Effect Of NCG On The Growth Performance Of Weanling Mice

Due to weaning stress, weaning animals will be loss of appetite, decreased immunity, slow growing and other symptoms. Early weaning stress is one of the main problems which hinder the development of Pig industry currently. Studies have shown that arginine (Arg) in the feed can not meet the need for animal growth after weaning, is one of the reasons causing these symptoms. Arginine is very important for weaning stress of piglets. So enhancing the endogenous synthesis of arginine is an effective method to cope with weaning stress.N-carbamoyl-L-glutamate (NCG) is an analogue of N-acetyl-L-glutamate (NAG). It can replace NAG to be the activator of CPS-I to promote the conversion of proline and glutaminate to arginine and increase endogenous synthesis of arginine. Besides, NCG is not the substrate of cell deacetylation enzymes or amino acid metabolism enzyme, so it is not degradable in the cell enzyme decomposition. Thus NCG has a more significant effect than NAG. Therefore NCG can play a crucial role in maintaining arginine homeostasis in piglets. It can be seen that NCG can effectively solve the weaning-stress problem originated by the deficiency of arginine. Now there are little research on the NCG and the biological activity of NCG is lack of a systematic study as well. This dissertation researched NCG and its combined effects with Arg on growth performance, serum biochemical parameters, serum arginine concentration and immune organ index of weanling mice, in order to provide a theoretical basis for the development of NCG as a new feed additive product.The main contents, results and conclusions in this dissertation are summarized as follows:1. The effect of different concentrations of NCG on the growth performance of weaned mice. Adding0.025%,0.05%,0.1%NCG in the weanling mice's basal feed, then monitored the changes of body weight, average daily gain, daily feed intake and feed/gain to research the effect of different concentrations of NCG on the growth performance of weaned mice. The results showed that:adding0.1%NCG in the weanling mice's feed, the average daily gain of this group increased by12.40%and the feed/gain ratio reduced by14.65%compared with control group. Conclusion: Adding appropriate concentration of NCG in diet can significantly improve the growth performance of weanling mice.2. The combined effects of NCG and arginine together on the growth performance of weanling mice. Methods:By simultaneous adding0.05%NCG and three different levels of arginine (0.025%,0.05%,0.1%) in the weanling mice's feed, studied the combined effects of NCG and arginine together on the growth performance of weanling mice. The results showed that:Simultaneous adding0.05%NCG and0.025%arginine in the weanling mice's feed, the average daily gain of this group increased by10.53%compared with control group. Conclusion:Appropriate concentration of NCG and arginine combined with together can also significantly improve the growth performance of weanling mice, which results are better than the single addition of NCG or arginine. Besides, adding arginine alone can improve the growth performance of weanling mice only at the initial stage of weaning. After that effects are poor. However, adding0.1%NCG, appropriate concentration of NCG and arginine combined with together can also improve the growth performance of weanling mice much better over the whole experimental stage.3. The effects of NCG on the content of serum glutamic-pyruvic transaminase (GPT), serum urea nitrogen (BUN), total protein, albumin, and globulin of weaned mice. Conclusion:NCG and the combined effects of NCG and arginine together have no significant effects on the content of serum glutamic-pyruvic transaminase (GPT). The BUN value of high NCG group and high arginine combined group was significantly higher than control group. So, high concentrations of NCG, high concentrations of Arg and the middle dose of NCG combined effects may cause some damage to the kidneys of mice. High NCG group and NCG combined arginine group have no significant effects on the content of serum total protein or albumin compared with control group. Middle NCG group, the total protein and albumin levels were significantly lower than control group. Therefore, the effect of NCG on the growth performance of weaned mice has no direct contact with serum total protein and albumin content.4. The effect of NCG on the mass concentration of free Arg in the serum of weanling mice. The research showed that:Adding0.05%,0.1%NCG in the weanling mice's feed, the mass concentration of free Arg in the serum of weanling mice respectively increased by21.00%and42.77%compared with control group. The NCG cause change in body Arg synthesis is not directly proportional to the NCG additive amount. Form average daily gain and serum free Arg content found: Improved growth rate has a relationship with enhancing the body Arg conversion, but not a direct proportion. The reason of NCG contribution to enhance the growth performance, in addition to the endogenous Arg synthesis, but also other impact.5. The effect of NCG on the immune organ index of weanling mice. The research results showed that:The effect of NCG on the spleen index of weaning mice has a linear relationship, but the effect is not significantly, and less impact on the thymus index. Both spleen index and thymus index of NCG combined arginine group have no significant difference compared with control group. Conclusion:The combined effects of NCG and arginine together have no significant impact on immune organ index of after weaning17days mice.