The lower frequency of inactivity and a higher presence in the feeder in the first week of life with blue and green lights respectively agrees with those found by Sultana et al. (2013), where the authors found a higher weight gain and greater inactivity in birds that had were reared in a blue and green light environment. Similarly, chickens raised under blue light condition presented a higher final weight and lower feed consumption than the treatment of green, red and white (Cao et al., 2008), agreeing with the present study.
The findings (Figure 1a e 1b) showed performance improvement since there is a permanent stimulus to the movement of birds in the first weeks of life. Similar behavioral patterns have also been observed in improving the weight gain in the first weeks of growth, providing more significant movement of birds in search of food and water (Rozenboim et al., 2004). Such an increase in weight gain may lead to an improvement in the immune response of broilers, as suggested by Zhang et al. (2014) that tested a combination between the blue-green and green-blue color during broiler rearing. Similarly, (Cao et al., 2008; Hassan et al., 2014) found better growth, development, and a higher final weight gain for chickens in a green and blue light environment. According to Soliman and El-Sabrout (2020), more than 50% of the broiler studies indicated that blue (450 nm) and green light (550 nm) had positive effects on body weight (>3%), whereas red light (700 nm) increased activity and aggressive behaviour of birds (>30%), negatively affecting body weight. In contrast, Assaf et al. (2015) reported that red and yellow lamps did not interfere in the chicken feed consumption.
The results of the present study are similar to those found by Kim et al. (2012) and Kim et al. (2013) when studying layers. The authors found an increase in sexual maturity, egg production, and shell quality in layers kept in red light, but such condition showed no effect on the hens’ feed intake and feed conversion. As seen in Figure 1, the decision tree is a graphical representation from the rules of classification and define a mathematical space in which a given class occurs. The algorithm J48 is an implementation of the C4.5 and identifies the features or variables that are most capable of generating classification rules. The decision tree is read as a semantic set of rules (IF feature/variable x AND/OR feature/variable y THAN Class). In the current study, two models are more relevant and found more fitted rules. As in Figure 1, the model also classifies with only one rule (IF frequency in the feeder at the 7-day of age is greater than 13 min THAN class is equal to male broiler subjected to green light).
Younger birds move more, and as they grow, they tend to decrease their movement spending more time in sedentary behavior, which can vary from 40% to 80% of the time (Bizeray et al., 2002; Amaral et al., 2011). Hartini et al. (2002) found that the birds exhibited pecking litter behavior and aggressiveness more often once they reached 5 to 6-weeks of life, showing a more aggressive behavior under white and red light rearing conditions. According to Kristensen et al. (2007), broilers foraged more but stood up significantly less under low intensity (5 lx) than under high intensity (100 lx) light, regardless of the light source. Nevertheless, in both studies, the birds’ behavior was recorded only over the photophase. It is also possible that rearing broilers in a lighting environment with minimal illumination contrast between the photophase and scotophase leads to less pronounced circadian rhythms of behavior. Hence, a different daily behavioral distribution will be seen if provided with a more extensive light-dark contrast period. The litter pecking behavior for broilers varied with age; the six-week-old chickens’ pecking behavior was more frequent than the first few weeks of age regardless of the color of light in the environment (Kristensen et al., 2007).
A considerable amount of research has examined chicken behavior under different light sources or colors that produce different light intensities. According to Vandenbert and Windowiski (2000), who studied hens’ preferences for high intensity and high-pressure sodium (HPS) light versus low-intensity incandescent light, hens spent more time preening, nesting, and pecking in the HPS light than in the incandescent light, and more time sitting and eating in the incandescent light than the HPS. However, birds sat more often in the central dark compartment, suggesting that they might prefer to rest in a darker environment.
These same authors also studied the behavior of chickens under different light sources or colors that produce different light intensities. They concluded that broilers raised on blue and green light conditions presented better results and were less active, representing calmer behavior (Vandenbert and Windowiski (2000). The benefits of broiler welfare from the light spectrum have been investigated in a few studies. Xie et al. (2008) suggested that blue light may reduce stress response in broilers due to a reduction in serum IL-1β. Blue light has also been found to reduce the fear reaction in a tonic immobility test displayed as the decreased period of tonic immobility, whereas red and red-yellow light increased the duration (Sultanna et al., 2013). Results presented in Figure 1b agree with those obtained by Vandenbert and Windowski (2000), which obtained more significant unrest with a high color brightness, between blue and green colors, with the latter being the highest brightness.
Male chickens kept under the condition of green lighting have better use of feeds and, consequently, higher growth and better development, showing an elevate gain of final weight (Cao et al., 2012). Similarly, Dias (2015) found that it is better to use a short-wave light source such as green and blue chickens in broilers’ first weeks of age, which stimulates the growth of the bird. Huber-Eicher, Suter, and Spring-Stähli (2013) found comparable results concerning broiler foraging behavior, pecking, and attending the bird feeder more often than the birds in red or white light environments. Similar results were observed by Newberry, Hunt, and Gardiner (1985), where broilers in low light intensity environments increase movement. Preening is a vital behavior to be observed since it shows comfort and allows the bird to keep a healthy plumage through the oily secretion distributed from the uropygial gland through their feathers (Appleby et al., 2004). Alvine et al. (2009) observed that birds reared in lower brightness environments indicated comfort and better welfare compared to the birds in higher brightness conditions.
Blatchford et al. (2009) showed that the daily activity rhythms of broilers were less pronounced under a 5 lx photophase with 1 lx scotophase lighting schedule than under either a 50 or 200 lx photophase with 1 lx scotophase. Although PID only provides a gross measure of general activity/inactivity relation rather than the actual time spent performing specific behaviors. Studying Pekin ducks under two different light sources (red light and white light), Campbell et al. (2015) found that. ducks raised under blue light were more active and had increased plasma corticosterone levels, suggesting that these birds were under stress.
The use of green light on the production of the male broiler enables faster growth in the first few weeks of life and better performance for the final phase of creation for chickens under blue light conditions (Rozenboim et al., 2004). The preference for a shorter wavelength was also noted by Heshmatollah (2007), who found that the chickens stayed in the green light environment longer than in the red, orange, and yellow environments. Such preference agrees with the results of the present study, since we indicate that the use of green and blue lights affects broiler behavior and welfare. Thus, the use of green, blue, white, and yellow LED lamps presented different effects on the behavior of broilers that varied depending on the age and sex of birds. The colors green and blue affected the behavior of male chicks beginning at 7- days of age, by extending the time spent in the feeder and reducing inactive periods.