| It is well established that broiler breeder is more sensitive to dietary energy level during the late laying period. Restriction of dietary energy level properly is a conventional strategy not only to reduce the fat accretion but also to avoid health complications. Maternal nutrition may alter the nutrient supply deposited in the egg and then affect the embryo development, early growth in offspring. The experiment was conducted to evaluate the effects of different dietary energy levels on laying performance, egg quality, egg components, maternal biochemical parameters and meat quality of Arbor Acres (AA) broiler breeders during the late laying period. All these researches would elect the best dietary energy level to keep broiler breeders health and egg quality during the late laying period. Moreover, it would provide theoretical and practical basis to make a better understanding of the relationship among the maternal nutritional status, egg nutrition deposition and offspring’s quality.A single factor design was adopted, a total of270females Arbor Acres broiler breeders at20weeks of age were selected from the breeder stock. These female birds were divided into3treatments randomly (each treatment represented by6replicates of15birds), including2experimental treatments and one control group. The study commenced at the beginning of the laying period, defined as the age when total egg production reached5%of the flock. From then on, the broilers in the control group were fed basal diet (ND,11.72MJ/kg of ME), and other groups were fed diets with120%(HD,14.04MJ/kg of ME),80%(LD,9.36MJ/kg of ME) energy levels of the basal diet, respectively. In addition to the energy level, nutritional levels of intake were the same in each group.The experiment was started at50-week-old, ended at60-week-old and lasted for10weeks. The results showed that:(1) Compared with ND, egg weight of HD were decreased most significantly (P<0.01) and no effected of80%dietary energy level on laying rate, qualified egg rate and crack egg rate of broiler breeders during the late laying period (P>0,05).(2) As dietary energy decreased, yolk color score numerically reduced in each group (P<0.05). Compared with ND, there were not significantly affected by120%,80%dietary energy levels in the diet on egg quality (P>0.05).(3) At55weeks old, Compared with ND, the contents of crude fat in yolk of HD were markedly increased (P<0.05). No effected of80%dietary energy level on yolk, eggshell, eggwhite and even components were found (P>0.05). Compared with HD, significantly lower displayed on yolk relative weight (P<0.05) as well as the ratio of egg white and yolk (P<0.01) in LD. At60weeks old, Compared with ND, the contents of crude protein in yolk of HD were markedly increased (P<0.05), the contents of crude fat in yolk in LD decreased significantly (P<0.01). Compared with HD, the ratio of egg white and yolk as well as yolk relative weight in LD were notably lower (P<0.01).(4) Broiler breeders from LD had lower abdominal fat percentage and muscle lipid bandwidth (P<0.01). Thigh and breast muscle percentage as well as skinfolds were not affected by the80%dietary energy level for broiler breeders during the late laying period (P>0.05).(5) Compared with ND, LD had higher a*value in breast and higher cooking loss in thigh, HD had higher b*value in muscle (P<0.05). Compared with HD, muscle’s shear force markedly increased and breast’s pH value in LD decreased significantly (P<0.05).(6) Compared with HD, LD has higher crude protein contents in muscle (P<0.05) as well as lower crude fat contents in muscle (P<0.01). Dry matter contents in muscle were not affected by the120%,80%dietary energy levels for broiler breeders during the late laying period (P>0.05).(7) Compared with ND, HD had higher TG contents than others (P<0.01). No effected of80%dietary energy level on TG, TP and ALB contents of broiler breeders during the late laying period (P>0.05).Compared with HD, LD had lower TG and TP contents than others (P<0.01). GLU and CHO contents were not affected by the120%,80%dietary energy levels for broiler breeders during the late laying period (P>0.05).The above results showed that different dietary energy levels had complex effected on broiler breeders during the late laying period. When dietary energy level decreased to9.36MJ/kg, the laying performance and egg quality were not affected adversely but improved the carcass characteristics and most suitable in production practice. |
