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ABSTRACT: To determine the effect of group composition on backtest (Bt) responses and to determine the predictive value of the Bt for the physiological stress response to weaning and mixing, 814 pigs were backtested at 3, 10 and 17 days of age. Twenty-nine percent of all pigs were cross-fostered at 3 days according to Bt responses and groups were formed of animals with high responses (HR) only, low responses (LR) only or mixed groups of animals with high, intermediate and low responses (MISC). Original litters (OR, no cross-fostering) were used as controls. Cortisol responses were measured in saliva after weaning at 4 weeks of age and after moving and mixing at 9 weeks of age. In HR groups, mean Bt responses decreased after cross-fostering while in LR groups, mean Bt scores increased. In both groups, Bt responses of individual animals before and after cross-fostering were not correlated. In MISC and OR groups, all Bt scores were correlated. Weaning and mixing caused a significant rise in cortisol in all animals while moving or weighing did not. No relations were found between Bt scores and cortisol levels. We conclude that Bt behaviour can change according to the social environment between 3 and 10 days. This could be intentional, to form a varied group, or it might be caused by a change in the hypothalamic-pituitary-adrenal (HPA) function due to social stress. At an older age, this ability is lost and common farm practises such as regrouping, weaning and mixing of piglets at ages >10 days might have a negative effect on the piglets.
Physiology & Behavior 03/2003; 78(3):479-88. · 2.87 Impact Factor
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ABSTRACT: Two studies were carried out with pigs to determine the relationship between back test results and production parameters and between back test results and other factors. In the first study, 823 piglets were tested with the back test at 10 and 17 days of age. Production parameters such as average daily weight gain and lean meat percentage were determined. In the second study, the back test was performed on 566 piglets at 3, 10, and 17 days of age. The number of escape attempts in the back test (back test score) of the mother was known for 364 piglets. Parameters concerning the health of the sow and piglets were recorded, as well as the sow's reaction to piglet removal for testing. The relationships between production parameters and back test scores of the animals were calculated, as well as the influence of birth weight, sex (all males were castrated), parents, and health parameters on back test scores. Back test scores were fairly consistent over successive tests for each piglet. Males had higher back test scores than females, and piglets from sows with low back test scores also had low scores. Finally, a higher back test score was correlated with a higher lean meat percentage and a better carcass grading at slaughter; no relation with daily weight gain was found. It is concluded that there are individual differences in the way pigs cope with a stressful situation, as measured with the back test, and that this coping behaviour is consistent. A positive correlation exists between back test scores at a young age and lean meat percentage at slaughter. The response to stress, and hence back test scores, is assumed to be inheritable.
Tijdschrift voor diergeneeskunde 12/2000; 125(21):649-52. · 0.19 Impact Factor
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ABSTRACT: To determine the effect of group composition on backtest (Bt) responses and to determine the predictive value of the Bt for the physiological stress response to weaning and mixing, 814 pigs were backtested at 3, 10 and 17 days of age. Twenty-nine percent of all pigs were cross-fostered at 3 days according to Bt responses and groups were formed of animals with high responses (HR) only, low responses (LR) only or mixed groups of animals with high, intermediate and low responses (MISC). Original litters (OR, no cross-fostering) were used as controls. Cortisol responses were measured in saliva after weaning at 4 weeks of age and after moving and mixing at 9 weeks of age.In HR groups, mean Bt responses decreased after cross-fostering while in LR groups, mean Bt scores increased. In both groups, Bt responses of individual animals before and after cross-fostering were not correlated. In MISC and OR groups, all Bt scores were correlated. Weaning and mixing caused a significant rise in cortisol in all animals while moving or weighing did not. No relations were found between Bt scores and cortisol levels.We conclude that Bt behaviour can change according to the social environment between 3 and 10 days. This could be intentional, to form a varied group, or it might be caused by a change in the hypothalamic–pituitary–adrenal (HPA) function due to social stress. At an older age, this ability is lost and common farm practises such as regrouping, weaning and mixing of piglets at ages >10 days might have a negative effect on the piglets.
Physiology & Behavior.
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Applied Animal Behaviour Science 66 (2000).
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Tijdschrift voor diergeneeskunde 125, 649-652.
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ABSTRACT: Two studies have been carried out in pigs to determine the relation between escape behaviour and production parameters and between escape behaviour and other factors. In the first, 823 piglets were tested with the backtest at 10 and 17 days of age. Production parameters, such as average daily weight gain and lean meat percentage, were recorded. In the second, the backtest was performed on 566 piglets at 3, 10 and 17 days of age. Escape behaviour in the backtest (backtest score) of the mother was known for 364 piglets. Parameters concerning the health of sow and piglets were recorded, as well as the sow's reaction on piglet removal for testing. Relations between production parameters and backtest scores of the animals were calculated, as well as the influence of birth weight, gender (all males were castrated), parents and health parameters on backtest scores. Backtest scores were fairly consistent over successive tests. Males had higher backtest scores than females, and piglets from sows with low backtest scores had low scores themselves. Finally, a higher backtest score gave a higher lean meat percentage and a better carcass grading at slaughter. No relation with daily weight gain was found. It is concluded that there are individual differences between the ways in which pigs cope with a stressful situation, as is measured with the backtest, and that this coping behaviour is consistent. A positive relation exists between backtest scores and lean meat percentage, and a heritability of backtest scores is assumed.
Applied Animal Behaviour Science 66 (2000) 3.
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ABSTRACT: Individual differences in animal behaviour could elucidate the differences in stress coping style, which have consequences for production, health and welfare. Therefore, individual behavioural differences in pigs and consistency of responses in different test situations were studied. If differences in behaviour reflect coping characteristics, then behaviour in one situation should predict behavioural reactions in other situations and at other times. In this study, a backtest was performed on 315 Great Yorkshire* Dutch Landrace piglets at 3, 10 and 17 days of age. On day 3, groups of approximately 10 piglets per sow were formed, based on escape behaviour in the first backtest (backtest score): high resisting (HR, all scores >3), low resisting (LR, all scores <3), miscellaneous (MISC, various scores between 0 and 10) or original (OR) litters to determine if group composition would influence coping behaviour. In weeks 5–7 and/or 10–12, a human approach test (HAT), a novel object test (NOT), and an open door test (ODT) were performed with all pigs simultaneously, in the home pen. Pearson correlation coefficients were calculated between the test results and a factor analysis was performed. Furthermore, data were analysed on pen level, and within MISC- and OR-pens on animal level, using multivariate linear models. Significant correlations were found between the backtests and between HAT, NOT and ODT. Backtest results on three ages loaded on the same factor, and HAT, NOT and ODT at one age also loaded on one factor. No differences were found in HAT, NOT and ODT for the different pens (HR, LR, MISC and OR). On animal level, animals with higher backtest scores also had higher HAT scores at 5–7 weeks (P<0.05) within the MISC-pens. At 10–12 weeks, no differences were found. This study suggests that there are consistencies in behaviour of pigs over time and across situations, so coping can be regarded as a trait variable. However, since correlations are well below one, we suggest that other factors such as time (development) and (test) situation may also play an important role in determining an individual's behavioural reaction. The absence of correlations between backtest and the group tests is explained by the theory that these different tests measure different aspects of the coping style.
Applied Animal Behaviour Science 75 (2002). - ISSN 0168-1591.
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ABSTRACT: Pigs vary in their individual behaviour in response to stress, and this coping behaviour can be measured with a backtest. In this test, a piglet is put on its back and escape attempts are counted during 1 min. Backtest results are linked to individual performance, and regrouping at 9 weeks of age on the basis of coping characteristics can influence production parameters. In the present study, piglets were cross-fostered at 3 days of age on the basis of backtest results, and pens with only active piglets (HR), with only reactive piglets (LR) and mixed pens were formed next to original litters. At 9 weeks animals were mixed and moved. The relation between backtest results and production performance was investigated. Cross-fostering induced a change in backtest results, resulting in approximately the same mean backtest results in each group and consequently on pen level no relations were found between initial coping behaviour and performance. Individual backtest results were linked to production parameters: active animals tended to grow faster and have a leaner carcass. If pig breeding companies would use the backtest to select the most active animals that are potentially the best performers, aggressive behaviour should also be considered (e.g. as part of the breeding goal), because of the link between activity and aggressive behaviour.
Livestock Production Science.
