| چکیده انگلیسی مقاله |
Backgrounds and objectives: The use of growth promoters and the strengthening of the immune system has been one of the concerns of livestock nutritionists. At first, using antibiotics was the best solution. But worries about their effects on livestock products have prompted scientists to find suitable alternatives. Probiotics as a natural product, along with some vitamins, were a good option. This study was conducted to investigate the effects of probiotic and vitamin E+ selenium supplements on performance and some blood and ruminal parameters of Holstein calves.Material and Methods: Twenty-four Holstein male calves were randomly assigned to 4 treatments after weightlifting and prenatal follow-up. The calves were transferred to individual cages and fed a sufficient amount of colostrum for the first 3 days. Treatments included: 1- basal diet (starter diet + milk), 2- basal diet with Bioguil probiotic (2 g), 3- basal diet with injectable supplement of vitamin E+ selenium (0.14 ml per kg live weight), and 4- basal diet with probiotic and vitmin E + selenium. Probiotics were given daily and vitamin E+ selenium at birth and 14 days of age. The calves were fed milk twice a day. The starter was also given to them from the beginning of the second week of the experiment. The calves were weighed at the beginning of the experiment as well as once every two weeks. The amount of feed intake was calculated daily. Skeletal growth indices including body length, withers height, hip height, hip width, and heart girth were measured and recorded on the days of entering the experiment, 14, 28, 42, and 56. At 7, 21, 42 and 56 days old, blood sampling was done four hours after morning feeding by venoject tubes via jugular vein. Blood metabolites including glucose, albumin, total protein, beta hydroxyl butyric acid, cholesterol, triglyceride, urea and immunoglobulin G (IgG) were measured. The rumen fluid was collected using an esophageal catheter on days 21, 42, and 60 days to measure ammoniacal nitrogen and determine the fatty acids profile. The data were analyzed using SAS software according to MIXED procedure. Results: Probiotic and Vitamin E + selenium did not have any significant effect on weight gain and feed intake of calves (P >0.05). However, in calves receiving probiotic and probiotic combination with vitamin E + selenium, despite the lower initial weight, total and daily weight gain was numerically higher than control and those recipient vitamin E + selenium. The amount of feed conversion ratio (FCR) in the probiotic treatment showed a tendency to improve compared to the control (P = 0.09). Except for total protein (P= 0.002) and IgG (P=0.0004), the other blood parameters were not affected by treatments (P>0.05). Probiotic, vitamin E+ selenium and their combination reduced blood protein level compared to control. In contrast, these treatments increased IgG level. Treatments had no any effect on volatile fatty acid concentration (P>0.05). However, the use of probiotics and vitamin E + selenium increased the amount of acetate and propionate numerically. The amount of ammoniacal nitrogen and pH were not affected by the treatments (P>0.05).Conclusion: Probiotic treatment improved feed conversion ratio (FCR) and increased some skeletal growth indices in dairy calves. The use of probiotics, vitamin E + selenium and their combination increased the absorption of IgG, which can lead to calf resistance to infectious diseases such as diarrhea. |