ARS | Publication request: DIFFERENT BREEDING SCHEDULES AT 6 MONTH INTERVALS IN FOUR BREEDS OF SHEEP

Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: March 13, 2002
Publication Date: August 19, 2002
Citation: Pala, A., Leymaster, K.A., Mccraw, R.L., Young, L.D., Robison, O.W. 2002. Different breeding schedules at 6 month intervals in four breeds of sheep. Proceedings of the 7th World Congress of Genetics Applied in Livestock Production. CD-ROM Communication No. 02-42. Montpellier, France.

Interpretive Summary: Sheep are typically managed in annual production systems, that is, ewes lamb at 12-month intervals. Due to the 5-month gestation period of sheep, it is possible to increase productivity by implementing 6-month breeding schedules. Four breeds of sheep were evaluated in three different 6-month schedules (breeding during August and February, September and March, and October and April). Ewes of each breed were less productive during spring breeding and when exposed to rams while lactating. Productivity of breeds was influenced by 6-month breeding schedules, indicating that breeds and breeding schedules should be matched to maximize productivity.

Technical Abstract: Dorset, Finnsheep, Composite I (50% Finnsheep, 25% Dorset, and 25% Rambouillet), and Composite II (50% Finnsheep, 25% Suffolk, and 25% Targhee) sheep were evaluated under three twice-a-year breeding schedules. Lactation status had a significant effect on conception rate but number of lambs suckling did not (P > .05). Composite I ewes had highest conception rates and litter size (P < 0.01) while Composite II had heaviest litters and greatest litter weaning weight per ewe exposed (P < 0.01). While there was no difference between Finnsheep and Composite I (P > 0.10), both had larger litters (P < 0.01) than the other two breeds. Animals bred in schedule I had the heaviest and largest litters, heaviest lambs, highest conception rate and litter weaning weight per ewe exposed (P < 0.01). Efficiency of 6-month lambing systems is greatly affected by breeds, breeding schedules and seasons.