Abstract:
Animal Production in Australia THE EFFECT OF A S UPPLEMENT OF LUP IN SEED ON THE TESTICULAR SIZE AND LH PROFILES OF MERI NO AND BOOROOLA RAMS S.R.D. SUTHERLAND* and G.B. MARTIN* tary Six Merino (mean live weight 71 kg) and six Booroola rams (mean live weight 50 kg) were fed a maintenance diet of 0.9 kg per day of an 8 : 1 mixture of oaten chaff : lucerne chaff (approx. 6% crude protein) for five weeks. Three of each group were then fed this roughage diet ad lib. plus 750 g of lupin seed (Langus ._ t_ . -.-. . . .- ifolius cv. Uniwhite) per day for nine weeks while the other three remained on .--P.-e the maintenance diet. The rams were weighed and testicular size measured by corn parative palpation weekly. Serial blood samples were taken over 24 hours from each ram before and eight weeks after supplemen&ation began, every 20 or 30 minutes respectively. Plasma was stored at -20�C until LH was measured with a double-antibody radioimmunoassay. In the supplemented Merino rams, live weight increased by 29% (PKO.05) and testicular size by 58% (P< O-05), and the mean number of LH pulse; in 24 hours increased from 1.3 to 2.7 (P <O.lO). The control Merino rams showed no changes. In the supplemented Booroola rams live weight increased by 23% (P cO.10) and testicular size by 63% (P x0.10). In the control Booroola rams live weight did not change but testicular size increased by 32% (P '0.10) and the difference in testicular size between supplemented and control Booroola rams after nine weeks was not significant. The mean frequency of LH pulses in Booroola rams was initially higher than in Merino rams but did not change significantly with supplementation (3/24 hours compared to 3.7/24 hours). Testicular growth in Merino rams in response to dietary supplementation is associated with increasing frequency of LH pulses. The higher frequency of LH pulses in Booroola rams may be a genetic character and related to the higher fecundity of Booroolas. The control Booroola rams were fed the same amount of maintenance diet, but had lower live weight than the Merino rams, so they may have been in a positive protein and/or energy balance. This may account for the testicular growth in these rams and in part for the higher frequency of LH pulses in Booroolas. In cannot be concluded whether or not Booroola rams respond in testicular size or LH pulse frequency to dietary supplementation. KNIGHT, T.W., OLDHAM, C-M. and LINDSAY, D-R. (1975). Aust.J.Agric.Res. 2:567 LINCOLN, G.A. (1979). Abstract in Society for the study of fertility, Annual conference, Glascow, 1979, p.33. OLDHAM, CM., ADAMS, N-R., GHERARDI, P.B., LINDSAY, D-R. and MACKINTOSH, J-B. (1978). Aust.J.Agric.Res. 29:173. X * Department of Animal Science and Production, University of Western Australia, Nedlands, W.A. 6009, 459
