Effects of Texel or Rouge de l'Ouest genes in lowland ewes and rams on ewe prolificacy, lamb viability and weaned lamb output

An evaluation of the effects of the proportion of Texel or Rouge de l'Ouest (Rouge) genes in ewes (0, 0(.)5 or 1(.)0; the remainder being Greyface (Border Leicester X Scottish Blackface)) on prolificacy, lamb viability and lamb output was undertaken. A comparison of Texel and Rouge sires was carried out on Greyface, Texel and Rouge ewes. Prolificacy was higher in Greyface compared with Texel ewes (P = 0(.)06) but was lower in Greyface compared with Rouge ewes (P < 0(.)001). Prolificacy was similar in Greyface and Texel X Greyface ewes mated to Texel rams and in Greyface and Rouge X Greyface ewes mated to Rouge rams. The level of dystocia was similar in Greyface and Texel X Greyface ewes but significantly higher in Texel ewes (P < 0(.)001). The proportion of Rouge genes in the ewe had no effect on the level of dystocia. Litter weight of lambs at birth was significantly heavier in Greyface (P < 0(.)001) and Texel X Greyface (P < 0(.)01) ewes compared with Texel ewes. The proportion of Rouge genes in the ewe had no significant effect on litter weight. Lamb mortality (no. of lambs born dead and died birth to weaning) was significantly greater with Rouge ewes compared with the other ewe breed types (P < 0(.)001). The number of lambs which died from birth to weaning was lower with Texel X Greyface compared with Greyface ewes (P < 0(.)01). Expressed on a unit metabolic weight basis, Greyface ewes produced a significantly greater weight of lamb compared with Texel (P < 0(.)05) and Rouge ewes (P < 0(.)001). Texel X Greyface ewes produced a significantly greater weight of Texel-sired lamb compared with Greyface (P < 0(.)01) and Texel ewes (P < 0(.)001). Sire had a significant effect on a number of parameters. The number of productive ewes was significantly lower in ewes mated with Texel sires (P < 0(.)001). Lamb birth weights and pre-weaning growth rates were greater with Rouge sires (P < 0(.)05). Number of lambs weaned per ewe lambed was significantly greater with Texel sires (P < 0(.)01). Overall weight of weaned lamb produced per ewe was not significantly affected by sire breed.