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Feeding Pattern Responses to Changes in Dietary Energy or Environmental Temperature in the Domestic Fowl1
Feeding Pattern Responses to Changes in Dietary Energy or Environmental Temperature in the Domestic Fowl1 A. I. TAHER, EARL W. GLEAVES, 2 and F. B. MATHER 3 Department of Animal Science, University of Nebraska, Lincoln, Nebraska 68583-0820 (Received for publication March 19, 1984)
1985 Poultry Science 64:986-990 INTRODUCTION When fed ad libitum, m o s t animals concentrate their feeding in discrete b o u t s , or " m e a l s " , separated b y periods devoted to o t h e r activities. Typically, t h e meals of birds studied have been briefer and m o r e n u m e r o u s t h a n those of m a m m a l s (Savory, 1 9 7 9 ) . Meal freq u e n c y ranges from less t h a n 2 0 per d a y in some d o m e s t i c fowl and pigeons ( D u n c a n et al, 1 9 7 0 ; Zeigler et al, 1 9 7 1 ) t o m o r e t h a n 20 per h o u r in s o m e h u m m i n g b i r d s (Wolf and Hainsworth, 1 9 7 7 ) . Diurnal variations in meal size and meal frequency have been studied with zebra finches, quail, and pigeons. Z e b r a finches show a peak in feeding at t h e start of t h e d a y d u e to an increase in meal frequency and a n o t h e r in t h e evening due to an increase in meal length (Slater, 1 9 7 4 ) . In J a p a n e s e quail, changes in feeding activity from h o u r to h o u r
1 Published as paper 7443, Journal Series, Nebraska Agricultural Experiment Station, Lincoln, NE 685830704. 2 To whom correspondence should be addressed. 3 Department of Poultry Science, University of Florida, Gainsville, FL 32611.
are correlated w i t h changes in m e a l frequency with s o m e birds showing an increase in feeding at the end of t h e d a y d u e mainly to an increase in meal length (Savory, 1 9 7 9 ) . Pigeons tend to eat m o s t at t h e end of t h e d a y , b u t these peaks are associated with increases in b o t h meal frequency and meal length (Zeigler et al, 1971). Meal size and frequency also vary according to diet c o m p o s i t i o n . In rats, differences in food c o n s u m p t i o n b e t w e e n diets of different energy c o n t e n t are d u e to differences in meal size and n o t meal frequency ( S n o w d o n , 1 9 6 9 ) . However, LeMagnen ( 1 9 7 1 ) showed t h a t rats respond t o changes in n o r m a l and diluted diets b y adjusting meal frequency first and n o t meal size, b u t meal size adapts after a few days and meal f r e q u e n c y r e t u r n s t o n o r m a l . T h o m a s and Mayer ( 1 9 6 8 ) and Davies ( 1 9 7 7 ) f o u n d in b o t h rats and quail t h a t short-term changes in feeding are associated mainly with meal size and t h a t some long-term regulatory signals also affect meal size directly. Van Hemel and Myer ( 1 9 6 9 ) and Savory ( 1 9 8 0 ) reported t h a t quail ate less food from n o r m a l mash t h a n from t h e same mash diluted w i t h indigestible cellulose p o w d e r . T h e y also s p e n t less t i m e eating and showed a m o r e p r o n o u n c e d feeding r h y t h m .
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ABSTRACT Two experiments using 64-week-old Single Comb White Leghorn roosters were conducted to determine the meal response to an abrupt change in dietary energy or environmental temperature. In the first experiment, dietary energy level was changed from 200 kcal to either 250 or 150 kcal/75 g. In the second experiment, environmental temperature was changed from 22.2 C to either 13.3 or 30.0 C. Feeding behavior was recorded throughout both experiments. Meal size, meal frequency, and time spent eating a meal were measured. Roosters changed to high-energy or low-energy diets consumed low or high amounts of feed, respectively. Those fed the high-energy diet tended to decrease meal size and meal duration and to increase the number of meals. Roosters changed to the low-energy diet decreased meal size and meal duration and increased the number of meals eaten. The results tend to confirm the chemostatic mechanism in birds as food intake was related to energy in the diet. Roosters changed to high or low environmental temperature responded by decreasing or increasing their feed intake, respectively. Roosters changed to a high environmental temperature significantly decreased meal size, meal duration, and increased the number of meals. Those changed to a low environmental temperature significantly increased meal size and decreased meal frequency and meal duration. (Key words: feeding patterns, dietary energy, environmental temperature, feed intake)
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FEEDING PATTERN RESPONSES
Masic et al. (1974) reported that differences in feed intake between young broilers and layers of the same age were due to meal size, not interval length. The objective of these experiments was to determine the feeding behavior of Single Comb White Leghorn roosters in response to changes in either the energy level of the diet or environmental temperature.
MATERIALS AND METHODS
In the first experiment, following acclimation, feed intake patterns were established on a 200 kcal ME/75 g diet for 1 week (preexperimental period); the roosters were then randomly divided into two groups of 3 birds each. One group was changed to a high-energy diet (250 kcal ME/75 g diet) and the other group was changed to a low energy diet (150 kcal ME/75 g diet). Diets were formulated to provide 150, 200, and 250 kcal ME/75 g diet (Table 1). Energy was the only dietary variable, and all diets had the same density (.86 g/ml diet). Feeding patterns were recorded for another 4 weeks. Seventy-five grams of feed was the approximate daily intake for light
TABLE 1. Composition of experimental diets Experiment 1 Ingredients Ground yellow corn Ground milo Dehydrated alfalfa meal Fish meal Soybean meal (47%) Blood meal Animal fat Sand Solka floe Dicalcium phosphate Calcium carbonate Vitamin concentrate 1 Salt Trace mineral mix 2 Total
150 kcal
200 kcal
250 kcal
6.55 5.43 6.19
8.52 7.06 8.05
10.48 8.69 9.91
.86 3.79 .72 11.19 21.54 12.62 2.00 2.65 .90 .50 .05 74.99
1.12 4.94 .94 15.19 12.44 10.65 2.00 2.65 .90 .50 .05 75.01
1.38 6.07 1.15 19.21 3.39 8.68 2.00 2.65 .90 .50 .05 75.06
Calculated analyses (nutrients iri 75 g diet): Crude protein, g 5.00 7.99 6.50 Lysine, g .29 .46 .36 Methionine, g .08 .12 .10 .13 Tryptophan,g .08 .10 Calcium, g 1.59 1.67 1.63 250.0 Energy, ME 3 kcal 150.0 200.0 Density, g/ml .86 .86 .86 1 Vitamin concentrate provided the following micronutrients per kilogram diet; vitamin A, 5550 USP; vitamin D 3 500 IU; vitamin E, 11 IU; riboflavin, 4.41 mg; vitamin B 1 2 , 8.8 mg; pantothenic acid, 8.6 mg; choline chloride, 500 mg. 2
Trace mineral mix provided the following in parts per million: manganese, 50.0; iron, 50.0; copper, 5.0; cobalt, .5; zinc 50.0. 3
ME = Metabolizable energy.
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Two experiments were conducted using roosters to eliminate the variable of egg production. Dietary energy and environmental temperature changes might have affected food intake indirectly by altering the rate of egg production with laying hens. Eighteen 64week-old roosters, weighing 2100 to 2306 g, were housed in an environmentally-controlled room at 22.2 C. The birds were kept in single cages (30 X 45 X 55 cm) and fed a diet of 200 kcal metabolizable energy (ME)/75 g for an acclimination period of 4 weeks. Cages were located within a metal rack such that the birds were visually isolated from each other. All cages were equipped with automatic waterers' and individual feeders. Each feeder was suspended from a calibrated strain gauge transducer connected to a recorder for monitoring meal frequency, meal size, and time spent eating a meal. A meal in these studies is defined as a period of continuous eating with no interruptions for an interval of more than 2 min (Duncan et al, 1970). Feed was added twice a day in a random manner (at 0900, 1000, 1100, or 1200 hr and at 1400, 1500, 1600, or 1700 hr). This procedure was followed to minimize the effect of adding feed on the feeding behavior of the roosters. The lighting pattern was 14L:10D using fluorescent light.
weight roosters as reported by Ahmad (1973), and the method of diet formulation was that of Gleaves et al. (1963, 1968). Environmental temperature was maintained at 22.2 C (72 F) throughout the experiment. Because of problems with high variance in the first experiment, the number of replications was doubled in the second experiment. After feeding patterns were established with 200 kcal ME/75 g diets at 22.2 C (72 F) for 1 week (preexperimental period), 12 roosters were randomly divided into two groups of 6 birds each. One group was changed to a high environmental temperature (30 C) and the other to a low environmental temperature (13.3 C). Individuals in each group were randomly caged
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in similar cages under the same circumstances. Feeding patterns were recorded for 3 weeks. All data were analyzed by analysis of variance (Snedecor, 1956) for: the response to the abrupt change in dietary energy or environmental temperature and the feeding patterns following the changes. Several statistical analyses were tried in Experiment 1 but the variance proved to be too high. Doubling the replications in Experiment 2 strengthened precision enough to demonstrate significance.
Experiment 1. There were no significant differences in any of the parameters measured between the preexperimental and experimental periods. Precision in this experiment was inadequate to overcome coefficients of variation of 13.4 to 41.6%. It is apparent from the means in Table 2 that there were no abrupt changes in feed intake. However, over time there was a gradual change. The nonsignificant trend was for roosters on the high- and low-energy diets to consume less and more feed, respectively, following the change. Those changed to the high-energy diet overconsumed energy in the first 2 weeks after the change but consumed less energy in the 3rd
TABLE 2. Feeding pattern responses to changes in dietary energy
Parameter Food intake, g/bird/day Energy intake, kcal/ME
Preexperimental 1 period (1 week)
Energy level
Overall experi-
Experimen tal period after the:change 1 week
2 weeks
3 weeks
4 weeks
average
85.4 71.2
High Low
81.2 61.1
71.5 85.1
57.6 91.8
51.4 107.4
65.4 a 86.4 b
227.1 189.4
High Low
270.5 122.3
238.2 170.3
191.7 183.6
171.1 214.9
217.9 a 172.8 b
Meal size, g Energy intake/ meal, kcal/ME
7.9 4.8
High Low
6.1 4.4
5.9 4.5
5.4 4.3
6.1 5.1
5.9 a 4.6b
21.1 12.8
High Low
20.5 8.7
19.8 9.0
18.1 8.5
20.4 10.2
19.7 a 9.1 b
Number of meals, bird/day
11.1 15.4
High Low
13.5 13.8
12.6 18.0
11.3 22.4
9.0 22.1
11.6 a 19.1 b
Time spent eating/ meal, min
20.0 15.8
High Low
19.0 19.8
16.8 15.2
13.8 11.5
17.1 13.1
16.7 14.9
a,b Means with different letters were significantly different (P<.05). 'During the preexperimental period all birds were fed a medium-energy [200 kcal metabolizable energy (ME)/75 g] diet. After feeding patterns were established on this diet, one group was changed to a high-energy (250 kcal ME/75 g) diet and the other group was changed to a low-energy (150 kcal ME/75 g) diet.
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RESULTS AND DISCUSSION
and 4th weeks. Roosters changed to the lowenergy diet decreased energy intake after the change and only in the 4th week ate more energy than in the preexperimental period. Overall, roosters on the high-energy diet consumed significantly (P<.05) less feed but more energy than those on the low energy diet. The results support the chemostatic theory of feed intake control (Jensen, 1977; Smith, 1979; Cherry, 1979). Roosters appeared to eat to satisfy their energy requirement, and it is impossible to know whether or not the adjustment was complete. Ahmad et al. (1974) reported that roosters adjust food and energy intake responses almost completely in 4 weeks. However, data from this experiment indicate that it may take roosters longer than 4 weeks to adjust. Meal size, energy intake per meal, number of meals, and time spent eating a meal are presented in Table 2. There were no significant abrupt changes in feeding behavior. However, trends were apparent. Meal size and energy intake per meal decreased when roosters were changed either to the high or to the low energy diet, but the decrease in meal size was more pronounced for those changed to the high energy diet. Roosters changed to the lowenergy diet attempted to adjust their feed and
FEEDING PATTERN RESPONSES
for roosters changed to the low environmental temperature was to eat less feed and energy in the first week after the change but then to increase feed and energy intake slightly until the end of the experiment. The results support the thermostatic control theory of feed intake (Jones et al, 1976; Kraly and Blass, 1976; de Andrade et al., 1976, 1977). Roosters maintained at the low environmental temperature were less active during the experimental period. They appeared to try to conserve energy and to keep warm. There was a continuous significant decrease (P<.05) in feed and energy intake per meal for roosters changed to the higher environmental temperature (Table 3). Roosters changed to the low environmental temperature ate significantly (P<.05) more feed and energy per meal each week after the change. Both groups significantly (P<.05) decreased the time spent eating a meal. Roosters in the high environmental temperature increased the number of meals while those in the low environmental temperature decreased the number. This effect was only significant (P<.05) in the 2nd and 3rd weeks after the change. Birds in the high
TABLE 3. Feeding pattern responses to changes in environmental
Parameter
Preexperimental 1 period (week)
Environmental temperature
temperature Overall experi-
Experimental period weeks after change 1 week
2 weeks
3 weeks
average
78.7 77.2
High Low
45.6* 73.0
45.5* 85.3
40.7* 78.0
43.9 a 78.8 b
Energy intake, ME2 kcal/bird/day
209.9 206.0
High Low
121.6* 194.7
121.3* 227.5
108.5* 208.0
117.l a 210.1b
Meal size, g Energy intake/meal, kcal/ME
8.3 5.5
High Low
4.3* 5.8*
4.0* 7.1*
3.8* 7.3*
4.0 a 6.7 b
22.1 14.6
High Low
11.4* 15.4*
10.7* 18.9*
10.1* 19.4*
10.7 a 17.9 b
Number of meals, bird/day
9.5 14.1
High Low
10.5 12.7
11.4 12.1*
10.8 10.7*
10.9 a 12.2 b
Time spent eating/ meal, min
17.8 12.4
High Low
11.2* 8.4*
11.6* 8.6*
10.8 a 8.1b
Food intake, g/bird/day
9.7* 7.5*
a ' b Means with different letters were significantly different (P<.05). 1 During the preexperimental period all birds were kept at 22.2 C (72 F). After feeding patterns were established on this temperature, one group was changed to high temperature 30 C and the other group was changed to low temperature 13.3 C. 2
ME = Metabolizable energy.
'Values are significantly different from the preexperimental period (P<.05).
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energy intake by large increases in the number of meals as compared with the slight increase in those on the high-energy diet. The large increase in the number of meals by birds fed the low-energy diet supports the possibility that gut-filling sensations may be the most active mechanism responsible for terminating a meal. This is in agreement with Richardson (1970), who found that a meal may be initiated when crop contents dropped to a threshold volume and that gut-filling might be responsible for terminating meals. Davis and Levine (1977) also concluded that intestinal distension is an effective stimulus for shutting off an ongoing meal. Roosters on the high-energy diet overconsumed energy in the first 2 weeks after the change. As time progressed, they decreased slightly the number of meals eaten per day. This suggests a long-term control when highenergy diets are fed. A similar response was reported by Lepkovsky and Futura (1971). Experiment 2. Roosters changed to a high environmental temperature ate significantly (P<.05) less feed and energy immediately after the change than in the preexperimental period (Table 3). However, the nonsignificant trend
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TAHER ET AL.
These experiments showed the presence of relationships between dietary energy level, environmental temperature, and feed intake that support the existence of chemostatic and thermostatic control mechanisms in the domestic fowl. Birds tend to change both meal size and meal frequency to adjust their feed and energy intake due to changes in dietary energy level or environmental temperature. It was also apparent that other factors such as the gastrointestinal tract and adipose tissue may be involved in initiation or cessation of eating. REFERENCES Ahmad, M. M., 1973. Effect of environmental temperature and dietary energy on feed intake in chickens. Ph.D. Diss., Univ. Nebraska, Lincoln, NE. Ahmad, M. M., F. B. Mather, and E. W. Gleaves, 1974. Feed intake response to changes in environmental temperature and dietary energy in roosters. Poultry Sci. 53:1043-1052. Cherry, J. A., 1979. Adaptation in food intake after changes in dietary energy. Pages 77—87 in Food Intake Regulation in Poultry. British Poultry Science Symposium No. 14. K. N. Boorman and B. M. Freeman, ed. Davies, R. F., 1977. Long and short-term regulation of feed intake patterns in the rat. J. Comp. Physiol. Psychol. 91:574-585. Davis, J. D., and M. W. Levine, 1977. A model of the control of ingestion. Psychol. Rev. 84:379—412. de Andrade, A. N., J. C. Rogler, and W. R. Featherston, 1976. Influence of constant elevated temperature and diet on egg production and shell quality. Poultry Sci. 55:685-693. de Andrade, A. N., J. C. Rogler, W. R. Featherston, and C. W. Alliston, 1977. Interrelationship between diets and elevated temperatures (Cyclic and constant) on egg production and shell quality. Poultry Sci. 56:1178-1188. Duncan, I.J.H., A. R. Home, B. O. Hughes, and D.G.M. Wood-Gush, 1970. The pattern of food intake in female Brown Leghorn fowls as recorded in a skinner box. Anim. Behav. 18:245— 255.
Gleaves, E. W., L. V. Tonkinson, J. B. Wolf, C. K. Harman, R. H. Thayer, and R. D. Morrison, 1968. The action and interaction of physiological food intake regulators in the laying hen. Poultry Sci. 4 7 : 3 8 - 6 7 . Gleaves, E. W., L. V. Tonkinson, J. B. Wolf, M. H. Henley, C. K. Harman, and R. H. Thayer, 1963. Poultry Nutrition Manual. Misc. Publ., Dept. Poult. Sci., Oklahoma State Univ., Stillwater, OK. Jensen, L. S., 1977. Dietary energy studies with laying hens. Pages 40—46 in Proc. 1977 Maryland. Nutr. Conf. Jones, J. E., B. L. Hughes, and B. D. Barnett, 1976. Effect of changing dietary levels and environmental temperatures on feed consumption and egg production of Single Comb White Leghorns. Poultry Sci. 55:274-277. Kraly, F. S., and E. M. Blass, 1976. Increased feeding in rats in a low ambient temperature. Page 77—78 in Hunger, Basic mechanisms and Clinical Implications. D. Novin, W. Wyrwicka, and G. Bray, ed. Raven Press, New York, NY. Le Magnen, 1971. Advances in studies on the physiological control and regulation of food intake. Prog. Physiol. Psychol. 4 : 2 0 3 - 2 6 1 . Lepkovsky, S., and F. Futura, 1971. The role of homeostasis in adipose tissues upon the regulation of food intake of White Leghorn cockerels. Poultry Sci. 50:753-576. Mask, B., D. G. M. Wood-Gush, I.J.H. Duncan, C. McCorguodale, and C. J. Savory, 1974. A comparison of the feeding behaviour of young broiler and layer males. Br. Poult. Sci. 15:499-505. Richardson, A. J., 1970. The role of the crop in the feeding behavior of the domestic chicken. Behavior 18:633-639. Savory, S. J., 1979. Feeding behavior. Pages 277-323 in Food Intake Regulation in Poultry British Poultry Science Symposium No. 14. N. Boorman and B. M. Freeman.ed. Savory, C. J., 1980. Meal occurrence in Japanese quail in relation to particle size and nutrient density. Anim. Behav. 2 8 : 1 6 0 - 1 7 1 . Slater, P.J.B., 1974. The temporal pattern of feeding in the Zebra finch. Anim. Behav. 22:506-515. Smith, C.J.V., 1979. The hypothalamus and the regulation of food intake. Poultry Sci. 58: 1619-1624. Snedecor, C. T., 1956. Statistical Methods. 5th ed. The Iowa State Coll. Press, Ames, IA. Snowdon, C. T., 1969. Motivation, regulation and the control of meal parameter with oral and intragastic feeding. J. Comp. Physiol. Psychol. 59:171-175. Thomas, D. W., and J. Mayer, 1968. Meal taking and regulation of food intake by normal and hypothalamic hyperphagic rats. J. Comp. Physiol. Psychol. 66:642-653. Van Hemel, S. B., and J. S. Myer, 1969. Feeding patterns and response to caloric dilution in the Japanese quail. Physiol. Behav. 4:339—344. Wolf, L. L., and F. R. Hainsworth, 1977. Temporal patterning of feeding by hummingbirds. Anim. Behav. 25:976-989. Zeigler, H. P., L. Green, and R. Lehrer, 1971. Patterns of feeding behavior in the pigeon. J. Comp. Physiol. Psychol. 4 6 8 - 4 7 7 .
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environmental temperature compensated for the decrease in meal size by increasing the number of meals. However, the roosters were able to decrease their activity by eating more feed per meal, decrease the number of meals, and decrease time spent eating a meal at the low environmental temperature. They tried to conserve energy, and it may have been the digestive system that terminated a meal and prevented the increase in feed intake. These results agree with those of Davies (1977), who reported that adjustments in feed and energy intake in rats occurred in response to changes in environmental temperature; adjustments were by meal size.
1985 Poultry Science 64:986-990 INTRODUCTION When fed ad libitum, m o s t animals concentrate their feeding in discrete b o u t s , or " m e a l s " , separated b y periods devoted to o t h e r activities. Typically, t h e meals of birds studied have been briefer and m o r e n u m e r o u s t h a n those of m a m m a l s (Savory, 1 9 7 9 ) . Meal freq u e n c y ranges from less t h a n 2 0 per d a y in some d o m e s t i c fowl and pigeons ( D u n c a n et al, 1 9 7 0 ; Zeigler et al, 1 9 7 1 ) t o m o r e t h a n 20 per h o u r in s o m e h u m m i n g b i r d s (Wolf and Hainsworth, 1 9 7 7 ) . Diurnal variations in meal size and meal frequency have been studied with zebra finches, quail, and pigeons. Z e b r a finches show a peak in feeding at t h e start of t h e d a y d u e to an increase in meal frequency and a n o t h e r in t h e evening due to an increase in meal length (Slater, 1 9 7 4 ) . In J a p a n e s e quail, changes in feeding activity from h o u r to h o u r
1 Published as paper 7443, Journal Series, Nebraska Agricultural Experiment Station, Lincoln, NE 685830704. 2 To whom correspondence should be addressed. 3 Department of Poultry Science, University of Florida, Gainsville, FL 32611.
are correlated w i t h changes in m e a l frequency with s o m e birds showing an increase in feeding at the end of t h e d a y d u e mainly to an increase in meal length (Savory, 1 9 7 9 ) . Pigeons tend to eat m o s t at t h e end of t h e d a y , b u t these peaks are associated with increases in b o t h meal frequency and meal length (Zeigler et al, 1971). Meal size and frequency also vary according to diet c o m p o s i t i o n . In rats, differences in food c o n s u m p t i o n b e t w e e n diets of different energy c o n t e n t are d u e to differences in meal size and n o t meal frequency ( S n o w d o n , 1 9 6 9 ) . However, LeMagnen ( 1 9 7 1 ) showed t h a t rats respond t o changes in n o r m a l and diluted diets b y adjusting meal frequency first and n o t meal size, b u t meal size adapts after a few days and meal f r e q u e n c y r e t u r n s t o n o r m a l . T h o m a s and Mayer ( 1 9 6 8 ) and Davies ( 1 9 7 7 ) f o u n d in b o t h rats and quail t h a t short-term changes in feeding are associated mainly with meal size and t h a t some long-term regulatory signals also affect meal size directly. Van Hemel and Myer ( 1 9 6 9 ) and Savory ( 1 9 8 0 ) reported t h a t quail ate less food from n o r m a l mash t h a n from t h e same mash diluted w i t h indigestible cellulose p o w d e r . T h e y also s p e n t less t i m e eating and showed a m o r e p r o n o u n c e d feeding r h y t h m .
986
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 15, 2015
ABSTRACT Two experiments using 64-week-old Single Comb White Leghorn roosters were conducted to determine the meal response to an abrupt change in dietary energy or environmental temperature. In the first experiment, dietary energy level was changed from 200 kcal to either 250 or 150 kcal/75 g. In the second experiment, environmental temperature was changed from 22.2 C to either 13.3 or 30.0 C. Feeding behavior was recorded throughout both experiments. Meal size, meal frequency, and time spent eating a meal were measured. Roosters changed to high-energy or low-energy diets consumed low or high amounts of feed, respectively. Those fed the high-energy diet tended to decrease meal size and meal duration and to increase the number of meals. Roosters changed to the low-energy diet decreased meal size and meal duration and increased the number of meals eaten. The results tend to confirm the chemostatic mechanism in birds as food intake was related to energy in the diet. Roosters changed to high or low environmental temperature responded by decreasing or increasing their feed intake, respectively. Roosters changed to a high environmental temperature significantly decreased meal size, meal duration, and increased the number of meals. Those changed to a low environmental temperature significantly increased meal size and decreased meal frequency and meal duration. (Key words: feeding patterns, dietary energy, environmental temperature, feed intake)
987
FEEDING PATTERN RESPONSES
Masic et al. (1974) reported that differences in feed intake between young broilers and layers of the same age were due to meal size, not interval length. The objective of these experiments was to determine the feeding behavior of Single Comb White Leghorn roosters in response to changes in either the energy level of the diet or environmental temperature.
MATERIALS AND METHODS
In the first experiment, following acclimation, feed intake patterns were established on a 200 kcal ME/75 g diet for 1 week (preexperimental period); the roosters were then randomly divided into two groups of 3 birds each. One group was changed to a high-energy diet (250 kcal ME/75 g diet) and the other group was changed to a low energy diet (150 kcal ME/75 g diet). Diets were formulated to provide 150, 200, and 250 kcal ME/75 g diet (Table 1). Energy was the only dietary variable, and all diets had the same density (.86 g/ml diet). Feeding patterns were recorded for another 4 weeks. Seventy-five grams of feed was the approximate daily intake for light
TABLE 1. Composition of experimental diets Experiment 1 Ingredients Ground yellow corn Ground milo Dehydrated alfalfa meal Fish meal Soybean meal (47%) Blood meal Animal fat Sand Solka floe Dicalcium phosphate Calcium carbonate Vitamin concentrate 1 Salt Trace mineral mix 2 Total
150 kcal
200 kcal
250 kcal
6.55 5.43 6.19
8.52 7.06 8.05
10.48 8.69 9.91
.86 3.79 .72 11.19 21.54 12.62 2.00 2.65 .90 .50 .05 74.99
1.12 4.94 .94 15.19 12.44 10.65 2.00 2.65 .90 .50 .05 75.01
1.38 6.07 1.15 19.21 3.39 8.68 2.00 2.65 .90 .50 .05 75.06
Calculated analyses (nutrients iri 75 g diet): Crude protein, g 5.00 7.99 6.50 Lysine, g .29 .46 .36 Methionine, g .08 .12 .10 .13 Tryptophan,g .08 .10 Calcium, g 1.59 1.67 1.63 250.0 Energy, ME 3 kcal 150.0 200.0 Density, g/ml .86 .86 .86 1 Vitamin concentrate provided the following micronutrients per kilogram diet; vitamin A, 5550 USP; vitamin D 3 500 IU; vitamin E, 11 IU; riboflavin, 4.41 mg; vitamin B 1 2 , 8.8 mg; pantothenic acid, 8.6 mg; choline chloride, 500 mg. 2
Trace mineral mix provided the following in parts per million: manganese, 50.0; iron, 50.0; copper, 5.0; cobalt, .5; zinc 50.0. 3
ME = Metabolizable energy.
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Two experiments were conducted using roosters to eliminate the variable of egg production. Dietary energy and environmental temperature changes might have affected food intake indirectly by altering the rate of egg production with laying hens. Eighteen 64week-old roosters, weighing 2100 to 2306 g, were housed in an environmentally-controlled room at 22.2 C. The birds were kept in single cages (30 X 45 X 55 cm) and fed a diet of 200 kcal metabolizable energy (ME)/75 g for an acclimination period of 4 weeks. Cages were located within a metal rack such that the birds were visually isolated from each other. All cages were equipped with automatic waterers' and individual feeders. Each feeder was suspended from a calibrated strain gauge transducer connected to a recorder for monitoring meal frequency, meal size, and time spent eating a meal. A meal in these studies is defined as a period of continuous eating with no interruptions for an interval of more than 2 min (Duncan et al, 1970). Feed was added twice a day in a random manner (at 0900, 1000, 1100, or 1200 hr and at 1400, 1500, 1600, or 1700 hr). This procedure was followed to minimize the effect of adding feed on the feeding behavior of the roosters. The lighting pattern was 14L:10D using fluorescent light.
weight roosters as reported by Ahmad (1973), and the method of diet formulation was that of Gleaves et al. (1963, 1968). Environmental temperature was maintained at 22.2 C (72 F) throughout the experiment. Because of problems with high variance in the first experiment, the number of replications was doubled in the second experiment. After feeding patterns were established with 200 kcal ME/75 g diets at 22.2 C (72 F) for 1 week (preexperimental period), 12 roosters were randomly divided into two groups of 6 birds each. One group was changed to a high environmental temperature (30 C) and the other to a low environmental temperature (13.3 C). Individuals in each group were randomly caged
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in similar cages under the same circumstances. Feeding patterns were recorded for 3 weeks. All data were analyzed by analysis of variance (Snedecor, 1956) for: the response to the abrupt change in dietary energy or environmental temperature and the feeding patterns following the changes. Several statistical analyses were tried in Experiment 1 but the variance proved to be too high. Doubling the replications in Experiment 2 strengthened precision enough to demonstrate significance.
Experiment 1. There were no significant differences in any of the parameters measured between the preexperimental and experimental periods. Precision in this experiment was inadequate to overcome coefficients of variation of 13.4 to 41.6%. It is apparent from the means in Table 2 that there were no abrupt changes in feed intake. However, over time there was a gradual change. The nonsignificant trend was for roosters on the high- and low-energy diets to consume less and more feed, respectively, following the change. Those changed to the high-energy diet overconsumed energy in the first 2 weeks after the change but consumed less energy in the 3rd
TABLE 2. Feeding pattern responses to changes in dietary energy
Parameter Food intake, g/bird/day Energy intake, kcal/ME
Preexperimental 1 period (1 week)
Energy level
Overall experi-
Experimen tal period after the:change 1 week
2 weeks
3 weeks
4 weeks
average
85.4 71.2
High Low
81.2 61.1
71.5 85.1
57.6 91.8
51.4 107.4
65.4 a 86.4 b
227.1 189.4
High Low
270.5 122.3
238.2 170.3
191.7 183.6
171.1 214.9
217.9 a 172.8 b
Meal size, g Energy intake/ meal, kcal/ME
7.9 4.8
High Low
6.1 4.4
5.9 4.5
5.4 4.3
6.1 5.1
5.9 a 4.6b
21.1 12.8
High Low
20.5 8.7
19.8 9.0
18.1 8.5
20.4 10.2
19.7 a 9.1 b
Number of meals, bird/day
11.1 15.4
High Low
13.5 13.8
12.6 18.0
11.3 22.4
9.0 22.1
11.6 a 19.1 b
Time spent eating/ meal, min
20.0 15.8
High Low
19.0 19.8
16.8 15.2
13.8 11.5
17.1 13.1
16.7 14.9
a,b Means with different letters were significantly different (P<.05). 'During the preexperimental period all birds were fed a medium-energy [200 kcal metabolizable energy (ME)/75 g] diet. After feeding patterns were established on this diet, one group was changed to a high-energy (250 kcal ME/75 g) diet and the other group was changed to a low-energy (150 kcal ME/75 g) diet.
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RESULTS AND DISCUSSION
and 4th weeks. Roosters changed to the lowenergy diet decreased energy intake after the change and only in the 4th week ate more energy than in the preexperimental period. Overall, roosters on the high-energy diet consumed significantly (P<.05) less feed but more energy than those on the low energy diet. The results support the chemostatic theory of feed intake control (Jensen, 1977; Smith, 1979; Cherry, 1979). Roosters appeared to eat to satisfy their energy requirement, and it is impossible to know whether or not the adjustment was complete. Ahmad et al. (1974) reported that roosters adjust food and energy intake responses almost completely in 4 weeks. However, data from this experiment indicate that it may take roosters longer than 4 weeks to adjust. Meal size, energy intake per meal, number of meals, and time spent eating a meal are presented in Table 2. There were no significant abrupt changes in feeding behavior. However, trends were apparent. Meal size and energy intake per meal decreased when roosters were changed either to the high or to the low energy diet, but the decrease in meal size was more pronounced for those changed to the high energy diet. Roosters changed to the lowenergy diet attempted to adjust their feed and
FEEDING PATTERN RESPONSES
for roosters changed to the low environmental temperature was to eat less feed and energy in the first week after the change but then to increase feed and energy intake slightly until the end of the experiment. The results support the thermostatic control theory of feed intake (Jones et al, 1976; Kraly and Blass, 1976; de Andrade et al., 1976, 1977). Roosters maintained at the low environmental temperature were less active during the experimental period. They appeared to try to conserve energy and to keep warm. There was a continuous significant decrease (P<.05) in feed and energy intake per meal for roosters changed to the higher environmental temperature (Table 3). Roosters changed to the low environmental temperature ate significantly (P<.05) more feed and energy per meal each week after the change. Both groups significantly (P<.05) decreased the time spent eating a meal. Roosters in the high environmental temperature increased the number of meals while those in the low environmental temperature decreased the number. This effect was only significant (P<.05) in the 2nd and 3rd weeks after the change. Birds in the high
TABLE 3. Feeding pattern responses to changes in environmental
Parameter
Preexperimental 1 period (week)
Environmental temperature
temperature Overall experi-
Experimental period weeks after change 1 week
2 weeks
3 weeks
average
78.7 77.2
High Low
45.6* 73.0
45.5* 85.3
40.7* 78.0
43.9 a 78.8 b
Energy intake, ME2 kcal/bird/day
209.9 206.0
High Low
121.6* 194.7
121.3* 227.5
108.5* 208.0
117.l a 210.1b
Meal size, g Energy intake/meal, kcal/ME
8.3 5.5
High Low
4.3* 5.8*
4.0* 7.1*
3.8* 7.3*
4.0 a 6.7 b
22.1 14.6
High Low
11.4* 15.4*
10.7* 18.9*
10.1* 19.4*
10.7 a 17.9 b
Number of meals, bird/day
9.5 14.1
High Low
10.5 12.7
11.4 12.1*
10.8 10.7*
10.9 a 12.2 b
Time spent eating/ meal, min
17.8 12.4
High Low
11.2* 8.4*
11.6* 8.6*
10.8 a 8.1b
Food intake, g/bird/day
9.7* 7.5*
a ' b Means with different letters were significantly different (P<.05). 1 During the preexperimental period all birds were kept at 22.2 C (72 F). After feeding patterns were established on this temperature, one group was changed to high temperature 30 C and the other group was changed to low temperature 13.3 C. 2
ME = Metabolizable energy.
'Values are significantly different from the preexperimental period (P<.05).
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energy intake by large increases in the number of meals as compared with the slight increase in those on the high-energy diet. The large increase in the number of meals by birds fed the low-energy diet supports the possibility that gut-filling sensations may be the most active mechanism responsible for terminating a meal. This is in agreement with Richardson (1970), who found that a meal may be initiated when crop contents dropped to a threshold volume and that gut-filling might be responsible for terminating meals. Davis and Levine (1977) also concluded that intestinal distension is an effective stimulus for shutting off an ongoing meal. Roosters on the high-energy diet overconsumed energy in the first 2 weeks after the change. As time progressed, they decreased slightly the number of meals eaten per day. This suggests a long-term control when highenergy diets are fed. A similar response was reported by Lepkovsky and Futura (1971). Experiment 2. Roosters changed to a high environmental temperature ate significantly (P<.05) less feed and energy immediately after the change than in the preexperimental period (Table 3). However, the nonsignificant trend
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These experiments showed the presence of relationships between dietary energy level, environmental temperature, and feed intake that support the existence of chemostatic and thermostatic control mechanisms in the domestic fowl. Birds tend to change both meal size and meal frequency to adjust their feed and energy intake due to changes in dietary energy level or environmental temperature. It was also apparent that other factors such as the gastrointestinal tract and adipose tissue may be involved in initiation or cessation of eating. REFERENCES Ahmad, M. M., 1973. Effect of environmental temperature and dietary energy on feed intake in chickens. Ph.D. Diss., Univ. Nebraska, Lincoln, NE. Ahmad, M. M., F. B. Mather, and E. W. Gleaves, 1974. Feed intake response to changes in environmental temperature and dietary energy in roosters. Poultry Sci. 53:1043-1052. Cherry, J. A., 1979. Adaptation in food intake after changes in dietary energy. Pages 77—87 in Food Intake Regulation in Poultry. British Poultry Science Symposium No. 14. K. N. Boorman and B. M. Freeman, ed. Davies, R. F., 1977. Long and short-term regulation of feed intake patterns in the rat. J. Comp. Physiol. Psychol. 91:574-585. Davis, J. D., and M. W. Levine, 1977. A model of the control of ingestion. Psychol. Rev. 84:379—412. de Andrade, A. N., J. C. Rogler, and W. R. Featherston, 1976. Influence of constant elevated temperature and diet on egg production and shell quality. Poultry Sci. 55:685-693. de Andrade, A. N., J. C. Rogler, W. R. Featherston, and C. W. Alliston, 1977. Interrelationship between diets and elevated temperatures (Cyclic and constant) on egg production and shell quality. Poultry Sci. 56:1178-1188. Duncan, I.J.H., A. R. Home, B. O. Hughes, and D.G.M. Wood-Gush, 1970. The pattern of food intake in female Brown Leghorn fowls as recorded in a skinner box. Anim. Behav. 18:245— 255.
Gleaves, E. W., L. V. Tonkinson, J. B. Wolf, C. K. Harman, R. H. Thayer, and R. D. Morrison, 1968. The action and interaction of physiological food intake regulators in the laying hen. Poultry Sci. 4 7 : 3 8 - 6 7 . Gleaves, E. W., L. V. Tonkinson, J. B. Wolf, M. H. Henley, C. K. Harman, and R. H. Thayer, 1963. Poultry Nutrition Manual. Misc. Publ., Dept. Poult. Sci., Oklahoma State Univ., Stillwater, OK. Jensen, L. S., 1977. Dietary energy studies with laying hens. Pages 40—46 in Proc. 1977 Maryland. Nutr. Conf. Jones, J. E., B. L. Hughes, and B. D. Barnett, 1976. Effect of changing dietary levels and environmental temperatures on feed consumption and egg production of Single Comb White Leghorns. Poultry Sci. 55:274-277. Kraly, F. S., and E. M. Blass, 1976. Increased feeding in rats in a low ambient temperature. Page 77—78 in Hunger, Basic mechanisms and Clinical Implications. D. Novin, W. Wyrwicka, and G. Bray, ed. Raven Press, New York, NY. Le Magnen, 1971. Advances in studies on the physiological control and regulation of food intake. Prog. Physiol. Psychol. 4 : 2 0 3 - 2 6 1 . Lepkovsky, S., and F. Futura, 1971. The role of homeostasis in adipose tissues upon the regulation of food intake of White Leghorn cockerels. Poultry Sci. 50:753-576. Mask, B., D. G. M. Wood-Gush, I.J.H. Duncan, C. McCorguodale, and C. J. Savory, 1974. A comparison of the feeding behaviour of young broiler and layer males. Br. Poult. Sci. 15:499-505. Richardson, A. J., 1970. The role of the crop in the feeding behavior of the domestic chicken. Behavior 18:633-639. Savory, S. J., 1979. Feeding behavior. Pages 277-323 in Food Intake Regulation in Poultry British Poultry Science Symposium No. 14. N. Boorman and B. M. Freeman.ed. Savory, C. J., 1980. Meal occurrence in Japanese quail in relation to particle size and nutrient density. Anim. Behav. 2 8 : 1 6 0 - 1 7 1 . Slater, P.J.B., 1974. The temporal pattern of feeding in the Zebra finch. Anim. Behav. 22:506-515. Smith, C.J.V., 1979. The hypothalamus and the regulation of food intake. Poultry Sci. 58: 1619-1624. Snedecor, C. T., 1956. Statistical Methods. 5th ed. The Iowa State Coll. Press, Ames, IA. Snowdon, C. T., 1969. Motivation, regulation and the control of meal parameter with oral and intragastic feeding. J. Comp. Physiol. Psychol. 59:171-175. Thomas, D. W., and J. Mayer, 1968. Meal taking and regulation of food intake by normal and hypothalamic hyperphagic rats. J. Comp. Physiol. Psychol. 66:642-653. Van Hemel, S. B., and J. S. Myer, 1969. Feeding patterns and response to caloric dilution in the Japanese quail. Physiol. Behav. 4:339—344. Wolf, L. L., and F. R. Hainsworth, 1977. Temporal patterning of feeding by hummingbirds. Anim. Behav. 25:976-989. Zeigler, H. P., L. Green, and R. Lehrer, 1971. Patterns of feeding behavior in the pigeon. J. Comp. Physiol. Psychol. 4 6 8 - 4 7 7 .
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environmental temperature compensated for the decrease in meal size by increasing the number of meals. However, the roosters were able to decrease their activity by eating more feed per meal, decrease the number of meals, and decrease time spent eating a meal at the low environmental temperature. They tried to conserve energy, and it may have been the digestive system that terminated a meal and prevented the increase in feed intake. These results agree with those of Davies (1977), who reported that adjustments in feed and energy intake in rats occurred in response to changes in environmental temperature; adjustments were by meal size.