Broiler Growth and Carcass Traits

In the present study, the workflow for the experiment is illustrated in Fig. 1, and all chickens were obtained from the fast-growing white-feathered pure line B. Line B is a synthetic line produced by Foshan Gaoming Xinguang Agricultural and Animal Industrials Co., Ltd. (Foshan, China), and it has been selected for high body weight and growth rate traits for seven generations. In generation 6, a total of 189 male broiler breeders at 24 d of age, which were produced in the same hatch from 68 sires and 127 dams in generation 5, were randomly selected. They were housed in identical individual cages and provided with water and feed ad libitum. Each day, the amount of fresh feed provided was recorded individually, and residual feed was recorded daily and removed for an intervening period at 28 d of age. The broilers were fed a common corn-soybean meal diet until the end of the trial (42 d of age). The diet contained 2,900 kcal/kg metabolic energy and 183 g/kg crude protein, and detailed information about the diet is summarized in Table 1. The birds were slaughtered at 43 d of age after a 12-h overnight fast to obtain records of carcass traits, including abdominal fat weight (AbF).
Fig. 1

The workflow for the experiment in the current study

Table 1

Ingredient and nutrient composition of the experimental diet

Ingredients, %		Nutrients composition
Corn	67.35	Metabolizable energy, kcal/kg	2,900
Soybean meal	28.00	Crude protein, %	18.30
Soybean oil	0.40	Arginine, %	1.14
Limestone	1.90	Lysine, %	1.07
Monocalcium phosphate	1.00	Methionine, %	0.47
Salt	0.40	Methionine + Cystine, %	0.77
Lysine	0.22	Threonine, %	0.73
Methionine	0.17	Tryptophan, %	0.24
Choline chloride	0.14	Calcium, %	1.01
Premix1	0.42	Available phosphorus, %	0.31
Total	100

¹Premix supplied per kilogram of diet: vitamin A, 13,200 IU; vitamin D₃, 5,000 IU; vitamin E, 60 IU; vitamin K₃, 8.0 mg; thiamine, 4.0 mg; riboflavin, 12.0 mg; pyridoxine, 12.0 mg; cobalamin, 0.4 mg; nicotinic acid, 80 mg; pantothenic acid, 24 mg; folic acid, 2.0 mg; biotin, 3.0 mg; iron, 70.0 mg; copper, 8.5 mg; zinc, 45.0 mg; manganese, 60.0 mg; iodine, 0.85 mg; selenium, 0.20 mg; cobalt, 0.25 mg