Physiology& Behavior, Vol. 48, pp. 49-53. ©PergamonPress pie, 1990. Printedin the U.S.A.
0031-9384/90$3.00 + .00
Meal Patterns of Pygmy Goats Fed Hay and Concentrate Ad Lib M. S E N N , x W . L A N G H A N S 1 A N D E. S C H A R R E R
Institute o f Veterinary Physiology, University o f Zarich, Zfirich, Switzerland Received 17 October 1989
SENN, M., W. LANGHANS AND E. SCHARRER. Meal patterns ofpygmy goatsfed hay and concentratead lib. PHYSIOL BEHAV 48(1) 49-53, 1990.--The meal patterns of pygmy goats fed hay and pelleted concentrate ad lib were recorded and analyzed. The pygmy goats consumed 8 hay meals [6 during the light phase ( = light)/2 during the dark phase ( = dark)] and 10 concentrate meals (7 during light/3 during dark) during 24 hr (12 hr light/12 hr dark). Sixty-two percent of hay and 74% of concentrate intake occurred during light. Total 24-hr hay (280 g) and concentrate (264 g) intakes were similar, but concentrate was preferred during dark. Concentrate meals were smaller during light than during dark. The mean feeding rate (g/rain) within meals for both hay and concentrate was higher during dark than during light. Meal size and duration of postmeal interval were positively correlated for concentrate but not for hay. No significant positive correlation was found between meal size and duration of premeal interval. Separate analysis of diurnal and nocturnal meals indicated that the postmeal correlation for concentrate was evident primarily during dark. The results demonstrate that food intake in pygmy goats shows distinct diurnal variations and suggest that food intake in ruminants is regulated from meal to meal, with different factors prevailing during light and dark. Meal patterns
Goats
Hay and concentrate
Ad lib
ENERGY intake in man and animals occurs in clusters of feeding bouts (meals). The size, duration and frequency of meals as well as their diurnal distribution vary from species to species (1, 2, 6, 8, 11, 16, 20, 22, 26). Under ad lib feeding conditions, a positive correlation between meal size and duration of the postmeal interval (postmeal correlation) has been observed in the laboratory rat (7, 14-17) and also in pigs (1), dogs (20), rhesus monkeys (11), rabbits (22) and under some conditions in sheep (2) and goats (13). In contrast, a positive correlation between meal size and duration of the premeal interval (premeal correlation) was found in man (8) as well as in sheep (2), cattle (19) and goats (13) under some conditions. The existence of a post- or premeal correlation indicates that food intake is regulated from meal to meal and is matched to energy requirements through variations in meal frequency or meal size, respectively. There is evidence that meal size and meal frequency are regulated by pre- and postabsorptive feedback signals, respectively (23). Therefore, analysis of feeding patterns may help to explain the mechanism of food intake regulation. The meal patterns of the laboratory rat have been extensively investigated under various feeding conditions [e.g., (4, 7, 16--18, 21, 25)]. In contrast, there are only a few investigations of meal patterns in ruminants (2, 6, 13, 19, 25) and these data were obtained with roughage alone (2,19) or with a complete mixed diet (6, 13, 26). In the present study we therefore recorded and analyzed the feeding behavior of pygmy goats eating hay and a pelleted concentrate ad lib. This might provide further insight into the complex relationships between intake of roughage and concentrate, which seem to be regulated differently (3,5) and may
affect each other at least under some conditions (10). METHOD
Animals and Housing Conditions Eight adult, female, nonlactating, nonpregnant pygmy goats, weighing 29-37 kg, were kept individually in boxes (1.35 x 2.50 m) on wood shavings. The goats' body weight did not change during the experiment. Room temperature was 21---3°C. The room was kept on an artificial dark-light cycle of 12 hr light and 12 hr dark with the lights on at 9.00 hr. Tap water from selfwatering devices in which the water level was kept constant by a float and salt blocks were always available. The goats were fed ad lib with chopped hay and a pelleted concentrate (UFA 865, VOLG Winterthur). The following values for the composition of the concentrate were given by the manufacturer: 14-16% crude protein, 4-7% crude fibre, 11-13% digestible protein and 6.7 MJ net energy for lactation per kg (in dry matter). The composition of hay was estimated (24) as follows: about 15% crude protein, 25% crude fibre, 10% digestible protein and 5.5 MJ net energy for lactation per kg (in dry matter). Food was replenished every 12 hr at the beginning of each light and each dark phase. Goats were adapted to the feeding and maintenance conditions for several weeks before the experiment.
Data Acquisition Our system for recording of meal patterns has been described in detail elsewhere (13). Each goat had continuous access to two food containers, filled with chopped hay and with concentrate, respec-
~Present address: Institut fur Nutztierwissenschaften, Gruppe Physiologie und Tierhaltung, ETH-Zentrum, CH-8092 Ztirich, Switzerland.
49
50
SENN, LANGHANS AND SCHARRER
TABLE 1 MEAL PARAMETERS AND CUMULATIVEFOOD INTAKE OF PYGMY GOATS FED CHOPPED HAY AND CONCENTRATE AD LIB Light Meal frequency Meal size (g) Meal duration (min)
Dark
Concentrate Hay
7 6
± ±
0.7 0.4
Concentrate Hay
22 28
-----
Concentrate Hay
15 34
0.2t O. li"
3
-~-
2
+
2 2
33 33
± ±
4t
± -
2 2*
11
± ---
3
24
3.6 ± 0.8 -+
0.7 0.1
4
2t
6.1± 1.5 ±
Feeding rate (g/min)
Concentrate Hay
Duration of IMI (min)
Concentrate Hay
81 79
---
8 7
231 326
--- 28t ± 35"t
Cumulative food intake (g)
Concentrate Hay
164 208
__+ ±
12 18
100 72
___ ±
0.9t O.l*t
7t 8*t
Values are means --- SEM of the 8 goats' individual values. *Significantly (p
0031-9384/90$3.00 + .00
Meal Patterns of Pygmy Goats Fed Hay and Concentrate Ad Lib M. S E N N , x W . L A N G H A N S 1 A N D E. S C H A R R E R
Institute o f Veterinary Physiology, University o f Zarich, Zfirich, Switzerland Received 17 October 1989
SENN, M., W. LANGHANS AND E. SCHARRER. Meal patterns ofpygmy goatsfed hay and concentratead lib. PHYSIOL BEHAV 48(1) 49-53, 1990.--The meal patterns of pygmy goats fed hay and pelleted concentrate ad lib were recorded and analyzed. The pygmy goats consumed 8 hay meals [6 during the light phase ( = light)/2 during the dark phase ( = dark)] and 10 concentrate meals (7 during light/3 during dark) during 24 hr (12 hr light/12 hr dark). Sixty-two percent of hay and 74% of concentrate intake occurred during light. Total 24-hr hay (280 g) and concentrate (264 g) intakes were similar, but concentrate was preferred during dark. Concentrate meals were smaller during light than during dark. The mean feeding rate (g/rain) within meals for both hay and concentrate was higher during dark than during light. Meal size and duration of postmeal interval were positively correlated for concentrate but not for hay. No significant positive correlation was found between meal size and duration of premeal interval. Separate analysis of diurnal and nocturnal meals indicated that the postmeal correlation for concentrate was evident primarily during dark. The results demonstrate that food intake in pygmy goats shows distinct diurnal variations and suggest that food intake in ruminants is regulated from meal to meal, with different factors prevailing during light and dark. Meal patterns
Goats
Hay and concentrate
Ad lib
ENERGY intake in man and animals occurs in clusters of feeding bouts (meals). The size, duration and frequency of meals as well as their diurnal distribution vary from species to species (1, 2, 6, 8, 11, 16, 20, 22, 26). Under ad lib feeding conditions, a positive correlation between meal size and duration of the postmeal interval (postmeal correlation) has been observed in the laboratory rat (7, 14-17) and also in pigs (1), dogs (20), rhesus monkeys (11), rabbits (22) and under some conditions in sheep (2) and goats (13). In contrast, a positive correlation between meal size and duration of the premeal interval (premeal correlation) was found in man (8) as well as in sheep (2), cattle (19) and goats (13) under some conditions. The existence of a post- or premeal correlation indicates that food intake is regulated from meal to meal and is matched to energy requirements through variations in meal frequency or meal size, respectively. There is evidence that meal size and meal frequency are regulated by pre- and postabsorptive feedback signals, respectively (23). Therefore, analysis of feeding patterns may help to explain the mechanism of food intake regulation. The meal patterns of the laboratory rat have been extensively investigated under various feeding conditions [e.g., (4, 7, 16--18, 21, 25)]. In contrast, there are only a few investigations of meal patterns in ruminants (2, 6, 13, 19, 25) and these data were obtained with roughage alone (2,19) or with a complete mixed diet (6, 13, 26). In the present study we therefore recorded and analyzed the feeding behavior of pygmy goats eating hay and a pelleted concentrate ad lib. This might provide further insight into the complex relationships between intake of roughage and concentrate, which seem to be regulated differently (3,5) and may
affect each other at least under some conditions (10). METHOD
Animals and Housing Conditions Eight adult, female, nonlactating, nonpregnant pygmy goats, weighing 29-37 kg, were kept individually in boxes (1.35 x 2.50 m) on wood shavings. The goats' body weight did not change during the experiment. Room temperature was 21---3°C. The room was kept on an artificial dark-light cycle of 12 hr light and 12 hr dark with the lights on at 9.00 hr. Tap water from selfwatering devices in which the water level was kept constant by a float and salt blocks were always available. The goats were fed ad lib with chopped hay and a pelleted concentrate (UFA 865, VOLG Winterthur). The following values for the composition of the concentrate were given by the manufacturer: 14-16% crude protein, 4-7% crude fibre, 11-13% digestible protein and 6.7 MJ net energy for lactation per kg (in dry matter). The composition of hay was estimated (24) as follows: about 15% crude protein, 25% crude fibre, 10% digestible protein and 5.5 MJ net energy for lactation per kg (in dry matter). Food was replenished every 12 hr at the beginning of each light and each dark phase. Goats were adapted to the feeding and maintenance conditions for several weeks before the experiment.
Data Acquisition Our system for recording of meal patterns has been described in detail elsewhere (13). Each goat had continuous access to two food containers, filled with chopped hay and with concentrate, respec-
~Present address: Institut fur Nutztierwissenschaften, Gruppe Physiologie und Tierhaltung, ETH-Zentrum, CH-8092 Ztirich, Switzerland.
49
50
SENN, LANGHANS AND SCHARRER
TABLE 1 MEAL PARAMETERS AND CUMULATIVEFOOD INTAKE OF PYGMY GOATS FED CHOPPED HAY AND CONCENTRATE AD LIB Light Meal frequency Meal size (g) Meal duration (min)
Dark
Concentrate Hay
7 6
± ±
0.7 0.4
Concentrate Hay
22 28
-----
Concentrate Hay
15 34
0.2t O. li"
3
-~-
2
+
2 2
33 33
± ±
4t
± -
2 2*
11
± ---
3
24
3.6 ± 0.8 -+
0.7 0.1
4
2t
6.1± 1.5 ±
Feeding rate (g/min)
Concentrate Hay
Duration of IMI (min)
Concentrate Hay
81 79
---
8 7
231 326
--- 28t ± 35"t
Cumulative food intake (g)
Concentrate Hay
164 208
__+ ±
12 18
100 72
___ ±
0.9t O.l*t
7t 8*t
Values are means --- SEM of the 8 goats' individual values. *Significantly (p
