Livestock Research for Rural Development 20 (10) 2008 | Guide for preparation of papers | LRRD News | Citation of this paper |
Pre-incubational egg storage has the objective of minimizing transportation costs to the hatchery, to obtain enough eggs to fill incubator racks and to a better planning of chick hatches. The objective of this research was to evaluate the effects of egg storage in a domestic refrigerator (7.5±1 ºC) on incubation performance and egg characteristics. The egg collection of Japanese quails (Coturnix japonica) was done in alternate days, totalizing 440 eggs. They were identified and weighted individually and divided according to storage period: 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 days. They were stored in a domestic refrigerator (7.5±1 ºC and 50±5% relative humidity). After storage, 220 eggs were incubated at 37.5ºC with 60%RH and turning every 30 minutes. The other 220 eggs were submitted to weight measurements of components. The quail chicks were weighted at hatch.
The results showed that the hatchability was satisfactory in all groups. The lowest hatchability was found in eggs stored for 20 days (75%). Egg weight loss during storage was linear and reached 3.74% at 20th day. It was not found relation between storage period and egg weight loss during incubation. The storage of eggs showed no statistical influence on hatch weight and also the percentage of egg components.
We concluded that storage of Japanese quail eggs in a domestic refrigerator is suitable, it can be an alternative for small breeders and it can promote high levels of hatchability even in eggs stored for long periods.
Key-words: incubation, quail, refrigerator, storage
Quail raising became 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 breeders. Incubation procedures are important to maintenance and improvement of quail egg production in Brazil, which is increasing over the last years. Hatching eggs are often stored at cool temperatures for extended periods.
The main reasons for egg storage are to minimize transportation costs to the hatchery and to obtain enough eggs to fill incubator racks. It can also be useful for a better planning of chick hatches. Lower storage temperatures are recommended should the length of egg storage increase. For example, for chicken eggs held less than 4 days, the egg room temperature should be 20 to 25°C. For eggs stored from 4 to 7 days, the temperature should be held at 16 to 17°C, and for eggs stored for more than 7 days, the temperature should be lowered to 10 to 12°C (Meijerhof 1992).
Water loss is a normal process during incubation, usually 12 to 14% of water is lost in broilers and turkeys eggs (Rahn et al 1981) and 11.32% in quail eggs (Soliman et al 1994). However, too low or too high water loss influences embryo development (Rahn and Ar 1974), and, consequently, egg hatchability (Meir et al 1984). Excess loss of water from the egg through evaporation at a rate that is influenced by the temperature and relative humidity during the 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; Samli et al 2005). Albumen quality is a standard measure of egg quality (Silversides and Scott 2001). However the characteristics of the albumen are not the only measures of egg quality. The advent of the egg breaking industry has greatly increased the importance of the relative proportion of the egg components (Ahn et al 1997).
There are few studies about incubation techniques for Japanese quails, especially on alternative methods for egg storage. The objective of this research was to evaluate the storage of Japanese quail eggs in domestic refrigerator (7.5±1ºC) and its effects on hatchability, egg weight loss and the relative proportion of egg components.
Japanese quails specialized for egg laying production were used for serial egg collections. The birds were reared in experimental cages in the Laboratory of Ornithology of Veterinary School of Ceara State University. They were lodged in the ratio of two females and one male in each cage. Birds were 12 week old and averaged 90% of egg production. Quails were supplied with balanced feed and water ad libitum. They were also exposed to 17 hours/day of light.
The collections were performed at 7:00am in alternate days. Eggs were candled and selected according to industrial parameters for egg incubation. Forty eggs were selected per day, during 11 alternate days, totaling 440 eggs. The eggs were placed in a refrigerator (7.5±1ºC and 50±5% of relative humidity) after the daily collection. They were submitted to different periods of storage, from 0 day up to 20 days. The groups of eggs according to storage lengths (days) were 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20. A total of 220 eggs were used for incubation, while the other 220 eggs were used for evaluation of storage effects on egg characteristics.
All eggs were identified, individually and weighted on their collection day and during the storage period to verify egg weight loss. The eggs which were incubated were also weighted during incubation period at the 1st, 5th, 10th, and 15th day of incubation. All quail chicks were weighted at hatch with a precision balance (0.001g).
Eggs were incubated in horizontal position by automatic hatcheries with temperature of 37.5°C, relative humidity of 60% and egg turning every 30 minutes. Egg turning was stopped two days before hatching and eggs were transferred to the hatcher with same temperature and humidity conditions.
Some eggs were submitted to storage but they were not incubated, totaling 220 eggs. They were weighted along storage and opened to evaluate the egg components. Eggshell and yolk were separated and weighted individually with a precision balance (0.001g). The weight of each component was used to calculate the relative proportion of each part.
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 stored up to 20 days at low temperatures (7.5±1ºC) in a domestic refrigerator.
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The eggs stored from 0 day up to 20 days at 7.5±1°C averaged 87.7% of hatchability. It is known that optimum hatchability after long-term storage (>14 days) can be achieved when storage temperature is about 12°C for chicken eggs (Olsen and Haynes 1948; Funk and Forward 1960). Despite these reports, Japanese quails eggs stored at domestic refrigerator (7.5±1°C) presented high levels of hatchability that varied between 75% and 95%. The reason that 12°C is the optimum for long term storage is that this temperature is the lowest possible for sufficient moisture holding capacity to prevent dehydration of the embryo.
The impact of this dehydration can be demonstrated by simply storing eggs for 2 weeks in a home refrigerator at 4ºC (Brake et al 1997). Although relative humidity during storage is not extremely critical (Funk and Forward 1960), dehydration can occur at the low extreme (Proudfoot and Hulan 1976). 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.
There was a decrease on hatchability since the 16th day of storage, reaching 75% in eggs stored for 20 days. Becker (1964) observed that excessively long storage prior to incubation causes a decline in hatchability. Some researchers have reported the decrease in hatchability due to storage in turkey eggs, Japanese quail eggs (Sittmann et al 1971), broiler eggs (Kirk et al 1980) and ostrich eggs (Deeming 1996).
Seker et al (2005) stored Japanese quail eggs at 9-12°C and 70-75% RH up to 15 days and found the following hatchability of fertile eggs: 90% for eggs stored up to 3 days, 88.74% for eggs stored from 4 up to 6 days, 67.96% for eggs stored from 7 up to 9 days, 72.45% for eggs stored from 10 up to 12 days, and 50.31% for eggs stored from 13 up to 15 days. Sittmann et al (1971) studied the quail egg hatchability from 4 days up to 38 days of storage (13.3ºC) and found 78.6% of hatchability for 4 days, 76.9% for 8 days, 72.4% for 13 days, 59.7% for 18 days and 47.5% for 23 days of storage.
Compared to Seker et al (2005) and Sittmann et al (1971) we verified a better hatchability of eggs stored up to 20 days, despite the use of a lower temperature (7.5±1°C) in a domestic refrigerator.
Table 1 shows the percentage of egg weight loss during the storage period and incubation until transference of Japanese quail eggs submitted to different egg storage lengths in domestic refrigerator (7.5±1ºC).
Table 1. Egg weight loss (%) of Japanese quail eggs stored at low temperatures |
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Storage length, days |
Storage |
Incubation (Mean ± SD), % |
||
5 days |
10 days |
15 days |
||
0 |
0.00 ± 0.00 a |
3.11 ± 0.37 ab |
5.55 ± 0.74 ab |
8.45 ± 1.22 ab |
2 |
0.32 ± 0.07 ab |
2.95 ± 0.28 ab |
5.35 ± 0.55 ab |
8.41 ± 1.25 ab |
4 |
0.55 ± 0.15 ab |
2.84 ± 0.33 ab |
5.34 ± 0.66 ab |
8.14 ± 0.92 abc |
6 |
0.94 ± 0.22 bc |
2.87 ± 0.31 ab |
5.35 ± 0.62 ab |
8.17 ± 0.94 abc |
8 |
1.06 ± 0.22 bc |
2.83 ± 0.35 ab |
5.29 ± 0.66 b |
8.17 ± 0.99 abc |
10 |
1.63 ± 0.27 cd |
2.74 ± 0.28 a |
5.19 ± 0.55 b |
7.98 ± 0.84 abc |
12 |
1.77 ± 0.31 cde |
3.04 ± 0.34 ab |
5.20 ± 0.62 b |
7.60 ± 0.93 bc |
14 |
2.37 ± 0.69 def |
3.08 ± 0.32 ab |
5.20 ± 0.58 b |
7.53 ± 0.84 bc |
16 |
2.07 ± 0.39 def |
2.84 ± 0.30 ab |
4.96 ± 0.50 b |
7.16 ± 0.72 c |
18 |
3.38 ± 0.89 ef |
3.10 ± 0.37 ab |
5.37 ± 0.68 ab |
7.79 ± 1.02 bc |
20 |
3.74 ± 0.78 f |
3.20 ± 0.50 b |
6.07 ± 0.85 a |
9.06 ± 1.24 a |
a-f Means in a column with no common superscript differ significantly (P < 0.05) |
The egg weight loss during storage increased along the days reaching a maximum of 3.74% at 20 days of storage. Eggs weight loss during storage increase regularly with a rate around 0.77grams/per week, in chicken eggs (Silversides and Villeneuve 1994). Samli et al (2005) stored chickens eggs at 5ºC for 2, 5 and 10 days and observed 0.27%, 0.51% and 0.66% of egg weight loss during storage, respectively. Our egg weight loss during storage for Japanese quail eggs was superior despite the different temperature (7.5±1ºC). It was 0.32%, 0.94% and 1.63% at 2, 6 and 10 days of storage respectively.
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 Tullett 1983). Egg weight loss during incubation was verified at 5, 10 and 15 days of incubation. There were statistical differences among the groups according to storage length, however it was not verified a direct relation between storage length of eggs and egg weight loss during incubation. The egg weight loss averaged 8.04% at 15 days of incubation, presenting variation from 7.16% up to 9.06% among groups.
Table 2 shows the chick weight at hatch of Japanese quail eggs stored in a domestic refrigerator.
Table 2. Hatch weight of Japanese quail |
|
Storage length, days |
Hatch weight, g (Mean ± SD) |
7.77 ± 0.56 |
|
2 |
7.51± 0.60 |
4 |
7.63 ± 0.58 |
6 |
7.59 ± 0.64 |
8 |
7.47 ± 0.42 |
10 |
7.51 ± 0.57 |
12 |
7.68 ± 0.54 |
14 |
7.58 ± 0.61 |
16 |
7.37 ± 0.69 |
18 |
7.59 ± 0.63 |
20 |
7.32 ± 0.69 |
All quail chicks were weighted at hatch. There was not statistical differences among hatch weight for different storage lengths (P<0.05), this way, it was not verified a correlation between the 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 average of quail chick weight at hatch was 7.55 ± 0.59g. Chick weight values were not statistically different.
Storage time and temperature affects chick weight at hatch which can also be affected by other factors, including species, breed, egg nutrient levels, egg environment, egg size (Wilson 1991), weight loss during incubation period, weight of shell and other residues at hatch (Tullett and Burton 1982), shell quality and, incubator conditions (Peebles and Brake 1987). However Silversides and Scott (2001) reported that initial egg weight is the most important factor that determines hatch weight.
Table 3 shows the effect of storage in a domestic refrigerator (7.5±1 °C) on the percentage of Japanese quail egg components
Table 3. Effect of storage in a domestic refrigerator (7.5±1 °C) on Japanese quail eggs components |
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Storage length, days |
Albumen ± SD, % |
Yolk ± SD, % |
Shell ± SD, % |
0 |
61.2 ± 2.87 |
30.7 ± 2.82 |
8.14 ± 0.23 ab |
2 |
62.1 ± 1.48 |
30.0 ± 1.61 |
7.98 ± 0.37 b |
4 |
61.0 ± 1.40 |
31.0 ± 1.71 |
8.29 ± 0.38 ab |
6 |
61.8 ± 1.28 |
30.1 ± 1.34 |
8.45 ± 0.23 ab |
8 |
60.8 ± 1.81 |
31.3 ± 1.62 |
8.43 ± 0.51 ab |
10 |
61.1 ± 1.97 |
31.2 ± 2.25 |
8.26 ± 0.34 ab |
12 |
61.4 ± 1.62 |
31.1 ± 1.66 |
8.11 ± 0.31 ab |
14 |
59.8 ± 1.58 |
32.9 ± 1.85 |
8.41 ± 0.47 ab |
16 |
60.5 ± 0.85 |
31.6 ± 1.29 |
8.87 ± 0.57 a |
18 |
61.5 ± 1.10 |
31.5 ± 1.16 |
8.31 ± 0.38 ab |
20 |
61.6 ± 2.66 |
31.4 ± 3.21 |
8.4 ± 0.44 ab |
a-b Means in a column with no common superscript differ significantly (P < 0.05) |
Storage time and temperature appear to be the most crucial factors affecting albumen quality (Samli et al 2005). According to many studies, the Haugh unit, albumen weight, yolk weight, egg weight, shell weight, shell thickness are affected by storage time (Altan et al 1997; Suk and Park 2001; Tilki and Inal 2004).
It was verified no statistical difference for albumen percentage along storage length. These findings are in agreement with Tilki and Saatci (2004) that studied the effects of storage on egg components of partridges. The albumen percentage can decrease over the storage period due to egg weight loss to environment by evaporation (Romanoff and Romanoff 1949). According to Samli et al (2005) the egg weight loss in low temperatures (5°C) does not alter statistically with storage length increase.
It was not verified a significant influence of storage on yolk weight and percentage which is according to Fasenko et al (2001). Silversides and Villeneuve (1994) studied the effects of storage on chicken eggs and verified that the storage can reduce the albumen percentage through the transference of water to environment and yolk, this way the yolk percentage can increse along storage.
Storage at low temperatures of Japanese quail eggs presented no clear influence on eggshell weight or percentage. According to Silversides and Villeneuve (1994) the weight of eggshell along storage does not alter.
We concluded that storage of Japanese quail eggs in a domestic refrigerator at low temperatures (7.5±1ºC) is suitable. It promoted high levels of hatchability even in eggs stored for long periods, the chick weight at hatch, weight loss during incubation and egg components were not considerably influenced by storage. It can also be an alternative for small scale Japanese quail breeders.
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Received 3 August 2008; Accepted 8 August 2008; Published 3 October 2008