Effect of Light Intensity on Live Performance and Processing Characteristics of Broilers

Transcription

1 Effect of Light Intensity on Live Performance and Processing Characteristics of Broilers R. J. Lien, 1 J. B. Hess, S. R. McKee, and S. F. Bilgili Department of Poultry Science, Auburn University, Auburn, AL ABSTRACT This study investigated the effects of different BW and feed consumption were greater in the Dim treatment. light intensities provided via an increasing photo- period program on broiler live performance and processing characteristics. A total of 1,080 male broilers were evenly distributed in 12 rooms. Six rooms were subjected to intensities of either 15 footcandles (FC) from 1 to 51 d (Bright), or 0.5 FC from 1 to 9 d and 0.1 FC from 9 to 51 d (Dim). Both intensity treatments were provided in an increasing photoperiod program (23L:1D, 1 to 9 d; 12L:12D, 9 to 16 d; 14L:10D, 16 to 23 d; 17L:7D, 23 to 30 d; 20L:4D, 30 to 37 d; and 23L:1D, 37 to 51 d). Feed consumption and BW were determined, and feed conversions were calculated approximately weekly. Mortalities were necropsied and recorded daily. At 51 d, 30 birds from each room were processed and cut up to determine weights and yields. Beginning at 23 and 30 d, respectively, At 51 d, Dim treatment BW was 4.7% greater and feed consumption was 3.9% greater. Feed conversion, metabolic and total mortality, and BW uniformity were not influenced by light intensity. Weights of lean carcass, total breast, fillets, tenders, and legs were from 4.9 to 6.2% greater in the Dim treatment, which was proportional to the BW difference and resulted in similar yields of these parts. However, wings were 9.9% heavier in the Dim treatment, which resulted in greater wing yield. Equal fat pad weights resulted in reduced fat pad yield in the Dim treatment. These results indicate that BW, feed consumption, and most parts weights were increased proportionally by providing 0.1 vs. 15 FC of light intensity via an increasing photoperiod program, and that only the yields of minor parts were affected by intensity. Key words: broiler, lighting, light intensity, growth, parts yield 2008 Poultry Science 87: doi: /ps INTRODUCTION There have been relatively few reports on the effects of light intensity on broiler performance (Barott and Pringle, 1951; Cherry and Barwick, 1962; Skoglund and Palmer, 1962; Dorminey and Nakaue, 1977; Wathes et al., 1982; Newberry et al., 1986, 1988; Deaton et al., 1988; Buyse et al., 1996; Kristensen et al., 2006) and most have documented effects under continuous or near continuous photoperiods. An interaction effect was recently observed between intensities of 1 and 0.1 FC and photoperiods of 23L:1D and 18L:6D on broiler BW and parts yields (Lien et al., 2007). There are only 2 reports on the influence of different intensities provided with increasing photoperiod programs (Charles et al., 1992; Downs et al., 2006). Increasing photoperiod programs provide a long photoperiod (23L:1D to 18L:6D) to approximately 1 wk of age, a short photoperiod (6L:18D to 12L:12D) for the next 1 to 2 wk, and increasing photoperiods until a long photo Poultry Science Association Inc. Received July 5, Accepted February 7, Corresponding author: lienrog@auburn.edu period is provided for 1 to 3 wk before slaughter. They have been widely used in commercial broiler production. Their benefits are reductions in feed conversion (Classen and Riddell, 1989; Blair et al., 1993; Gordon, 1994; Scott, 2002) and reduced incidences of skeletal and metabolic diseases, and mortality (Classen and Riddell, 1989; Classen et al., 1991; Charles et al., 1992; Riddell and Classen, 1992; Blair et al., 1993; Gordon, 1994; Lott et al., 1996; Rozenboim et al., 1999; Scott, 2002). These benefits are due to reduced feed consumption and growth during short photoperiods at younger ages, followed by compensatory growth when photoperiods are increased at later ages and support and supply organs are better developed, which results in similar BW at slaughter ages. However, these programs have been reported to reduce breast meat in the studies in which this was measured (Renden et al., 1993; Downs et al., 2006). Concern over lighting programs is increasing as guidelines on minimum intensities, and amounts and durations of darkness provided daily, are being established (Food Marketing Institute and National Council of Chain Restaurants, 2003; Commission of the European Communities, 2005; National Chicken Council, 2005). These restrict the use of photoperiods greater than 20 h and intensities 853

2 854 LIEN ET AL. of less than 2 FC. They have led researchers to investigate the consequences of different photoperiods and intensities on broiler production and well-being. There are few reports on the effects of lighting programs on carcass parts yields. However, relative to continuous or near-continuous light, restricted (Renden et al., 1992b, 1994, 1996; Schwean-Lardner et al., 2006; Lien et al., 2007), intermittent (Renden et al., 1992a), and increasing photoperiod (Renden et al., 1993; Downs et al., 2006) programs influenced parts yields even when equal slaughter BW were attained. Reduced intensity also had this effect (Downs et al., 2006; Lien et al., 2007). The purpose of the present study was to determine the effects of different intensities (15 vs. 0.1 FC) provided by an increasing photoperiod program on live performance and on carcass and parts yields of broilers. MATERIALS AND METHODS Bird Management A total of 1,080 male day-old Ross 508 (Aviagen Inc., Huntsville, AL) chicks were vaccinated for Newcastle disease, infectious bronchitis, and Marek s disease at a commercial hatchery. Ninety chicks were randomly placed in each of 12 rooms (3.66 m long 3.05 m wide 2.15 m high). Temperatures were maintained at 31 to 33 C from 1 to 9 d; 28 to 30 C from 9 to 16 d; 24 to 26 C from 16 to 23 d; and 21 to 31 C from 23 to 51 d, respectively. There was an electric forced-draft heater in each room. A thermostat and cycle timer-controlled exhaust fan in each room drew outside air in at 46.7 m 3 /min. From 23 to 51 d, ceiling fans provided an air speed of 2.24 m/s at bird height when temperatures exceeded 27 C, and positive pressure evaporative coolers provided cooling when temperatures exceeded 29 C. This study was conducted in Auburn, Alabama, from September through November. Outside ambient temperatures ranged from 9 to 33 C. Birds were provided standard corn-soy broiler starter (fed d 1 to 16), grower (fed d 16 to 30), finisher (fed d 30 to 44), and withdrawal (fed d 44 to 51) feeds containing 22.5, 20.8, 18.9, and 16.7% CP and 3,080, 3,115, 3,150, and 3,190 kcal of ME/kg, respectively. The starter was crumbled, whereas other feeds were pelleted. Two tube feeders, 2 bell-type drinkers, and a 10- cm layer of fresh pine shavings were provided in each room. Feed and water were provided continuously. The Auburn University Institutional Animal Care and Use Committee approved all procedures. Experimental Treatments All rooms were provided increasing photoperiods (23L:1D, 1 to 9 d; 12L:12D, 9 to 16 d; 14L:10D, 16 to 23 d; 17L:7D, 23 to 30 d; 20L:4D, 30 to 37 d; and 23L:1D, 37 to 51 d). Six replicate rooms were provided intensities of either 15 FC from 1 to 51 d (Bright treatment), or 0.5 FC from 1 to 9 d and 0.1 FC from 9 to 51 d (Dim treatment). Light was provided by 4 evenly spaced incandescent bulbs controlled by a rheostat and clock in each room. Intensity was monitored with a digital illuminometer (Greenlee Textron Inc., Rockford, IL) at bird head height twice weekly. Walls and ceilings were painted white to ensure consistent light intensity. Measurements Individual BW were determined and uniformity (% within ± 10% of BW mean) was calculated at 51 d. Pen BW was determined at 9, 23, 37, and 44 d. Feed consumption was determined by room at 9, 16, 23, 30, 37, 44, and 51 d. Feed conversions were calculated at 9, 23, 37, 44, and 51 d. Mortalities were recorded daily, necropsied, and the cause of death was classified as either metabolic (ascites, skeletal disorders, or sudden death syndrome) or nonmetabolic (other causes). At 51 d, 30 birds per room were randomly selected for processing, weighed, subjected to a 10-h feed-withdrawal period, and placed in transport coops. Birds were hung on shackles, electrically stunned (50 V, 20 ma, 400 Hz), and killed by a single cut severing the right carotid artery and jugular vein. After a 95-s bleed-out, birds were subscalded in a steam-injected scalder at 56.6 C for 90 s; defeathered in a 1.22-m-long picker for 42 s; automatically eviscerated; and chilled in a static slush of ice and water for 2 h. Carcasses were drained, weighed, and deboned to obtain skinless, boneless breast fillets (pectoralis major muscles), breast tenders (pectoralis minor muscles), total breast, wings, legs, and abdominal fat pad weights. Yields were calculated as a percentage of live weight. Statistical Analysis Six replicate rooms served as experimental units for each intensity treatment. Treatment effects were determined by using PROC GLM (2004 version, SAS Institute Inc., Cary, NC). Percentage data were arcsine transformed before analysis to improve normality. Unless otherwise specified, statistical significance was set at the P 0.05 level. RESULTS AND DISCUSSION Live Performance From 23 to 51 d, BW were consistently from 4.4 to 5.1% greater (P < 0.05) in the Dim (0.1 FC) than the Bright treatment (15 FC; Table 1). Charles et al. (1992) also observed greater BW from 3 to 8 wk in broilers provided 0.5 vs. 15 FC in both 23L:1D and increasing photoperiods. We previously observed increased BW from 2 to 5 wk, but not at later ages in broilers provided 0.25 instead of 2 FC in both 23L:1D and increasing photoperiods (Downs et al., 2006). Early reports indicate that broiler BW were consistently greater under intensities of 1 to 5 FC, relative to 6 to 120 FC, but continued BW increases under 0.5 to 0.01 FC were smaller and inconsistent (Barott and Pringle, 1951; Cherry and Barwick, 1962: Skoglund and Palmer,

3 LIGHT INTENSITY AND BROILER PERFORMANCE 855 Table 1. Influence of light intensity on BW, feed consumption, and feed conversion of male broilers Age (d) Item BW (g) Dim a 2,420 a 3,087 a 3,750 a Bright b 2,302 b 2,956 b 3,582 b SEM P-value Cumulative feed consumption (g/bird) Intensity treatment Dim ,253 2,315 a 3,746 a 5,262 a 6,801 a Bright ,208 2,229 b 3,603 b 5,053 b 6,547 b SEM P-value Cumulative feed conversion (g of feed/g of gain) Intensity treatment Dim Bright SEM P-value a,b Means within a column and parameter with no common superscript differ (P 0.05). 1 Both treatments were subjected to increasing photoperiods (23L:1D, 1 to 9 d; 12L:12D, 9 to 16 d; 14L:10D, 16 to 23 d; 17L:7D, 23 to 30 d; 20L:4D, 30 to 37 d; and 23L:1D, 37 to 51 d). The Bright treatment was provided an intensity of 15 footcandles (FC) from 1 to 51 d. The Dim treatment was provided an intensity of 0.5 FC from 1to9dand0.1FCfrom9to51d. 1962; Wathes et al., 1982). More recently, no differences in broiler BW were observed in response to intensities of 0.25 and 1 FC (Dorminey and Nakaue, 1977), ranging incrementally from 0.01 to 10 FC (Newberry et al., 1986), of 0.2 and 5.2 FC (Deaton et al., 1988), of 0.6 and 18 FC (Newberry et al., 1988), or ranging from 0.5 to 0.6 FC vs. from 10 to 11.6 FC (Kristensen et al., 2006). Recently, greater BW were observed at 7 wk when broilers under 18L:6D were provided an intensity of 0.1 instead of 1 FC; however, under 23L:1D, BW were greater when provided 1 rather than 0.1 FC (Lien et al., 2007). From 30 to 51 d, cumulative feed consumption was consistently 3.9 to 4.1% greater (P < 0.05) in the Dim treatment (Table 1). At 23 d, the 3.7% greater feed consumption only approached significance (P = 0.085). Increased feed consumption was previously observed from 2 to 7 wk, but not at 8 wk, in broilers provided 0.25 instead of 2 FC in both 23L:1D and increasing photoperiods (Downs et al., 2006). However, a transitory decrease in feed consumption from 2 to 3 wk, but not thereafter, was more recently seen in broilers subjected to 0.1 vs. 1 FC in either 23L:1D or 18L:6D photoperiods (Lien et al., 2007). In several earlier studies on intensity, feed consumption was not reported (Barott and Pringle, 1951; Skoglund and Palmer, 1962; Dorminey and Nakaue, 1977; Deaton et al., 1988; Charles et al., 1992). However, Cherry and Barwick (1962) observed no effect of intensities from 10 to 0.1 FC on feed consumption, and Newberry et al. reported no effect of intensities from 0.05 to 3 FC (1986) and of 18 and 0.6 FC (1988) on feed consumption. Similarly no effect of intensities ranging from 5 to 6 FC as opposed to 10 to 11.6 FC was observed on feed consumption (Kristensen et al., 2006). Conversely, Wathes et al. (1982) observed the greatest feed consumption at 0.3 FC relative to that occurring at 0.07, 1.5, or 4.65 FC, and Newberry et al. (1986) observed an increase in feed consumption through 6 wk, but not 9 wk, in response to greater intensities in the range of 0.1 to 10 FC. Because of similar relative changes in BW and feed consumption occurring in the 2 treatments throughout the trial, feed conversion was not significantly affected by intensity at any time (Table 1). In early studies on intensity, feed conversion was sometimes not reported (Barott and Pringle, 1951; Skoglund and Palmer, 1962); however, Cherry and Barwick (1962) observed improved feed conversion as intensities were decreased from 10 to 0.1 FC. Newberry et al. (1986) observed a decrease in feed conversion at 6 and 9 wk in response to lower intensities in the range of 0.1 to 10 FC. However, no effect on feed conversion was observed in response to intensities of 1 vs FC (Dorminey and Nakaue, 1977), 0.2 vs. 5.2 FC (Deaton et al., 1988), or 18 vs. 0.6 FC, and even though standing, walking, and total activity increased with intensity in the later trial, feeding and drinking activity did not (Newberry et al. 1988). It is generally accepted that changes in photoperiod result in changes in consumption and, subsequently, BW (Charles et al., 1992; Renden et al., 1993). It has also been assumed that lower intensities may improve feed conversion because of a reduction in activity (Newberry et al., 1986; Charles et al., 1992; Downs et al., 2006). This would result in increased BW if feed consumption did not decrease proportionally or if it remained the same. Alternatively, it could result in increased carcass fat if muscular growth was not increased. This situation was observed by Charles et al. (1992) but not others (Deaton et al., 1988; Downs et al., 2006). If muscular growth increased because of improved feed conversion, this could lead to increased

4 856 LIEN ET AL. Table 2. Influence of light intensity on uniformity and mortality of male broilers at 51 d Item Dim Bright SEM P-value Uniformity (%) Metabolic mortality (%) Other mortality (%) Total mortality (%) Both treatments were subjected to increasing photoperiods (23L:1D, 1 to 9 d; 12L:12D, 9 to 16 d; 14L:10D, 16 to 23 d; 17L:7D, 23 to 30 d; 20L:4D, 30 to 37 d; and 23L:1D, 37 to 51 d). The Bright treatment was provided an intensity of 15 footcandles (FC) from 1 to 51 d. The Dim treatment was provided an intensity of 0.5 FC from 1 to 9 d and 0.1 FCfrom9to51d. feed consumption to meet increased metabolic needs and, if this cycle persisted, significantly greater BW should be observed. The temporal relationship of significant increases in BW preceding significant increases in feed consumption, coupled with the consistent but nonsignificant improvement in feed conversion in the Dim treatment in the present study, may demonstrate this effect. However, from these data it cannot be definitively determined whether increased feed consumption resulted in greater BW or vice versa. Uniformity was not influenced by treatment (Table 2). Uniformity is a commercially important production parameter; however, few have mentioned the influence of light intensity on uniformity. Lien et al. (2007) observed a transient reduction in uniformity caused by a decrease from 3 to 0.1 FC early in the rearing period, whereas the intensity decrease at that age in the Dim treatment of the present study was only from 0.5 to 0.1 FC. Downs et al. (2006) observed no effect of intensity on uniformity. Metabolic, other, and total mortality were not influenced by treatment (Table 2). Several reports have observed no effect of intensity on mortality (Dorminey and Nakaue, 1977; Wathes et al., 1982; Newberry et al., 1986; Deaton et al., 1988; Charles et al., 1992; Downs et al., 2006; Kristensen et al., 2006; Lien et al., 2007), although Newberry et al. (1988) observed an increase in mortality attributable to 0.6 vs. 18 FC. Mortality differences attributable to lighting programs are often not observed unless levels approach 10% (Downs et al., 2006; Lien et al., 2007). Processing Characteristics Weights of lean carcass, total breast, fillets (P = ), tenders, and legs were from 4.9 to 6.3% greater in the Dim treatment (Table 3), which was proportional to BW differences and resulted in similar yields of these parts in the 2 treatments. However, wings were 9.9% heavier in the Dim than the Bright treatment, which resulted in greater wing yield. A previous report indicated a similar increase in wing yield along with a decrease in fillet yield with exposure to 0.25 vs. 2.0 FC (Downs et al., 2006). Decreases in carcass and whole breast yields, as well as whole breast, fillet, and tender weights attributable to exposure to 0.1 vs. 1.0 FC have also been observed (Lien Table 3. Influence of light intensity on weights and yields of male broiler carcasses and parts at 51 d Item Dim Bright SEM P-value Live weight (g) 3,759 a 3,569 b Lean carcass Weight (g) 2,701 a 2,572 b Yield Total breast Weight (g) 739 a 704 b Yield Fillets Weight (g) Yield Tenders Weight (g) 137 a 130 b Yield Wings Weight (g) 300 a 273 b Yield a 7.66 b Legs Weight (g) 855 a 804 b Yield Fat pad Weight (g) Yield a,b Means within a column with no common superscript differ (P 0.05). 1 Both treatments were subjected to increasing photoperiods (23L:1D, 1 to 9 d; 12L:12D, 9 to 16 d; 14L:10D, 16 to 23 d; 17L:7D, 23 to 30 d; 20L:4D, 30 to 37 d; and 23L:1D, 37 to 51 d). The Bright treatment was provided an intensity of 15 footcandles (FC) from 1 to 51 d. The Dim treatment was provided an intensity of 0.5 FC from 1 to 9 d and 0.1 FCfrom9to51d. 2 Yields are expressed as a percentage of live weight. et al., 2007). Similarly, Charles et al. (1992) observed a decrease in whole body protein percentage with exposure of broilers to 0.5 vs. 15 FC, although carcass parameters were not observed. Both intensity treatments in the present study were provided an increasing photoperiod program, which has been observed to decrease breast meat yield relative to a fixed long photoperiod such as 23L:1D (Renden et al., 1993; Downs et al., 2006). Apparently, compensatory growth occurring under photoperiods that initially delay growth favors the development of legs and wings, perhaps because of a delay in the progression of the growth of the different carcass parts. In a recent report, we observed that either dim light (0.1 vs. 1.0 FC), a shortened photoperiod (18L:6D vs. 23L1D), or both reduced breast meat to a similar extent (Lien et al., 2007). Therefore, potential negative effects of the Dim treatment on carcass parts yields in the present study may have been obscured by an overriding effect of the increasing photoperiod program. Equal fat pad weights (Table 3) resulted in a reduced fat pad yield (P = ) in the Dim vs. the Bright treatment. Others have reported an increase in fat pad weights and whole body fat weight and percentage in broilers subjected to dim light (Charles et al., 1992) or no effect of light intensity on fat pad weights or yield (Downs et al.,

5 LIGHT INTENSITY AND BROILER PERFORMANCE ). The results of the current study indicate that under an increasing photoperiod program, BW, feed consumption, and most parts weights are proportionally increased by providing 0.1 vs. 15 FC of light intensity, and that only yields of minor parts are affected by intensity. ACKNOWLEDGMENTS The excellent technical and organizational assistance of Frank Dillman is sincerely appreciated and will be sorely missed. REFERENCES Barott, H. G., and E. M. Pringle Effect of environment on growth and feed and water consumption in chickens. IV. The effect of light on early growth. J. Nutr. 45: Blair, R., R. C. Newberry, and E. E. Gardiner Effects of lighting pattern and dietary tryptophan supplementation on growth and mortality in broilers. Poult. Sci. 72: Buyse, J., P. C. M. Simons, F. M. G. Boshouwers, and E. Decuypere Effect of intermittent lighting, light intensity and source on the performance and welfare of broilers. World s Poult. Sci. 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