Comparison of East Friesian-crossbred and Lacaune-crossbred Ewe Lambs for Dairy Sheep Production First-year Results from a Multi-year Trial

East Friesian-sired F1 ewe lambs (n = 27) and Lacaune-sired F1 ewe lambs (n = 31) born in 1999 were compared for lamb production, lactation performance, and udder morphology traits in a dairy sheep production environment in 2000. The ewe lambs were the progeny of seven East Friesian and five Lacaune sires. A contemporary group of high percentage East Friesian ewe lambs (> 3/4 East Friesian, n = 15), sired by two East Friesian sires, also were evaluated. Approximately 2/3 of the F1 ewe lambs were mated to a ram of the same breed as their breed of sire, and the remaining 1/3 were mated to a ram of the opposite breed. All of the high percentage East Friesian ewe lambs were mated to East Friesian rams. The F1 East Friesian and F1 Lacaune ewe lambs were similar for lamb production and udder morphology traits. The F1 East Friesian ewe lambs were superior to the F1 Lacaune ewe lambs by 15% for lactation length, 21% for milk yield, 9% for milk fat yield, and 10% for milk protein yield. However, none of the differences between the two ewe groups in lactation traits were statistically significant. Performance data will need to be collected on more ewes sired by East Friesian or Lacaune rams over additional years to determine if there are real differences between the two breeds for traits of economic importance. The high percentage East Friesian ewe lambs, mated to East Friesian rams, gave birth to more (P < .05) lambs, but the lambs had a higher (P < .05) mortality than lambs from the F1 East Friesian or F1 Lacaune ewes. This finding supports earlier results from our flock indicating that, at levels of East Friesian breeding greater than 50%, lamb mortality increases as the proportion of East Friesian breeding of the lamb increases.