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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: Over the last 30 years concern about farm animal welfare has increased and has become a public issue in the Netherlands. Public discussion has stimulated research in this field, financed by both government and industry. Dutch society in general and consumers of animal products in particular, want to see high standards of welfare for production animals. Good animal welfare has gradually gained more impact in the total quality concept of the product. This will encourage scientists to continue to analyse the welfare status of animals and to come up with innovative solutions for the remaining problems. At ID-Lelystad much effort is put into farm animal welfare research. This research includes for example, the development of behavioural tests for quantifying and interpreting fear in cattle, investigations into the effects of dietary iron supply and a lack of roughage on behaviour, immunology, stress physiology, and pathology in veal calves, studies of the ontogeny of tail biting in finishing pigs and feather pecking in laying hens as well as evaluation of the welfare effects of automatic milking in dairy cows. The results of these projects contribute to concrete improvements in animal husbandry and expertise and support policy making and legislation. The animal industry as well as retailers should aim at the further implementation of this knowledge and to specify welfare standards to guarantee consumer acceptance of animal production.
The Veterinary quarterly 11/2000; 22(4):217-22. · 1.47 Impact Factor
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ABSTRACT: To study the effects of environmental enrichment on physiological responses to stressors and behavior in growing pigs, pigs were housed in either a poor environment (standard farrowing pens followed by standard rearing and fattening pens) or in an enriched environment (larger farrowing pens followed by larger rearing and fattening pens, provision of straw). Body temperature, heart rate and salivary cortisol were measured during baseline conditions and in response to relocation, isolation and restraint. Pigs housed in the poor environment performed more manipulative social behavior directed to penmates than pigs housed in the enriched environment. Physiological responses to the stressors were the same for enriched- and poor-housed pigs. Surprisingly, enriched-housed pigs had significantly higher baseline salivary cortisol concentrations, especially at 14 and 17 weeks of age. Moreover, enriched housed pigs had a lower baseline body temperature at 17 weeks of age. Thus, provision of straw has an effect on behavior, baseline HPA-axis activity and baseline body temperature in growing pigs.
Physiology & Behavior 07/1998; 64(3):303-10. · 2.87 Impact Factor
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ABSTRACT: This experiment was designed to examine circadian rhythmicity of cortisol in saliva of growing pigs, in relation to age, gender, and (time of) stressor application. Additionally, the acute cortisol response to a stressor was studied. Five groups, each consisting of 3 barrows and 3 gilts, were involved in the experiment. In a Control Group, saliva samples were taken at 1-h intervals at 12, 16, 20, and 24 weeks of age. Within 1 week, rhythmicity of cortisol was assessed during two 24-h spans (Monday and Friday). Rhythm characteristics were evaluated by cosinor analysis, describing the rhythm by several parameters. In 2 groups at 12 weeks and 2 other groups at 20 weeks of age, a stressor was applied (4 h of isolation) on Thursday morning or evening. Again, rhythmicity was assessed on Monday and Friday by sampling at 2-h intervals. Acute cortisol effects were studied by sampling at several time-points during isolation. Between 12 and 24 weeks of age, basal cortisol concentrations decreased and a rather stable and adult circadian rhythm was reached at 20 weeks of age. Average basal cortisol concentrations were higher in barrows than in gilts. Furthermore, after isolation, the amplitude of the rhythm was increased in barrows but was unchanged in gilts. The rhythm was more unstable and the maximum value tended to shift only after evening isolation. Stressor timing, but also age, was found to affect average cortisol concentrations. Moreover, stressor timing was important for the acute cortisol response: the increase was higher in the morning. The results of this study emphasize the importance of considering the circadian rhythmicity of cortisol, in relation to age, gender, and (time of) stressor application, when studying the cortisol response of animals to stressors.
Physiology & Behavior 10/1997; 62(3):623-30. · 2.87 Impact Factor
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ABSTRACT: The present study describes an experiment that was carried out to study the effects of mixing pigs once at 25 kg, preceded by transportation for 1.5 h, on the behavior and the circadian rhythmicity of salivary cortisol. The frequency of agonistic interactions was higher for mixed pigs. This was not only the case immediately after mixing, when pigs started to fight to establish a new social rank (p < 0.05), but also 5 to 6 weeks later; still more headknocks and bites towards other pigs were seen at that time among mixed pigs (p < 0.01). However, neither the basal cortisol concentration, assessed as the MESOR of the circadian rhythm of salivary cortisol, nor the amplitude of that rhythm was different between the groups.
Physiology & Behavior 07/1997; 62(1):181-4. · 2.87 Impact Factor
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ABSTRACT: This study describes the effects of housing pigs under optimal climatic conditions in a Specific-Stress-Free (SSF) housing system on health, behavior, immunological responsiveness, and production performance of 78 pigs from 10 litters. Pigs housed in an SSF system, where they were neither mixed nor transported, were compared with a control group of pigs for which transport was simulated and which were mixed at approximately 25 kg; transportation to another location and mixing are usual procedures in two-site systems. The SSF pigs had a higher growth rate for the finishing period (P < .01), but this was a smaller improvement in performance than in previous studies, probably due to less mixing in this study. Clinical signs were hardly seen in the SSF group, but aggression after mixing caused ear lesions in the control group. Pigs that were not mixed had a higher response 12 and 18 h after an intradermal injection of phytohemagglutinin (P < .001) compared to the control pigs. At 1 d ad 1 mo after mixing the control pigs, more agonistic interactions were seen in these pigs compared with the SSF pigs (P < .05 and P < .01, respectively). In conclusion, health, welfare, and production performance of pigs are improved when pigs are kept in an SSF housing system where they are not mixed or transported.
Journal of Animal Science 10/1996; 74(9):2081-7. · 2.10 Impact Factor
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ABSTRACT: Single and population-mean cosinor analyses document a circadian rhythm in salivary cortisol of pigs (p < 0.001). The midline estimated statistic of rhythm, the MESOR (M), is 1.50 +/- 0.07 ng/ml. For the group of 14 pigs studied there was a predictable variation of 64% around this mean in salivary cortisol within a day: the double circadian amplitude, 2A, was 0.96 ng/ml, with a 95% confidence interval ranging from 0.60 to 1.32 ng/ml. A measure of timing, the acrophase, phi, was 10 h 52 min from the phase reference (0030, the middle of the daily dark span of the 24-h light-dark cycle in which the pigs were kept). The 95% confidence interval of phi extended from 9 h 48 min to 12 h 12 min from the reference time. The chronobiologic approach provides indispensable quantitive characteristics as reference standards for future basic or applied work.
Physiology & Behavior 10/1996; 60(3):985-9. · 2.87 Impact Factor
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ABSTRACT: The present study describes two experiments to standardize the phytohaemagglutinin (PHA) skin test as an indicator of lymphocyte reactivity in pigs after exposure to stressful situations in practical pig husbandry. The first experiment was a dose-response experiment. No time dose interaction was found, so the pattern of the reaction was the same for all doses used, although the magnitude of the reaction differed. The second experiment was carried out to determine stress-induced changes in lymphocyte reactivity. One half of a group of 48 pigs was exposed to stress (mixing, moving, and an increased stocking density). The immune reactivity to intradermally injected PHA of stressed animals differed significantly (P < 0.01) from that of unstressed controls. The reaction of stressed animals can be characterized by a delayed reaction with a lower peak. It can be concluded that frequent measurements are preferable to single measurements when the effects of stress on immunological processes are studied.
The Veterinary quarterly 01/1996; 17(4):143-6. · 1.47 Impact Factor
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ABSTRACT: An experiment was conducted to determine the health, welfare, and growth performance of pigs housed under optimal climatic conditions in a Specific-Stress-Free (SSF) housing system. This system was compared to a conventional housing system with the same climatic conditions. Two identical experimental rooms with five pens each were used. In each room five litters were used for the experiments. The SSF pigs were not mixed or transported, whereas the pigs in the conventional housing system were mixed at weaning and mixed and transported at 25 kg. Average daily gain for the SSF pigs was higher (P < .05) both for the rearing period and for the finishing period (P < .01). Live weight at 143 d was, therefore, higher in the SSF group (95.09 kg vs 84.8 kg, P < .001). Clinical signs were hardly seen in the SSF group, but in the control group high levels of aggression after mixing caused ear, skin, and tail lesions. Cortisol concentration of the saliva was lower in SSF pigs after weaning (P < .01). Seven and 21 d after mixing, the SSF pigs had a higher response to an intradermal injection of phytohemagglutinin (P < .001) than the control pigs. In conclusion, production performance, health, and welfare are improved when pigs are kept in an SSF housing system where they are not mixed or transported.
Journal of Animal Science 06/1995; 73(6):1544-51. · 2.10 Impact Factor
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Veterinary quarterly 22, 2000, 217-222.
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Physiology & behaviour 62, 1997, 623-630.
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Proceedings 31st international congress of the ISAE, Prague, 1997, pp. 213-214.
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Tijdschrift voor diergeneeskunde 125, 2000, 649-652.
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Journal of Animal Science 80 (2002) Suppl. 1. - ISSN 0021-8812. - abstract #1481.
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[S.l.] : [s.n.], 2001. - (ID-Lelystad onderzoeksrapport ; 2109).
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Applied Animal Behaviour Science 66 (2000).
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In: Proceedings of the 35th Congres of the International Society for Applied Ethology, Davis, 2001. - [S.l.] : [s.n.], 2001.
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Tijdschrift voor diergeneeskunde 125, 649-652.
