The effect of heat load on nutrient utilization and blood parameters of Awassi ram lambs fed different types and levels of forages

This study was carried out to determine the season effect (heat load) on nutrient utilization and blood-rumen parameters of Awassi ram lambs fed different levels and types of forages. Total sixteen 2-year-old Awassi ram lambs (44.3 ± 1.5 kg) for each apparent digestion trials were used as experimental animals. Experiment was arranged in 2 × 2 × 2 factorial in which season (summer versus fall), forage type (wheat straw versus alfalfa hay), and forage level (30% versus 70%) were the main effects to be investigated. Season and forage type did not affect dry matter intake (DMI) of ram lambs. Changing forage level from 70 to 30% increased DMI of ram lambs (P < 0.05). Daily water consumption of ram lambs was altered by season and forage type (P < 0.05). Dry matter and organic matter (OM) digestibilities in diets were affected by forage type and forage level (P < 0.05), however season affect was only observed in OM digestibilities (P < 0.05). While ADF digestibilities were changed by season and forage type, NDF digestibilities were only affected by season (P < 0.05). Season altered pH values of rumen fluid (P < 0.05) and during the summer pH values were lower than fall (5.87 versus 6.34). Serum Ca and K concentrations were affected by forage type and forage level (P < 0.05) but not season (P > 0.05). Serum Cl concentrations were changed by forage level (P < 0.05) but not season and forage type (P > 0.05). Effect of season (heat load) in this study was lower than expected probably due to low level of humidity.