Proportion of rams and the condition of ewe lambs at joining influences their breeding performance
2010
Kenyon, P.R. | Morris, S.T. | West, D.M.
The aim of the present study was to examine the effects of ram:ewe lamb ratio and condition score on the reproductive performance of ewe lambs. In the 2007 study, ewe lambs were bred with rams, at ram:ewe lamb ratios of 1:30, 1:50, 1:75 or 1:100. In the 2008 study, ewe lambs were bred at ratios of 1:31, 1:50, 1:75 or 1:100. Ewe lambs were bred over two 17-day periods. In both studies, ewe lambs bred in the first 17 days of breeding only were heavier (P 0.05) in pregnancy rates among the different ram:ewe lamb ratios. While in the 2008 study, pregnancy rates after 34 days were greater (P < 0.05) in the 1:50 compared with both the 1:75 and 1:100 treatments. Pregnancy rates of 1:31 ewe lambs were greater (P < 0.05) than those of 1:75 ewe lambs. In the 2007 study, pregnancy rates of ewe lambs to the first 17 days of breeding were greater (P < 0.05) for those bred at a ratio of 1:75 than for those bred at 1:50, and tended to be greater (P = 0.08) than for those bred at 1:100. In addition, those bred at a ratio of 1:30 tended to have higher pregnancy rates (P = 0.07) than those bred at 1:50. While in the 2008 study, pregnancy rates to the first 17 days of breeding were greatest (P < 0.05) in the 1:31 and 1:50 treatments groups. In conclusion, the results of the present study indicate that achieving greater liveweights and higher condition scores of ewe lambs at breeding will increase the proportion pregnant, especially early in the breeding period. The data also suggest, in combination with the results of previous research, that farmers should consider utilising ram:ewe lamb ratios lower than 1:100, although further studies are warranted.
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