1 2 3 4 5 6 7 8 9 10111 1 2 3 4 5 6 7 8 9 20111 1 2 3 4 5 6 7 8 9 30111 1 2 3 4 5 6 7 8 9 40111 1 2 3 4 5 6 7 8 9 50111 1 2 3 4 5 6 7 8 9 60111 INTRODUCTION Pre-incubation egg storage is inevitable in the broiler breeder industry. It is cost effective in that it decreases the number of individual incu- bations and provides hatcheries with exibility to meet market uctuations in demand for chicken meat. Egg storage however, may be detrimental to the developing embryo and thereby compromise hatchability. There are a number of conicting reports concerning the appropriate storage conditions for optimal hatchability and it remains unclear how these storage conditions affect water vapour loss during incubation, chick weight at hatch and hatching time. Early studies reported that storage periods exceeding 7 d reduced hatchability (Waite, 1919) and this detrimental effect was more pro- nounced if eggs were stored above 21·1°C (Funk et al., 1950). In contrast, raising the storage tem- perature above 18°C during short storage peri- ods of 2 to 3 d increased hatchability (El Jack and Kaltofen, 1968; Kirk et al., 1980). In the light of these results, Mayes and Takeballi (1984) rec- ommended the following storage times and temperatures for optimising hatchability; for storage periods of 1 to 3 d the temperature range should be maintained between 18 and 30°C but for storage periods exceeding 7 d should be 10 to 12°C. Recent studies however, have suggested that increasing the storage tem- perature during short storage periods has no effect on hatchability (Meijerhof et al., 1994; Reis et al., 1997). Meijerhof et al. (1994) found that increasing storage temperature from 15 to 20°C did not improve hatchability of fertile eggs stored for 2 d while Reis et al. (1997) found no improvement after storage temperature was increased from 16 to 21°C during storage peri- ods of either 1 or 2 d. It is well established that hatchability declines with storage periods exceeding 3 d irre- spective of storage temperature (Bohren et al., 1961; Byng and Nash, 1962; Merritt, 1964; Mayes and Takeballi, 1984; Meijerhof, 1992; Meijerhof et al., 1994; Reis et al., 1997). Apart from its detrimental effect on hatchability, egg storage prolongs incubation time (Bohren et al., 1961; Mather and Laughlin, 1976), reduces post-hatch body weight (Merritt, 1964) and retards embryonic development (Arora and Kosin, 1966a). However, there are few data con- cerning the effect on incubation time and chick weight at hatch of varying the storage tempera- ture at different storage durations. Effect of pre-incubation storage conditions on hatchability, chick weight at hatch and hatching time in broiler breeders J. RUIZ AND C.A. LUNAM Department of Anatomy and Histology, Flinders University of South Australia, Adelaide, Australia Abstract 1. Eggs were stored for two different times at varying temperatures. The effects on hatch- ability, chick weight at hatch and hatching time were examined in two broiler breeder lines from 33 to 58 weeks of age. 2. Short storage (1 to 3 d). Storage at 20°C compared with 16·5°C reduced hatchability of all eggs set. No effect was observed on hatchability of fertile eggs, hatching time or chick weight. 3. Long storage (9 to 11 d). Storage at 16·5°C compared with 10°C decreased both hatchability of fertile eggs and chick weight at hatch. Incidence of early embryonic death increased and incuba- tion time decreased at 16·5°C compared with 10°C. 4. Chicks from morning eggs were heavier than those from afternoon eggs irrespective of storage conditions. 5. Hatchability (all eggs set and fertile eggs) and chick weight varied with hen age irrespective of storage conditions. During long storage, hatching time varied with hen age independently of breeder line, storage temperature or egg laying time. 6. Hatchability (all eggs set and fertile eggs) was higher in line A than in line B. Line B eggs hatched later and produced heavier chicks than line A eggs irrespective of storage time. ISSN 0007–1668(print)/ISSN 1466–1799(online)/02/030374–10 © 2002 British Poultry Science Ltd DOI: 10.1080/00071660120103648 Correspondence to: Dr. C.A. Lunam, Department of Anatomy and Histology, School of Medicine, Flinders University of South Australia, GPO Box 2100, Adelaide, SA 5001, Australia. Tel: +61-8-8204-4704. Fax: +61-8-8277-0085. E-mail: chris.lunam@Flinders.edu.au Accepted for publication 11th December 2001.