Measuring hunger in the pig using operant conditioning: The effect of food restriction

1988 ◽  
Vol 47 (1) ◽  
pp. 131-137 ◽  
Author(s):  
A. B. Lawrence ◽  
M. C. Appleby ◽  
H. A. Macleod
Keyword(s):  
Operant Conditioning ◽  
Food Restriction ◽  
Response Rate ◽  
Response Rates ◽  
Time Of Day ◽  
Operant Response ◽  
Large White ◽  
Post Feeding ◽  
Feeding Motivation ◽  
Ad Libitum

AbstractOperant conditioning techniques were used to measure the feeding motivation (hunger) of pigs restricted to the low food levels used under certain commercial conditions. Six Large White × Landrace boars were maintained in individual pens where they received their daily food allowance. Initially food was available ad libitum; subsequently boars were restricted proportionately to 0·8, 0·6 and 0·4 of their ad libitum intake in a Latin-square design. Finally boars were again offered their previously measured ad libitum intake (treatment 1·0). Hunger was measured by conditioning boars to press a panel 10 times to receive a 7-g reward of food. Operant response rates were measured over 20-min sessions during each of the treatments and at three times of day (pre-feeding, immediately post feeding and 5 h post feeding).Operant response rate was strongly affected by restricting food allowance (means: treatment 1·0, 42 panel presses; 0·8, 212; 0·6, 266; 0·4, 320). There was a signficant interaction between food allowance and time of day (P < 0·001). Treatments did not vary in response rate before feeding. Treatments 1·0 and 0·8 depressed response rate post feeding (P < 0·001) and treatment 1·0 also 5 h post feeding (P < 0·001). Response rates on treatments 0·6 and 0·4 did not vary significantly from one another or with time of day.Restricting pigs to low food levels resulted in a high level of hunger throughout the day. This was so even for food allowances that met current recommended feeding levels sufficient for maintenance and low weight gain (treatment 0·6 equivalent to 1·3 times maintenance). Commercial levels of feeding for the pig breeding population whilst meeting production needs do not satisfy feeding motivation. The hunger resulting from low food levels may act as a major source of stress under certain husbandry conditions such as tether and stall systems for dry sows, where sows are subject to both physical and food restriction.

Measuring hunger in the pig using operant conditioning: the effect of dietary bulk

1989 ◽  
Vol 48 (1) ◽  
pp. 213-220 ◽  
Author(s):  
A. B. Lawrence ◽  
M. C. Appleby ◽  
A. W. Illius ◽  
H. A. MacLeod
Keyword(s):  
Operant Conditioning ◽  
Physical Restraint ◽  
Dry Weight ◽  
Response Rates ◽  
Operant Response ◽  
Large White ◽  
Housing Systems ◽  
Period 2 ◽  
Daily Food ◽  
Feeding Motivation

ABSTRACTOperant conditioning was used to measure the effect on the feeding motivation (hunger) of pigs of diluting nutrient restricted food allowances with straw. Twelve Large White × Landrace boars were maintained in individual pens where they received their daily food allowance. Prior to the experiment, the boars were conditioned in separate rooms to press a panel so as to receive small rewards of food. The effect of diluting meal with straw on panel pressing was investigated in two trials. In trial 1, the boars were allocated to the following treatments: high (H) (3·5 of maintenance (A/)), low (L) (1·5 M) and low/straw (LS) (1·5 M + 0·15 times the dry weight of meal as chopped straw). This dilution increased the food volume by proportionately 0·29. Operant response rates were measured in six 1-h tests in each of two periods at the start (days 3 to 10, period 1) and at the end (days 20 to 28, period 2) of the 28-day experiment. In trial 2, nine of the above boars were allocated to the following treatments: high (H) (3·0 A/), low (L) (1·5 M) and low/straw (LS) (1·5 M + 0·30 the dry weight of meal as ground straw). This dilution increased the food volume by proportionately 0·75. Operant response rates were measured as above between days 10 to 17, following a 9-day adjustment period to the new regimes.In both trials, operant response rate was strongly affected by treatment. Overall in trial 1, animals on the H treatment made few responses (mean 60 responses per session), animals on the L treatment made significantly more responses (mean 825, P < 0·001) and animals on the LS teatment significantly more responses yet again (1263, P < 0·05). This last difference was associated with the difficulty of the LS animals consuming all of the diluted diet during period 1. In trial 2, response rates were again higher on the L than on the H treatments. There was, however, no difference between the L and LS treatments (means: 60 v. 1035 v. 1200). Proportionately only 0·04 of the diet was refused during the period of testing.The present results show that short-term satiety arising from gut distension does not reduce the feeding motivation of animals on chronic nutrient restriction. This suggests that hunger will remain high i n pigs on restricted food allowances, even when they have access to high fibre foods. This hunger will be a potential source of stress, particularly in housing systems involving physical restraint such as tether stalls.

The effects of food level and a foraging device on the behaviour of sows

1993 ◽  
Vol 1993 ◽  
pp. 85-85
Author(s):  
Robert J. Young ◽  
Alistair B. Lawrence
Keyword(s):  
Operant Conditioning ◽  
Food Restriction ◽  
Foraging Behaviour ◽  
Food Level ◽  
Food Ration ◽  
Breeding Stock ◽  
Feeding Motivation ◽  
Stereotypic Behaviour ◽  
Ad Libitum ◽  
Poor Welfare

Economic and production reasons dictate that the breeding stock of domestic pigs are normally fed a food ration less than their ad libitum intake (Whittemore 1987), and commercial levels of food restriction have been shown using operant conditioning to result in sustained feeding motivation (Lawrence et al 1988). However, operant conditioning procedures can be criticised on the basis that they impose artificial conditions on the animal.The practice of food restriction with dry sows has been directly linked to the performance of stereotypic behaviour (Appleby and Lawrence 1987) which maybe interpreted as an indicator of poor welfare (Mason 1991). Stereotypies in sows have often been associated with physically restrictive housing such as stalls and tethers. However, stereotypies can also develop in loose housed sows if they are also food restricted (Terlouw et al 1991). The performance of stereotypies may then reflect underlying feeding motivation and the subsequent potentiation foraging behaviour (Hughes and Duncan 1988). Stereotypies may arise where restrictive housing in some way interferes with the expression of that foraging behaviour perhaps by modifying or channelling complex and variable foraging behaviour into more simple and often repeated forms (Lawrence and Terlouw, in press.

Operant Response Rate as a Function of Time of Day and Early Electromagnetic Exposure on Rats Tested as Adults

1992 ◽  
pp. 151-166
Author(s):  
Steven J. Freimark ◽  
Kurt Salzinger ◽  
Malcolm McCullough ◽  
Donald Phillips ◽  
Leo Birenbaum
Keyword(s):  
Response Rate ◽  
Time Of Day ◽  
Operant Response

Effect of meal frequency and rate of nutrient supply on the post-feeding behaviour of the pig

1995 ◽  
Vol 61 (3) ◽  
pp. 565-573 ◽  
Author(s):  
C. A. Morgan ◽  
A. B. Lawrence ◽  
E. A. Hunter ◽  
J. D. Oldham
Keyword(s):  
Feeding Behaviour ◽  
Food Restriction ◽  
Guar Gum ◽  
Live Weight ◽  
Meal Frequency ◽  
Feeding Period ◽  
Short Term ◽  
Post Feeding ◽  
Ad Libitum ◽  
Short Term Effects

AbstractThere have been suggestions that positive feedback from the meal may stimulate the performance of undesirable behaviour, such as stereotypies, in the post-feeding period. The aim of this work was to measure the short-term effects of a meal on the post-feeding behaviour of the pig.Pigs (70 kg live weight) were offered food ad libitum for 7 days and then given a restricted food allowance for 23 days (experiment 1) or 14 days (experiment 2). In experiment 1, the food allowance was given in one, two or three meals per day. In experiment 2, the food allowance was given in two meals per day and comprised ingredients which supplied glucose at different rates (starch, glucose/starch, starch/guar gum). The pigs' posture and behaviour were recorded in three 1-h periods during the day on 2 days consecutively during the ad libitum feeding period (time period 1) and on pairs of days on three (periods 2, 3 and 4: experiment 1) or two (periods 2 and 3: experiment 2) subsequent occasions during food restriction. The meal frequency or estimated rate of glucose supply had no significant effects on posture or behaviour. In both experiments activity increased with the duration of food restriction. In periods 1, 2, 3 and 4 of experiment 1 the proportions of observations spent were: standing 0·244, 0·260, 0·706 and 0·728 (s.e.d. 0·0346); nosing 0·073, 0·094, 0·229 and 0·253 (s.e.d. 0·0169); rooting 0·032, 0·037, 0·108 and 0·133 (s.e.d. 0·0133). In periods 1, 2 and 3 of experiment 2 the proportions were: standing 0·247, 0·302 and 0·446 (s.e.d. 0·0240); nosing 0·045, 0·075 and 0·138 (s.e.d. 0·0113); chewing 0·101, 0·126, 0·155 (s.e.d. 0·0121). In experiment 1 feeding rate increased with duration of restriction (P < 0·001), but was unaffected by treatment. It is concluded that post-feeding behaviour was influenced more by long-term changes in state (i.e. prolonged food restriction) than by short-term effects of the meal.

The effect of giving the food allowance in one, two or three meals per day on the post-feeding behaviour of pigs

1995 ◽  
Vol 1995 ◽  
pp. 33-33
Author(s):  
C A Morgan ◽  
A.B. Lawrence
Keyword(s):  
Negative Feedback ◽  
Positive Feedback ◽  
Feeding Behaviour ◽  
Food Restriction ◽  
Foraging Behaviour ◽  
Growing Pigs ◽  
Post Feeding ◽  
Feeding Motivation ◽  
Stereotypic Behaviour

Stereotypic behaviour in pregnant sows is related to food restriction, occurs in the post prandial period (Terlouw, Lawrence and Illius, 1991) and may be linked to continued existence of feeding motivation after a small meal of concentrate food (Lawrence and Illius 1989). Lawrence and Terlouw (1993) suggested that feeding motivation is heightened by positive feedback from the act of eating, while the negative feedback from absorbed nutrients may be insufficient to produce satiation. The resulting foraging behaviour is then channelled towards simple and repeated behavioural acts. In an attempt to manipulate positive feedback signals growing pigs were given a restricted food allowance in one, two or three meals per day and their behaviour was observed during the post-prandial period.

Further quantification of pigs needs for food using operant conditioning

1989 ◽  
Vol 1989 ◽  
pp. 91-91
Author(s):  
A.B. Lawrence ◽  
A.W. Illius
Keyword(s):  
Operant Conditioning ◽  
Food Restriction ◽  
Food Reward ◽  
Fixed Ratio ◽  
Progressive Ratio ◽  
Operant Responding ◽  
Motivational States ◽  
Feeding Motivation ◽  
Ad Libitum Intake ◽  
High Level

The study of motivational states underlying behaviour is seen as critical to understanding the implications of restricted husbandry conditions on animal welfare. Yet the measurement of the strength of motivation remains a perennial problem in welfare studies. Previous work at Edinburgh using operant conditioning identified an apparently high level of feeding motivation throughout the day in pigs fed [ARC, 1981] recommended levels for sows and boars [Lawrence et al. 1988]. Pigs trained to press a panel consistently 10 times for a food reward (fixed ratio or FR responding) maintained high levels of panel pressing across the day when offered 0.6 of their ad libitum intake approximating to ARC (1981) recommended feeding levels. However, as the level of operant responding required was not great, it is arguable to what extend these results demonstrate a strong need for food by pigs on restricted feeding. The present paper reports on an experiment to test more accutely the strength of feeding motivation in relation to food restriction by comparing responding on FR with that on a progressive ratio (PR) where the animal has to work progressively harder for successive rewards. It was hoped that PR. reputedly a sensitive measure of motivation, would indicate with greater certainty restrict fed pigs need for food.

Does straw reduce the hunger of pigs on restricted food allowances?

1988 ◽  
Vol 1988 ◽  
pp. 9-9
Author(s):  
A.B. Lawrence ◽  
M.C. Appleby ◽  
A.W. Illius ◽  
H.A. MacLeod
Keyword(s):  
Response Rate ◽  
Operant Response ◽  
Feeding Motivation ◽  
Potential Sources ◽  
Feeding Regimes

There is increasing evidence that hunger and frustration of feeding motivation are potential sources of stress for pigs on restricted food levels such as tethered, pregnant sows. However, it is not clear what factor(s) of feeding regimes are critical in this respect. It has been suggested that the hunger of pigs on restricted food allowances may result in part from the use of concentrated foods lacking dietary bulk. This paper reports on 2 experiments conducted to examine the effect of straw as dietary bulk on hunger as measured by operant response rate.

The effect of giving the food allowance in one, two or three meals per day on the post-feeding behaviour of pigs

1995 ◽  
Vol 1995 ◽  
pp. 33-33
Author(s):  
C A Morgan ◽  
A.B. Lawrence
Keyword(s):  
Negative Feedback ◽  
Positive Feedback ◽  
Feeding Behaviour ◽  
Food Restriction ◽  
Foraging Behaviour ◽  
Growing Pigs ◽  
Post Feeding ◽  
Feeding Motivation ◽  
Stereotypic Behaviour

Stereotypic behaviour in pregnant sows is related to food restriction, occurs in the post prandial period (Terlouw, Lawrence and Illius, 1991) and may be linked to continued existence of feeding motivation after a small meal of concentrate food (Lawrence and Illius 1989). Lawrence and Terlouw (1993) suggested that feeding motivation is heightened by positive feedback from the act of eating, while the negative feedback from absorbed nutrients may be insufficient to produce satiation. The resulting foraging behaviour is then channelled towards simple and repeated behavioural acts. In an attempt to manipulate positive feedback signals growing pigs were given a restricted food allowance in one, two or three meals per day and their behaviour was observed during the post-prandial period.

Differences in the composition and tissue distribution of pig carcasses due to selection and feeding level

1991 ◽  
Vol 53 (1) ◽  
pp. 97-103 ◽  
Author(s):  
N. W. Godfrey ◽  
P. G. Frapple ◽  
A. M. Paterson ◽  
H. G. Payne
Keyword(s):  
Tissue Distribution ◽  
Food Restriction ◽  
Live Weight ◽  
Restricted Feeding ◽  
Large White ◽  
Feeding Level ◽  
Males And Females ◽  
Ad Libitum ◽  
Pig Carcasses ◽  
Weaner Pigs

ABSTRACTA total of 96 Large White weaner pigs, comprising equal numbers of entire males and females, and of controls and eighth generation index-selected genotypes, were fed ad libitum until 40 kg live weight. From 40 kg until slaughter at 85 kg live weight pigs within genotype and sex groups were fed either ad libitum or 2·2 times maintenance. The left sides of the carcasses were divided into shoulder, middle and ham portions and the middles further divided into eye, wedge and belly dorso-ventral portions. Tissue dissection was performed on all portions separately.Selected pigs yielded proportionately 0·15 less fat, 0·08 more muscle, a smaller muscle: bone ratio and 4·05 mm less P2 backfat depth than the controls. When the data were adjusted to the same mean P2 fat depth, the carcasses of selected pigs had 0·07 less fat and 0·03 more muscle. There were no appreciable differences between the genotypes in cranio-caudal tissue distribution. However, there were differences in dorso-ventral tissue distribution since the middles of selected pigs had proportionately and absolutely more of each tissue in the belly. There was no evidence that selection against fat at the P2 site had caused any increase in fat lateral to the m. longissimus.Food restriction increased carcass muscle by 0·10 and decreased fat by 0·17, but had no effect on muscle: bone ratio or cranio-caudal or dorso-ventral tissue distribution. At the same carcass side weight and P2 fat depth, restricted feeding decreased fat by 0·10 and increased muscle by 0·06 in the carcass side.It is concluded that carcasses of the selected pigs would be undervalued relative to the controls due to less fat and more muscle at the same weight and P2 fat depth. Also, restriction on food intake can cause carcasses to be undervalued relative to feeding ad libitum.

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