عنوان مقاله [English]
Introduction: Proper nutrition management during calf rearing is one of the most important factors which influence herd profitability. Environmental stressors and immature immune system of calves, reduce the viability of the animal. Today, attempts are being made to increase immune system postnatal calf life in various ways. Supplying unsaturated fats, which have double bonds on their structure, in starter diet, is one of the suggested solutions to improve the calf’s immune system. Infant ruminants do not have the ability to biosynthesize fat-soluble vitamins (A, D3, E), while these vitamins play a major role in the animal's immune system and their performance. Supplying fat-soluble vitamins in the calves’ diets is critical for the normal growth of muscles and the body skeleton, as they have an improvement role to improve the immune system in animals. The common symptoms of a fat soluble vitamin deficiency in suckling calves are growth retardation, coarse hair, and susceptibility to infectious diseases.
Materials and Methods: In this experiment, twenty eight Holstein female calves with an average weight of 37.74 kg (± 4/76) were used from birth to 56 days. After birth claves were separated from their dam and after weighing they transferred to individual pen. On the fourth day, the calves were randomly assigned to one of four treatments. All calves received colostrum for the first 3 d and then whole milk at 8% of bodyweight in the two equal part in the morning (4.00 A.M) and evening (16 P.M) until weaning. The experimental treatments included: 1) control: whole milk with starter 2) control diet supplemented with flaxseed oil (0.3ml per kilogram of body weight) 3) control diet and weekly injection of 7 cc of fat-soluble vitamins (A, D3, E) 4) The control diet which supplemented with flaxseed oil (0.3ml per kilogram of body weight) plus weekly injection of 7 cc of fat-soluble vitamins. Flaxseed oil was mixed into milk (morning feeding) until weaning. During the experiment period, calves had ad libitum access to chopped alfalfa hay and starter diet. Water from a plastic bucket (7 liters), filled twice a day, and was provided throughout the study. Composition of starter did not change throughout the experiment. Starter intake was recorded daily. Body weight gain determined weekly until the end of experiment. Fecal consistencies were scored twice a day. Blood sample were harvested from jugular vein for collection of blood serum. Blood metabolites, glucose, cholesterol, triglycerides were analyzed using commercially available colorimetric and enzymatic assay kits. Data were analyzed using SAS version 9.4 as a randomized completely randomized design experiment. For all results, significant differences between treatments were reported at P≤ 0.05 and tendencies were reported at 0.05 < P≤ 0.10. Least square means for each treatment are reported in the tables and were separated using Tukey’s test.
Results and Discussion: The results of this study showed that the use of flaxseed oil and injection of fat-soluble vitamins during pre-weaning period had no significant effect on the starter feed intake, daily weight gain, rectal temperature and skeletal growth parameters of calves.
Serum concentrations of total protein, triglyceride, creatinine and urea were not affected by experimental treatments. Claves received flaxseed oil and fat soluble vitamins injection tended to have the lowest serum glucose concentration (P<0.10). Calves received flax seed oil and fat soluble vitamins injection had the highest cholesterol concentration.
Conclusion: The results of this study indicated that inclusion of flaxseed oil and injection of fat-soluble vitamins (A, D, E) had no any marked effects on weight gain, daily feed intake and skeletal bone growth.