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Performance of Male Broiler Chicks Exposed to Heat from Infrared or Microwave Sources
Performance of Male Broiler Chicks Exposed to Heat from Infrared or Microwave Sources W. D. MORRISON,1 E. AMYOT,1 I. McMILLAN,' L. OTTEN2 Department of Animal and Poultry Science and School of Engineering, University ofGuelph, Guelph, Ontario, Canada NIC 2W1 and D. C. T. PEI
(Received for publication February 2, 1987) ABSTRACT In eight trials, 240 male broiler birds, initially 7 days old, were randomly allocated to three treatments. Treatments were: continuous infrared (CI), intermittent infrared (II; 4 min on, 2 min off, 10 cycles/h), and intermittent microwaves (IM; 2 min on, 4 min off, 10 cycles/h). At the conclusion of the 14-day experimental period the 21-day-oId birds were killed. Although there were significant differences (P=£.05) in mean gain over the 2-wk treatment period between trials, no differences (P>.05) were attributed to treatments. There were, however, significant differences in feed:gain ratios between trials and between treatments. Feed:gain ratios of birds kept under CI and II treatments did not differ significantly (P>.05). However, feed:gain ratios, 1.61 ± .04 and 1.57 ± .04 for CI and II, respectively, differed significantly (P«s.05) from that of the IM treatment (1.76 ± .04). The protein content of chicks under II was significantly (P«.05) lower than that of birds under IM. There were no differences (P>.05) in fat, ash, calcium, and phosphorus content of chicks among treatments. (Key words: infrared heat, microwave heat, male broilers, performance) 1987 Poultry Science 66:1762-1765 INTRODUCTION
MATERIALS AND METHODS
There is evidence that chicks (Morrison et al., 1986) and pigs (Morrison et al., unpublished data) subjected to microwaves as a heat source respond similarly to animals kept under infrared and other conventional heat sources. Although these experiments have shown microwaves adequate to raise these species, the efficiency of microwaves as an alternative to conventional heat sources was not compared. The purposes of the trials reported herein were: 1) to determine the growth and feed efficiency response of male broiler chicks to microwaves as a heat source; 2) to determine the effect of such procedures on body composition and mortality; and 3) to compare these performances with those of similar groups of chicks exposed to intermittent and continuous infrared heat source.
Two hundred and forty male broiler birds, initially 7 days old, were used for this experiment conducted in eight trials. Ten birds were randomly placed in three identical chambers for a 2-wk period. Conditions maintained in the chambers were: 1) continuous infrared (CI); 2) intermittent infrared (II; 4 min on, 2 min off, 10 cycles/h); and 3) intermittent microwaves (IM; 2 min on, 4 min off, 10 cycles/h). Cycles were controlled by a microcomputer (IBM PC Jr., Model 4860, IBM, Armonk, NY). The environmental temperature of the room was kept at 16 C for the duration of the experimental period. Supplemental heat was provided by a 250-W infrared lamp located 40 cm above the litter or 10 mW/cm of microwaves delivered by a generator with a maximum capacity of 700 W. The generator was constructed in the Department of Chemical Engineering, University of Waterloo. Chicks in every chamber were fed ad libitum a conventional broiler diet, calculated to provide
'Department of Animal and Poultry Science. School of Engineering.
2
1762
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3GI
INFRARED AND MICROWAVE HEAT
22% protein and 3,050 kcal metabolizable energy/kg. Weight and mortality were recorded on an individual bird basis whereas feed intake was based on all birds in a chamber. Data collected during the growing period were analyzed for variation in feed efficiency and rate of gain ofbirds maintained under CI, II, and IM heating
regimes. Birds were killed by cervical dislocation at 21 days of age. Carcasses were ground on a chamber basis and analyzed for protein (nitrogen), fat, ash, calcium, and phosphorus content (Association of Official Analytical Chemists, 1984). The statistical model used for these tests was a randomized complete block
T A B L E 1. Mean gain and feed:gain of chicks per treatment over a 2-wk growing period
All trials
and per trial
Treatment1
Gain
Feedrgain
(g) CI II IM x
438.1 434.0 418.0 430.04c
(g/g) 1.73 1.88 1.97 1.86a
CI II IM x
448.3 449.6 423.7 440.52c
1.55 1.36 1.61 1.51c
CI II IM
462.0 463.0 460.3 461.78abc
1.58 1.55 1.50 1.54bc
CI II IM x
506.0 485.9 489.6 493.83a
1.72 1.49 2.09 1.76ab
CI II IM
433.6 463.8 463.6 453.64bc
1.57 1.62 1.74 1.64abc
CI II IM
490.2 486.0 453.8 476.67ab
1.50 1.52 1.62 1.55bc
CI II IM
344.0 431.4 350.1 375.17d
1.55 1.58 1.92 1.68abc
CI II IM
480.2 463.6 490.9 478.24ab
1.67 1.54 1.60 1.60bc
CI II IM
449.4a 459.3a 443.5a
1.61a 1.57 a 1.76b
Means for trials on t r e a t m e n t s followed b y different superscripts are significantly different ( P < . 0 5 ) . CI = C o n t i n u o u s infrared; II = i n t e r m i t t e n t infrared; and IM = i n t e r m i t t e n t microwave.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
Trial
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MORRISON ET AL.
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TABLE 2. Mean fat, protein, ash, calcium, and phosphorus content of the dried carcass by trial and treatment
Calcium
Phosphorus
7.69 a 7.46 a 7.01ab 6.92 a b 6.94 a b 7.11ab 5.88 b
2.16 a 2.28 a 1.81 a 1.56a 1.71 a 1.47a 1.41 a
1.80a 1.84 a 1.55a 1.34a 1.40a 1.29a 1.41 a
.44
.26
.19
Trial1
Fat
Protein
Ash
1 2 3 5 6 7 8
3 3.09 a b 29.63 c 30.71bc 31.21bc 31.69 b c 31.36 b c 35.97 a
58.37 a b 59.92 a b 60.05 a b 58.22 a b 57.58 b 59.03 a b 60.44 a
.94
.76
^ ,u)
a
32.17 32.34 a 31.34 a
CI II IM
Standard error
.62
ab
58.86 58.27 b 60.1 3 a .50
a
a
6.90 7.03 a 7.07 a
1.72 1.80a 1.80a
1.47 a 1.57 a 1.51 2
.29
.17
.12
Means within trials and treatments followed by different superscripts are significantly different (P<.05). 1
Data for one group of birds (Trial 4) were inadvertently lost, so that trial is omitted from this analysis. CI Continuous infrared; II = intermittent infrared; and IM = intermittent microwave heat.
design with blocks representing trials and treatments being the three sources of heat. Means were compared with Duncan's multiple range test. For the composition factors, data from one trial were lost and thus only seven trials were included in the analyses. A post-mortem examination was conducted for all the birds that died. RESULTS AND DISCUSSION
There were significant differences in mean gain over the 2-wk treatment period (P=£.05) between trials, however no significant differences (P>.05) were attributed to treatments (Table 1). There were significant differences in feed:gain ratio between trials and between treatments. The standard error of feed:gain is only estimable on a per trial basis or on a per treatment basis since the feed:gain ratio was calculated on a chamber basis.The CI and II treatments did not differ significantly (P>.05) in feed:gain ratio. However, birds from these treatments had a better feed:gain ratio (P=s.05) than birds from the IM treatment. The fact that continuous supplemental heat did not result in an improved feed:gain ratio compared with intermittent heat requires explanation. One possible reason might be that continuously heated chicks simply moved from beneath the direct radiation and thereby were, in
essence, intermittently heated. A second reason might be that the intermittently-heated birds conserved heat more efficiently than those heated continuously. In earlier work with piglets (Morrison et al., unpublished data) it was observed that intermittently-heated animals were as efficient as continuously-heated animals on a feed:gain basis. There was a significant difference (P^.05) in fat content between trials. When compared to one another (multiple comparisons) only Trials 2 and 8 were different from the others in terms of fat content (Table 2). Carcass protein content in Trial 6 was significantly (P^.05) lower than that in Trial 8 and carcass ash content in Trial 8 was significantly (P=s.05) lower than that in Trials 1 and 2. The protein content for chicks under II was significantly (P=£.05) lower than that for chicks under IM. There were no differences in calcium and phosphorus content between trials and between treatments. There was a total of eight deaths from sudden death syndrome during this experiment: three each in CI and IM treatments and 2 in the II treatment. These mortality rates did not differ significantly between trials or between treatments. The choice of 10 mW/cm2 intensity and a cycle of 2 min on and 4 min off emerged from previous studies that focussed on the recognition
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
Standard error
INFRARED AND MICROWAVE HEAT
of microwaves as a heat source (Morrison et al., unpublished data). Thus, the performance of birds in terms of feed:gain could improve using a different intensity or a different cycle of microwave delivery to reach levels comparable to the ones seen for birds subjected to infrared treatments. Nevertheless, there were no differences in average gain, carcass composition, and mortality rate between the treatments considered.
This work was supported by the Ontario
Ministry of Agriculture and Food and the Natural Sciences and Engineering Research Council.
REFERENCES Association of Official Analytical Chemists, 1984. Official Methods of Analysis. 14th ed. Assoc. Offic. Anal. Chem., Arlington, VA. Morrison, W. D., I. McMillan, L. A. Bate, and L. Otten, 1986. Behavioral observations and operant procedures using microwaves as a heat source for young chicks. Poultry Sci. 65:1516-1521.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
ACKNOWLEDGMENTS
1765
(Received for publication February 2, 1987) ABSTRACT In eight trials, 240 male broiler birds, initially 7 days old, were randomly allocated to three treatments. Treatments were: continuous infrared (CI), intermittent infrared (II; 4 min on, 2 min off, 10 cycles/h), and intermittent microwaves (IM; 2 min on, 4 min off, 10 cycles/h). At the conclusion of the 14-day experimental period the 21-day-oId birds were killed. Although there were significant differences (P=£.05) in mean gain over the 2-wk treatment period between trials, no differences (P>.05) were attributed to treatments. There were, however, significant differences in feed:gain ratios between trials and between treatments. Feed:gain ratios of birds kept under CI and II treatments did not differ significantly (P>.05). However, feed:gain ratios, 1.61 ± .04 and 1.57 ± .04 for CI and II, respectively, differed significantly (P«s.05) from that of the IM treatment (1.76 ± .04). The protein content of chicks under II was significantly (P«.05) lower than that of birds under IM. There were no differences (P>.05) in fat, ash, calcium, and phosphorus content of chicks among treatments. (Key words: infrared heat, microwave heat, male broilers, performance) 1987 Poultry Science 66:1762-1765 INTRODUCTION
MATERIALS AND METHODS
There is evidence that chicks (Morrison et al., 1986) and pigs (Morrison et al., unpublished data) subjected to microwaves as a heat source respond similarly to animals kept under infrared and other conventional heat sources. Although these experiments have shown microwaves adequate to raise these species, the efficiency of microwaves as an alternative to conventional heat sources was not compared. The purposes of the trials reported herein were: 1) to determine the growth and feed efficiency response of male broiler chicks to microwaves as a heat source; 2) to determine the effect of such procedures on body composition and mortality; and 3) to compare these performances with those of similar groups of chicks exposed to intermittent and continuous infrared heat source.
Two hundred and forty male broiler birds, initially 7 days old, were used for this experiment conducted in eight trials. Ten birds were randomly placed in three identical chambers for a 2-wk period. Conditions maintained in the chambers were: 1) continuous infrared (CI); 2) intermittent infrared (II; 4 min on, 2 min off, 10 cycles/h); and 3) intermittent microwaves (IM; 2 min on, 4 min off, 10 cycles/h). Cycles were controlled by a microcomputer (IBM PC Jr., Model 4860, IBM, Armonk, NY). The environmental temperature of the room was kept at 16 C for the duration of the experimental period. Supplemental heat was provided by a 250-W infrared lamp located 40 cm above the litter or 10 mW/cm of microwaves delivered by a generator with a maximum capacity of 700 W. The generator was constructed in the Department of Chemical Engineering, University of Waterloo. Chicks in every chamber were fed ad libitum a conventional broiler diet, calculated to provide
'Department of Animal and Poultry Science. School of Engineering.
2
1762
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3GI
INFRARED AND MICROWAVE HEAT
22% protein and 3,050 kcal metabolizable energy/kg. Weight and mortality were recorded on an individual bird basis whereas feed intake was based on all birds in a chamber. Data collected during the growing period were analyzed for variation in feed efficiency and rate of gain ofbirds maintained under CI, II, and IM heating
regimes. Birds were killed by cervical dislocation at 21 days of age. Carcasses were ground on a chamber basis and analyzed for protein (nitrogen), fat, ash, calcium, and phosphorus content (Association of Official Analytical Chemists, 1984). The statistical model used for these tests was a randomized complete block
T A B L E 1. Mean gain and feed:gain of chicks per treatment over a 2-wk growing period
All trials
and per trial
Treatment1
Gain
Feedrgain
(g) CI II IM x
438.1 434.0 418.0 430.04c
(g/g) 1.73 1.88 1.97 1.86a
CI II IM x
448.3 449.6 423.7 440.52c
1.55 1.36 1.61 1.51c
CI II IM
462.0 463.0 460.3 461.78abc
1.58 1.55 1.50 1.54bc
CI II IM x
506.0 485.9 489.6 493.83a
1.72 1.49 2.09 1.76ab
CI II IM
433.6 463.8 463.6 453.64bc
1.57 1.62 1.74 1.64abc
CI II IM
490.2 486.0 453.8 476.67ab
1.50 1.52 1.62 1.55bc
CI II IM
344.0 431.4 350.1 375.17d
1.55 1.58 1.92 1.68abc
CI II IM
480.2 463.6 490.9 478.24ab
1.67 1.54 1.60 1.60bc
CI II IM
449.4a 459.3a 443.5a
1.61a 1.57 a 1.76b
Means for trials on t r e a t m e n t s followed b y different superscripts are significantly different ( P < . 0 5 ) . CI = C o n t i n u o u s infrared; II = i n t e r m i t t e n t infrared; and IM = i n t e r m i t t e n t microwave.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
Trial
1763
MORRISON ET AL.
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TABLE 2. Mean fat, protein, ash, calcium, and phosphorus content of the dried carcass by trial and treatment
Calcium
Phosphorus
7.69 a 7.46 a 7.01ab 6.92 a b 6.94 a b 7.11ab 5.88 b
2.16 a 2.28 a 1.81 a 1.56a 1.71 a 1.47a 1.41 a
1.80a 1.84 a 1.55a 1.34a 1.40a 1.29a 1.41 a
.44
.26
.19
Trial1
Fat
Protein
Ash
1 2 3 5 6 7 8
3 3.09 a b 29.63 c 30.71bc 31.21bc 31.69 b c 31.36 b c 35.97 a
58.37 a b 59.92 a b 60.05 a b 58.22 a b 57.58 b 59.03 a b 60.44 a
.94
.76
^ ,u)
a
32.17 32.34 a 31.34 a
CI II IM
Standard error
.62
ab
58.86 58.27 b 60.1 3 a .50
a
a
6.90 7.03 a 7.07 a
1.72 1.80a 1.80a
1.47 a 1.57 a 1.51 2
.29
.17
.12
Means within trials and treatments followed by different superscripts are significantly different (P<.05). 1
Data for one group of birds (Trial 4) were inadvertently lost, so that trial is omitted from this analysis. CI Continuous infrared; II = intermittent infrared; and IM = intermittent microwave heat.
design with blocks representing trials and treatments being the three sources of heat. Means were compared with Duncan's multiple range test. For the composition factors, data from one trial were lost and thus only seven trials were included in the analyses. A post-mortem examination was conducted for all the birds that died. RESULTS AND DISCUSSION
There were significant differences in mean gain over the 2-wk treatment period (P=£.05) between trials, however no significant differences (P>.05) were attributed to treatments (Table 1). There were significant differences in feed:gain ratio between trials and between treatments. The standard error of feed:gain is only estimable on a per trial basis or on a per treatment basis since the feed:gain ratio was calculated on a chamber basis.The CI and II treatments did not differ significantly (P>.05) in feed:gain ratio. However, birds from these treatments had a better feed:gain ratio (P=s.05) than birds from the IM treatment. The fact that continuous supplemental heat did not result in an improved feed:gain ratio compared with intermittent heat requires explanation. One possible reason might be that continuously heated chicks simply moved from beneath the direct radiation and thereby were, in
essence, intermittently heated. A second reason might be that the intermittently-heated birds conserved heat more efficiently than those heated continuously. In earlier work with piglets (Morrison et al., unpublished data) it was observed that intermittently-heated animals were as efficient as continuously-heated animals on a feed:gain basis. There was a significant difference (P^.05) in fat content between trials. When compared to one another (multiple comparisons) only Trials 2 and 8 were different from the others in terms of fat content (Table 2). Carcass protein content in Trial 6 was significantly (P^.05) lower than that in Trial 8 and carcass ash content in Trial 8 was significantly (P=s.05) lower than that in Trials 1 and 2. The protein content for chicks under II was significantly (P=£.05) lower than that for chicks under IM. There were no differences in calcium and phosphorus content between trials and between treatments. There was a total of eight deaths from sudden death syndrome during this experiment: three each in CI and IM treatments and 2 in the II treatment. These mortality rates did not differ significantly between trials or between treatments. The choice of 10 mW/cm2 intensity and a cycle of 2 min on and 4 min off emerged from previous studies that focussed on the recognition
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
Standard error
INFRARED AND MICROWAVE HEAT
of microwaves as a heat source (Morrison et al., unpublished data). Thus, the performance of birds in terms of feed:gain could improve using a different intensity or a different cycle of microwave delivery to reach levels comparable to the ones seen for birds subjected to infrared treatments. Nevertheless, there were no differences in average gain, carcass composition, and mortality rate between the treatments considered.
This work was supported by the Ontario
Ministry of Agriculture and Food and the Natural Sciences and Engineering Research Council.
REFERENCES Association of Official Analytical Chemists, 1984. Official Methods of Analysis. 14th ed. Assoc. Offic. Anal. Chem., Arlington, VA. Morrison, W. D., I. McMillan, L. A. Bate, and L. Otten, 1986. Behavioral observations and operant procedures using microwaves as a heat source for young chicks. Poultry Sci. 65:1516-1521.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 3, 2015
ACKNOWLEDGMENTS
1765