عنوان مقاله [English]
Introduction: Utilization of minerals and vitamins is essential for maximum production and animal health. Vitamin E and selenium perform important functions in the cow. Deficiencies of one, or both, of these nutrients have been implicated in white muscle disease, retained placentas, oxidized milk, lower immune function and mastitis.The roles of these two nutrients are closely related. Both selenium and vitamin E protect cells from the detrimental effects of oxidation but they do so in different ways. Vitamin E, an antioxidant present in the cell membrane, prevents the formation of harmful free radicals. Selenium functions throughout the cell to destroy peroxides, another harmful compound. This explains why selenium will correct some deficiency symptoms of vitamin E and not others. Although feeding large amounts of selenium does reduce the need for vitamin E and vice versa, high levels of one nutrient does not eliminate the need for the other.
Selenium and vitamin E have positive and important effects on the growth and maintenance of normal physiological function in animals, especially suckling calves. As recommended by the National Research Association (NRC,2001) the daily requirement of growing calves for Selenium is about 0.30 mg and 40 IU for vitamin E, and the Agricultural Research Association (ARC,1980) for 0.10 mg and 15 IU for selenium and Vitamin E is recommended for growing suckling calves. Selenium as an essential but Low Consumption mineral is important in light of its variation in ruminant vegetable sources (Belali et al 2008) as well as soil selenium deficiency in many parts of the world and Iran (Kajouri & Shirazi 2007, Malekuti et al 2002 and Mehri et al. 2011), on the other hand, since selenium uptake in ruminants is lower than in non-ruminant animals. The importance of providing enough selenium in ruminants' rations doubles and consequently a lack of it can lead to negative changes in the health status and performance of animals. The objective of this study was performed to compare the levels of selenium and vitamin E recommended in NRC and ARC by oral and injectable methods on some blood metabolites, digestibility, performance and Skeletal Growth Indices of suckling Holstein Calves.
Material and methods: Twenty five Holstein calves with mean weight of 40±2.7 and 20±5 days and selenium and vitamin E levels of 0.3 mg and 40 IU (as recommended by NRC) and 0.1 mg and 15 IU (as recommended by ARC) respectively, were recruited for this experiment. Were used in a completely randomized design with 5 treatments and 5 replications. Experimental treatments included: 1) control (no selenium and vitamin E), 2) selenium and vitamin E injections as recommended by NRC, 3) selenium and vitamin E injections as recommended by ARC, 4) oral selenium and vitamin E as recommended by NRC, 5 Oral Selenium and Vitamin E were as per ARC recommendation. The duration of the experiment was 35 days. During the experiment, calves were kept in separate locations. The rations were based on NRC (2001). The rations were provided by TMR in calves at 8 am and 16 pm and also had free access to water. Milk feeding was also performed in the morning and evening (10% of body weight). Animals were weighed weekly. To determine the dry matter digestibility of the diets, the calves' feed and faeces were sampled for six consecutive days and kept at -29 ° C until the experiment. Digestibility was determined according to AOAC (1990) methods. Three days a week, the calves' faeces was randomly evaluated. Faeces scores were determined according to the method of Khan et al (2011). On the last day, three hours after morning meal, calves were sampled from the veins and blood parameters, glutathione peroxidase activity and tetrodotyronine and triiodothyronine hormone levels were determined using Pars Test automated analyzer and kit. Measurement of skeletal growth in the body by standard meter and caliper according to the method of Khan et al. (2007).
Results and discussion: The results of this experiment showed There was no significant difference between treatments in terms of weight performance, dry matter intake, feed conversion ratio and dry matter digestibility (P >0.05). Intake of selenium and vitamin E did not show significant differences between different treatments of glucose, cholesterol, urea nitrogen, total protein, albumin and blood globulin (P>0.05). But blood triglyceride concentration was higher in calves receiving selenium and vitamin E than control (P <0.05). Glutathione peroxidase enzyme activity and blood levels of tetradotyronine and triiodothyronine were also increased in calves receiving selenium and vitamin E compared to control (P <0.05). The results also show that selenium and vitamin E injections orally and according to NRC and ARC recommendation were no significantly different from the control group in terms of faeces score, number of calves with diarrhea and days of calf diarrhea. Did not (P >0.05).There was no significant difference between calves for different skeletal growth indices (P >0.05). Finally, Using selenium and vitamin E in both oral and intravenous methods and both NRC and ARC recommendation did not differ in functional parameters, digestibility and blood metabolites but use of selenium and vitamin E According to the NRC method, the highest increase in blood triglyceride concentration and increased activity of whole blood glutathione peroxidase enzyme and concentration of tetradotyronine hormones and serum triglyceride hormones were higher than other treatments.
Conclusion: Overall, the results of this study showed that the use of selenium and vitamin E in both oral and intravenous methods and both NRC and ARC recommendations caused differences in weight gain, dry matter digestibility, stool consistency, skeletal growth and metabolite indices. Blood transfusions are not possible, but the use of selenium and vitamin E injectable and according to the NRC recommends the highest increase in blood triglyceride concentration and increased activity of whole blood glutathione peroxidase enzyme and the concentration of tetradotyronine hormones and other thyridothyronine ratios. It has consequences. Overall, it can be suggested that selenium and vitamin E may be used in suckling calves Nutrition whit Injection, probably because of their higher absorption and according to the NRC method.