Modelling broodiness in reproductive turkeys (Meleagris gallopavo)

Turkey (Meleagris gallopavo) is the second most popular poultry species in Europe with about 15% of thismarket. This position is, in part, the consequence of moderate production costs originating from rapid growthrates and effective feed efficiency. Unfortunately, selection on growth traits may impair reproductiveperformances including fertility and laying rates. In fact, one of the major problems is the decrease inegg production which is mainly due to broodiness, an incubation behaviour that is still present in modernturkey breeder strains (up to 20% to 30% of breeder hens). Broodiness is generally expressed during the firstweeks of the reproductive season. It is generally characterized by a marked reduction up to a total arrest offeed consumption during the days preceding broodiness.One of the objectives of our study was to collect field information from a relatively high population (47,000) of turkey breeder hens in order to possibly anticipate or, at least limit broodiness and therefore facilitate flock management. Birds used were from two commercial strains, one defined as ‘‘heavy’’ (Big6, Aviagen-BUT, Cheshire, UK, n ¼ 3; 360 females) while the other is considered as a ‘‘medium’’ type (BUT9, Aviagen-BUT, 4,200 females). Each strain was housed within two barns divided into 42 laying pens. Each broody female was individually identified and referenced by a coloured wing tag. The incidence and pattern of incubation behaviour along with the delay to return in lay were recorded throughout the period ofreproduction.The results of this study indicate the possibility to develop a model of broodiness. A higher percentage of incubation behaviour was observed in the Big6 hens compared to the BUT9 (16% versus 12%). In both strains, the average duration of stay in broody pens increased with hen’s age. Hens expressing incubationbehaviour after 18–20 weeks of lay tended not to return to egg production. Among females having experiencedbroodiness, those having experienced it twice stayed longer in broody pens than those having experiencedit once. Among hens getting broody once, 17–19% (BUT9) or 23% (Big6) went back to broodiness asecond time and among the latter ones, 15–22% (BUT9) or 20–26% (Big6) went back to broodiness a third time