The effects of the duration and onset of light stimulation during incubation on the behavior, plasma melatonin levels, and productivity of broiler chickens1

Abstract

Light stimulation during incubation can affect the behavior, health, and performance of poultry posthatch. However, there has been relatively little work systematically assessing the pattern of light stimulation needed to produce these effects or the mechanism underlying them. We conducted 2 experiments to assess the effects of duration and onset of light exposure during incubation on Cobb 500 broiler chickens. In the first, eggs (n = 1,404) were incubated under photoperiods of either 0 h of light and 24 h of darkness (0 L:24 D), 1 h of light and 23 h of darkness (1 L:23 D), 6 h of light and 18 h of darkness (6L:18D), or 12 h of light and 12 h of darkness (12L:12D). In the second, eggs (n = 1,008) were incubated in either complete darkness or under 12L:12D, which was applied either for the entire incubation period or with light onset beginning at either 7 or 14 d of incubation. Broilers were then housed in floor pens under a 12L:12D cycle posthatch. Measurements included performance outcomes, plasma melatonin, general behavioral activity assessed using passive infrared detection, and feeding activity assessed using automated continuous monitoring of feed intake at wk 5 of age. There were no treatment differences in hatchability, mortality, growth, feed consumption, feed conversion ratio, overall feeding behavior activity, or general behavioral activity over a 24-h period in either experiment. However, broilers incubated under 12L:12D fed more (P < 0.05) than the 0 L:24 D broilers during the first 3 h after the lights came on in Exp. 1 and during the first hour after the lights came on in Exp. 2. In Exp. 1, general activity levels measured using passive infrared detection at night also differed (P = 0.05), with 0 L:24 D more active than 12L:12D. There was a treatment difference between the 0 L:12 D and 12 L:12 D in their plasma melatonin rhythms during d 19 of incubation, but this difference had disappeared when broilers were sampled at wk 5 posthatch. The results of this study indicate that providing 12 h of light during incubation can have a long-lasting effect on the diurnal rhythms of behavior, although the mechanism underlying this does not appear to be related to a persistent change in melatonin rhythm.

Exposing broiler eggs to green, red and white light during incubation

“…Specifically, white light and monochromatic red light increased the hatchability when compared with the dark incubated eggs. The improved hatchability with white light in this present study agrees with previous findings Mench, 2014a and2014b;Archer, 2015b and2016). Hluchý et al (2012) had similar findings to this present study with red light increasing hatchability, however, Archer (2016) did not see an increase in hatchability in broiler eggs exposed to red light during incubation.…”

“…Chick quality was also improved by exposing eggs to white and red light during incubation in this present study which agrees with previous research Mench, 2014a and2014b;Archer, 2015b and2016). Most of this improved chick quality was due to increased navel maturation resulting is less unhealed navels and navel tags.…”

“…Tonic immobility (TI) was conducted at 5 weeks of age by again collecting the 10 random birds from a pen, bringing them to a separate area, and placing them in a holding container. Methods were modified from previous research by Jones (1986) and Archer and Mench (2014a). A 21 cm wide by 22 cm high by 30 cm long wooden cradle with the sides sloping out at a 108°angle from the base was obtained, covered in a black cloth and placed on a table.…”

“…Factors such as temperature, humidity, turning and even carbon dioxide concentrations during incubation have been the most researched areas. These factors are extremely important, however, there is evidence that exposing embryos to light during incubation can have an effect on hatchability (Cooper, 1972;Shafey, 2004;Mench, 2014a and2014b;Archer, 2015a) and decrease incubation time (Ghatpande et al, 1995;Fairchild and Christensen, 2000;Tong et al, 2015). Light exposure has been seen to improve animal welfare posthatch as well (Archer et al, 2009;Özkan et al, 2012;Mench, 2014a and2014b).…”

“…These factors are extremely important, however, there is evidence that exposing embryos to light during incubation can have an effect on hatchability (Cooper, 1972;Shafey, 2004;Mench, 2014a and2014b;Archer, 2015a) and decrease incubation time (Ghatpande et al, 1995;Fairchild and Christensen, 2000;Tong et al, 2015). Light exposure has been seen to improve animal welfare posthatch as well (Archer et al, 2009;Özkan et al, 2012;Mench, 2014a and2014b). Reductions in fear responses (Dimond, 1968;Mench, 2014b and2016) and stress susceptibility (Archer et al, 2009;Mench, 2013 and2014b) have been observed as a result of light exposure during incubation.…”