, the FAMACHA^© system has been used. However, few small analytical changes have been made. The objective of this study was to examine the influence of different diagnoses linked to packed cell volume (PCV) and FAMACHA^© system scores in native ewes, using a multivariate approach. Ewes were classified into three categories according to their score in the FAMACHA^© system (FS) and their packed cell volumes (PCV) as follows: Group AG (FS between 1 and 2 and PCV ≥ 30%); Group BG (FS score of 3 and PCV between 21 and 29%); Group CG (FS between 4 and 5 and PCV ≤ 20%). The animals were evaluated using performance characteristics, parasitological examinations, blood values and serum biochemistry. The data show that the use of a multivariate approach for different diagnoses using the FAMACHA^© system and PCV measurements gives similar results, although they have particular pathophysiological indicator patterns.

Keywords: Adaptation; FAMACHA(©)system; Native sheep; Pathophysiological indicators; Principal components analysis.