The effect of adding sources of fat to milk on performance, growth, health,blood and ruminal parameters of Holstein female dairy calves in the firstmonth after birth

The aim of this research was to investigate the effect of adding fat powder and flaxseed oil in milk on performance, growth, health, blood and rumen parameters of 45 suckling calves (avarage body weight = 38 ± 0.5 kg) in a compeletly randomized design in 10℃ of average temperature from d 3 to 30 of age in individual boxes. Experimental treatments included: 1- basal starter and milk without fat supplement (control) 2- basal starter and milk with fat powder (10 g/liter of milk) 3- basal starter and milk with flaxseed oil (10 g/liter of milk). Daily weight gain from d 3 to 30 and weight at d 30 were higher in flaxseed oil treatment than control treatment (P ≤ 0.05). Calves fed flaxseed oil treatment had higher hip height than control treatment at d 30 (P ≤ 0.05). Blood cholesterol concentration was higher in control treatmentthan flaxseed oil treatment and blood cortisol concentration was lower in flaxseed oil treatment than control treatment (P ≤ 0.05). The ratio oftotal protein to albumin in flaxseed oil treatment was lower than control treatment (P ≤ 0.05). Ruminal parameters were not affected by the experimental treatments. The results of this research indicated that using of fat sources including linolenic acid as flaxseed oil in milk have a positive effect on the performance, growth and health during the first month after birth of dairy calves.