The Effect of Ewe Age on Birth Weight and Litter Size of Texel Cross Sheep Mated with Dorper and Awassi Rams

This study evaluates the effects of ewe age and parity on lamb birth weight and litter size in Texel cross sheep bred with Dorper and Awassi rams in Indonesia. The research involved 110 Texel cross ewes divided into three parity groups based on age, mated with purebred Dorper and Awassi rams. Data on birth weight, litter size, and lamb sex ratios were collected and analyzed using ANOVA with Bonferroni post-hoc test, regression analysis, and Chi-Square tests. Results showed no significant effect of maternal age on lamb birth weight or litter size in either crossbreed (P>0.05), although there was a tendency for both to increase with advancing maternal age. Dorper x Texel cross lambs averaged 2.00±0.71 kg for birth weight and 1.56±0.71 for litter size, while Awassi x Texel cross lambs averaged 2.31±0.83 kg and 1.43±0.61, respectively. Litter size significantly influenced lamb birth weight (P<0.05), with single births producing the highest weights (Dorper cross: 2.24±0.86 kg; Awassi cross: 2.86±0.77 kg), followed by twins (Dorper cross: 2.11±0.78 kg; Awassi cross: 2.04±0.58 kg) and triplets (Dorper cross: 1.46±0.36 kg; Awassi cross: 1.41±0.50 kg). Higher variability in birth weights was observed in Dorper x Texel cross (CV 24.66%-47.12%) compared to Awassi x Texel cross (CV 25.69%-41.40%). Lamb sex did not significantly affect birth weight in either crossbreed (P>0.05). Sex ratios did not significantly deviate from the theoretical 1:1 ratio (χ² = 2.40 and 1.38, P>0.05) for both crosses. This study demonstrates that while maternal age does not significantly impact reproductive parameters, litter size substantially affects lamb birth weight in both crossbreeds under Indonesian conditions.