EFFECTS OF Haemonchus contortus INFECTION ON SODIUM STATUS OF SHEEP EFEITOS DA INFECÇÃO DE Haemonchus contortus SOBRE O STATUS DE SÓDIO EM OVINOS

Eight five-month-old male lambs received a diet with marginal levels of sodium (0.5 g Na/kg DM); four lambs were given a single dose of infective Haemonchus contortus larvae (4,600 L3/ head) and four were kept uninfected. The lambs were slaughtered 30 days after the infection. Sodium concentration was determined in the abomasal fluid at the slaughter. The balance between intake and faecal excretion of sodium was evaluated. Saliva was collected at days zero, 20 and 30 to determine the Na:K ratio. The mean total worm burden retrieved was 1390. The infection increased abomasal sodium concentration (p< 0.001) and reduced faecal sodium excretion (p<0.02), but there was not a significant relationship between worm burden and abomasal (p >0.082) or faecal sodium excretion (p>0.5). The higher the abomasum sodium concentration, the lower the faecal sodium excretion (p < 0.001). Apparent digestibility of sodium was similar between infected and uninfected. At the end of the experiment a slight decrease in the salivary Na:K ratio was observed, in animals of both groups, caused mostly by diet rather than the parasitism. It was concluded that although H. contortus infection increased the loss of sodium into the abomasum there was a greater compensatory intestinal absorption to prevent a significant change in the sodium status of sheep.