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| Livestock Research for Rural Development 22 (1) 2010 | Guide for preparation of papers | LRRD News | Citation of this paper |
This work aimed to verify the effect of storage of Japanese quail eggs at tropical temperatures (28±1ºC) in hatchability, egg weight loss, hatching time, and embryo mortality. Sixty quails were used for egg collection. Thirty eggs were selected per day, during 15 days consecutively. The eggs were stored at tropical temperature (28±1ºC and 60% of RH) and submitted to different periods of storage, from 0 day until 14 days, forming 15 experimental groups. The eggs were weighed during the storage, incubation and at hatching. The incubation occurred at 37.5ºC and 60% RH. Unhatched eggs were opened for embryonic mortality classification.
The storage of quail eggs at tropical temperatures seems to be suitable up to 6 days when hatchability is 70%. After one week of storage there was an increasing rate of unhatched eggs, mainly because of pre-incubation mortality or embryo early embryo death. It was also observed that the storage length influenced the rates of egg mass loss during incubation and the hatching time.
Key words: egg weight loss, embryo mortality, hatchability, hatch time, hatch weight
Quail production is an important poultry business in Brazil. Japanese quails have been reared for both egg and meat production all over the country, mainly by small and medium size poultry producers. Incubation procedures are important to maintenance and improvement of quail egg production.
In order to obtain a sufficient number of eggs to fill incubators, eggs are usually accumulated in storage over a period from 1 day up to 3 weeks before their incubation (Kuurman et al 2002). To avoid the embryonic development during storage period, eggs must be stored at low temperatures.
The objective of storing eggs at temperatures well below physiological zero is to prevent abnormal growth of the embryo that could occur if eggs were held at temperatures between physiological zero and normal incubation temperature of 37.5ºC (Fasenko et al 2001). To store eggs at low temperatures in tropical countries such as Brazil, it is necessary the use of coolers in order to reduce the normal air temperature. Such practice demands electricity use and can increase the production costs.
The storage promotes water loss from the egg through evaporation at a rate that is influenced by temperature and relative humidity during long-term storage conditions and has generally been reported to be detrimental to table and hatching egg quality (Samli et al 2005; Scott and Silversides 2000). Too low or too high water loss influences embryo development (Rahn and Ar 1974), and, consequently, egg hatchability (Meir et al 1984).
It is reported that the increase in the number of storage days elevates the proportion of embryonic mortality during storage and incubation and thereby increases the probability of failure to hatch (Whitehead et al 1985; Yoo and Wientjes 1991; Scott and Mackenzie 1993). Some researchers have reported a decline in hatchability by as much as 5% per day after 7 days of storage (Mayes and Takeballi 1984). Comparing to Gallus gallus incubation literature, there are few studies about incubation techniques for Japanese quails.
The objective of this research was to verify the effects of storing Japanese quail eggs at tropical temperatures (28±1ºC) on hatchability, egg weight loss, hatching time, and embryonic mortality.
Sixty Japanese quails (Coturnix japonica) for meat and egg production were used for egg collection. They were reared in experimental cages for reproduction in the Laboratory of Ornithology of Veterinary School of Ceara State University, Brazil (3.78º S, 38.5ºW). There were three females and one male in each cage. The birds were 32 week old and averaged 90% of egg production. The quails were supplied with water and balanced feed ad libitum and exposed to 17 hours/day of light.
Egg collections were performed at 5:00 pm every day. The eggs were candled and selected according to industrial parameters for egg incubation. Thirty eggs were selected per day, during 15 consecutive days, totaling 450 eggs. The eggs were placed at room temperature (28±1ºC and 60% of relative humidity) after the daily collection. They were submitted to different periods of storage, from 0 day until 14 days, according to their collection day, performing 15 experimental groups (G0, G1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G12, G13, and G14).
All eggs were identified individually, and weighed on their collection day and every day during the storage period to verify egg weight loss. They were also weighed during incubation period at the 2nd, 4th, 6th, 8th, 10th, 12th and 14th day of incubation. All quail chicks and eggshells were weighed after hatching.
Incubation process was done by automatic hatcheries with temperature of 37.5ºC, relative humidity of 60% and egg turning in every 30 minutes. At the 14th day of incubation (336h) egg turning was stopped and the eggs were transferred to the hatcher.
The eggs that failed to hatch were opened for macroscopically observation, thus they were classified according to time of embryonic mortality. They were staged as infertile-early death embryos, which were the eggs with true infertility, pre-incubation mortality or initial stage mortality. Unhatched eggs classified as late death were the ones with presence of final stage embryos or pipped eggs.
All data were analyzed using the Statistix software 8.0 (2003). The results were submitted to Analysis of Variance through general linear model and the means were compared with the test of Tukey. Statements of significance were based on P<0.05
Figure 1 shows the hatchability of Japanese quail eggs exposed to different periods of storage, since 0 day to 14 days.
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The figure 1 shows that the eggs stored from 0 day up to 6 days averaged 71.4% of hatchability. The eggs stored for 4 days (G4) presented 80% of hatchability, which was the highest rate according to the storage length. There was an intense decrease on hatchability of eggs stored from 7 days up to 10 days, when the hatch rate was 0% and was maintained until 14 days of storage.
The figure 2 shows the percentage of egg weight loss during the storage period and the weight loss during incubation until transference of the eggs that hatched.
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Figure 2 shows mass loss of the eggs that hatched at different periods of storage. The mass loss during storage increased along the days reaching 2.07% after one week of storage. Most of the groups were statistically different. It is also shown the egg weight loss during the incubation period until egg transference (14 days). The eggs that were not submitted to storage (G0) presented 5% of mass loss during incubation and this rate decreased following the increase of days of storage of the other groups. The eggs that were submitted to 9 days of storage showed a 3.48% mass loss. As the storage length increases the mass loss during incubation decreases, probably an embryo mechanism to prevent an excessive weight loss.
There was statistical difference between the group of eggs that was not stored and the groups stored for 5 and 6 days. The others were statistically similar.
The figure 3 shows the distribution of Japanese quail egg hatches according to their length of incubation before hatching.
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Figure 3 shows that as the storage length increased the hatching time was delayed. The eggs which were not stored or stored for 1 day hatched within the 16th and 17th day of incubation.
The eggs stored for 2 days (G2) presented highest rate of hatches in the 16th day. The ones stored from 2 up to 5 days of storage hatched between 16-18 days of incubation. The eggs stored for 6 and 7 days hatched until 19 and 20 days of incubation, respectively. The overall of hatches were mainly concentrated at 16 and 17 days, which were statistically superior to the number of hatches at 18, 19, and 20 days of incubation.
The figure 4 shows the percentage of different embryonic mortality rate of the eggs that did not hatch.
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It was observed that the eggs from the groups G0 and G1 presented an infertility-early death of 30% and 36.7%, respectively. The groups G2 until G6 presented similar percentages of both classifications of unhatched eggs with a mean of 14.7% for infertility-early death and 11.3% for final death. There was no statistical difference of groups stored until seven days.
The rate of infertility-early death increased in the eggs stored for more than 6 days (G6 up to G14) reaching 100% at groups G12, G13, and G14. The groups stored for more than seven days were statistically different from the groups stored until six days. The final death, compared to early death, had lower rates in most of the groups and averaged 8.1% of mortality. This one was more regular regarding the variation of storage length and there was no statistical difference among the groups.
Excessively long storage prior to incubation causes a decline in hatchability even at lower storage temperatures (Becker 1964). Some researchers have reported the decrease in hatchability of turkey eggs, Japanese quail eggs (Sittmann et al 1971), broiler eggs (Kirk et al 1980) and ostrich eggs (Deeming 1996). Sittmann et al (1971) observed the quail egg hatchability from 4 up to 38 days of storage (13.3ºC) and found 78.6% of hatchability for 4 days, 76.9% for 8 days and 72.4% for 13 days of storage. Despite the use of tropical storage temperature (28±1ºC) in our experiment, the hatchability was similar to results found by Sittmann et al (1971) for 4 days of storage. However their results showed a small decrease on hatchability until 13 days and ours were satisfactory until six days. This comparison reveals the negative correlation between storage temperature and hatchability. Samli et al (2005) verified that elevated temperature storage (29ºC) promotes a higher increase in pH of albumen when compared to lower ones (5 and 21ºC). It has been reported that pH is a useful tool for describing the changes in albumen quality over time during storage (Silversides and Villeneuve 1994). The optimal albumen pH for embryo has been estimated to be 8.2 and 8.8 (Sauveur et al 1967; Walsh 1993). The decline in hatchability due to inappropriate albumen appears to be related to the time of storage (Walsh et al 1995). However the storage at tropical temperature does not seem to be detrimental to hatchability of Japanese quail eggs until six days of storage. These findings are according to Meijerhof et al (1994) who found that a relative increase in temperatures of storage area does not decrease hatchability in eggs from 37 week old hens during relatively short storage.
The egg weight loss is an important parameter for incubation. It has been used to estimate vital gas exchange (Paganelli et al 1978; Rahn et al 1979) and has been correlated with the rate of embryonic metabolism and development (Rahn and Ar 1980; Burton and Tullet 1983). Compared to Silversides and Villeneuve, (1994) who observed 1.35% dehydration rate per week of chicken eggs at room temperature (22ºC) our results were higher, reaching 2.07% of mass loss after one week of storage. However our storage was performed at tropical temperatures (28±1ºC). Samli et al (2005) observed a higher storage temperature (29ºC) in chicken eggs and verified an increased rate of mass loss when compared to quail eggs that was 0.65%, 2.11% and 3.13% for 2, 5 and 10 days of storage, respectively. Excess loss of water from the egg through evaporation at a rate that is influenced by the temperature and relative humidity during long-term storage conditions has generally been reported to be detrimental to table and hatching egg quality (Walsh et al 1995; Hinton 1968; Scott and Silversides 2000). Although relative humidity during storage is not extremely critical (Funk and Forward 1960). It appears that only eggs from older flocks with poorer albumen quality are very sensitive to lower humidity (Walsh 1993); this fact is probably why Kaufman (1939) concluded that moisture loss was not the reason for high mortality after long-term storage.
The incubation time can be influenced by many factors like temperature (Suarez et al 1996; Wilson 1991), egg weight (Burton and Tullet 1985), age of breeder (Smith and Bohren 1975) and also preincubation storage (MacLaury and Isko 1968; Bohren 1978). The differences of hatching time of Japanese eggs in this experiment were attributed to storage time, considering the use of uniform egg weights, same age breeders and equal incubation parameters. It was also observed in chicken eggs that as the storage time increased the hatching time was delayed by 11hours for 14 days of storage (Christensen et al 2002) or at least by 15 hours for 18 days of storage (Tona et al 2003).
The increase of storage length enhances the proportion of embryonic mortality during storage and incubation and thereby increases the probability of failure to hatch (Whitehead et al 1985; Yoo and Wientjes 1991; Scott and Mackenzie 1993). It was observed that the increase in unhatched eggs stored for more than 6 days was mainly promoted by embryo early death, because the state of being or not fertile does not depend on storage. Deaths of very young embryos increase with storage age in a non-linear manner (Sittmann et al 1971). In chickens, there are two phases of increased embryonic mortality during incubation: the first phase occurs during the first week of incubation and the second phase during the last week (Jassim et al 1996). The same was observed in Japanese quail incubation, in which early and late embryo deaths were the most often mortalities.
All hatched chicks were weighed. However, it was not verified a correlation between storage length and chick body weight, similar to the findings of Petek et al (2005), in contrast to Sachdev et al (1988) who reported that the body weight of quails hatched from eggs stored over a short period was enhanced. The eggshells weighed from hatched eggs showed no correlation according to the number of storage days. This is according to Silversides and Villeneuve (1994) who observed that storage length does not influence shell weight.
The tropical temperature storage can save energy as was similarly reported by Bourassa et al, (2003) that studied chicken eggs storage. It can also be an alternative for low input systems of quail production in which incubation procedures are used. The storage of quail eggs at tropical temperatures seems to be suitable up to 6 days when hatchability is 70%. Storing eggs for more than a week increased the rate of unhatched eggs, mainly by pre-incubation mortality or embryo early death. It was also observed that the storage length influenced the rates of egg mass loss during incubation and the hatching time which was delayed with storage increase.
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Received 18 December 2008; Accepted 26 October 2009; Published 1 January 2010
