Ruminant protein nutrition research, from traditional crude protein or digestible protein systems, to degraded and non-degraded protein systems and small intestine digestible protein systems, has so far shifted the focus of research to the amino acid source, quantity, composition and protein turnover of the small intestine. . The amino acid requirement of ruminants is the basis of amino acid regulation in the small intestine of ruminants. It is through the regulation of feed and digestive system, so that the amino acids entering the small intestine can meet the production needs of animals. The amino acids absorbed in the small intestine of ruminants include the degradation of three source proteins: 1 rumen microbial protein; 2 feed non-degrading protein; 3 endogenous protein. Feed non-degradable protein and rumen microbial protein are digested and absorbed in the small intestine. Microbial protein is the main source of amino acids in the small intestine. The jejunal ileum is the main absorption site of amino acids. Therefore, rumen microbial protein production and amino acid composition, amino acid nutrition and amino acids of ruminants The pattern has an important impact. 1 ruminant ideal protein model Ideal Amino Acid Model The ideal protein is an important concept in modern animal nutrition, that is, the amino acid needs to satisfy animal maintenance and body protein deposition or as a bioactive precursor synthesis, with the best dietary pattern between essential amino acids. The ideal protein is based on the nutritional and genetic potential of animals and has evolved from a theory to a practical technique that has been extensively studied and applied in the nutrition of monogastric animals (pig chicken). The need for protein in ruminants is fundamentally different from that of monogastric animals. When the dietary amino acid passes through the rumen, its form undergoes a fundamental change, that is, the conversion of dietary protein into microbial protein. In fact, it is impossible to study the ideal amino acid pattern of ruminants with amino acid balance model diet, but the development of ruminant nutrition research methods such as fistula technique, perfusion technique, blood intubation technique and isotope tracer technique is the study of amino acid balance model of ruminants. A useful tool is provided. In addition, considerable progress has been made in the study of the ideal amino acid pattern of ruminants, which provides a theoretical basis for the determination of amino acid requirements in ruminants. In particular, Lu Dexun proposed a new concept of metabolite amino acids. The first connection between the rumen and the small intestine can accurately reflect the metabolic protein of the whole body, and can be used as an ideal indicator for the overall optimization of protein and amino acid nutrition. Coupled with the development of computer technology and predictive models, it has become possible to control the supply of amino acids in the small intestine through diet coordination. 2 ruminant restricted amino acid The amino acid composition imbalance diet is the research object. In the essential amino acids, the amino acid utilization rate of the animal is reduced due to the lack of certain amino acids, and the deficiency amino acid is called a limiting amino acid. In the monogastric animal nutrition research and feed protein nutritional value assessment, the concept of limiting amino acids has received sufficient attention and application. In the case of ruminants, when production performance is improved, amino acid transport, absorption and utilization of the small intestine, and microbial protein production are limited, resulting in an increase in amino acid requirements, exhibiting certain amino acid restriction effects. Therefore, there are also limiting amino acids in ruminant nutrition. Experimental studies have shown that lysine, methionine and histidine are the first, second and third limiting amino acids of dairy cows, and phenylalanine is a potentially limiting amino acid (Rulquin, 1987; Fraser et al., 1991; Schwab et al. 1992). The limiting amino acids of growing cattle are methionine, lysine, arginine, leucine, threonine. (Hatfield, 1978; Titgemeger et al., 1990; Ragland-Gray, 1997). The limiting amino acids of growing sheep are methionine, lysine, threonine, histidine, arginine (Nimrich, 1970; Orskov, 1984). Leucine, isoleucine, valine, and sulfur-containing amino acids may be potential limiting amino acids in dairy cows (Tigemeyer, 1992). Due to the complexity of the digestive physiology of ruminants and the limitations of research methods, the limiting amino acids and sequences of ruminants have not been fully determined under practical dietary conditions. 3 regulation of rumen protein in the diet 3.1 Increase the rumen protein through the rumen protection protein 3.1.1 Chemical Treatment 3.1.1.1 Formaldehyde Protection Law The formaldehyde is highly reductive, and the amino group, carboxyl group and sulfhydryl group of the protein molecule are alkylated, so that the solubility is lowered, and the protein is reversibly reacted under acidic conditions, so that the degradation rate of the protected protein in the rumen is decreased. In the post-ruminal digestive tract, it is separated from formaldehyde by the decrease in pH and is digested by protease. Wright (1971) demonstrated that sulfur-containing amino acids treated with formaldehyde can increase body weight and hair production. Ren Li et al. (2001) reported that using 0.7% formaldehyde to protect cottonseed cake, sunflower cake and flax cake reduced the degradation rate of protein in the rumen and had no adverse effect on sheep performance. . However, formaldehyde concentration, treatment time, temperature and pressure, and the type of feed treated can significantly affect the protective effect, the most important of which is the formaldehyde concentration. When Thomas et al. (1979) treated soy flour with formaldehyde, it was found that when the amount of formaldehyde was 0.4% of crude protein, the degradation rate of rumen protein was significantly reduced, while the amount of degradation increased from 0.4% to 0.8%, the degradation rate was not obvious (P> 0.05). Deng Weidong et al. (2000) also proved that the dosage of formaldehyde is 0.4% (g/100gCP), which is the best treatment effect for protecting bean cake. This dosage can effectively reduce the degradation of dry matter, organic matter and crude protein in the rumen without affecting its Digestion in the stomach and small intestine; treatment of rapeseed cake with 0.4% and 0.6% can greatly reduce the degradation rate of dry matter and crude protein in the rumen, and basically does not affect its digestion in the stomach and small intestine. The difference between these two levels was not significant (P>0.05), so the optimal level of formaldehyde-protected rapeseed cake was 0.4%. Li Qihua et al (1999) found that 2g/kg DM formaldehyde treatment can greatly reduce the degradation rate of bean biscuit material and crude protein in the rumen without substantially affecting its digestion in the stomach and small intestine. If the amount of formaldehyde exceeds 2g/kg DM, Will cause overprotection. The results of Spear et al. (1980) and Vicini et al. (1983) showed that the higher the concentration of formaldehyde, the higher the protection of protein from degradation in the rumen, but the excessive concentration of formaldehyde would overprotect the protein and affect the protein. Digestion of the digestive tract. Sengar et al. (1982) studied the rumen degradation of peanut cake with formaldehyde. It showed that the ammonia concentration in the rumen decreased significantly with the increase of formaldehyde dosage, and the digestion of ammonia by microorganisms and enzymes depends on the duration of formaldehyde treatment. According to Phillips (1981), the optimum amount of formaldehyde for ruminant livestock to use nitrogen is 35~58g/kg crude protein. However, since formaldehyde is toxic and easily remains in the livestock, it is controversial. Petri Dishes (Stackable & Slippable)
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