Abstract

Resistance to facial eczema (FE) in cattle is known to be a heritable trait. The commonly used indicators of susceptibility in affected groups of animals are gamma glutamyl-transferase (GGT) and glutamate dehydrogenase (GDH), which indicate the severity of the liver injury associated with FE. Published research using mouse models suggests that glutathione-S-transferase (GST) may be a downstream indicator of variation in FE susceptibility, and a study was carried outin calves to test this. Friesian-sired and Jerseysired bull calves were purchased from dairy herds in spring 2004, artificially reared from about four days of age, weaned at 75-80 kg, monitored for base-line GGT activity in blood, and then dosed orally with sporidesmin. At 14 and 21 days after dosing, blood samples were taken to measure the activities of both GDH and GGT. A sample of 45 Friesian calves and 45 Jersey calves from the high and low outliers (using GDH activity within breed, 14 days after dosing) wereblood-sampled 15 or 16 days after dosing and measured for GST activity, with 20-25 animals sampled each day, in balanced groups. There were significant differences in GST activity between high and low GDH groups (P < 0.01), and the pooled within-analysisday regression of GST activity on logGGT activity (day21) was negative (P < 0.05). Results confirmed that low erythrocytic GST activity is an indicator of FEsusceptibility, although the differences seen between resistant and susceptible animals are insufficient for use as a predictive tool.

CA, Morris, NG Cullen, and R Munday

Proceedings of the New Zealand Society of Animal Production, Volume 67, Wanaka, 361-364, 2007