عنوان مقاله [English]
Introduction Before weaning, dairy calves are susceptible to many pathogens and nutritional problems. For several years antibiotics have been used to overcome these problems also to obtain economic benefits in terms of improved calves performance and reduced medication costs. However, the use of antibiotics in animal husbandry is in question because of antibiotic resistance of microorganisms. In an effort to replace antibiotics from animal feeds, many additives have been proposed. Probiotic, prebiotics and Organic and inorganic mineral salts are examples of these additives. Prebiotics are non-digestible carbohydrates which are not metabolized in the small intestine and fermented in large intestine. Mannan oligosaccharides and β-glucan are prebiotics which derived from saccharomyeces cereviciae cell wall and are able to block fimbriae of patho genic bacteria, and thus prevent their adhesion to the mucous epithelium. The administration of prebiotic to calves can decrease coliform population of large intestine and colon of calves. More recently, prebiotics have been shown to have immune-enhancing characteristics Also, Copper is a microelement that is present in many important processes in the body and plays a vital role. Copper deficiency in some parts of the world is a major problem in ruminants. For this reason, dietary supplements are commonly used to regulate the diet of calf to compensate for copper deficiency. Therefore, the purpose of this study was to investigate the effects of copper nanoxide and prebiotics on blood cell count and growth performance in Holstein suckling calves.
Materials and methods Twenty-eight Holstein calves with an average age of 1 to 8 days and an average weight of 39±1 kg were used in a factorial experiment as a completely randomized design with 4 treatments and 7 replications. Experimental treatments include: 1) Basal diet without additives, 2) Basic diet with 4 gr of prebiotic per day, 3) Basic diet with 15 ppm nanoparticles of copper per day, 4) Basic diet + 4 gr of prebiotic + 15 ppm nanoparticles of copper per day. The diet containing feed and milk was given two times a day i.e. in the morning (8:00 am) and evening (18:00 pm). Water was offered adlibitum. Whole blood samples were collected from jugular veins on d 60, approximately 3 h after the morning feeding. Samples were sent to the laboratory under refrigeration (4°C) till analyzed for WBC count, neutrophil, lymphocyte and monocyte concentration.
Results and Discussion The results showed that the copper nanoxide, prebiotics and the interaction of copper nanoxide and prebiotics could not affect the final weight of suckling calves. The results showed that feed intake, daily weight gain and feed conversion ratio of suckling calves were not significantly affected by supplementation of prebiotic and copper nanoxide in the diet during the first, second month and experimental period. Also, Body length, Wither height and Heart girth of Holstein suckling calves were not affected by copper nanoparticles and prebiotics supplementation. Prebiotic, copper nanoxide and their interaction had no significant effect on white blood cells, red blood cells, hemoglobin and hematocrit. In contrast, copper nanoxide and prebiotics significantly increased the neutrophil percentage (P <0.05).
Research has shown that probiotic consumption had no significant effect on functional parameters of Baluch sheep including final weight, daily gain, feed intake and dietary intake. However the result of the other study suggests that prebiotic can be supplemented to the calves for better performance. In contrary to the results of the present study, other researchers have indicated that copper nanoparticles could improve growth performance and modulate intestinal microflora and intestinalmucosal morphology in weaned piglets. In the study addition of pro- prebiotic and symbiotic to the whole milk of dairy female calves increased average daily gain but dry matter intake and blood parameters related to immune system and cell-mediated immune response were not affected. However, when a combination of probiotic and prebiotic added to the milk a better improvement in average daily gain was observed. A study reported that haematological traits (WBC count, neutrophil, monocyte, lymphocyte and hemoglobin) were unaffected by prebiotic and synbiotic in weaned pigs. However, the other study showed that immune parameters such as lymphocytes, leukocyte and neutrophils tended to increase in supplementation of symbiotic.
Conclusion In general, results of this experiment indicated that using prebiotics and copper nanoxide did not improve growth performance and blood cell count except neutrophil percentage.