عنوان مقاله [English]
Introduction: Proper nutrition management during calf rearing is one of the most important factors which influence on herd profitability. During prenatal and postnatal periods life, due to the presence of environmental stressors and the lack of development of the immune system of calve, the viability of the animal is greatly reduced. 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. On the other hand, lack of fat in the diet and lack of biosynthesis of some vitamins leads to limited growth of the animal. Infant ruminants do not have the ability to biosynthesis fat-soluble vitamins (A, D, E), while these vitamins play a major role in the animal's immune system and their performance. Supplying of fat-soluble vitamins in the calves diets is critical for the normal growth of muscles and the body skeleton, as well as the 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, 28 Holstein female calves with an average weight of 37.74 (± 4/76) were used from birth to 56 days. After birth calves 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 milk replacer at 8% of body weight 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 flax seed oil (0.3 body weight) 3) control diet and weekly injection of 7 cc of fat-soluble vitamins (A, D, E) 4) The control diet which supplemented with flaxseed oil (0.3 body weight) plus weekly injection of 7 cc of fat-soluble vitamins. Flax seed oil was mixed into milk (morning feeding) until weaning. During the experiment period, calves had ad libitum access to chopped alfalfa hay and starter grain. 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 and were transferred either in tubes containing EDTA for hematological parameters or into tubes without anticoagulant for collection of blood serum. Obtain serum was stored in -020 until further analysis. Blood metabolites, glucose, cholesterol, triglycerides were analyzed using commercially available colorimetric and enzymatic assay kits. Obtained data for body weight gain, starter intakes, blood metabolites and skeletal growth were analyzed using SAS version 9.4 (SAS Institute Inc., Cary, NC) as a randomized completely randomized design experiment. For all results, significant differences between treatments were declared at P≤ 0.05 and tendencies were declared 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 during preweaning the use of flaxseed oil and injection of fat-soluble vitamins had no significant effect on the starter feed intake, daily weight gain, rectal temperature and skeletal growth parameters of calves.
Also, serum blood metabolites such as total protein, glucose, triglyceride, creatinine and serum urea were not affected by experimental treatments.However, Calves given flax seed oil and fat soluble vitamins showed a trend to lower serum glucose and urea concentration.Serum glucose and urea concentrations in flaxseed oil and vitamin treatment were lower than other treatments, but the concentration of triglyceride and creatinine in control treatment was higher than other treatments numerically. Significant increases in the cholesterol and of ALP level (p<0.05) were determined between tested treatments. Supplemented Flaxseed oil with or without injection of fat soluble vitamin (A, D, E) showed had higher cholesterol and HDL levels than the other two treatments, respectively.
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, however, they can improve some blood metabolites and hence increase immune system. Thus, in general, both supplementation were advantageous in making the calves in healthy condition and increase herd profitability.