The effect of pre-storage incubation on post-peak production broiler breeder eggs
By Tyler C. Gamble
Poultry Diagnostic and Research Center, Department of Population Health,
University of Georgia, Athens, GA
and Dennis R. Ingram
School of Animal Sciences, Louisiana Agricultural Experiment Station,
Louisiana State University, Baton Rouge, LA
Three trials were conducted with eggs from 57 to 62 week old Ross 708 broiler breeders to determine if hatchability could be improved by pre-storage incubation. Each trial used 1,440 freshly laid eggs from 2 flocks. Eggs were randomized into 6 treatment groups of 0, 12, 15, 18, 21, and 24 hours of pre-storage incubation. Each treatment was incubated in a NatureForm© Setter at 37.5°C with a 60% relative humidity. The control group remained in the egg cooler. After each incubation interval, the eggs were stored for 3 days. Following storage, the eggs were incubated for 18 days. On day 7, eggs were candled to determine infertile and early fertile dead. On day 18, eggs were transferred to a NatureForm© Hatcher at 37°C with a 75% relative humidity. On day 21, chicks, unhatched eggs, and pips were counted. Unhatched eggs were broken and the embryos were classified as early (1 to 7 days), mid (8 to 14 days), or late (15 to 21 days) dead. Heating for 21 and 24 hours in-creased (P < 0.0001) early dead. Warming for 24 hours increased (P = 0.0085) mid-dead. All treatments except 15 hours decreased (P = 0.0003) late dead. Warming for 21 and 24 hours increased (P < 0.0001) total embryonic mortality. Warming for 12 hours improved (P = 0.0008) fertile hatchability when compared to the control (86.6% vs. 81.8% respectively).
At the time of oviposition, a fertile egg will be composed of approximately 20,000 viable cells (Bell and Weaver, 2001). Embryos in eggs laid by older birds are more advanced at oviposition than those from younger birds. This may be due to eggs spending more time in the oviduct, either because the oviduct is longer or the rate of passage is reduced (Mather and Laughlin, 1979). The lower hatchability of breeders could be due to the stage of the embryo at oviposition. A young breeder will lay a fertile egg containing an embryo that has developed to the gastrula stage. If an older breeder lays an egg developmentally more advanced, the embryo may be going through a more active stage of development, therefore reducing its resistance to storage.
Incubating eggs prior to storage may increase the developmental stage of older broiler breeder eggs to a less active state, helping them better withstand storage (Fasenko, 2007). Hays and Nicolaides (1934) were the first to recognize that hens with higher hatchability had a more advanced blastoderm at oviposition. Fasenko (2007) suggested that there are particular embryonic developmental stages that are better able to survive storage. Embryos that have completed hypoblast formation may be at a relatively inactive stage and may better withstand developmental arrest. Fasenko et al. (2001) concluded that although their experiment yielded the best results with a pre-incubation treatment of 6 hours and a 14 day storage period, the ac-tual optimum pre-storage incubation treatment may be somewhere between 0 and 12 hours. Lancaster and Jones (1986) had similar results when pre-incubating eggs before prolonged storage. Their best results occurred in eggs coming from a breeder flock that was experiencing less than “high hatchability.” According to North and Bell (1990), “hatching eggs are pre-incubated to increase the percentage of hatchability.”
This study was conducted to test the hypothesis that pre-storage incubation of post-peak broiler breeder eggs would allow the embryo to better withstand storage and the incuba-tion process, resulting in an increase in fertile hatchability.
Materials and Methods
From a commercial hatchery, 1,440 Ross 708 broiler breeder eggs were transported for approximately 4 hours to the research farm. The eggs were collected from 2 flocks of the same age (trial 1, 57 weeks; trial 2, 62 weeks; trial 3, 59 weeks). All of the eggs were given 24 hours of adjustment time in an egg cooler at 15.5° C with a 60% relative humidity to reduce the effect of prolonged transportation. Eggs were then randomized into 6 pre-storage incubation groups of 0, 12, 15, 18, 21 and 24 hours. Each treatment group, with the exception of the control group, was incubated in a NatureForm© Setter 2000 at 37.5° C with a 60% relative humidity. The control group remained in the egg cooler. After each incubation interval was complete, the eggs were stored in the same egg cooler for 3 days. Following storage, the eggs were set into a randomized block design and incubated for 18 days in the same setter at 37.5° C with a 60% relative humidity. Unused levels in the incubator were set with non-experimental eggs in order to maintain airflow integrity. Candling of eggs to determine infertile and early fertile dead occurred on day 7. The eggs thought to be infertile were removed and broken to determine true fertility. On the 18th day, the eggs were transferred to a NatureForm© Hatcher 2000 at 37° C with a 75% relative humidity. On day 21, chicks, unhatched eggs, and pips were recorded. Unhatched eggs were broken and the embryos classified as early (1 to 7 days), mid (8 to 14 days), or late (15 to 21 days) dead. Trials 2 and 3 were conducted identically to trial 1. A randomized block design was used for statistical analysis, with each level in the incubator serving as the block, and a group of 30 eggs was the experimental unit. All percentages underwent square root arcsine conversion before analysis. When significant effects were found, means were separated by Duncan’s Multiple Range test. Regression analysis was used to obtain a prediction equation for fertile hatchability. With no significant trial by treatment interaction, data from trials 1, 2, and 3 were combined.
Results and Discussion
Total hatchability, early, mid, and late embryonic mortality as well as pips were significantly (P < 0.05) different among trials 1, 2, and 3. This is to be expected, since these effects are probably due to differences in flock age and farm management. There was not a significant trial effect on fertile hatchability nor total embryonic mortality (Table 1).
True fertility was not a dependent variable because fertilization occurred before any experimental treatments were applied. However, since fertility is a component of total hatchability, it was necessary to establish that there were no significant (P < 0.05) differences in fertility. The true fertility was not significantly different between treatments (Table 2).Early embryonic mortality was significantly (P < 0.0001) increased by 21 and 24 hours of pre-storage warming. Mid embryonic mortality was significantly (P = 0.0085) increased by 24 hours of pre-storage warming, whereas late embryonic mortality was significantly (P = 0.0003) decreased by 12, 18, 21, and 24 hours of pre-storage warming. Total embryonic mortality was not affected by 12, 15, or 18 hours of treatment, however, 21 and 24 hours of treatment significantly (P < 0.0001) increased total embryonic mortality (Table 3). This suggests that the stage of the embryo at oviposition after 12, 15, or 18 hours of pre-incubation can with-stand storage and the incubation process better than the stage of the embryo after 21 or 24 hours of incubation, which is detrimental to livability. This effect disagrees with previous re-search in our lab, however, those experiments were conducted using different strains, shorter pre-storage incubation treatments, and without an adjustment period after transportation (Dowden, 2009; Wiggins, 2008). Treatment did not significantly (P > 0.05) affect pips (Table 3). Fertile hatchability was significantly (P = 0.0008) decreased by 21 and 24 hours of pre-storage incubation. Twelve hours of pre-storage incubation significantly (P = 0.0008) improved fertile hatchability by 4.8% when compared to the control (Figure 1). It appears that the increase in fertile hatchability is due to, at least in part, a reduction in late embryonic mortality. When regression analysis was conducted to determine a prediction equation, 9 hours of pre-storage incubation produced the optimal result (Figure 2). This agrees with the Fasenko et al. (2001) conclusion that the optimal pre-storage heating treatment is somewhere between 0 to 12 hours when stored for long periods of time. Further research in this area is required to elucidate a true causal relationship between pre-storage incubation, embryonic development, and improved hatchability. However, adapting management procedures of post-peak broiler breeder flocks with sub-optimal hatchability to include 9 hours of pre-storage incubation may prove to be beneficial to hatchability.
Bell, D.D. and W.D. Weaver, 2001. Commercial Chicken Production Manual. 5th edition. Avi., New York, NY.
Dowden, J.M., 2009. Effects of warming end of lay broiler breeder eggs during the storage period on hatchability. Masters Thesis. Louisiana State University.
Fasenko, G.M., 2007. Egg storage and the embryo. Poultry Sci. 86:1020-1024.
Fasenko, G.M., F.E. Robinson, A.I. Whelan, K.M. Kremeniuk, and J.A. Walker, 2001. Prestorage incubation of long-term stored broiler breeder eggs: I. Effect on hatchability. Poultry Sci. 80:1406-1411.
Hays, F.A. and C. Nicolaides, 1934. Variability in development of fresh-laid hen eggs. Poultry Sci. 13:74-90.
Lancaster, F.M. and D.R. Jones, 1986. The pre-heating of broiler hatching eggs prior to storage. Br. Poultry Sci. 27:157.
Mather, C.M. and K.F. Laughlin, 1979. Storage of hatching eggs: the interaction between parental age and early embryonic development. Br. Poultry Sci. 20:595-604.
North, M.O. and D.D. Bell, 1990. Commercial Chicken Production Manual. 4th Edition. Avi, New York, NY.
Wiggins, C.B., 2008. Hatchability of post peak egg production broiler breeder eggs as influenced by pre-incubation warming. Masters Thesis. Louisiana State University.
About the author
Dr. Tyler Gamble was born and raised in Soso, Mississippi— a small southern town with a thriving poultry industry. Here he developed an interest in poultry while working odd jobs on small, family owned farms. He pursued his passion at Louisiana State University where he obtained a bachelor’s degree in poultry science. Dr. Gamble then returned home to Mississippi State University for veterinary school. He received his doctorate degree in veterinary medicine in 2015 and is currently enrolled in the University of Georgia’s Master of Avian Medicine program.
Article courtesy of The Poultry Informed Professional
Published by the Department of Population Health, University of Georgia
Editor: Dr Stephen Collett, Associate Professor