Stereotypies in female farm mink (Mustela vison) may be genetically transmitted and associated with higher fertility due to effects on body weight

Effects of simple cage enrichment and its removal on the behavior and welfare of American mink (Neogale vison)

Environmental enrichment may reduce stereotypies in fur-farmed mink. North American mink standards require manipulable enrichment objects within cages. However, mink can rapidly destroy objects inhibiting continuous enrichment presence, which may have negative welfare impacts. This experimental study determined the effects of removing simple cage manipulable enrichments (plastic chains and dumbbells), either short-term or longer-term, on the behavioral expression of welfare in fur-farmed mink. Locomotor stereotypies, normal activity, sub-types of inactivity related to boredom, and tail fur-chewing were recorded across four treatment groups with either (1) no enrichment, (2) continuous enrichment, (3) short (temporary), or (4) long-term enrichment removal. Contrary to predictions, locomotor stereotypies, and scrabbling were not reduced by the enrichments, nor affected by the enrichment removal. Observations at the beginning of the trial showed the non-enriched mink spent the least amount of time lying with their eyes open (i.e., the least bored). The lack of enrichment may have increased fur-chewing on the tail, but larger sample sizes would be needed for statistical confirmation. This research contributes to the literature on evaluating simple, practical enrichments for improving fur-farmed mink welfare.

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.

Aggressiveness, ADHD-like behaviour, and environment influence repetitive behaviour in dogs

Repetitive behaviour ranges from variants of normal repetitive behaviours to abnormal repetitive behaviours. The domestic dog spontaneously performs different repetitive behaviours, which can be severe and impair the quality of life and the dog-owner relationship. We collected comprehensive behavioural questionnaire data from almost 4500 Finnish pet dogs and studied the effect of several demographic, environmental, and behavioural factors on canine repetitive behaviour with logistic regression. We replicated findings from previous studies by revealing comorbidity between repetitive behaviour and behavioural factors aggressiveness, hyperactivity/impulsivity, and inattention. We also found a novel association between repetitive behaviour and the owner’s dog experience. In addition, we showed that repetitive behaviour is more common in dogs that live without conspecifics, dogs that were given a low amount of exercise, dogs that lived in larger families, young dogs and elderly dogs, and neutered dogs. Finally, we identified breed differences in repetitive behaviour, suggesting that some breeds are more vulnerable to repetitive behaviour and indicate a genetic susceptibility. As abnormal repetitive behaviour can considerably worsen the well-being of dogs and impair the dog-owner relationship, a better understanding of the environmental, lifestyle, and molecular factors affecting canine repetitive behaviour can benefit both dogs and humans.

Stereotypic behaviour predicts reproductive performance and litter sex ratio in giant pandas

Breeding and welfare problems confront many conservation breeding programs. Stereotypies-repetitive, unvarying, functionless behaviours -are common abnormal behaviours that often arise in suboptimal conditions. While the role of stereotypies in welfare assessment is well studied, few investigations address the relationship between stereotypic behaviour and reproduction. We examined the correlation between stereotypic behaviour and reproductive performance in 101 giant pandas (Ailuropoda melanoleuca). High stereotyping males copulated more and produced more cubs, suggesting that highly sexually motivated males were prone to stereotypy but also had high reproductive competence. Female stereotypies were negatively associated with all reproductive measures closely tied to behavioural competence: high stereotyping females were less likely to copulate, less likely to mother-rear cubs, and-probably a result of poor maternal care-had lower cub survival. However, females that exhibited stereotypies were more likely to produce a cub, suggesting stereotypies are tied to behavioural but not physiological competence. High stereotyping female pandas also displayed strong and consistent bias toward production of female offspring while paternal relationship to sex allocation was the reverse. These results are consistent with stress-mediated sex allocation theory. Our findings raise concern about differential reproductive success among high and low stereotyping pandas, and possible genetic adaptation to captivity.

Early weaning increases aggression and stereotypic behaviour in cats

Behaviour problems are common in companion felines, and problematic behaviour may be a sign of chronic stress. In laboratory animals, early weaning increases the risk for aggression, anxiety, and stereotypic behaviour. However, very few studies have focused on early weaning in one of the world’s most popular pets, the domestic cat, although weaning soon after the critical period of socialisation is common practice. To study the effects of early weaning (<12 weeks) on behaviour, a large data set (N = 5726, 40 breeds) was collected from home-living domestic cats through a questionnaire survey. The results show that weaning before 8 weeks of age increases the risk for aggression, but not fearful behaviour. Moreover, cats weaned after 14 weeks of age have a lower probability for aggression towards strangers than early weaned cats and a lower probability for stereotypic behaviour (excessive grooming) than cats weaned at 12 weeks. The effect of weaning age on stereotypic behaviour is partially explained by the effects on aggression. These findings indicate that early weaning has a detrimental effect on behaviour, and suggest delayed weaning as a simple and inexpensive approach to significantly improve the welfare of millions of domestic cats.

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.

Decreased litter size in inactive female mink (Neovison vison): Mediating variables and implications for overall productivity

Meagher, R., Bechard, A., Palme, R., Díez-León, M., Hunter, D. B. and Mason, G. 2012. Decreased litter size in inactive female mink ( Neovison vison ): Mediating variables and implications for overall productivity. Can. J. Anim. Sci. 92: 131–141. Farmed mink vary dramatically in activity: very inactive individuals rarely leave the nest-box, while others spend hours active daily, often performing stereotypic behaviour (SB). SB typically correlates with increased reproductive output, and inactivity, with decreased output. Our objectives were to determine whether SB or inactivity best predicted litter size (LS), and to test three hypothesized reasons for inactive dams’ reduced LS: H1, excess fat; H2, chronic stress (potentially underlying inactivity because fear motivates hiding); and H3, health problems. We assessed time budgets pre-breeding, scored body condition visually, conducted health exams, and assessed stress using faecal cortisol metabolites (FCM) and "glove tests" for fear. Results did not support H2 and H3: inactive females were no more fearful than active females (P>0.10), they excreted lower levels of FCM (P=0.033), and were considered healthy. As predicted by H1, inactive females had higher body condition scores (P<0.0001), which predicted decreased LS (P=0.040). However, path analysis determined this was unlikely to mediate the inactivity–LS relationship. Compared with SB, inactivity more consistently predicted both LS (negatively, P ≤ 0.038) and kit weight (positively, P ≤ 0.037). Therefore, decreasing inactivity in farmed mink, rather than increasing their SB or decreasing their body condition should most improve productivity.

Hippocampal neurogenesis increase with stereotypic behavior in mink (Neovison vison)

We investigated the hypothesis that performance of abnormal behavior is a stress response concurrent with reduced cell formation in the hippocampal region of the brain, using groups of adult female American mink with high occurrence of stereotypic behavior (STEREO, n=12), high occurrence of fur-chewing behavior (FURCHEW, n=12), or without abnormal behavior (CONTROL, n=12). Following repeated injections of Bromodeoxyuridine (BrdU) as a marker of dividing cells, animals were sacrificed and brain tissue fixated. After brain sectioning and a mink-adapted free-floating BrdU/NeuN doublestaining protocol, we counted the number of cells formed in the subgranular zone (SGZ) and the granular cell layer (GCL) of the dentate gyrus (DG) in the mink hippocampus.

RESULTS

(1) proliferation of cells in the SGZ and the GCL of the ventral hippocampal DG was demonstrated for the first time in adult mink, (2) with no significant difference between the experimental groups (

CONTROL

1509 (191.1); FURCHEW: 1377 (199.8); STEREO: 1968 (288.8); P=0.18), (3) however, with a positive correlation between the amount of stereotypic behavior performed and the number of new hippocampal cells formed (P=0.016). In conclusion, our results do not support that abnormal behavior in mink is concurrent with reduced hippocampal neurogenesis. On the contrary, cell proliferation increased with increasing performance of stereotypic behavior, being of an active/locomotory nature in mink.

Stress and stereotypic behaviour in mink (Mustela vison): a focus on adrenocortical activity

We examined whether female mink with low (LS) and high (HS) occurrence of stereotypic behaviour differ in their adrenocortical activity in baseline conditions or in response to immobilisation (Experiment 1), handling, adrenocorticotropic hormone (ACTH) challenge (Experiment 2) and excretion of circulating cortisol (Experiment 3). Faeces are the predominating excretory route of cortisol (83%), with peak concentrations after 4.2 h (urine: 3.4 h). Faecal cortisol metabolites (FCMs) reflected changes in relation to handling/ACTH challenge. In Experiment 1 (n = 162), HS mink had approximately 54% higher baseline level of FCM than LS mink (P < 0.001), with markedly elevated FCM on the days after an immobilisation stressor. In Experiment 2 (n = 48), LS and HS mink did not differ in adrenocortical activity after an ACTH challenge. However, HS mink reacted more in response to handling, evident in the FCM level 4-20 h after the handling (P = 0.001). In Experiment 3 (n = 16), the excretion of infused (3)H-cortisol did not differ between LS and HS mink. Stereotypic behaviour is concurrent with higher baseline concentrations of FCM, which cannot be explained by a greater adrenocortical reactivity or a different excretion of the circulating cortisol. Instead, we conclude that mink with a high level of stereotypic behaviour have a greater perception of stress, or increased sensitivity to stressors at the pituitary level.

Breeding for behavioural change in farm animals: practical, economic and ethical considerations

In farm animal breeding, behavioural traits are rarely included in selection programmes despite their potential to improve animal production and welfare. Breeding goals have been broadened beyond production traits in most farm animal species to include health and functional traits, and opportunities exist to increase the inclusion of behaviour in breeding indices. On a technical level, breeding for behaviour presents a number of particular challenges compared to physical traits. It is much more difficult and time-consuming to directly measure behaviour in a consistent and reliable manner in order to evaluate the large numbers of animals necessary for a breeding programme. For this reason, the development and validation of proxy measures of key behavioural traits is often required. Despite these difficulties, behavioural traits have been introduced by certain breeders. For example, ease of handling is now included in some beef cattle breeding programmes. While breeding for behaviour is potentially beneficial, ethical concerns have been raised. Since animals are adapted to the environment rather than the other way around, there may be a loss of ‘naturalness’ and/or animal integrity. Some examples, such as breeding for good maternal behaviour, could enhance welfare, production and naturalness, although dilemmas emerge where improved welfare could result from breeding away from natural behaviour. Selection against certain behaviours may carry a risk of creating animals which are generally unreactive (‘zombies’), although such broad effects could be measured and controlled. Finally, breeding against behavioural measures of welfare could inadvertently result in resilient animals (‘stoics’) that do not show behavioural signs of low welfare yet may still be suffering. To prevent this, other measures of the underlying problem should be used, although cases where this is not possible remain troubling.

Novel SNPs of the bovine GAD1/gad67 gene and their association with growth traits in three native Chinese cattle breeds

In this study, polymorphism in the exon 1, 2, 3, 4 and 5 of bovine GAD1 gene was detected by PCR-SSCP and DNA sequencing methods in 726 individuals from three Chinese cattle breeds. Two haplotypes (T and C) and three observed genotypes (TT, TC, and CC) were detected. The result of DNA sequence showed one mutations (T12345C) by comparisons with NC_007300: g.12345T>C. The mutation was at the exon 3, and was identified a missense mutation Phe (TTT)>Leu (CTT) at position 51 (p.F51L). Polymorphism of the GAD1 gene was shown to be associated with growth traits in the Nanyang breed. The SNP in the bovine GAD1 gene had significant effects on body length, body weight, heart girth, and average daily gain at 24 months (P < 0.05). Therefore, these results suggest that the GAD1 gene is a strong candidate gene that affects growth traits in cattle.