Title: LAMB PRODUCTION FROM EWES OF FOUR BREEDS AND THEIR TWO-, THREE-, AND FOUR-BREED CROSSES
Abstract:Fertility, prolificacy, numbers of lambs weaned, and total weight of lamb weaned per ewe exposed to rams were studied in Romnelet, Columbia, Suffolk, and North Country Cheviot breeds of sheep and thei...Fertility, prolificacy, numbers of lambs weaned, and total weight of lamb weaned per ewe exposed to rams were studied in Romnelet, Columbia, Suffolk, and North Country Cheviot breeds of sheep and their 2-breed crosses. Such ewes were bred by purebred and 2-breed cross rams giving rise to purebred, 2-, 3-, and 4-breed cross lambs. In total weight of lamb weaned per ewe exposed to rams, the production of 3- and 4-breed cross lambs surpassed the production of purebred lambs by 26 and 30%. Females from these matings in the first 2 yr were retained until the age of 6 and 7 yr for estimating their longevity and lifetime production. Dorset Horn (D) and Finnish Landrace (F) rams were used to breed these ewes. Purebreds tended, in all 7 yr of life, to have lower fertility and prolificacy levels. Mortality of crossbred ewes did not differ from that of the purebreds. Purebred ewes mated to rams of the same breed produced in their lifetime (up to 7 yr of age) an average of 124 kg of weaned lamb, whereas purebred ewes mated to D or F rams produced 148 kg. Two-breed, 3-breed, and 4-breed cross ewes mated to D or F rams produced 180, 189, and 189 kg of weaned lamb per ewe exposed.Read More