Kikuyu (Pennisetum clandestinum) pasture for sheep. 2. Production and nutritional status of ewes with or without lupin (Lupinus albus) supplementation

Kikuyu pasture was grazed continuously for 12 months by 20 dry and 40 produ cing South African Mutton Merino (SAMM) and Merino ewes at a stocking densi ty of 23 ewes ha(-1) Supplementary sweet lupin seed was supplied to one gro up of producing ewes of each breed during pregnancy and lactation at a rate of 0.5% of the liveweights of the ewes. Rumen fluid samples for the determ ination of pH, volatile fatty acids (VFA), and ammonia-nitrogen (NH3-N) wer e collected from rumen-fistulated wethers corresponding to the periods of l ate pregnancy and early lactation of ewes. Rumen NH3-N concentrations (8.7 mg 100 ml(-1) and 5.4 mg 100 ml(-1)) were low during both periods of sampli ng. Rumen VFA concentrations (12.3 mmol 100 ml(-1) and 9.2 mmol 100ml(-1)) were within normal ranges. Supplementation significantly increased blood ur ea concentration of ewes. Supplemented ewes lost less weight than the unsup plemented ewes (P less than or equal to 0.02) during the experimental perio d. Pregnancy (P less than or equal to 0.001) as well as lactation (P less t han or equal to 0.0001) reduced greasy wool production. Supplementation inc reased birthweight of lambs by 21% (P less than or equal to 0.0007). Rumen parameters indicated no severe deficiency in either protein or energy intak e. A lack of response in wool and lamb growth due to lupin supplementation was primarily ascribed to a high CP degradability of lupin seed. Production of the different breeds was in accordance with their respective genetic po tential.