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The effect of air velocity on broiler performance and feed and water consumption1
The Effect of Air Velocity on Broiler Performance and Feed and Water Consumption1 J. D. May,2 B. D. Lott, and J. D. Simmons USDA/ARS, South Central Poultry Research Laboratory, Mississippi State, Mississippi 39762-5367 ABSTRACT Two trials were conducted to determine the effect of air velocity on feed and water consumption at a constant temperature of 27 C and a daily cyclic temperature of 22-32-22 C. Air velocity over the broilers was <15 or 120 m/min. These temperature and air velocity treatments were arranged in a 2 × 2 factorial design in eight environmental chambers, with two replications of each treatment. The air velocity treatments were applied,
and total feed and water consumption and daily patterns of consumption were determined for broilers from 21 to 49 d of age. Broilers exposed to the high air velocity consumed less water and more feed, gained more weight, and had an improved feed:gain ratio. The high air velocity had little effect on daily patterns of feed and water consumption. Both feed and water consumption were depressed during the peak of the daily cyclic temperature.
(Key words: air velocity, temperature, feed:gain, broilers) 2000 Poultry Science 79:1396–1400
INTRODUCTION Increasing the air velocity around broilers is an effective technique for improving broiler performance and wellbeing when temperatures are above the thermoneutral zone. Convective heat loss increases, and panting decreases, as air velocity increases (Simmons et al., 1997). Birds pant to increase respiratory evaporation and prevent unacceptable increases in body temperature. Production efficiency is reduced, because energy is expended for panting, and growth is slowed due to lower feed consumption. Convective heat loss is related to body size, temperature, and air velocity. Therefore, the usefulness of increasing air velocity is related to body size and temperature. Air velocity becomes more beneficial as body weight increases. Humidity is also a factor, because it affects respiratory evaporation. High air velocity is beneficial at warm temperatures, but may be detrimental at lower temperatures if heat loss is excessive. Some broiler growers have stated that when broilers become chilled, they sit down and stop eating. It is unknown whether this behavior results in changes in feed consumption patterns or is detrimental to performance in some other way. Patterns of feed consumption are important for several reasons. May et al. (1988) first
Received for publication December 2, 1999. Accepted for publication May 24, 2000. 1 Trade names in this article are used solely to provide specific information. Use of trade names does not constitute a guarantee or warranty by the USDA and does not signify that the product is approved to the exclusion of other comparable products. 2 To whom correspondence should be addressed: dmay@ra. msstate.edu.
reported meal feeding as an important consideration in uniformity of gut clearance. Our recent observations have suggested that quiescence of broilers may not be indicative of a lack of well-being. The objective of this research was to determine the effect of air velocity at 120 m/min on feed and water consumption by broilers in constant and cyclic temperatures.
MATERIALS AND METHODS Male Ross × Ross chicks were obtained from a commercial hatchery and reared on pine shavings litter in two trials. The chicks were maintained in a controlled-environment house that was initially set at 32 C, and the temperature was reduced by 0.3 C daily to 21 d. Lighting was
TABLE 1. The effect of cyclic temperature and air velocity on growth and feed:gain of male broilers from 21 to 49 d of age1 Age
Temperature, C
Air velocity (m/min)
21 to 35 d
27 27 22-32-22 22-32-22
<15 120 <15 120
1,131.6 1,206.8 1,149.8 1,195.4
± ± ± ±
27 27 22-32-22 22-32-22
<15 120 <15 120
1.754 1.761 1.699 1.735
± ± ± ±
35 to 49 d (Wt gain, g) 11.0b 907.6 10.2a 1,142.5 10.2b 902.4 11.3a 1,102.7 (Feed:gain) 0.026a 2.505 0.029a 2.170 0.016b 2.432 0.035ab 2.133
± ± ± ±
45.1b 57.0a 49.1b 53.7a
± ± ± ±
0.115a 0.052b 0.044a 0.045b
a,b Means within age and performance parameters with no common superscript differ significantly (P < 0.05). 1 Values are means ± SE.
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EFFECT OF AIR VELOCITY ON BROILERS
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FIGURE 1. Effect of air velocity on daily water consumption patterns as a percentage of body weight for the cyclic temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of 3 d for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
FIGURE 2. Effect of air velocity on daily water consumption patterns as a percentage of body weight for the constant temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of 3 d for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
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MAY ET AL.
weight. The body weights for each 30-min period were calculated from the actual pen weights that were determined weekly. Reece and Lott (1983) have shown that body weight increase is linear for these periods. Cornsoybean meal diets were formulated to meet or exceed NRC (1994) requirements. Mortality was recorded as it occurred.
Statistical Analysis The weight gain and feed conversion data were analyzed by weeks with PCSAS Release 6.12.3 Duncan’s (1955) multiple range test was used to identify significant differences among means for weight gain and feed:gain. Daily feed and water consumption data were combined by trials and analyzed by PCSAS Release 6.12. Individual day comparisons were made by F-test. Mortality data were analyzed by Chi Square. All statements of significance were based on P < 0.05.
RESULTS AND DISCUSSION
FIGURE 3. Effect of air velocity on daily water consumption for: A) 21 to 35 d, and B) 35 to 49 d in constant temperature (䊉–䊉 = < 15 m/ min; ▲–▲ = 120 m/min; *P < 0.05).
constant, and feed and water were provided ad libitum. Eight environmental chambers described by Reece and Deaton (1969) were used during two experimental periods (21 to 35 d and 35 to 49 d). Four chambers each had two 1.14 × 1.87-m pens, and air velocity was <15 m/min. The remaining four chambers each had one 1.14 × 1.87-m pens, and a fan and return air duct to give 120 m/min air velocity across the pen at bird level. Each pen had seven nipple drinkers spaced 20 cm apart on one side, and one tubetype feeder with a 35-cm diameter pan with access around it. Each pen was stocked with 25 broilers when they were 21 d of age. After 14 d, they were removed, and the pens were restocked with different broilers from the controlledenvironment house for the period of 35 to 49 d of age. Restocking was conducted to shorten the treatment periods and obtain a more accurate measurement of treatment for body weight. Body weights were determined at 21, 28, 35, 42, and 49 d, and feed:gain was determined at 28, 35, 42, and 49 d. Two chambers at each air velocity were maintained at 27 C and an 18-C dewpoint. The other two chambers were maintained at a daily curvilinear cyclic temperature of 2232-22 C and a constant 18-C dewpoint. Feed and water consumption were recorded at 30-min intervals by computer using the system described by Lott et al. (1992). The consumption values are reported as a percentage of body
3
SAS Institute Inc., Cary, NC 25711.
The effects of cyclic temperature and air velocity on weight gain and feed:gain are given in Table 1. Cyclic temperature did not affect weight gain for either age or air velocity. Similar results were observed for feed:gain, except that the cyclic temperature resulted in feed:gain that was superior to that of the constant temperature at the low air velocity for 21 to 35 d. Conflicting results have been reported on the effects of cyclic temperatures compared with constant temperatures, and the results of the present study are similar to some previous reports. See Charles (1986) for an excellent review. Increasing the air velocity improved weight gains for both treatment periods and temperature regimens and improved feed:gain for the 35 to 49-d period, but not for the 21 to 35-d period. These results show that increasing sensible heat loss by increasing air velocity improved weight gain but not feed:gain for the 21 to 35-d period. Increased feed intake is the logical explanation for the increased gain. The effects of cyclic temperature and air velocity on water consumption patterns are presented in Figure 1. As expected, water consumption declined with increasing age. The most notable treatment effect was the inverse relationship of temperature and water consumption that was first seen by 33 to 35 d and was most pronounced by 47 to 49 d. This result has been previously reported (May et al., 1997) as inhibition of water consumption from nipples by panting broilers. Increasing the air velocity did not alleviate this response, but the pattern was not as evident for the high air velocity at 33 to 35 d, and the reduction in consumption began 2 h later for the high air velocity at 40 to 42 d. The effect of air velocity at a constant temperature on water consumption patterns is presented in Figure 2. More variation seemed to exist for high air velocity at 40 to 42 d and 47 to 49 d than for low air velocity. The higher air velocity resulted in lower water consumption by 33 to 35 d, and the effect was more pronounced at greater ages.
EFFECT OF AIR VELOCITY ON BROILERS
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FIGURE 4. Effect of air velocity on daily feed consumption patterns as a percentage of body weight for the cyclic temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of three days for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
FIGURE 5. Effect of air velocity on daily feed consumption patterns as a percentage of body weight for the constant temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of 3 d for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
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FIGURE 6. Effect of air velocity on daily feed consumption for A) 21 to 35 d, and B) 35 to 49 d in constant temperature (䊉–䊉 = < 15 m/ min; ▲–▲ = 120 m/min).
The total daily water consumption for the 24 to 35-d and 37 to 49-d periods is presented in Figure 3. There appeared to be no effect due to air velocity until about 31 d. Thereafter, broilers experiencing the higher air velocity consumed less water than the controls. The data were analyzed for the 24 to 36-d and 37 to 49-d periods, and broilers in the high air velocity treatment consumed significantly less water during both periods. Water consumption in the cyclic temperature was not different from that in the constant temperature. The effects of air velocity and cyclic temperature on feed consumption patterns are presented in Figure 4. High air velocity caused increased feed consumption as temperature declined at 26 to 28 d, but air velocity generally did not have a pronounced effect on feed consumption patterns. By the 47 to 49-d period, controls and 120-m/min air velocity treatments showed a change in feed consumption similar to that observed for water consumption; there was a reduction in feed consumption during the peak temperature. Increasing the air velocity did not result in feed consumption patterns that might cause problems with feed withdrawal at the temperatures examined in this study. The effect of air velocity at a constant temperature on feed consumption patterns is presented in Figure 5. Consumption was constant throughout the day for both treatments, with little effect due to air velocity. The effect of
air velocity on total daily feed consumption by broilers in a constant temperature of 24 C for the 21 to 35-d and 35 to 49-d periods is presented in Figure 6. The data were also analyzed for the effect of cyclic temperature. Constant temperature and increased air velocity resulted in increased feed consumption compared with cyclic temperature and low air velocity, respectively. This increase in feed consumption occurred for both experimental periods. High temperatures are known to inhibit feed consumption, and lowering the minimum temperature of a cyclic temperature improved growth (Deaton et al., 1984). In this research, an average temperature equally different from the extremes resulted in greater feed consumption than the cyclic regimen. Increasing the air velocity was more effective in increasing feed consumption than maintaining a constant temperature. The air movement increases sensible heat loss and improves feed consumption. These results suggest that for the temperatures examined, increasing air velocity did not change the feed and water consumption patterns. Cyclic temperatures resulted in consumption patterns that may impact gut clearance. May et al. (1990) states that the best preparation for feed withdrawal is to prevent meal feeding prior to preprocessing feed withdrawal. This research shows that cyclic temperature has more effect on feed consumption patterns than the combination of cyclic temperature and air velocity. Also, high air velocity did not influence behavior that would hinder feed consumption.
REFERENCES Charles, D. R., 1986. Temperature for broilers. World’s Poult. Sci. J. 42:249–258. Deaton, J. W., F. N. Reece, and B. D. Lott, 1984. Effect of differing temperature cycles on broiler performance. Poultry Sci. 63:612–615. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1–42. Lott, B. D., J. D. Simmons, and J. D. May, 1992. An automated feed and water consumption measuring system for poultry research. Appl. Eng. Agric. 8:521–523. May, J. D., S. L. Branton, J. W. Deaton, and J. D. Simmons, 1988. Effect of environmental temperature and feeding regimen on quantity of digestive tract contents of broilers. Poultry Sci. 67:64–71. May, J. D., B. D. Lott, and J. W. Deaton, 1990. The effect of light and environmental temperature on broiler digestive tract contents after feed withdrawal. Poultry Sci. 69:1681–1684. May, J. D., B. D. Lott, and J. D. Simmons, 1997. Water consumption by broilers in high cyclic temperatures: Bell vs. nipple waterers. Poultry Sci. 76:944–947. NRC, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. Reece, F. N., and J. W. Deaton, 1969. Environmental control for poultry research. Agric. Eng. 50:670–671. Reece, F. N., and B. D. Lott, 1983. The effects of temperature and age on body weight and feed efficiency of broiler chickens. Poultry Sci. 62:1906–1908. Simmons, J. D., B. D. Lott, and J. D. May, 1997. Heat loss from broiler chickens subjected to various air speeds and ambient temperatures. Appl. Eng. Agric. 13:665–669.
and total feed and water consumption and daily patterns of consumption were determined for broilers from 21 to 49 d of age. Broilers exposed to the high air velocity consumed less water and more feed, gained more weight, and had an improved feed:gain ratio. The high air velocity had little effect on daily patterns of feed and water consumption. Both feed and water consumption were depressed during the peak of the daily cyclic temperature.
(Key words: air velocity, temperature, feed:gain, broilers) 2000 Poultry Science 79:1396–1400
INTRODUCTION Increasing the air velocity around broilers is an effective technique for improving broiler performance and wellbeing when temperatures are above the thermoneutral zone. Convective heat loss increases, and panting decreases, as air velocity increases (Simmons et al., 1997). Birds pant to increase respiratory evaporation and prevent unacceptable increases in body temperature. Production efficiency is reduced, because energy is expended for panting, and growth is slowed due to lower feed consumption. Convective heat loss is related to body size, temperature, and air velocity. Therefore, the usefulness of increasing air velocity is related to body size and temperature. Air velocity becomes more beneficial as body weight increases. Humidity is also a factor, because it affects respiratory evaporation. High air velocity is beneficial at warm temperatures, but may be detrimental at lower temperatures if heat loss is excessive. Some broiler growers have stated that when broilers become chilled, they sit down and stop eating. It is unknown whether this behavior results in changes in feed consumption patterns or is detrimental to performance in some other way. Patterns of feed consumption are important for several reasons. May et al. (1988) first
Received for publication December 2, 1999. Accepted for publication May 24, 2000. 1 Trade names in this article are used solely to provide specific information. Use of trade names does not constitute a guarantee or warranty by the USDA and does not signify that the product is approved to the exclusion of other comparable products. 2 To whom correspondence should be addressed: dmay@ra. msstate.edu.
reported meal feeding as an important consideration in uniformity of gut clearance. Our recent observations have suggested that quiescence of broilers may not be indicative of a lack of well-being. The objective of this research was to determine the effect of air velocity at 120 m/min on feed and water consumption by broilers in constant and cyclic temperatures.
MATERIALS AND METHODS Male Ross × Ross chicks were obtained from a commercial hatchery and reared on pine shavings litter in two trials. The chicks were maintained in a controlled-environment house that was initially set at 32 C, and the temperature was reduced by 0.3 C daily to 21 d. Lighting was
TABLE 1. The effect of cyclic temperature and air velocity on growth and feed:gain of male broilers from 21 to 49 d of age1 Age
Temperature, C
Air velocity (m/min)
21 to 35 d
27 27 22-32-22 22-32-22
<15 120 <15 120
1,131.6 1,206.8 1,149.8 1,195.4
± ± ± ±
27 27 22-32-22 22-32-22
<15 120 <15 120
1.754 1.761 1.699 1.735
± ± ± ±
35 to 49 d (Wt gain, g) 11.0b 907.6 10.2a 1,142.5 10.2b 902.4 11.3a 1,102.7 (Feed:gain) 0.026a 2.505 0.029a 2.170 0.016b 2.432 0.035ab 2.133
± ± ± ±
45.1b 57.0a 49.1b 53.7a
± ± ± ±
0.115a 0.052b 0.044a 0.045b
a,b Means within age and performance parameters with no common superscript differ significantly (P < 0.05). 1 Values are means ± SE.
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FIGURE 1. Effect of air velocity on daily water consumption patterns as a percentage of body weight for the cyclic temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of 3 d for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
FIGURE 2. Effect of air velocity on daily water consumption patterns as a percentage of body weight for the constant temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of 3 d for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
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MAY ET AL.
weight. The body weights for each 30-min period were calculated from the actual pen weights that were determined weekly. Reece and Lott (1983) have shown that body weight increase is linear for these periods. Cornsoybean meal diets were formulated to meet or exceed NRC (1994) requirements. Mortality was recorded as it occurred.
Statistical Analysis The weight gain and feed conversion data were analyzed by weeks with PCSAS Release 6.12.3 Duncan’s (1955) multiple range test was used to identify significant differences among means for weight gain and feed:gain. Daily feed and water consumption data were combined by trials and analyzed by PCSAS Release 6.12. Individual day comparisons were made by F-test. Mortality data were analyzed by Chi Square. All statements of significance were based on P < 0.05.
RESULTS AND DISCUSSION
FIGURE 3. Effect of air velocity on daily water consumption for: A) 21 to 35 d, and B) 35 to 49 d in constant temperature (䊉–䊉 = < 15 m/ min; ▲–▲ = 120 m/min; *P < 0.05).
constant, and feed and water were provided ad libitum. Eight environmental chambers described by Reece and Deaton (1969) were used during two experimental periods (21 to 35 d and 35 to 49 d). Four chambers each had two 1.14 × 1.87-m pens, and air velocity was <15 m/min. The remaining four chambers each had one 1.14 × 1.87-m pens, and a fan and return air duct to give 120 m/min air velocity across the pen at bird level. Each pen had seven nipple drinkers spaced 20 cm apart on one side, and one tubetype feeder with a 35-cm diameter pan with access around it. Each pen was stocked with 25 broilers when they were 21 d of age. After 14 d, they were removed, and the pens were restocked with different broilers from the controlledenvironment house for the period of 35 to 49 d of age. Restocking was conducted to shorten the treatment periods and obtain a more accurate measurement of treatment for body weight. Body weights were determined at 21, 28, 35, 42, and 49 d, and feed:gain was determined at 28, 35, 42, and 49 d. Two chambers at each air velocity were maintained at 27 C and an 18-C dewpoint. The other two chambers were maintained at a daily curvilinear cyclic temperature of 2232-22 C and a constant 18-C dewpoint. Feed and water consumption were recorded at 30-min intervals by computer using the system described by Lott et al. (1992). The consumption values are reported as a percentage of body
3
SAS Institute Inc., Cary, NC 25711.
The effects of cyclic temperature and air velocity on weight gain and feed:gain are given in Table 1. Cyclic temperature did not affect weight gain for either age or air velocity. Similar results were observed for feed:gain, except that the cyclic temperature resulted in feed:gain that was superior to that of the constant temperature at the low air velocity for 21 to 35 d. Conflicting results have been reported on the effects of cyclic temperatures compared with constant temperatures, and the results of the present study are similar to some previous reports. See Charles (1986) for an excellent review. Increasing the air velocity improved weight gains for both treatment periods and temperature regimens and improved feed:gain for the 35 to 49-d period, but not for the 21 to 35-d period. These results show that increasing sensible heat loss by increasing air velocity improved weight gain but not feed:gain for the 21 to 35-d period. Increased feed intake is the logical explanation for the increased gain. The effects of cyclic temperature and air velocity on water consumption patterns are presented in Figure 1. As expected, water consumption declined with increasing age. The most notable treatment effect was the inverse relationship of temperature and water consumption that was first seen by 33 to 35 d and was most pronounced by 47 to 49 d. This result has been previously reported (May et al., 1997) as inhibition of water consumption from nipples by panting broilers. Increasing the air velocity did not alleviate this response, but the pattern was not as evident for the high air velocity at 33 to 35 d, and the reduction in consumption began 2 h later for the high air velocity at 40 to 42 d. The effect of air velocity at a constant temperature on water consumption patterns is presented in Figure 2. More variation seemed to exist for high air velocity at 40 to 42 d and 47 to 49 d than for low air velocity. The higher air velocity resulted in lower water consumption by 33 to 35 d, and the effect was more pronounced at greater ages.
EFFECT OF AIR VELOCITY ON BROILERS
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FIGURE 4. Effect of air velocity on daily feed consumption patterns as a percentage of body weight for the cyclic temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of three days for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
FIGURE 5. Effect of air velocity on daily feed consumption patterns as a percentage of body weight for the constant temperature treatment. Values are for 2-h periods, but have been multiplied by 12 for comparison with daily consumption values. Results shown are the average of 3 d for: A) 26 to 28 d, B) 33 to 35 d, C) 40 to 42 d, and D) 47 to 49 d of age (䊉–䊉 = < 15 m/min; ▲–▲ = 120 m/min).
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FIGURE 6. Effect of air velocity on daily feed consumption for A) 21 to 35 d, and B) 35 to 49 d in constant temperature (䊉–䊉 = < 15 m/ min; ▲–▲ = 120 m/min).
The total daily water consumption for the 24 to 35-d and 37 to 49-d periods is presented in Figure 3. There appeared to be no effect due to air velocity until about 31 d. Thereafter, broilers experiencing the higher air velocity consumed less water than the controls. The data were analyzed for the 24 to 36-d and 37 to 49-d periods, and broilers in the high air velocity treatment consumed significantly less water during both periods. Water consumption in the cyclic temperature was not different from that in the constant temperature. The effects of air velocity and cyclic temperature on feed consumption patterns are presented in Figure 4. High air velocity caused increased feed consumption as temperature declined at 26 to 28 d, but air velocity generally did not have a pronounced effect on feed consumption patterns. By the 47 to 49-d period, controls and 120-m/min air velocity treatments showed a change in feed consumption similar to that observed for water consumption; there was a reduction in feed consumption during the peak temperature. Increasing the air velocity did not result in feed consumption patterns that might cause problems with feed withdrawal at the temperatures examined in this study. The effect of air velocity at a constant temperature on feed consumption patterns is presented in Figure 5. Consumption was constant throughout the day for both treatments, with little effect due to air velocity. The effect of
air velocity on total daily feed consumption by broilers in a constant temperature of 24 C for the 21 to 35-d and 35 to 49-d periods is presented in Figure 6. The data were also analyzed for the effect of cyclic temperature. Constant temperature and increased air velocity resulted in increased feed consumption compared with cyclic temperature and low air velocity, respectively. This increase in feed consumption occurred for both experimental periods. High temperatures are known to inhibit feed consumption, and lowering the minimum temperature of a cyclic temperature improved growth (Deaton et al., 1984). In this research, an average temperature equally different from the extremes resulted in greater feed consumption than the cyclic regimen. Increasing the air velocity was more effective in increasing feed consumption than maintaining a constant temperature. The air movement increases sensible heat loss and improves feed consumption. These results suggest that for the temperatures examined, increasing air velocity did not change the feed and water consumption patterns. Cyclic temperatures resulted in consumption patterns that may impact gut clearance. May et al. (1990) states that the best preparation for feed withdrawal is to prevent meal feeding prior to preprocessing feed withdrawal. This research shows that cyclic temperature has more effect on feed consumption patterns than the combination of cyclic temperature and air velocity. Also, high air velocity did not influence behavior that would hinder feed consumption.
REFERENCES Charles, D. R., 1986. Temperature for broilers. World’s Poult. Sci. J. 42:249–258. Deaton, J. W., F. N. Reece, and B. D. Lott, 1984. Effect of differing temperature cycles on broiler performance. Poultry Sci. 63:612–615. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1–42. Lott, B. D., J. D. Simmons, and J. D. May, 1992. An automated feed and water consumption measuring system for poultry research. Appl. Eng. Agric. 8:521–523. May, J. D., S. L. Branton, J. W. Deaton, and J. D. Simmons, 1988. Effect of environmental temperature and feeding regimen on quantity of digestive tract contents of broilers. Poultry Sci. 67:64–71. May, J. D., B. D. Lott, and J. W. Deaton, 1990. The effect of light and environmental temperature on broiler digestive tract contents after feed withdrawal. Poultry Sci. 69:1681–1684. May, J. D., B. D. Lott, and J. D. Simmons, 1997. Water consumption by broilers in high cyclic temperatures: Bell vs. nipple waterers. Poultry Sci. 76:944–947. NRC, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. Reece, F. N., and J. W. Deaton, 1969. Environmental control for poultry research. Agric. Eng. 50:670–671. Reece, F. N., and B. D. Lott, 1983. The effects of temperature and age on body weight and feed efficiency of broiler chickens. Poultry Sci. 62:1906–1908. Simmons, J. D., B. D. Lott, and J. D. May, 1997. Heat loss from broiler chickens subjected to various air speeds and ambient temperatures. Appl. Eng. Agric. 13:665–669.