Results of two fattening trials, with 49 crossbred ram lambs fattened on an all-concentrate diet given ad libitum with toasted soya bean meal as the main protein source, are presented.
In the first 84-day trial (January to March 1979) there were 32 twin- and triplet-born ram lambs of five genotypes, i.e. Finn-Awassi F2 (FAF 2), Romanov-Awassi F2 (RAF2), Assaf × Finn-Mutton Merino (AsFMM), Suffolk × Finn-Awassi (SuFA) and Suffolk × Finn-Mutton Merino (SuFMM). The overall means ( + s.d.) of the parameters investigated were: initial age, 64·6( + 4·5) days; initial weight, 17·6(±3·0)kg; final weight, 52·2(±4-l)kg; daily gain, 411( + 38)g; food intake, 1·5(±0·3)kg dry matter per day; and food conversion, 3·6( + 0·8)kg dry matter per kg gain.
In the second 56-day trial (August to September 1979) there were 17 single-, twin- and triplet-born FAF2 and Assaf × Finn-Awassi (AsFA) ram lambs. The overall means (±s.d. ) of the parameters investigated were: initial age, 64·1(±8·7) days; initial weight, 24·3(+ 3·6)kg; final weight, 48·5(±5·6)kg; daily gain, 431(±24)g; food intake, l-5(±0·3)kg dry matter per day; and food conversion, 3·5( + 0·7)kg dry matter per kg gain.
In both trials the differences between genotypes in daily gain, food intake and food conversion were not statistically significant and the performance of the progeny of Australian Suffolk and Assaf rams was similar to that of the progeny sired by Finn-Awassi and Romanov-Awassi rams.
Food intake and food conversion were highly correlated with weight of lambs, i.e. r = 0·8864 and r = 0·8857 (d.f. 36), respectively.
In both trials the relationships between daily gain and the pre-fattening performance of the lambs (birth weight, type of birth, weaning age and weight, rates of growth to weaning and from weaning to the start of the trials, as well as the initial age and weight) were not statistically significant.