Effect of egg storage temperature and fumigation on hatchability of Cobb 500 and Hubbard broiler strains

Hatchability of Cobb 500 and Hubbard broiler strain eggs subjected to different levels of egg storage temperature and fumigation was studied at Debre Zeit Agricultural Research Center, Ethiopia. The different egg storage temperature levels employed were 10, 16 and 23°C and fumigation levels employed were fumigated and unfumigated. Fertility and hatchability were tested during the experimental period. Fertility is not dependent on egg storage treatments employed. Egg storage temperature at 16°C and fumigation significantly (P<0.001) improved hatchability in both Cobb 500 and Hubbard broiler strains. Cobb 500 broilers had high mean percentage hatchability than Hubbard, but the differences were not significant (P>0.05). Egg storage temperature at 23°C resulted in slightly lower mean percentage hatchability than storage at 10°C, but the differences were not significant (P>0.05). From the result of the current experiment, it was concluded that fumigation and medium egg storage temperature, 16°C is important for better hatching yield.


INTRODUCTION
Poultry is an important farm animal species in almost all countries.It is an important source of animal protein and can be raised in situations with limited feed and housing resources.Chickens are "waste converters"; they "convert" a scavenged feed resource base into animal protein.
They are therefore, one of the most important species for generating income for rural family, especially for developing country like Ethiopia.All over the world, more than 300 breeds of the domestic chicken species (Gallus domesticus) exist.Three main categories of chicken breeds are distinguished: pure commercial breeds, hybrid breeds resulting from cross-breeding and local breeds or land races.
Chicken population of Ethiopia is estimated to be 38.3 million (CSA, 2009).To meet food self-sufficiency and poverty reduction, Ethiopia has launched a short and long-term plan program from 1995 onwards.One of the strategies is to exploit poultry resources in the development process.The effort made in improving the poultry industry is one of such strategy that gave more *Corresponding author.E-mail: melakuuu@yahoo.com.Tel: +25191 138 2333.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License emphasis to the introduction of exotic germplasm.At this juncture, broiler production may contribute in meeting the food self-sufficiency for the rapidly increasing Ethiopian human population and to meet the growing demands of animal protein in the country.Their short production cycle, high feed efficiency and high biomass per unit of agricultural land are particularly attractive for Ethiopia where the demand and price for animal protein foods is escalating.
Egg storage is a necessary process in poultry industry to accumulate sufficient number of eggs necessary for each setting.The goal, then, of egg storage is to bring to a standstill embryo development while maintaining their ability to resume development and produce viable and healthy chicks.Hatching eggs are often stored on broiler breeder farms as well as at hatcheries to minimize transportation costs or to provide for enough eggs available to fill the large incubators.Egg storage conditions prior to incubation can influence hatchability and are, thus of considerable concern to commercial hatchery enterprises (Butler, 1991).One of the most important conditions is temperature.Storage conditions should be sufficiently cool to prevent embryonic development during this period.For most bird species, the critical temperature for the initiation of embryonic development appears to be about 25 to 27°C (Drent, 1975).The hatchability of an egg does not necessarily correlate with the quality of chick (Tona et al., 2005).The quality of chick that emerges out of an egg depends on factors such as the age of breeder, length and storage condition of egg before incubation and the incubation conditions (Tona et al., 2005).In the commercial broiler, breeder farms and hatcheries, formaldehyde fumigation is routinely carried out to disinfect hatching eggs (Feras and Beleh, 2008).
Nowadays, new broiler breeds are introduced into the country to solve the scarcity of day old broiler chicks requirement by producers and their by increase the supply of animal protein in the country.However, recommended pre-hatching storage condition of eggs is not well studied.Hence, producers use by adopting information available for commercial layers hatching egg management.In Ethiopia, farmers store eggs at room temperature, but the temperature of the area may vary according to altitude and season.Fumigation of eggs before storing is not also practiced by producers.One of the reasons for not employing proper storage conditions and fumigation could be due to lack of appropriate and locally generated recommendation available as a package with the breed.Thus, it is necessary to make the information available before the distribution of the breed starts.Secondly, the effect of storage condition and hatching egg treatment on hatchability under local condition is not documented.Therefore, knowing the hatchability of Cobb 500 and Hubbard broiler strains subjected to different egg storage temperature and fumigation treatment seems to be very important and timely.The present work was designed to generate data under local condition and improve strategies that realize high percentage hatchability of Cobb 500 and Hubbard broiler strains with the objective of determining the effect of different egg storage temperature, fumigation, breeds and their interaction on hatchability.

Description of the study area
The experiment investigated the effect of egg storage temperature and fumigation on hatchability of Cobb-500 and Hubbard broiler strain eggs.
The experiment was conducted at Debrezeit Agricultural Research Center (DZARC), Ethiopia.The site is located at an altitude of 1900 m.a.s.l. and 45 km south east of Addis Ababa.The area receives an average annual rainfall of 851 mm and a minimum and maximum temperature of 8.9 and 26.2°C, respectively.The average humidity level of the site is 58.6% (Duguma et al., 2005).

Experimental eggs and their management
A total of 720 freshly laid eggs were collected from Cobb 500 and Hubbard broiler strain breeders.Eggs of Cobb 500 were obtained from Alema Farms Private Limited Company located at Bishoftu and Hubbard were obtained from Debrezeit Agricultural Research Center.All eggs used for the experiment were taken from eggs laid at the same day.At the time of collection, 360 eggs were selected at random from each broiler strain breeders and randomly distributed into two equal groups (180 eggs) and numbered.One group was fumigated with potassium permanganate and formalin at ratio of 1:2 for 15 min and the other group remained unfumigated.To fumigate, the eggs were placed in closed room with 22.5 m 3 volume and 49.5 g of potassium permanganate with 99 ml of formalin, 38% concentration were used.The two groups of eggs from each breeds was further divided in to three groups of 60 eggs at random and exposed to different storage temperature (10, 16 and 23°C) and replicated twice (30 eggs) and stored for 7 days before setting into the incubator.Storage temperature was controlled by adjusting a digital adjustment of cold room, which was originally made for milk storage at 10°C and this room was used for treatment one (T1), egg stored at 10°C.Seed storage room, with average temperature of 16°C was used for treatment two (T2), storing egg at 16°C, for treatment three (T3) ambient temperature of the study area, was used.According to thermometer reading, the average temperature in the storage room during storage was 23°C.

Management of incubator
The eggs were incubated in an incubator of 2592 setter capacity with a ventilation system and an automatic egg turner.The relative humidity and temperature were maintained at 60% and 37°C, respectively.The eggs were placed in an incubator on the same stage with eggs leveled by treatment and replication and arranged horizontally.There were 30 and 60 eggs per replicate and treatment, respectively (Table 4).After 18th day, the eggs were transferred from setter to the hatchery unit with a plastic tray.This was done for two reasons.The eggs are laid on their sides to allow free movement of the chick out of the shell at hatching.It also assists hygiene; large quantities of fluff are generated during hatching and could spread this potential contamination around the hatchery.Hatcher temperature was maintained at 36°C, which is   slightly lower than those of the setter to reduce the risk of overheating.

Experimental design
The experiment was arranged in 3*2*2 factorial in CRD (Table 1-3).There were three factors and one of the factors with three levels and the rest with two levels are as follows: Factor B; Breed (B), levels: B1 -Egg from Cobb 500 breeder B2 -Egg from Hubbard breeder Factor T; Egg storage temperature before incubation for 7 days (T), levels: Factor F; Fumigation (F), levels: F1 -Non-fumigated F2-Fumigated

Hatchability measurement
Candling was conducted on day 8 and 15 to determine fertility.The fertile eggs showed a small dark spot that looked like a "spider".Infertile eggs were clean and only showed the shadow of the yolk.
Hatchability was calculated on the basis of set and fertile eggs and the number of chicks hatched as depicted in the following formulas.

Statistical analysis
The experimental design was ompletely randomized design with All eggs were incubated in the same incubator and on the same stare.
factorial structure.The hatchability were analyzed by ANOVA with three levels of egg storage temperature (10, 16 and 23°C), two levels of egg fumigation (fumigated and non-fumigated) and two breeds of broiler strain (Cobb 500 and Hubbard).
All the data were analyzed by using the General Linear model (GLM) procedure of Statistical Analysis Systems for window 9.0 (SAS Institute, Inc., 2002).Least Significant Difference (LSD) was used for mean comparisons.The storage temperature, fumigation and breed are the main effects.The model for the design is given by: Yijkl = μ + αi+βj + γk+(αβ)ij+ (αγ)ik + (βγ)jk + (αβγ)ijk + eijkl where Yijk = observation taken at the i th breed, j th temperature, and k th fumigation, μ = overall mean of the population for yijk, αi = effect due to the i th breed, βj = effect due to the j th temperature, γk = effect due to the k th fumigation, (αβ)ij = effect due to interaction between the i th breed and the j th temperature, (αγ)ik = effect due to the interaction between the i th breed and the k th fumigation, (βγ)jk = effect due to the interaction between the j th temperature and k th fumigation, (αβγ)ijk = effect due to the interaction between i th breed, j th temperature and k th fumigation, and eijkl = random error associated with the observation yijk.

Fertility and hatchability
The main effect of varying levels of egg storage temperature (10, 16 and 23°C); fumigation (fumigated and not-fumigated); broiler strain (Cobb 500 and Hubbard classic) and the interaction effect of these factors on fertility and hatchability are presented in Tables 6 to 7.
Statistical analysis indicated that there was no significant difference (P>0.05)among the treatment groups in fertility.The present result indicated that fertility is not dependent on egg storage treatments employed.The result is expected because fertility mainly depends on sex ratio of the parent stock, season, flock age and other factors in the laying room than storage temperature and fumigation.North (1984) reported that fertility is the result of laying house management rather than hatchery management procedures.
The results of the mean percentage hatchability on fertile eggs from each treatment groups are presented in Tables 5 to 7. Egg storage temperature of 16°C and fumigation (P<0.001)improved hatchability.Cobb 500 broilers had high mean percentage hatchability than Hubbard, but the differences were not significant (P>0.05).Egg storage temperature at 23°C resulted in slightly lower mean percentage hatchability than storage at 10°C, but the differences were not significant (P>0.05).No two way interaction existed for breed by fumigation and temperature by fumigation.However, interaction existed for breed by temperature.Accordingly, both breeds perform significantly better when the egg is stored at 16°C for 7 days.Egg storage at less than 16°C for Cobb 500 and greater than 16°C for Hubbard seems to have negative effect on hatchability.In accordance with the present result, Kirk et al. (1980) confirmed that the shorter the storage period, the higher the optimum storage temperature for best hatching results.The findings of the present experiment was in agreement with those of Das and Ali (1999) who reported that fertility and hatchability of eggs produced in summer and early spring (when storage temperature is high) was low.Wilson (1991) reviewed literature reporting optimum storage temperature and concluded that storage temperature decreases as length of storage increased.In general, the suggested temperatures by Wilson (1991), based on literature review were: 20 to 25°C when storing eggs for less than four days; 16 to 17°C for four to seven days; and 10 to 12°C for storage of eggs for more than seven  days.Egg storage temperature used in the current experiment, which yielded better hatchability agreed with this earlier works.There was significant (P<0.01)difference in mean percent hatchability on fertile eggs between treatments with fumigated groups showing higher mean percent hatchability as compared to non-fumigated groups.This result is also the same for mean percent hatchability on total set eggs (P<0.01).The present result showed the necessity of pre-incubation fumigation under our case.The findings of this study were comparable with the findings of Proudfoot and Stewart (1970), who reported that pre-storage and pre-incubation fumigation with potassium permanganate and formalin resulted in higher hatchability than with eggs not fumigated, but the difference in their study only approached statistical significance.The present findings did not agree with Clarenburg and Romijn (1954), who reported no ) groups as well as the result reported by Turk (1968), who used 10 g of paraformaldehyde per m 3 (that is, 600 mg released formaldehyde per m 3 ) and found similar result with Clarenburg and Romijn (1954).

Conclusion
In Ethiopia, now a days, new broiler breeds are introduced in to the country to solve the scarcity of day old broiler chicks requirement by producers and their by increase the supply of animal protein in the country.However, the recommended pre-hatching storage handling of eggs is not well studied.In poultry production, it is very important to store the eggs in suitable conditions before hatching.The experiments were conducted by using 360 eggs from each Cobb 500 and Hubbard breeders for hatchability experiment at the DebreZeit Agricultural Research Center for 28 days.
Eggs from the two breeds were stored for seven days at 10, 16 and 23°C before set into the incubator, each group was divided into two equal groups, one group fumigated with formaldehyde and the other group was not fumigated.There were three factors and one of the factors with three levels the rest two factors with two levels.The experimental design was completely randomized design with factorial structure.The parameters considered were fertility and hatchability on set and fertile eggs.
There was no significant (P>0.05)difference among the treatment groups in fertility.Egg stored at 16°C and fumigation showed significantly (P<0.001) higher mean percentage hatchability both on fertile and total set eggs basis.The highest hatchability was obtained from the interaction of 16°C egg storage temperature with fumigation.
Therefore, under the condition of the current experiments, storing egg at an average of 16°C if the egg storage period is one week and fumigation with formaldehyde before set into the incubator is recommended to gate high yield of hatchability.

Scope for future work
The fumigation level on this experiment was limited to fumigated and not fumigated; hence, the effect of fumigation at different concentration of fumigant has to be looked into.The present study should also be conducted during different seasons under varied climatic conditions of the country since season and climate may affect hatchability.
(a, b, c)  Means within a column with different superscript are and under the same factor interaction significantly (P<0.05)different.

Table 1 .
Treatment combinations of the experiment.

Table 4 .
Layout of the experiment

Table 5 .
Mean values for main effects of breed, egg storage temperature and fumigation on fertility and hatchability of fertile eggs and total eggs set.Means within a column with different superscript under the same main effect are significantly (P<0.05)different.

Table 6 .
Mean values for two factor interaction effects of breed, egg storage temperature and fumigation on fertility and hatchability of fertile eggs and total eggs set.

Table 7 .
Mean values for three factor interaction effects of breed, egg storage temperature and fumigation on fertility and hatchability of fertile eggs and total eggs set.