Effect of Fat Supplements in Starter Diet on Performance, Blood and Rumen Parameters of Holstein Calves

To determine the effects of addition of the protected saturated and unsaturated fats on performance, blood and rumen parameters of Holstein suckling calves an experiment using 40 newborn calves (20 females and 20 males) with 5±2 days old and an average weight of 35±2 kg after colostrum administration was carried out in a completely randomized design with four treatments and 10 replicate for 70 days. Experimental groups included: 1) control diet, without fat supplementation, 2) diet with 2% calcium-unsaturated fatty acid supplementation, 3) diet with 2% calcium-unsaturated fatty acid supplementation, and 4) diet with an equal mixture 1% of both were complemented. In order to evaluate changes in body weight, chest circumference and height, the data were measured and recorded weekly at 10 a.m. To determine the blood parameters, blood samples were taken from the jugular vein on the 30th and 70th days experiment. The results of this study showed that the addition of unsaturated and unsaturated fat supplements did not have a significant effect on calves' performance so that weight gain, feed intake, feed efficiency and fecal index were not significantly different in experimental groups. Also, skeletal growth of calves was not affected by dietary fat supplementation. Dietary supplementation significantly affected the digestibility of the diet (p<0.05). The digestibility of dry matter, organic matter and neutral detergent fiber was higher in all experimental groups receiving fat supplement than the control group (p<0.05). The highest fat digestibility was in the experimental group containing unsaturated fatty acids. Fat supplementation had no significant effect on ruminal fluid and blood parameters of calves. Due to the uniformity of energy and crude protein in the experimental diets, it was expected that the most important factor in the possible improvement of calf performance was the positive effect of these supplements on the digestibility of the diet and the biological role of fatty acids, especially in health. The results of this study showed a positive effect of supplements on digestibility, but these changes may not be large enough to affect feed efficiency and weight gain in calves.