The influence of nutritional level on verminosis in merino lambs

Abstract

1. A mass mixed infestation of Haemonchus contortus and Oesophagostomum, columbianum larvae dosed to 7-8 month old merino lambs kept on two different planes of nutrition caused a peracute fatal verminosis in all the infested animals. 2. A similar infestation when dosed to 10-11 month old lambs under identical conditions caused a chronic verminosis. In this case the effect of nutrition on the response of the animals to verminosis was clearly demonstrated. 3. This finding demonstrates the greater susceptibility of young lambs to worm infestation, regardless of their diet, and emphasises the necessity of preventing mass infestation in young lambs under all conditions. 4. In the second experiment it was shown that an increase of the maize ration by 300 gm. a day caused a marked superiority in worm infested sheep as regards all of the following factors : - Body weight, appetite for roughage, haemoglobin level, fleece weight and wool fibre thickness. 5. In all the above respects the worm infested sheep receiving 400 gm. of maize per day were superior to the non-infested sheep receiving only 100 gm. of maize per day. 6. The pathological findings in cases of acute verminosis are described and the immediate cause of death was found to be acute, pulmonary oedema. 7. Phenothiazine was found to be superior to either tetrachlorethylene emulsion or copper tartrate and copper arsenate mixture as a vermifuge in that it appeared not only to kill all wire worm present but also to cause removal of the black-stained ingesta from the alimentary tract. It also appeared to promote normal bileflow. 8. The experiment clearly demonstrates the beneficial effects of a higher maize intake on the response of sheep to verminosis.