Reproduction in Targhee and Finnish Landrace × Targhee Ewes

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Abstract
Targhee and Finnish Landrace × Targhee (Finn-Targhee) crossbred yearling ewes were subjected to three nutritional treatments to investigate the effects of the genetic difference and genotype × environment interaction on reproductive traits. The three treatments were adjustments in feed intake sufficient to produce mean body weights of approximately 80, 90 and 105% of initial weights. Following attainment of the treatment weights, ovulation rate was measured by laparotomy twice for each ewe prior to flushing and a third time following breeding at the end of one cycle of flushing. Other traits measured were: onset of estrus, estrous cycle length, ova success, and lambing performance. Finn-Targhees averaged 14 days later and were somewhat more variable in onset of seasonal estrus, but had shorter (P<.01) estrous cycles and fewer missed estrous periods after cycling began. Ovulation rate was higher (P<.01) for Finn-Targhees, both before and after flushing. The significant (P<.01) pre-flushing treatment differences in ovulation rate were removed by flushing. Mean post-flushing ovulation rate was 1.89 for Targhees and 2.62 for Finn-Targhees. For all ewes lambing, 78% of the corpora lutea observed at the post-flushing laparotomy were represented by lambs born. Targhees lambing averaged 1.50 lambs per ewe compared to 2.22 lambs per Finn-Targhee ewe lambing. Although the Finn-Targhee ewes in this experiment were all sired by the same Finnish Landrace ram, the lambing results agree quite well with those from other studies of crosses with this breed. Copyright © 1973. American Society of Animal Science. Copyright 1973 by American Society of Animal Science.

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