title: Effect of immature body weight on laying performance.
abstract: Two trials were conducted to note the effect of immature body size of leghorn pullets on subsequent laying performance, and in particular, egg size. In Trial 1, birds were classified as small, medium or heavy at 15 wk of age (997, 1,100, and 1,226 g, respectively). In Trial 2, segregation at 19 wk resulted in groups with mean weights of 1308, 1411, and 1564 g, respectively. In each trial, weight groups were represented by 40 replicate groups of four individually caged birds. Original weight groupings were maintained throughout the trials (P less than .05). In both trials, immature weight classification had a consistent effect on both feed intake and egg weight (P less than .05); larger birds consumed more feed while producing larger size eggs. In Trial 1, medium weight birds produced more eggs over the 52 wk. Similarly, smaller weight birds produced more eggs than did heavy birds (P less than .05). In Trial 2, weight grouping had no overall effect on egg production, although during the 19 to 23-wk period, heavy birds produced more eggs (P less than .05). It is concluded that immature body weight (15 to 19 wk age) can influence egg weight and that this relationship is linked to levels of nutrient intake. Each 100-g increase in body weight was associated with approximately 3.5 g increase in feed intake and 1.2 g increase in egg weight.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Leeson
authors.forename: J D
authors.initials: JD
authors.lastname: Summers
mesh_terms: D000367:Age Factors; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000502:physiology*; D005260:Female; D010058:Oviposition