Abstract
The aim of this study was to evaluate different feeding schedules and their relationship to calcium (Ca) and phosphorus (P) plasma levels and egg quality of broiler breeders. The feeding schedules were: single feeding at 8:00 AM; twice daily feeding (50% at 8:00 AM and 50% at 3:00 PM) and single feeding at 3:00 PM. 330 female and 45 male Cobb 500 broiler breeders were used from 40 to 60 weeks of age. The experimental design was completely randomized, consisting of 3 treatments with 5 replicates each, with 22 females and 3 males. The nutritional requirements were according to guideline recommendations. The following parameters were assessed weekly: total egg production, egg specific gravity, egg and eggshell weight, and eggshell thickness. Ca and P plasma levels, tibia weight and its length and Seedor index were evaluated at the end of the study. To determine the effect of feeding schedules, the total calcium and phosphorus plasma at oviposition time and 21 h after oviposition was evaluated. At 60 weeks of age, tibias were taken from the right leg, dried, measured and weighted. There were no differences among treatments regarding egg production, tibia length and Seedor index. Hens fed at 8:00 AM showed higher tibia weight than hens fed twice daily. Broiler breeders fed at 3:00 PM had higher egg (P = 0.0105) and shell (P = 0.0066) weight than others, and hens fed at 3:00 PM had more specific gravity (P = 0.0219) and eggshell thickness (P = 0.0419) than hens fed at 8:00 AM. Ca (P = 0.758) and P (P = 0.811) plasma levels were higher in hens fed at 8:00 AM than hens fed at 3:00 PM after 21 h of oviposition. Broiler breeders fed at 3:00 PM had better egg quality without any change in production, as well as these hens showing higher available Ca and P plasma levels.
Highlights
Broiler breeders are continuously selected for weight gain
The egg specific gravity (P = 0.0219) and eggshell thickness (P = 0.0419) were significantly higher in hens fed at 3:00 PM than the broilers breeder fed once in the morning
Hens fed at 3:00 PM produced egg (P = 0.0105) and eggshells (P = 0.0066) that were heavier than the other groups (Table 3)
Summary
Broiler breeders are continuously selected for weight gain. To regulate this gain, limit health risks, and maintain high fertility, husbandry practices for the parent stock of broiler chickens encompass a high degree of feed restriction (Renema and Robinson, 2004). Feed restriction is typically performed as once a day feeding during the laying period This feed is rapidly consumed (about 4 h); the hens fast for a long time before their feeding (Spradley et al, 2008). The practice of feeding only once a day cannot supply the nutritional needs of hens, for eggshell formation (Bootwalla et al, 1983), which normally starts in the afternoon or evening. This is because broiler breeders are unable to retain calcium from the crop to the lower digestive tract at a uniform rate (Farmer et al, 1983a). It may be possible to improve eggshell quality if nutrients are supplied at times that correspond more closely to periods of eggshell deposition by changing the time of feed intake (Backhouse and Gous, 2005)
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