Reproductive and production efficiency of Chios ewes under an accelerated breeding system

Abstract

In a 5-year period, 145 Chios ewes, managed to lamb 3 times in 2 years, produced 464 lambing records, averaging 2.67 lactations (range 1–7). A group of 119 Chios ewes, maintained concurrently, was managed to lamb once a year as control. All ewes in the accelerated breeding systems were exposed to rams for rebreeding following weaning (42 ± 3 d post partum), with the exception of those lambing in November and December, which were rebred in April. All ewes, regardless of system, were handmated and oestrus was detected twice daily using vasectomized teaser rams. Ewes on both systems were kept indoors throughout the year and minimum grazing was practiced. Milk production was computed from monthly test-day records following weaning and reflects commercial yield. Ewe fertility in the accelerated breeding system (60%), although lower than that of the control group (92%), could be considered satisfactory. Differences in conception within the accelerated system probably reflect seasonal fertility. Lambing interval in the present study (294 days), appears to be realistic for dual purpose breeds. Ewes on the accelerated lambing system produced more lambs and total lamb weight per ewe at weaning than controls, despite the twice as high abortion rate. Total milk production per ewe, although somewhat higher in the accelerated breeding system, was not significantly different from control ewes. The use of prolific breeds appears to be advantageous for accelerated breeding systems.