Effect of increased energy level with dietary mixed soy-oil or soybean seeds as roasted or extruded on performance and oil availability in growing Holstein male calves

Oil sources could be fed in different forms in animal diets. The objective of the present study was to evaluate the effect of delivery method of soy oil in growing Holstein male calves. Eighteen growing Holstein bull calves (210±23 kg of BW) were randomly allocated in three different treatments with different delivery methods of soy-oil as follow; 1) dietary mixed soy oil (DMSO), 2) roasted soybean seed (RSB), 3) extruded soybean seed (ESB). The diets well balanced as isocaleric and isonitrogenous. The study lasted 10 weeks. Intake was recorded daily and weighing was done by monthly intervals throughout the experiment. Results show that performance parameters (intake, gain and feed conversion ratio) were not influenced with different treatments. Considering the blood metabolites results cleared that beta-hydroxy butyrate (BHBA) reduced in ESB treatment (P < 0=04). The TG concentration was increased in RSB treatment (P=0.01). Digestibility of nutrients also did not differ among treatments (P > 0.05). Delivery method of oil in diets did not influence chewing activity in Holstein calves. Results indicated that based on the experimental dietary fat level (39 g/kg DM), different delivery methods of soy oil may not influence growing calves’ performance and digestibility. Future research warranted to evaluate the delivery method of oil (fat) in higher levels in growing Holstein calves.