Influence of different colors of artificial illumination on the quality of japanese quail eggs

For the last years, coturniculture has awaken a great interest among producers and companies, since it is an activity that requires less investment and labor than other agriculture activities; in addition, some quail breeds present a short reproduction cycle, early maturation, good fertility, and optimal laying rate. Actually, Japanese quail may reach laying rates of up to 80% (TDNET, 2006).
In Brazil, egg production has showed a fast growing for the last 10 years. In 2001, the national flock reached six million birds, with a production of 93.334 thousand dozens of egg (IBGE, 2003). Furthermore, in 2007 this production grew to 131 thousand dozens of egg and by 2009 it reached 192.196 thousand dozens (IBGE, 2010).
This increase in production is the result, in part, due to change of habits in the modern man feeding, who goes more frequently to restaurants and an increase in the number of prepared rations in these establishments. The increase has been kept given the offering of the product, guaranteed by a higher productivity of this poultry segment based on the adaptation and modernization of traditional raising practices. (Bressan and Rosa, 2002).
For layers, the function of artificial lighting has been well known in the illumination programs, increasing the photoperiod and stimulating egg production, given the response of birds to this light stimulus. Furthermore, not this lighting technique adopted for this kind of exploitation, the productive indexes would not be enough to provide viability of this activity. According to Etches (1996), artificial lighting in commercial layers is a very powerful management tool for the poultry producer.
Jordan and Tavares (2005), and Jacome (2009), stated that the lighting sector is, to a great extent, responsible of waste in egg production. The lighting system normally used is formed by a number of high potent and low efficient lamps. Incandescent lamps, as popular as they may be, present a low conversion in lm W -¹, in addition to their short life, which may be 1,000 hours average, increasing the expenses in replacing them.
Considering that total waste and expenses on electric energy in poultry are both high, it is necessary to perform studies in order to modify and update of the different poultry sectors, making viable the competitiveness of the production. For this reason, the objective of this paper was to prove an alternative source of artificial illumination in layer quails cages, substituting the common incandescent lamps by light tubes.

The study was carried out in the poultry sector of the Universidad Federal de Santa Maria, campus Palmeira das Missões, RS, Brazil, latitude 27° 53' 58" south and longitude 53° 26' 45" west, with a height of 634 meters above sea level.
112 female, 45 days old, laying lineage, Japanese quails (Coturnix japonica), were treated with different illumination color by light tubes of different colors: yellow, red, blue, and green.
Analyses were performed along 140 days, divided by 5 periods of 28 days each, and every analysis lasted 4 days.
Data on total daily production were collected, and at every 28 days period, a representative sample was collected in order to analyze egg weight, albumen height, and Haugh units. Albumen height assessment was carried out on a flat surface, using a digital calibrator for measurements. In order to determine the egg weight, a digital scale was used with 0.05 Kg accuracy.
For Haugh unit calculation, egg weight and albumen height was used with the applying the next formula: UH = 100.log (A - 1 7P^0,37+ 7.6) (Haugh 1937; Brant et al., 1951), adapted for a spread sheet, Microsoft Office Excel 2007^®. Where UH = Haugh units, A = albumen height in millimeters; P = egg weight in grams.

Feed intake was measured weighing the feed left at the end of a 24 hours period for four days. Laying quail commercial feed was used. Management was manual with two feeders per row and nipple drinkers in all treatments.
From the first week in house, a light program was established; starting with a 13 hours photoperiod every day, with successive 30 minutes increase per week up to get 17 hours of light per day. The experimental design was completely random with four treatments and five repetitions. Results were subjected to F test, and means were compared applying Tukey test. Analyses were performed with the statistical software ASSISTAT (2010).

Regarding egg production, quails treated with green color light tubes were observed with higher production than those under blue light tubes (P<0.05), but when comparing those exposed to blue color with those exposed to yellow and red color light tubes, no difference was observed in production (P>0.05). Green light tube treatment were not statistically significant different from the treatments with yellow and red light tubes (P>0.05).
Egg production with treatments with green color light tubes (96%) and red (92%) was higher and the same, respectively, to egg production when quails were exposed to incandescent lamps, according to Borille et al. (2010) who recorded a production of 92% with incandescent light. In this way, it may be said that the change of kind of lighting from incandescent lamps to green or red color light tubes would not affect the production.

Table 1 - Egg production % (EP), ration consumption g (RC) in Japanese quails subjected to different kind of artificial illumination

Regarding consumption, it is possible to observe that birds under green color light tubes showed higher feed intake than those under blue color light, which did not differ from treatments with yellow and red light (P>0.05). In addition, no differences were observed between treatments with green, red, and yellow color light tubes (P>0.05).

Data on Table 1 confirm a reduction of 8% in feed intake of the birds in cages under blue light, related to the rest of the groups; which justifies a lower production of birds under blue light. On the other hand, an increase of 6% in feed intake is observed in birds under treatment of green light and, consequently, an increase in their production. At some extension, it may be attributed to a higher feed intake, the basis for a bird to express its maximum genetic potential on egg production.

Table 2 - Egg weight g (EW), albumen height (AH) and Haugh units (HU) in eggs from Japanese quails subjected to different kind of artificial illumination

Regarding egg weight, differences were identified between quails under green light from those under blue light (P<0.05), but these last did not showed differences from treatments with red and yellow light (P>0.05). When comparing green light treatment vs yellow and red light treatment, no differences were found (P>0.05). Based on data on Tables 1 and 2, we may conclude that quails subjected to green light, in addition to have a better yield in production, laid eggs were higher in weight. These data are similar to those published by Murakami and Ariki (1998) who found a mean of 10.39 g. However, data of egg weight are lower to those found by Borille et al. (2010) where leds were used as the source of artificial lighting, who found a mean of 11.82.

About albumen height and Haugh units, all results were similar, then finding significant differences between treatments (P>0.05) which confirms that, in our study, the kind of technology adopted did not interfere with the egg quality. For Rossi et al. (1995), production type and season of the year affect the hen egg composition and structure. This fact was not perceived in our study, since eggs submitted to analysis were fresh and the production system, as well as feed were similar to all treatments.

Based on the obtained results, it is concluded that the green light tube as source of artificial illumination was better for egg production, in comparison to the rest of test treatments and did not interfere with the quality of the product.

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