عنوان مقاله [English]
Introduction In recent years, the main policy in animal husbandry has been the use of livestock supplements with high production efficiency. To achieve this, in addition to using new and optimal nutrition methods, management can improve and accelerate efficiency-enhancing programs in livestock units by implementing various and appropriate methods and strategies. Due to the advances that have been made in the sheep and goat breeding industry, the need to use effective food additives to advance this goal and provide the nutrients needed for livestock has increased. On the other hand, rumen microbial population imbalances can play a major role in nutrient depletion. Several additives have been used to improve fermentation conditions in the rumen and increase the production of ruminant animals. These compounds include methane inhibitors, antibiotics, probiotics, growth factors and enzymes. The use of antibiotics in livestock has serious consequences such as bacterial resistance and intestinal disturbances. Therefore, the use of antibiotics is now limited in many countries and much effort is being made to find an alternative to antibiotics. Probiotics are live microbial feed supplements which beneficially affect the host animal by improving its microbial balance. A stable rumen environment is a key factor in achieving optimal milk production and animal health. Therefore, the use of additives that both reduce metabolic diseases in livestock and are useful in improving the microbial function of the rumen, is very necessary. Most of probiotic studies that were reported in the literatures used single or two strains probiotics rather that multi strains bacteria. Prebiotics are non-digestible carbohydrates which are not metabolized in the small intestine and fermented in large intestine. In this study, the effect of adding supplements on performance, blood metabolites and ruminal volatile fatty acids were investigated.
Materials and methods Forty Baluchi male lambs were used in four completely randomized treatments for 90 days. Treatments included: control group (initial diet), probiotic group (initial diet + 0.5 gr probiotic), prebiotic group (initial diet + 2 gr prebiotic) and symbiotic group (initial diet + 0.5 gr Probiotic and 2 gr of prebiotic). The amount of feed consumed per sheep daily and weight gain was calculated and recorded during the whole period. In order to determine the concentration of some blood parameters, blood samples were taken from the cervical vertebrae at the end of the week. Blood samples were taken at nine o'clock in the morning (two hours after the morning meal) on weekdays. To measure the concentration of metabolites, plasma samples were melting at room temperature to determine the serum levels of serum cholesterol, glucose, albumin, triglyceride and total protein plasma from a biosorbent kit and an autoanalyzer (model A15, France). Sampling from ruminal fluid was done after four hours feeding in the morning and using an oral catheter on day 90 of the experiment. Measurement of skeletal parameters including chest circumference by placing a tape measure around the chest just behind the front legs and shoulder blade, body length (shoulder-to-shoulder position), height at the withers, height at the hip or height at the hips, and the distance between the two hip bones was determined using biometric calipers in the first and last weeks.
Results and discussion The results of this study showed that probiotic consumption had no significant effect on functional parameters of Baluch sheep including final weight, daily gain, feed intake and dietary intake. Plasma glucose concentration increased with increasing of probiotic content in the diets and there was a significant difference (P <0.05) with the control group, but this difference was not significant between supplemented probiotic diets and diets with significant prebiotic supplement. With the use of probiotic supplements in all groups of consumption, the pH of ruminal fluid of Baluchi sheep increased and there was a significant difference (P <0.05) with the control group. The concentration of acetate and ruminal propionate of sheep fed the probiotic supplement was higher than that of those who did not (P <0.05).Glucose and triglycerides, total plasma protein concentrations and plasma albumin were not affected by probiotic and prebiotic supplements in the diets and no significant differences were observed between diets.
Conclusion In general, results of this experiment indicated that using probiotic and prebiotic supplements due to volatile fatty acids produced in this study improved ruminal fermentation, but supplementation could not have a significant effect on performance and skeletal growth indices in Baluchi sheep.