Abstract:
Proc. Aust. Soc. Anim. Prod. 1996 Vol. 21 GLUTATHIONE RESPONSES TO RUMEN PROTECTED METHIONINE IN GRAZING SHEEP G. MATA, D.G. MASTERS, D. BUSCALL and N. CHAMBERLAIN CSIRO Division of Animal Production, Private Bag, PO Wembley, W.A. 6014 Responses in wool or liveweight to inorganic sulphur and sulphur amino acids (SAA) supplied postruminally have been inconsistent, and there is currently no indicator of sulphur or SAA status that is useful in predicting responses to these nutrients. Sulphur in wool, plasma sulfate and SAA are unreliable as indicators. The tripeptide glutathione (GSH) may provide an indicator of SAA status. GSH contains cysteine and is found in many animal tissues including liver, muscle, skin and red blood cells. In non-ruminants, GSH has been shown to respond to changes in SAA intake. One hundred and twenty weaner wethers (mean liveweight = 32.7 kg f 0.3 sem) were allocated to 1 of 2 groups; rumen protected methionine (RPM) or control. The RPM group received 3 g methionine per day (10 g Lactet, Nippon Soda, Co. Lt., Japan) fed 3 times per week using crushed lupins as a carrier (50 g/day Dee Mar, 75 g/day Apr - June). It has been shown previously (Mata et aZ. 1995b) that this product is an effective supplier of postruminal SAA. The control group received the crushed lupins only. The supplements were offered between December and June (189 days) and the sheep were then managed as a single mob until shearing. Wool growth rate, liveweight and faecal dry matter output have previously been reported (Mata et a2. 1995a). Blood, liver, skin and muscle biopsies and GSH analysis were carried out in 8 sheep from each group as described by Mata et al. (1995b). Data are least square means with December value as covariate for comparisons. Table 1. Effect of rumen protected methionine (RPM) and season (S) on glutathione concentrations in tissues This work was in part funded by IWS and Nippon Soda, Co. Lt., Japan. MATA, G., MASTERS, D. G., BUSCALL, D., CHAMBERLAIN, N. and PORTER, T. (1995a). Ann. Zootech. 44: (Suppl. 1) 80. MATA, G., MASTERS, D. G., BUSCALL, D., STREET, K. and SCHLINK, A. C. (1995b). Amt. J. Agric. Res. 46: 1189 -204. 369