Maternal body weight and feed allowance of breeders affect performance of dwarf broiler breeders and tibial ossification of their progeny

Four hundred and eight dwarf broiler breeder hens were raised collectively in a floor pen to 21 wk of age. At this age they were classified into four groups with reference to their individual BW as heavy (1.95 +/- .1 kg), medium (1.80 +/-.1 kg), light (1.69 +/-.1 kg), and ultralight (1.57 +/-.1 kg). All groups were individually caged at 23 wk of age. During the reproductive period, each group was divided into three subgroups fed on liberal, intermediate, or severe feed restriction (reaching up to 135, 125, and 115 g of daily feed allowance at 29 wk of age, respectively). Intergroup differences in BW were maintained throughout the experiment (21 to 61 wk) but tended to decrease with age. Hen-day egg production was depressed by the lower feed allowance. Fertility and hatchability were impaired when hens received the largest quantities of food. Hen size influenced female breeder performance only slightly. Shell quality and albumen quality were affected by the level of feed consumption. Egg weights as well as BW of the progeny at hatching were enhanced by increased maternal BW and feed allowance. This positive maternal effect was still present at 40 days of age. Despite better overall BW perfomances of the male versus female broilers, the abdominal fat pad of female broilers was heavier than that of males and tended to increase with breeder size and breeder feed allowance. Accordingly, tibial breaking strength and percentage ash of the progeny at hatching were markedly improved in proportion to the breeders' BW and to their feed allowance. The effect of breeder size on broiler tibial quality was maintained up to 40 days of age but the effect of breeder feed intake tended to disappear with increasing age of the broilers. Tibial strength and mineralization were higher in male than in female broilers at 40 days of age. Dyschondroplasia was higher in broilers hatched from heavier breeder hens, but was not influenced by breeder feed intake. The incidence of varus and valgus in progeny was similar whatever the breeders' treatment. It is concluded that performance of dwarf breeders in a given flock depends mainly upon breeder feed allowance but that broiler performance and, especially, tibial ossification of broilers is greatly influenced by maternal size and, to a lesser extent, by maternal feed intake.