Novelty exploration, baseline cortisol level and fur-chewing in farm mink with different intensities of stereotypic behaviour

Changes in Stereotypies: Effects over Time and over Generations

Simple Summary

Herein, we propose that there should be discussion about the function and effects of stereotypies in relation to the time during which they are shown. In the first stages, stereotypies may help animals deal with challenges. However, behavior can potentially alter the brain, impairing its function due the absence of a diverse repertory, and change brain connections, neurophysiology and later neuroanatomy. The neuroanatomical changes in individuals showing stereotypies could be an effect rather than a cause of the stereotypy. As a consequence, studies showing different outcomes for animal welfare from stereotypy expression could be due to variation in a timeline of expression. Stereotypies are widely used as an animal welfare indicator, and their expression can tell us about psychological states. However, there are questions about the longer-term consequences if animals express stereotypies: do the stereotypies help in coping? During the prenatal period, stereotypic behavior expressed by the mother can change the phenotype of the offspring, especially regarding emotionality, one mechanism acting via methylation in the limbic system in the brain. Are individuals that show stereotypies for shorter or longer periods all better adjusted, and hence have better welfare, or is the later welfare of some worse than that of individuals that do not show the behavior?

Abstract

Stereotypies comprise a wide range of repeated and apparently functionless behaviors that develop in individuals whose neural condition or environment results in poor welfare. While stereotypies are an indicator of poor welfare at the time of occurrence, they may have various consequences. Environmental enrichment modifies causal factors and reduces the occurrence of stereotypies, providing evidence that stereotypies are an indicator of poor welfare. However, stereotypy occurrence and consequences change over time. Furthermore, there are complex direct and epigenetic effects when mother mammals that are kept in negative conditions do or do not show stereotypies. It is proposed that, when trying to deal with challenging situations, stereotypies might initially help animals to cope. After further time in the conditions, the performance of the stereotypy may impair brain function and change brain connections, neurophysiology and eventually neuroanatomy. It is possible that reported neuroanatomical changes are an effect of the stereotypy rather than a cause.

In-depth analysis of the emotional reactivity of American mink (Neovison vison) under behavioral tests

Currently, the importance of research into the behavior of farm animals is being highlighted. Monitoring animal temperament is a key aspect in improving their well-being. The aim of the study was to search for indicators facilitating classification of the emotional reactivity of mink (Neovison vison) using behavioral tests: glove and empathic tests. Both tests were applied to 760 mink in triplicate to assess their behavioral profile. Based on the obtained assessments, the animals subjected to the empathic test were classified into one of the four behavioral profiles: aggressive, curious, fearful, and neutral. The contact time of the mink with the new object in the empathic test clearly differentiates all four types of mink behavior. The significantly longest contact with the object was found for aggressive, and the shortest for neutral animals. The intensity and time of contact with the object may be an indicator of the behavioral profile of mink. Based on the results, it can be concluded that an additional predictor of the mink reactivity during behavioral tests should be taken into account, the intensity of contact with the object measured both by the intensity of direct contact and by the duration of this contact. The results shown in this study can be used as a selection indicator by including the temperament of farm mink in selection.

Determination of the Genetic Component of Fur-Chewing in Chinchillas (Chinchilla lanigera) and Its Economic Impact

Simple Summary

Many chinchillas kept in captivity develop fur-chewing. This behavior does not only affect fur price, but most importantly it can be the result of an animal welfare problem. The causes of this behavior are not well understood and a genetic component could exist. This is why the aim of this study was to determine the genetic component and the effect of this behavior on fur price. The data from a commercial fur-farm was used, it included information on 10,196 chinchillas recorded between 1990 and 2011. The heritability of the behavior and its effect on fur price were determined. The results show a significant genetic variation in fur-chewing with an estimated heritability of 0.16. At the same time, the behavior had an important negative effect on fur price. The selection and management practices used in fur-farming should be improved in order to decrease the incidence of this behavior.

Abstract

Fur-chewing is a common behavioral disorder developed by chinchillas kept in confinement that can indicate a past or present welfare problem. It also has a negative productive impact associated. The aim of this study was to determine the genetic component of fur-chewing, and the effect of this undesired behavior on fur price in a commercial fur-farming system of chinchillas (Chinchilla lanigera). The data for the analysis was derived from a commercial population of 10,196 chinchillas, recorded between the years 1990 and 2011. For determining differences in fur price according to presence of fur-chewing behavior, analysis of variance (ANOVA) was used, considering 3007 animals. For estimation of variance components of fur-chewing a sire-dam threshold (probit) mixed model was used, using data of 9, 033 individuals, and then heritability on the underlying liability scale was calculated. The analysis revealed a significant negative impact on fur price from fur-chewing chinchillas (p-value < 0.05). In addition, the study showed that fur-chewing presents significant genetic variation, with an estimated heritability of 0.16. The presentation of fur-chewing should be taken into account when selecting broodstock in these systems, in order to reduce the number of affected individuals.

Benefits of a ball and chain: simple environmental enrichments improve welfare and reproductive success in farmed American mink (Neovison vison)

Can simple enrichments enhance caged mink welfare? Pilot data from 756 sub-adults spanning three colour-types (strains) identified potentially practical enrichments, and suggested beneficial effects on temperament and fur-chewing. Our main experiment started with 2032 Black mink on three farms: from each of 508 families, one juvenile male-female pair was enriched (E) with two balls and a hanging plastic chain or length of hose, while a second pair was left as a non-enriched (NE) control. At 8 months, more than half the subjects were killed for pelts, and 302 new females were recruited (half enriched: ‘late E’). Several signs of improved welfare or productivity emerged. Access to enrichment increased play in juveniles. E mink were calmer (less aggressive in temperament tests; quieter when handled; less fearful, if male), and less likely to fur-chew, although other stereotypic behaviours were not reduced. On one farm, E females had lower cortisol (inferred from faecal metabolites). E males tended to copulate for longer. E females also weaned more offspring: about 10% more juveniles per E female, primarily caused by reduced rates of barrenness (‘late E’ females also giving birth to bigger litters on one farm), effects that our data cautiously suggest were partly mediated by reduced inactivity and changes in temperament. Pelt quality seemed unaffected, but E animals had cleaner cages. In a subsidiary side-study using 368 mink of a second colour-type (‘Demis’), similar temperament effects emerged, and while E did not reduce fur-chewing or improve reproductive success in this colour-type, E animals were judged to have better pelts. Overall, simple enrichments were thus beneficial. These findings should encourage welfare improvements on fur farms (which house 60-70 million mink p.a.) and in breeding centres where endangered mustelids (e.g. black-footed ferrets) often reproduce poorly. They should also stimulate future research into more effective practical enrichments.