Effects of Complete Replacement of Protein Feed with Soybean Meal on the Performance, Digestibility, Feeding Behaviors, and Blood Parameters of Atabay Lactating Ewes

Background: Soybean meal is the main source of protein for livestock, but unfortunately, this food source is an imported product.Thus, it seems necessary to research the use of secondary agricultural and industrial sources or their mixture with the same value as soybean meal, which are cultivated in any climate.On the other hand, more than 50% of soybean meal protein is digested in the rumen and turns into microbial protein, which is an unfavorable indicator.Therefore, finding a balanced source of degradable and transmissible protein that helps improve livestock growth and performance is of great importance.Protein feed is a mixture of bloodless meat powder, cotton scraps, rice bran, wheat bran, corn flour, pistachio powder, and liquid gluten, which can be used as a protein source.Protein feed is made from plant and animal products that provide the animal with passable protein and non-degradable protein at the same time, and it seems that it reduces the price of feed and environmental pollution, in addition to helping and improving the growth and performance of the animal.Considering that there is not much information in Iran about the effect of protein feed on the nutrition of ruminants, this study was conducted to investigate the effect of using different levels of protein feed in the diet of lactating ewes on performance, digestibility, rumination behavior, and blood parameters.Methods: To perform this experiment, 32 dairy ewes of the Atabai breed with an average weight of 41 2.8 kg were used in four treatments and eight replications in a completely randomized design.The treatments were a control treatment (a diet without adding protein feed), a second treatment (a diet containing 33% replacement of soybean meal with protein feed), a third treatment (a diet containing 67% replacement of soybean meal with protein feed), and a fourth treatment (a diet containing 100% replacing soybean meal with protein feed).Animals in each treatment were kept in individual cages after ensuring their health.The length of the test period was 56 days.The daily feed was provided to the animals in a completely mixed form.To determine the amount of dry matter intake, the remaining feed for each animal was weighed and recorded every day.The mean of each treatment was calculated from the average feed consumed by each animal during the period.Moreover, the increase in feed amount to ewes was calculated based on the post-feeding of each animal on the following day, so that the animal feed would increase if it was left less than 10% post-feeding.To calculate weight changes, ewes were weighed weekly.For the samples related to digestibility, the samples of feed, residue, and feces collected from each animal on days 51-55 were first collected for 5 days.Then, the samples were mixed together, and a 100-g sample of each was collected for each animal.They were removed and dried in an oven at 64 C for 48 h.The chemical composition of feed, residue, and feces samples was determined for insoluble fibers in neutral detergent by the Van Soest method.Crude protein, crude fat, and crude ash were measured by AOAC.Feed consumption behavior during days 55 and 56 of the experiment was recorded as active behavior, including activities such as eating, chewing, resting the jaw, drinking water, standing, lying down, and inappropriate behaviors, measured over a 24-hour period.On the last day of the experiment, blood samples were taken from the jugular vein of the animals before morning feeding.Blood metabolites, including glucose, triglyceride,