Effect of Synchronizing Rate of Ruminal Fermentation on Nitrogen Balance, Microbial Protein Synthesis and Growth Performance in Feedlot Male Lori Lambs

The synchronization of the ruminal fermentatin rate of carbohydrates and crude protein is a method to increasing microbial protein synthesis, improving nitrogen efficiency, decreasing urinary N excretion and improving animal performance. This research was done to evaluate the effect of synchronizing the rate of carbohydrate and protein ruminal fermentation on feed intake feed, digestibility, ruminl fermentation products, and growth performance of Lori feedlot male lambs which were fed with similar components or structure high concentrate diets.
Three diets were formulated for feedlot male lambs with same energy and crude protein but containing different synchrony index 0.59, 0.73 and 0.87 which calculated by using degradation parameters of organic matter and crude protein of feeds from the diets. The effects of synchrony index of diets by 21 Lori feedlot male lambs with an average weight of 25.79±3.38 kg for 95 days (14 days for adaptation and 81 days for main period) were assigned in a completely randomized design with seven replicates. Feed intake and its residual were measured daily. Apparent digestibility was determined using acid insoluble ash marker. The weight gain of lambs was determined to calculate feed efficiency and growth performance. Rumen fluid sampling (50th trial day) and bleeding (14th and 65th trial day) were done from lambs. Three lambs were selected from each treatment and transferred to metabolic cages on 55th fattening day and then after 3 days for adaptation, urine of lambs was collected for 6 consecutive days and microbial protein synthesis was estimated by measuring purine bases. Also nitrogen balance was calculated from the values of nitrogen consumption and excretion.
With increasing synchrony index, digestibility of dry matter, organic matter, neutral and acid detergent fiber and ether extract increased, but digestibility of crude protein, non fibrous carbohydrates and crude ash have not significant difference between treatments. The effects of experimental diets on rumen fluid pH and ammonia nitrogen concentration were not significant difference before the morning meal-time, but significant differences were observed on three hours after the feeding between treatments. The lowest synchrony index diet has highest rumen fluid pH and ammonia nitrogen concentration. There were not significant differences for microbial protein synthesis and its efficiency and total nitrogen excretion between the experimental treatments but with increasing synchrony index the amount of retained nitrogen increased and blood urea nitrogen concentration decreased (P With increasing synchrony index of the diets, microbial protein synthesis not increased but digestibility of dry matter and some nutrients and retained nitrogen increased whereas blood urea nitrogen concentration decreased. Also growth performance and feed efficiency tended to improve. Therefore using the high synchrony index diets can be useful for feed formulation or providing the perfect mix of feed items to meet nutritional requirements of feedlot livestock.