Effect of lupin grain supplement on reproductive characteristics of the ram.

Abstract

Proc. Aust. Soc. Anim. Prod. (1978) 12: 249 EFFECT OF LUPIN GRAIN SUPPLEMENT ON REPRODUCTIVE CHARACTERISTICS OF THE RAM I.A. CUMMING, S.J. HARVEY, A. MAKIN, S.R. McPHEE and W. BREMNER Lindsay, Gherardi and Oldham (1976) working in Western Australia during the period from December to March found that by feeding a high protein supplement of lupin grain, testicular volume of rams could be significantly increased above that of control rams. Spermatozoa are produced at a constant rate per g of testis (Lindsay - al. 1976). This et finding could be of considerable economic significance, for, if testis weight could be increased following supplementary feeding, then possibly a lower proportion of rams could be used. The aim of the present study was to determine whether such responses could be obtained prior to the normal mating season for prime lamb produc tion . At this time rams are usually fed basal die ts supplyi ng greater than maintenanc e requirement s. Two experiments, each of 60 days, were conducted at Werribee from mid-September to mid-October, 1976. Experiment 1 (Pen): There were three Merino and three Romney Marsh rams (mean live weight 64 kg) in a Supplemented and a Control Group. The six supplemented rams were fed 750 g daymA of lupin grain (Lupinus angustifolius c.v. Uniwhite) with 500 g day-l of lucerne-barley pellets (c-p. 13%). The Control rams received an isocaloric ration of the lucerne-barley pellets. All rams were individually penned. Experiment 2 (Paddock): Seven Corriedale and two Dorset Horn rams (mean live weight 69 kg) in both a Supplemented and Control Group were grazed The suppleon similar and adjoining 2 ha paddocks of annual.pasture. _ ment (750 g day-l lupin grain) was fed daily to individual rams heldfor about 1 hr in pens. Measurements taken: All rams in both experiments were weighed and testicles measured on an approximately weekly basis. A testis volume index was calculated by multiplying testis length by width by depth. Data were analysed by linear regression. In Experiment 1 peripheral plasma samples were obtained at 20 min intervals over 12 hrbefore supplementary feeding began and after four weeks of feeding. This plasma was assayed for testosterone and luteinizing hormone. Also in this experiment standard pen libido testswere carried out before supplementary feeding and after four and seven weeks of feeding. This data was subjected to analysis of variance. During the experiments the mean live weight of the Supplemented and Control rams in Experiment 1 increased by 9 and 5 kg respectively and in Experiment 2 by 17 and 22 kg respectively. No significant effect of supplementation was observed in any parameter measured in either experiment. Testis volume increased by 4% during Experiment land by 10% during Experiment 2. It is concluded that the feeding of a high quality protein supplement need not result in an increase in testis size. Thus, care must be taken to identify the conditions underwhich high protein supplementation might achieve physiolog ical re sponses in reproductive characteristics and economic advantages . LINDSAY, D.R., GHERARDI, P.B. and OLDHAM, CM. (1976). In 'Sheep Breeding', Proc. 1976 Int. Gong. Muresk. Ed. G.J. Tomes, D.E. Robertson and R.J. Lightfoot. Published by West. Aust. Inst. Tech. pi 294. Animal Research Institute, Department of Agriculture, Werribee, 3030. 249.