Milk yield and composition of Katahdin and Pelibuey ewes in tropical conditions.

Pelibuey and Katahdin are two the most extensively used hair sheep breeds in tropical regions characterized by high temperatures and humidity. Lactation influences profitability of sheep in dairy and non-dairy production systems. Therefore, the aim of this study was to evaluate the effect of breed and litter size (LS) on milk yield and milk composition of Pelibuey (n = 28) and Katahdin (n = 21) ewes reared under tropical conditions of Mexico. Milk, fat, protein and lactose yields, fat and energy-corrected milk, and fat, protein and lactose percentages were measured for seven weeks. Body weight (BW) of each ewe was measured weekly. Breed effects were significant (P < 0.001) favouring Katahdin breed on all yield traits. Ewes rearing two lambs had higher yields (P < 0.01) for all traits than ewes rearing one lamb. Fat percentage and BW were significantly (P < 0.05) affected by a triple interaction effect of Breed x LS x Week. So, important differences in milk yield and composition among breeds and LS were shown and might be considered in order to improve profitability of sheep production systems under tropical conditions. [ABSTRACT FROM AUTHOR]