Abstract
Infections with gastrointestinal nematodes, in particular Haemonchus contortus, are worldwide one of the most important factors causing high economic losses in sheep production. Different methods for detecting infections with H. contortus have been described, such as, e.g. the FAMACHA system, which categorises the colour of the conjunctivae from red to pale. When H. contortus is not the predominant parasite, the FAMACHA chart might not be suitable to detect nematode infections, because of the lack of a blood feeding parasite. Otherwise breed-specific differences in the colour of the mucosa could be responsible for the limitations of the FAMACHA system. The aim of the study was to compare different methods of measuring mucosa colour in the German sheep breeds Black Head Mutton (BH) and Leine sheep (LE). In a total of 232 6-months-old lambs, the colour of mucosa was measured using the FAMACHA chart (conjunctivae) as well as the colour analyser Minolta Chroma Meter CR-200b (gingivae). Faeces and blood samples were taken at the same time to determine faecal egg counts per gram faeces (FEC) and the packed cell volume (PCV), respectively. Lambs grazed on contaminated pastures and no anthelmintic treatment was used. Lambs were moderately infected with gastrointestinal nematodes with no significant difference between the two breeds (P>0.05). The prevalence of H. contortus was 23%, based on larvae differentiation of coproculture. There was no significant correlation between FEC and PCV, nor FEC and FAMACHA (P>0.05). Significant differences (P<0.05) were found between the BH and LE lambs with regard to the colour measurement traits Chroma, hue-angle and FAMACHA. Beside the relatively low parasite pressure, these differences in the mucosa colour between the two breeds could be responsible for the limitations of the FAMACHA chart as a useful indicator of a nematode infection. Measuring the colour of the mucosa by using a colour analyser seems to be more suitable to detect less developed anaemic situations in sheep (PCV> or =0.27l/l), as shown by significant correlation coefficients between PCV and Chroma and HA, respectively. It can be concluded, that the measurement of mucosa colour with a colour analyser is more sensitive in detecting anaemic states in sheep, compared to the FAMACHA chart. However, because the colour analyser is not suited for measurements in the field, an adaptation of the FAMACHA colour scales for different sheep breeds might be required.