Thoughts on the growth stage of broilers

After so many years of genetics and breeding, the production performance of broilers has been greatly improved (so are meat ducks), but we still use the previous stage division method when making feed formula: chicken stage: 0-21 days old; middle chicken stage: 21-42 days old; big chicken stage: 42 ~ out of the pen. The formula designed according to this division may not be suitable for the actual growth needs of broilers at present, especially in the previous stage. Should we divide it in this way? Early stage: 15 days old; middle stage: 15-40 days old; later stage: 40 days old. Because in many places, farmers no longer use the materials of the first stage to 21 days old, but use them according to the quantity, which is basically the pre-period material of 1 jin for a chicken. Please communicate more. I think the division is more reasonable as follows: 0-7 days: egg yolk absorption, nutrient conversion period 8-28 days, the first depilation period, amino acid requirements can be adjusted 29-out. Rapid fattening period-as far as I know, it is divided into stages: 1-14-15-35 36-out of the hurdle-I think it's more reasonable to divide it this way. May I ask Wang Bo If according to your stage, how to redefine the nutrition standard of each stage?-- the principle of the first stage: the design similar to the weaning feed of suckling pig. Based on high energy and sufficient protein, the second stage to prevent dyspepsia, the third stage to provide sufficient sulfur-containing amino acids, mainly lysine, the first principle of growth rate design on the whole, the benefit of this design is more prominent-the cost should be used on the knife edge-- learned ah. Brilliant! You need it-- after learning, Wang Bo's analysis is reasonable.-- I think Dr. Wang's stage division is very reasonable. 0Murray 7 days is a combination of self-nutrition and feed nutrition. The feed is mainly high in nutrition and easy to digest. Support the viewpoint of 1-14, 15-35, 36-out of the column, considering not only the factors of yolk absorption and hair changing, but also the need for nutrient elements at the rate of development of different organs. Such as muscle, bone, fat and so on-that makes sense! Thank you!