1 question raised
So far, a large number of studies have been conducted to determine the methionine and lysine requirements of broilers, because in actual corn-soybean meal diets, lysine and methionine are considered to be the first and second limiting amino acids, and It is usually supplemented in the form of crystalline amino acids.
In modern broiler diets, methionine is always absent without amino acid supplementation, but lysine may exceed its minimum requirement, depending on the price and effectiveness of the protein feed.
Since lysine is set as the reference amino acid (ARC) in the concept of "ideal protein", some people mistakenly infer the importance of this concept, so when it is combined with other amino acids other than lysine, simply keep lysine The "ideal" ratio, although dietary lysine levels may exceed actual needs, results in higher levels of essential amino acids than actually needed.
Recent studies have shown that when lysine and methionine levels exceed the recommended levels of NRC, production performance may be improved, especially breast meat production. Although a large number of experiments have been conducted to study the requirements of methionine and lysine, there are few studies considering these two amino acids, and the existence of specific interactions between them suggests that the two amino acids do not have to be between Maintain a certain percentage.
2 related research
A test was designed to assess the effect of lysine and methionine levels equal to or greater than the recommended amount of NRC broiler cock diet, and to determine whether methionine and lysine levels are present when both amino acids exceed the minimum level. There is interaction. Three experiments used the same design to study possible interactions between lysine and methionine. There were 2 trials of broilers in the hot weather during the study. The results of the trial showed that breast meat production was affected by lysine levels, but there was no evidence that production must be maximized above the NRC level because there was no intermediate level between 0.95% and 1.05%.
According to reports, for male and female broilers aged 22-43 days, the digestible lysine requirements were 0.85 and 0.78%, respectively, and the optimal feed conversion efficiency requirements were 0.89 and 0.85%, respectively. According to the analysis, there is no significant difference between the lysine requirement for maximal breast meat production and the predicted minimum feed conversion efficiency. They converted the digestible lysine requirement based on the corn-soybean-type diet to the optimal feed conversion efficiency and breast meat yield to total lysine requirement, 1.01% for cocks and 0.97% for hens. The mixture of male and female is 0.99%, which is basically consistent with the recommended total lysine content of NRC of 1.0%.
There are few reports on the effect of methionine on breast meat yield. It has been reported that lysine levels are higher than NRC recommended levels without increasing breast meat production unless methionine is simultaneously higher than the NRC recommended level. However, only two levels of methionine (NRC and NRC + 116%) were compared. Two breeds of broilers (Rose, Steggles x AA) were fed, and the methionine levels of 0-8 weeks of age were "lack" or "appropriate" and slaughtered at 6 and 8 weeks. Low methionine diets reduced body weight and breast meat yield, increased 6-week-old abdominal fat, but did not increase in 8-week-old abdominal fat. Feeding a “lack of†diet at 6-8 weeks of age is very close to the NRC requirement.
It has been confirmed that the addition of methionine to a methionine-deficient diet has a response to breast meat yield but does not estimate the amount required to achieve maximum yield.
According to reports, in order to achieve the maximum broth acid requirement for breast meat production, during the period of 14-38 days, a certain range of methionine and total sulfur-containing amino acid levels were fed, and the total sulfur-containing amino acid requirement for body weight gain was estimated to be 0.84%. The feed conversion efficiency and breast meat yield were 0.88% and 0.89%, respectively. This again shows that in order to maximize feed conversion efficiency, breast meat production must be maximized, consistent with previous results. It is difficult to compare the recommended amount with the NRC recommendation because the respective stages are different. For further processing, broilers are generally raised to 38 days of age or older, so some research results are less likely to be used in commercial broiler production.
It is clear that breast meat production represents a major part of the body's protein synthesis and is sensitive to the state of the amino acids in the diet. Broiler breeds that emphasize breast meat production require higher lysine than those that are primarily used for weight gain. The amino acid levels that maximize feed conversion efficiency appear to be close to the levels required to achieve maximum breast meat production.
3 Conclusions
The current study showed that there was no significant interaction between lysine and methionine levels when lysine and methionine in the diet equaled or exceeded the recommended NRC.
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