The effect of the diet on the immune response and performance of lambs artificially infected by Haemonchus contortus and Trichostrongylus colubriformis

Abstract

The study will be conducted in order to evaluate the effect of supplementation on the immune response and performance of lambs artificially infected simultaneously with Haemonchus contortus and Trichostrongylus colubriformis. The experiment will be conducted with a 2 x 4 factorial design (lambs infected and non-infected x four diets). Lambs will be allocated into eight groups: four groups will be infected with 1000 infective larvae (L3) of H. contortus and 1000 L3 of T. colubriformis every three days over 12 weeks; the other four groups will be kept free of infection (controls). The infected and control animals will receive one of the following diets: Diet 1 100% coast cross (Cynodon dactylon) hay; Diet 2 with 75% hay + 25% concentrate ; Diet 3: 50% hay + 50% concentrate; and Diet 4 with 25% hay + 75% concentrate. The animals will be kept in individual pens to allow assessing the daily dry matter intake and feed conversion. At the end of the experimental infection, the animals will be sacrificed for the quantification of parasites and the collection of tissue samples from the abomasum and small intestine. Parasitological and immunological tests will be also performed. Data will be analysed by one-way analysis of variance for the variables measured just once and analysis of variance with repeated measures for variables measured at several time points. (AU)