RESPONSE OF DORPER AND RED MAASAI LAMBS TO TRICKLE HAEMONCHUS-CONTORTUS INFECTIONS

Six-month-old red Maasai lambs were more resistant than Dorper lambs t o repeated infections at one to two week intervals with 1000 Haemonchu s contortus infective larvae. Resistance after infection was assessed by means of faecal egg counts, packed cell volumes, eosinophil counts, total serum protein concentrations and mortality rates. The weight ga ins of the infected animals were only marginally lower than those of t heir uninfected controls, mast probably because of their significantly higher feed consumption, and evidently the infected lambs were not ut ilising all of the extra feed for growth. This absence of anorexia in spite of the infection was probably due to the palatability of the hig h protein diet fed to the lambs.