THE EFFECT OF THE DIET AND IMMUNE-SUPPRESSION ON THE BIOLOGY OF HAEMONCHUS CONTORTUS IN LAMBS
Autor(es): Nadino Carvalho, José Henrique das Neves, Alessandro Francisco Talamini do Amarante
THE EFFECT OF THE DIET AND IMMUNE-SUPPRESSION ON THE BIOLOGY OF HAEMONCHUS CONTORTUS IN LAMBS
» Área de pesquisa: HELMINTOLOGIA
» Instituição: Programa de pós-graduação em Medicina Veterinária, FMVZ, UNESP
» Agência de fomento e patrocinadores: Coordenação de aperfeiçoamento de pessoal de nível superior - Bolsa de estrado
Conselho nacional de conhecimento científico e tecnológico - Bolsa de produtividade
The experiment was conducted to test if changes in pH and concentrations of volatile acids in rumen could cause impairment in larvae survival reducing worm establishment in abomasum. In order to test this hypothesis, one group of lambs were fed only with a grass diet, while another was supplemented with concentrate (amount corresponding to 3% of body weight). To minimize the influence of the acquired immune response in worm establishment, groups of lambs were immune-suppressed with prednisolone. The lambs were randomly allocated to four groups of seven and treated as follows: Group 1 Basal Diet – Normal; Group 2 Basal Diet – Immune-Suppressed; Group 3 Supplemented Diet – Normal and Group 4 Supplemented Diet – Immune-Suppressed. The two diets offered to lambs proved to create distinct rumen environments with differences in pH and in the volatile acid concentrations. Such changes, however, did not have any apparent effect on larvae exsheathment and larvae survival inside the rumen, with all groups presenting similar worm burdens (P>0.05). Groups supplemented presented stunted worms and females with fewer eggs inside uterus, for this reason they shed in average 3.2 times less eggs in faeces than animals fed with the basal diet (P<0.05). The immunosuppression caused a significant decrease in seric IgG anti-H. contortus and in the inflammatory cell numbers (mast cells and eosinophils) in the abomasal mucosa (P<0.05). Immune-suppressed lambs showed longer worms and females with more eggs, however, only the length of males were significantly affected (P<0.05). In conclusion, the changes caused in the rumen contents by supplementation with concentrate did not impair H. contortus establishment, however the high nutritional plan enhanced the resistance to a single infection independently of the immunosuppressive treatment indicating that some components related to innate immunity and mucosal maintenance were benefited by the improved nutrition.
