Lysine and methionine have independent effects in broiler diets

Since lysine is set as the reference amino acid 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 it with lysine. An ideal ratio, although dietary lysine levels may exceed actual needs. Recent studies have shown that there is no significant interaction between the two when the dietary lysine and methionine levels equal or exceed the NRC recommendation.

So far, a large number of studies have been conducted to determine the methionine and lysine requirements of broilers, because in the actual corn-soybean meal diet, 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; Baker and Han) 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 go Maintaining an "ideal" ratio of lysine, although dietary lysine levels may exceed actual needs, the result is that other essential amino acid levels are higher than actual needs.

Recent studies have shown that lysine and methionine levels above the recommended level of NRC may increase performance, especially breast meat production (Hickling et al.; Moran and Billgli; Schutte and Pack). 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. We designed this study to assess the effect of lysine and methionine levels equal to or greater than the NRC broiler cock diet recommended daily, and determine whether methionine and lysine levels are present when both amino acids exceed the minimum level. There is interaction. The three experiments used the same design to study possible interactions between lysine and methionine. Two broilers tested during the study just happened to be hot. The paper confirmed 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%. Han and Baker studied the digestible lysine requirement of male and female broilers aged 22 to 43 days. The digestible lysine requirements for weight gain in male and female chickens were estimated to be 0.85 and 0.78%, respectively, and the required feed conversion efficiency was 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. Studies by Hickling et al. showed that lysine levels were higher than NRC recommendations without increasing breast meat production, unless methionine was higher than NRC recommended at night. However, only two levels of methionine (NRC and NRC + 116%) were compared. Moran fed two breeds of broiler chickens (Rose x Rose, Steggles × AA), and the 0-8 state diet methionine levels were "lack" or "suitable" 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 “lack of” diets at 6-8 weeks of age is very close to the NRC requirement. Wallis confirmed the addition of methionine to the methionine-deficient diet, which responded to breast meat yield but did not estimate the amount needed to achieve maximum yield.

There are few reports on the amount of methionine needed to achieve maximum breast meat production, and Schutte and Pack's report is one of them. During the 14-38 days of age, feeding a range of methionine and total sulfur-containing amino acid levels, the estimated total weight of sulfur-containing amino acids was 0.84%, feed conversion efficiency and breast meat yield were 0.88% and 0.89, respectively. %. This again shows that to maximize feed conversion efficiency, breast meat production must be maximized, consistent with the results of Han and Baker. The recommended quantities of Schutte and Pack are difficult to compare with the NRC recommendations because the respective stage divisions are different. In the United States, for deep processing, broilers are generally raised to 38 days of age or older, so the results of Schutte and Pack's research are less likely to be used in US 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. 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.