Effects of Different Methods of Wheat Straw Processing on the Performance of Fattening Ghezel Lambs

Background: Food and nutrition are undoubtedly the most important topics of discussion in today's world.Increasing population and efforts to meet the nutritional needs of the next generation necessarily require effort and pursuit in various fields of agriculture, animal husbandry, and related sciences.Small ruminants are especially important in rapidly improving the nutrition of the world's growing population.The advantage of small ruminants is short generation distance, faster growth rate, and greater adaptability and tolerance to environmental conditions than large ruminants.Cereal straw is one of the most important food items used in ruminant nutrition.Cereal straw has high levels of lignin and silica, both of which play an important role in lowering its digestibility and nutritional value.The use of ordinary straw in animal feed is common in Iran, and in fact, farmers are more inclined to use straw due to the lack and high cost of forages such as alfalfa or corn silage, although they are aware of its low effectiveness in the production of livestock products.One of the methods to increase the digestibility of wood products is to increase the nitrogen available to the microbes that break down the fibers.The nutritional value of cereal straw can be increased by processing and using urea as a source of ammonia.Conventional processing of grain straw with urea in the country is a costly, difficult, and time-consuming method.The use of a machine is essential to facilitate or eliminate some of these operations.Lime has also been shown to improve the usability of lowquality forage sources by increasing nutrient availability for rumen micro-organisms.Based on our knowledge, few experiments have been done regarding the simultaneous use of lime and urea in the processing of wheat straw and its effects on the performance of fattening lambs.Therefore, this study was conducted to investigate wheat straw processing by different methods and their effects on the digestibility, NDF degradability, dry matter intake, and performance of Qezel fattening lambs.Methods: This experiment was performed on 36 fattening Ghezel lambs with an average weight of 30 kg and 3 months of age in a completely randomized statistical design.Experimental treatments included a control (feeding with a diet containing unprocessed wheat straw), feeding with a diet containing 5% urea-processed wheat straw, feeding with a diet containing 5% limeprocessed wheat straw, and feeding with a diet containing 5% urea + 5% lime-processed wheat straw.Dry matter intake, weight gain, feed conversion ratio (FCR), DM, OM, CP digestibility, fecal score, and blood parameters were determined in the experimental groups.The uNDF content of raw and processed wheat straws was also measured with the standard method.Results: Wheat straw processing with urea or lime led to a decrease in feed intake, but processing with a combination of urea + lime did not affect the total feed intake.In the first month of the fattening period, considering a 2-week adaptation, feed intake showed large fluctuations among the experimental groups, which was partly related to the nature of the feed and the kind of processing and partly related to the disease of some experimental animals.In the second month, feed intake showed a more stable trend, and the control and lime + urea groups presented more feed intake than the other two treatments.The consumption of feed dry matter showed a significant decrease in the two-month period in the treatments of straw processed with urea or lime compared to the other two groups.In accordance with the fluctuations of the consumed feed, the weight gain of the lambs also showed a fluctuating trend during the 2 months of the experiment.The total weight gain was not different among the experimental treatments, but the