a. mirshamsollahi

The shortage of feed, caused by the limitation and reduction of water resources, is the biggest challenge for the country's livestock industry. Every year, more than 20 million tons of by-products from the main agricultural production remain in the country, which are mainly used as animal feed. Agricultural by-products, which exceed the production of forage crops many times over, are valuable resources that can replace conventional feeds in animal nutrition. Due to their low protein content and low digestibility, they need to be processed. For almost a century, different processing methods have been used in many countries depending on the conditions and facilities, but unfortunately, the majority of these materials are still used raw and unprocessed as animal feed in the country, which is a waste of resources. Straw processing is carried out by various physical, chemical, and biological methods or a combination of these methods, with ammoniation being the most important chemical method. The use of ammonia gas for this purpose can facilitate and accelerate processing, especially with large quantities of by-products. This research was carried out to study the efficacy and economics of the method of ammonization of straw with ammonia gas and the use of the ammonia product in the diet of fattening calves.
Ammoniated wheat straw was prepared with ammonia gas at three weight percent of the dry matter of straw at 30% moisture by stacking method, and the chemical composition, digestibility, and gas production of the ammonia-containing product were determined. In the second phase, 30 Simmental crossbred fattening calves with an initial weight of 249.5±8.9 were divided into two control and experimental groups and for each group, considering three replicates of five calves for each group. Normal straw was used in the control group, and it was replaced by ammoniated straw in the experimental group. The duration of the trial was eight months, during which the weight gain of the calves was determined every 30 days, and the dry matter was consumed daily. Dry matter consumption, daily weight gain, feed conversion ratio, and the cost of weight gain of calves were determined and compared between the two groups.
The ammonia treatment of straw increased crude protein content in the ammoniated straw from 4.78% to 12.65%, and the amount of NDF and hemicellulose also decreased in ammoniated straw (from 71.33 to 66.80%, and from 30.75 to 26.25%, respectively), while the amount of ADF increased (from 38.7 to 41.20%). The ammonia treatment of straw increased the gas production per 24 hours from 25.71 mL to 38.06 mL and the estimated metabolizable energy from 5.69 to 6.8 MJ per kilogram of dry matter. The ammonia treatment improved the digestibility of dry matter (from 45.0 to 78.75%) and organic matter of straw (from 42.35 to 80.27%). Substituting normal straw for ammoniated straw in the diet of fattening calves increased daily dry matter consumption from 8.66 kg to 8.99 kg (P<0.01), daily weight gains from 1.33 kg to 1.48 kg, and average weight at the end of the fattening period from 423.98 kg to 440.67 kg (P<0.01), and improved feed conversion ratio from 6.43 to 6.01 (P<0.01). In addition, the use of ammoniated straw reduced the price of ration from 71230 Rials to 69210 Rials and the cost of feed for each kilogram of animal weight gain from 458008.9 Rials to 415952.1 Rials.
Ammoniation of straw with ammonia gas increased the metabolizable energy, crude protein, and digestibility of straw. The use of ammonia gas for this purpose increased the speed, ease, and efficiency of processing, making it suitable for processing large quantities of straw. The profitability of this method depends on the cost of the ammonia product, in particular the price of ammonia gas and its transportation costs. At the national level and from a macroeconomic perspective, this method increased the digestible nutrients of agricultural residues (metabolizable energy and crude protein), it is, in a sense, a type of food production by increasing productivity and without the consumption of water and other agricultural inputs. It provides more nutrients for livestock, which reduces dependence on traditional feed, reduces competition between humans and livestock for food, protects the environment, and makes production more sustainable.

Based on current knowledge, it has been proven that many edible ingredients in addition to meeting the needs of creatures, in terms of energy and protein, contain compounds that affect cellular actions and intracellular signaling pathways and can temporarily or permanently change the function of the cell. The use of molecular biology tools and genetic research defines the mechanisms through which gene expression is affected by food, and conversely, these genes also affect the absorption of food, metabolism, and excretion. From the point of view of nutrigenomics, dietary nutrients are signals that are received by sensitive cell systems and can affect the expression of genes and proteins and the production of metabolites. Nutritional manipulations and strategies are key tools to influence ruminant production. Fatty acids act on the nucleus by binding to and regulating the activity of specific nuclear receptors or transcription factors, thus playing a central role in regulating the expression of genes involved in fatty acid uptake by muscle cells. Interactions between diet nutrients and the expression of genes involved in lipid metabolism have many possibilities regarding the deposition of fatty acids in the tissue. The study of gene expression has enabled clarification of the mode of fatty acid metabolism in muscle and the accumulation of intramuscular fat or marbling and the role of the genes that promote fatty acid oxidation and mitochondrial respiration in the liver muscle and adipose tissue. Polyunsaturated fatty acids with multiple double bonds (PUFA) and monounsaturated fatty acids with one double bond (MUFA) have received much attention in the last decade, and their health benefits are increasingly evident. Therefore, this study investigated the effect of using calcium salts of fish oil, olive oil, and saturated fat on the expression of some genes related to fat metabolism in Lori Bakhtiari×Romanov fattening lambs.
This study was carried out at the educational research station of the Department of Animal Science of the College of Agriculture and Natural Resources, University of Tehran. 49 male lambs aged four to five months with an average initial weight of 29.97 ± 0.88 kg were divided into seven groups of seven lambs in a completely randomized design. The experiment consisted of seven treatments with a basic diet as follows: 1) Basic diet without fat powder (control), 2 and 3) Basic diet with calcium salt of fish oil (rich in omega-3 fatty acids) in the amount of 2% dry matter of the diet for 90 and 45 days, respectively, 4 and 5) Basic diet with calcium salt of olive oil (rich in omega-9 fatty acids) at the rate of 2% dry matter of the diet for 90 and 45 days, respectively, 6 and 7) Basic diet with saturated fat powder in the amount of 2% dry matter of the diet for 90 and 45 days, respectively. Rations were adjusted based on the NRC Sheep and Goat and using the fifth version of CNCPS (The Cornell Net Carbohydrate and Protein System) software so that they are the same in terms of energy and protein. Twenty-eight lambs were slaughtered and a liver sample was taken for nutrigenomics studies. Total RNA was extracted from liver tissue samples using the RNA extraction kit produced by Dena Bio Asia Company (Mashhad) and according to the protocol provided with the kit. The expression of four main genes involved in lipid metabolism in liver tissue was investigated to provide comprehensive information on the effects of omega-3, omega-9 fatty acids, and saturated fat at the molecular level.
The results showed that feeding with calcium salts of fish oil, olive oil, and saturated fat, both in the whole 90 days or the last 45 days of the fattening period, had no significant effect on the expression of FADS1 and FADS2 genes in liver tissue compared to the control group. However, the use of calcium salts of fish and olive oils in periods of 90 and 45 days significantly increased the hepatic mRNA expression of the CPT1 gene (P=0.001) and ACOX1 gene mRNA expression in liver tissue compared to control and saturated fat treatments (P=0.002). The CPT1 enzyme is responsible for a mitochondrial transport system and plays a key role in controlling the oxidation of long-chain fatty acids and stimulating mitochondrial β-oxidation.
The results of this study showed that diet supplementation with calcium salts of fish and olive unsaturated fatty acids, regardless of the period of consumption, increased the expression of genes involved in the lipolysis of liver tissue fats of lambs.