Body weight and/or fatness as potential determinants of the onset of egg production in broiler breeder hens

Abstract

In four trials during consecutive years individually-caged birds were weighed at first egg, and in the first two trials they were then killed to determine abdominal and skin fat, in order to establish whether there is a minimal body weight and/or body fat pool required for the start of egg production in broiler breeder hens. There were negative correlations ranging from significant to negligible between body weight and age at first egg. For birds of the same strain on a conventional food restriction regimen, the average weight range at first egg in the four trials was 3.3 to 3.7 kg, which may be a strain characteristic. In spite of severe food restriction, all birds were very fat at first egg. The correlations between fat concentration and age at first egg were negative. In mature pullets a minimum concentration of stored, easily mobilised fat may be essential for yolk formation and ovulation.

Effects of Radio Tags on Captive Northern Bobwhite (Colinus virginianus) Body Composition and Survival

“…These measurements diverged soon after we attached tags, and the effects persisted to the end of the study (12 wk). Thus, radio tags affected body composition of captive quail in a manner that is usually interpreted as deleterious (e.g., Robel, 1972;Robel et al, 1974;Bornstein et al, 1984;Wilson et al, 1992;Pietz et al, 1993;Rotella et al, 1993).…”

“…Radio-tagged birds often lose mass, presumably lipid mass, relative to untagged birds (Greenwood and Sargeant, 1973;Schulz and Upgren, 1977;Seamans, 1985). Loss of lipid mass may affect an animal's survival and reproductive success (e.g., Gates and Woehler, 1968;Robel, 1972;Robel et al, 1974;Bornstein et al, 1984;Wilson et al, 1992;Pietz et al, 1993;Rotella et al, 1993). Thus, consideration of the possible negative effects of radio tags on study animals is crucial to the interpretation of data based on radio telemetry.…”

Performance of early and late feathering broiler breeder females with different feeding regimens

“…These correlated responses may be circumvented partially by control of body weight through restricting food intake. Restriction of food intake during rearing delays sexual maturity (Pym and Dillon, 1974;Bornstein et al, 1984;Soller et al, 1984;Robbins et al, 1986) and increases egg size (Katanbaf et al, 19896). After the onset of lay, production of defective eggs can be reduced by controlling food intake (Hocking et al, 1987(Hocking et al, , 1989Katanbaf et al, 1989&).…”

Anorexia and sexual maturity in female white rock chickens. I. Increasing the feed intake

“…In chickens there are age and body-weight requirements for the onset of sexual maturity (Dunnington et al, 1983 as well as particular threshold levels for components of carcass composition (Bornstein et al, 1984;Brody et at., 1984 Selection for high and low juvenile body weight in White Plymouth Rock chickens has resulted in two distinct populations differing in growth, feed consumption, and feeding behavior Dunnington et al, 1987). Differences in feed consumption concomitant to selection for juvenile body weight have been hypothesized to be associated with alterations of a satiety center in the brain (Burkhart et al, 1983).…”