Vitamin E status of cattle and sheep 1: A background review

Observations on an outbreak of nutritional steatitis (yellow fat disease) in fitch (Mustella putorius furo)

An outbreak of nutritional steatitis in farmed fitch (Mustella putorius furo) caused by feeding high levels of dietary polyunsaturated fat was investigated. The disease affected mainly 13 to 15 week rapidly growing kits; 793 kits were affected and 183 died. The outbreak was quickly controlled by lowering the level of polyunsaturated fat in the diet and administering high doses of vitamin E. Affected animals had severe generalised steatitis characterised grossly by yellow brown granular fat, which histologically consisted of diffusely necrotic adipose tissue heavily infiltrated with macrophages and neutrophils. There were extensive deposits of PAS-positive, fluorescent lipopigment within macrophages and extracellularly throughout the inflamed fat. Affected fitch had normochromic microcytic anaemia, lowered liver iron levels, increased thrombocytes and acute inflammatory leucograms. Skeletal or cardiac myopathy was not observed grossly or histologically in any of the animals examined. The diet contained high levels of polyunsaturated fat (7.7%DM), a high proportion being docosahexaenoic and eicosapentaenoic acids which were derived from the squid component (40%) of the ration. The livers from affected fitch contained correspondingly high levels of polyunsaturated fatty acids. The diet provided 13 mg Vitamin E per fitch daily, which was clearly inadequate considering the high levels of polyunsaturated fat being fed. Liver selenium levels were extremely high as a result of the high selenium levels in the squid portion of the diet.

Selenium and vitamin E

Deficiency of selenium and vitamin E has recently been identified as a major health concern of sheep producers in certain regions of the United States, and familiarity with published data on these nutrients seems to be of value to small ruminant practitioners. This article begins with a description of the biochemical roles and metabolism of selenium and vitamin E. A literature review follows in which the influence of these nutrients on the musculoskeletal, reproductive, and immune systems, as well as on flock productivity, is discussed. Methods for detection of deficiency and supplementation strategies are also described.