Light has a profound effect on the production performance of broilers. A study was undertaken to evaluate the effect of different colours of light on economics of broiler production. A total of 240, day-old, straight run broiler chicks were divided into 4 treatments each comprising of four replicates of 15 birds each. Chicks of treatment group G1, G2, G3 and G4 were provided blue, green, red and plain incandescent light respectively. All treatments were provided continuous artificial photoperiod of 24 hours for entire rearing period (6wks). The economics of trial taking into consideration all the factors such as FCR, final body weight and mortality revealed better economic returns from the birds reared under blue light as compared to green and control group while as loss was encountered in the birds reared under red light.
Light represents the most important environmental exogenous factor composed of at least three aspects including wavelength, intensity and photoperiod responsible for controlling many internal and external processes in birds. Broilers reared under blue or green fluorescent lamps were found to gain more weight than those exposed to red or white light (Prayitno et al., 1997). Cao et al. (2008) found that broilers reared under blue or green light had significantly heavier body weights than those reared under white or red light. Hakan and Ali (2005) reported that wavelength between 435 and 600 nm (blue, green and yellow) had positive and higher wavelength like orange and red had negative effects on broiler performance. Manipulation of light can be done easily in closed poultry houses that are quite prevalent in north western temperate agro-climatic regions of the country. Therefore a study was undertaken to evaluate economics of broiler production under different colours of light.
Materials and Methods
Two hundred and forty, day old commercial broilers were distributed into four treatment groups with four replicates of 15 chicks each. Chicks allotted to each treatment were housed in a light proof enclosure subdivided into four separate pens. The light proofing was ensured through application of black curtains along enclosure partitions and windows. The chicks were brooded and grown on deep litter with standard management conditions with adlib feeding and watering and different treatments were lit with different colors of light viz. blue (G1) ,green (G2) and red (G3) of uniform intensity. The light intensity was monitored regularly using a digital luxmeter. The control group (G4) received a plain incandescent light of same intensity as that of other groups. Different color of light was produced by wrapping a cellophane paper of particular color around a plain incandescent bulb. Incandescent bulb of 60 watt power was invariably used for lighting.
The initial body weight, final body weight on individual basis and feed consumption on group basis was recorded. The weight gain and FCR was calculated. The economics was worked out on basis of feed cost per kg live weight gain (Product of FCR and Cost/Kg Feed), chick cost of Rs 27/DOC and the medicine cost of Rs 8/Chick. The product of feed cost per Kg live weight gain and final body weight in Kg was taken as feed cost per bird. Sum of feed cost per bird, chick cost and medicine cost was taken as total input per bird. Total input per group (Rs) was calculated by multiplying total input per bird (Rs) by number of birds in each group at the start of trail (60). Sale proceeds per group was also calculated as product of number of birds alive for sale, final body weight (Kg) and sale rate of Rs 120/Kg live weight gain. The difference between sale proceeds and total input cost was taken as loss/gain.
Data pertaining to initial and final body weight, feed consumption and FCR was analyzed through Analysis of variance (ANOVA) as per Snedecor and Cochran (1980). Statistical software SPSS 15.00 was used for analysis.
Results and Discussion
The initial and final body weight, body weight gain, feed consumption, FCR and various economic parameters of broilers reared under different colours of light is presented in Table 1. Body weight of the broiler chicks at hatch was 37.74±0.48, 38.07±0.31, 38.52±0.42, and 37.27±0.38g in groups G1, G2, G3 and G4 respectively with no significant difference between the groups. Significant differences in body weight was observed in the 6th week with birds reared under blue light (G1) having highest body weight of 1593.20±7.45g followed by 1541.76±4.28g in birds reared under plain incandescent light (G4 Control), 1530.58±25.03g in group reared under red light (G3) and 1470.23±6.40 g in birds reared under green light (G2). The body weight of blue light group was significantly higher than all the three groups. Though there was no significant difference in body weight of control (incandescent light group) and red light group numerically higher 6th week body weight was recorded in control. Green light group had the lowest 6th week body weight which was significantly different from all the three groups. It was also reported by Cao et al. (2008) that broilers reared under blue or green light had significantly heavier body weights than those raised under white or red light. Rozenboim et al. (2004) also reported that a combination of blue and green light stimulated growth in broiler chickens.
The overall body weight gain from 0 to 6 weeks of age was 1555.45±7.12g, 1432.16±6.39g, 1492.06±24.78g and 1504.50±4.12g in G1, G2, G3 and G4 respectively. Thus, body weight gain of G1 was significantly higher than the other three groups while weight gain in G2 was the least and it also was significantly lower than other three groups. Further there was no significant difference between the overall body weight gain of G3 and G4. It has been reported that broilers reared under blue and green lamps gained more weight than those exposed to white or red light (Prayitno et al., 1997). Further in case of broilers exposed to violet, blue or green light (415- 560nm) at the same irradiance body, the weight gain up to 11 weeks has been greater than those exposed to red or white light (Lewis and Morris, 2006).
Average feed consumption from 0 to 6 weeks of age was highest (3345.74±48.27g) in G1followed by 3335.74±67.35, 3302.50±27.36, 3056.39±38.60g in G3, G4, G2, respectively. This could be attributed to calming effect of birds which leads them to consume more feed. As per Perkins et al. (2002) broilers showed lower fear responses under blue light than they did under iso-illuminant white or red light that helped them to spent more time in feeding.
Significant difference in overall FCR between 0-6 weeks of age was observed. It was least 2.13±0.02 in green groups followed by 2.15±0.04 in blue group, 2.20±0.02 in yellow group and 2.24±0.03 in red group. Higher overall FCR in G3 as revealed in present study could be attributed to higher activity and aggressiveness. Long wavelengths such as that of red light penetrate the avian skull more than short wavelengths and stimulate reproductive development (Hartwig and Veen, 1979). This increase in penetration may explain the effects on activity. Broilers showing vigorous movements in the red lighted pen resulted in a large wastage of energy and consequently feed conversion rate was poorer. It has been documented by Son and Ravindran (2009) that FCR of birds receiving the blue light was more efficient than those receiving white and red lights.
The economics of trial taking into consideration all the factors such as FCR, final body weight and mortality reveals better economic returns from the birds reared under blue light as compared to green and control group while as loss was encountered in the group reared under red light. Feed cost/Kg live weight gain worked to be highest (Rs 85.12) for the birds reared under red light followed by Rs 83.60 for control group, Rs 81.70 for the blue group and the least (Rs 80.94) for green group. The feed cost per bird after taking into consideration the body weight achieved at 6 weeks of age was least in green group (Rs 119.00) while as for blue, red and control group it was Rs 130.16, 130.28 and 128.89 respectively. After including other inputs like chick cost and medication cost, the total input for 60 birds reared in each group worked out to Rs 9906, 9240, 9916 and 9833 G1, G2, G3 and G4 respectively. Keeping mortality into consideration the number of live broilers available for sale at the end of study were 57, 55, 52 and 54 in groups G1, G2, G3and G4 respectively. The total sale proceeds were Rs 10897 from G1, Rs 9703 from G2, Rs 9550 from G3 and Rs 9990 from G4. As is evident from Table1, highest profit of Rs 16.16/ bird was obtained in blue group. Profit/bird to the tune of Rs 7.72 and 2.62 were realized in green and the control group also but a loss of Rs 6.10 was incurred in case of the birds reared under red light.
Table 1: Performance of broilers and their economics under different colours of light
|Yellow (Control) G4|
|0 day body weight (g)||37.74±0.48||38.07±0.31||38.52±0.42||37.27±0.38|
|6th week body wt. (g)||1593.20±7.45c||1470.23±6.40a||1530.58±25.03b||1541.76±4.28b|
|0-6 body wt. gain (g)||1555.45±7.12c||1432.16±6.39a||1492.06±24.78b||1504.50±4.12b|
|0-6 feed consumption||3345.74±48.27b||3056.39±38.6a||3335.74±67.35b||3302.5±27.36b|
|FCR (0-6 week)||2.15±0.04ab||2.13±0.02a||2.24±0.03b||2.20±0.02ab|
|Feed cost/Kg live wt. gain (Rs)||81.70||80.94||85.12||83.60|
|Birds alive at the end of study (No.)||57||55||52||54|
|Feed cost/bird (Rs)||130.16||119.00||130.28||128.89|
|Total input/ bird (Rs)
|Total input/group (Rs)||9909.87||9240.028||9916.98||9833.47|
|Sale proceeds/group (Rs)||10897.49||9703.52||9550.82||9990.60|
|Loss/Gain per group(Rs)||987.62||463.49||-366.16||157.14|
|Loss/Gain per bird (Rs)||16.46||7.72||-6.10||2.62|
Means across columns bearing different superscripts differ significantly (P<0.05)
It was also reported by Cao et al. (2008) that broilers reared under blue or green light had significantly heavier body weights than those raised under white or red light while there was not much difference from the yellow and red group in terms of input costs, the higher mortality in the birds reared under red light jeopardized its economy as lesser number of birds were available for marketing. Similarly in terms of input costs, the green group was better off than blue group but higher mortality in the group resulted in lesser returns. The economics of different lighting programmes in broiler production has been worked such as between constant and intermittent lighting schedules (Abreu et al., 2011) and between different intensities (Ahmad et al., 2011). In these studies, the cost of electricity was also a variable factor which was not the case in present study as same wattage bulbs were used in all the four groups.
In above studies, after taking into account energy costs also the intermittent lighting schedule and low intensity light were found to be economical. Similarly upon working out the economics of using different sources of light, Ghuffar et al. (2009) reported highest profit per bird when metal halide light source was used and the least profit on using a higher power sodium lamp. No reports on economics of using different colours of light could be traced in contemporary literature to compare our results.
It could be concluded that birds reared under blue and green light performed better and the economics of trial taking into consideration all the factors such as FCR, final body weight and mortality revealed better economic returns from the birds reared under blue light as compared to green and control group while as loss was encountered in the birds reared under red light.