Steen Henrik Møller

The development of on-farm welfare assessment protocols for foxes and mink: the WelFur project

The WelFur project aims at the development of on-farm welfare assessment protocols for farmed foxes (the blue fox [Vulpes lagopus], the silver fox [Vulpes vulpes]) and mink (Neovison vison). The WelFur protocols are based on Welfare Quality® (WQ) principles and criteria. Here, we describe the WelFur protocols after two years of developmental work. Reviews for each of the 12 WQ welfare criteria were written for foxes and mink to identify the welfare measures that have been used in scientific studies. The reviews formed the basis for potential measures to be included in the WelFur protocols. All measures were evaluated for their validity, reliability and feasibility. At present, we have identified 15 fox and 9 mink animal-based (or outcome-based) welfare measures, and 11 and 13 input-based (resource-based or management-based) measures. For both foxes and mink, each of the four WQ principles is judged by at least one criterion, and seven out of the 12 criteria include animal-based measures. The protocols will be piloted in 2012. Using the WQ project and protocols as a model has been a fruitful approach in developing the WelFur protocols. The effects of the WelFur protocols will provide benchmarks from which the welfare of animals on European fur farms can be assessed.

Indirect genetic effects contribute substantially to heritable variation in aggression-related traits in group-housed mink (Neovison vison)

BackgroundSince the recommendations on group housing of mink (Neovison vison) were adopted by the Council of Europe in 1999, it has become common in mink production in Europe. Group housing is advantageous from a production perspective, but can lead to aggression between animals and thus raises a welfare issue. Bite marks on the animals are an indicator of this aggressive behaviour and thus selection against frequency of bite marks should reduce aggression and improve animal welfare. Bite marks on one individual reflect the aggression of its group members, which means that the number of bite marks carried by one individual depends on the behaviour of other individuals and that it may have a genetic basis. Thus, for a successful breeding strategy it could be crucial to consider both direct (DGE) and indirect (IGE) genetic effects on this trait. However, to date no study has investigated the genetic basis of bite marks in mink.Result and discussionA model that included DGE and IGE fitted the data significantly better than a model with DGE only, and IGE contributed a substantial proportion of the heritable variation available for response to selection. In the model with IGE, the total heritable variation expressed as the proportion of phenotypic variance (T2) was six times greater than classical heritability (h2). For instance, for total bite marks, T2 was equal to 0.61, while h2 was equal to 0.10. The genetic correlation between direct and indirect effects ranged from 0.55 for neck bite marks to 0.99 for tail bite marks. This positive correlation suggests that mink have a tendency to fight in a reciprocal way (giving and receiving bites) and thus, a genotype that confers a tendency to bite other individuals can also cause its bearer to receive more bites.ConclusionBoth direct and indirect genetic effects contribute to variation in number of bite marks in group-housed mink. Thus, a genetic selection design that includes both direct genetic and indirect genetic effects could reduce the frequency of bite marks and probably aggression behaviour in group-housed mink.

The Application of a Temperament Test to On-Farm Selection of Mink

The welfare of production animals can be improved by adapting the production system to the needs of the animals and/or by selecting those animals best adapted to the production system. As no documented improvements of mink welfare resulting from altered housing are readily available, a temperament test (the stick test) is now being applied for use under commercial farm conditions. The test, categorising the mink as fearful, exploratory or aggressive when a stick is inserted into the cage, has been developed and used for selection under experimental conditions. It has been demonstrated that the temperaments categorised in the stick test are related to reactions in novel object and intruder tests as well as to cortisone response to handling. In order to facilitate the use of the stick test in practice, it has been simplified and implemented on six Danish mink farms. On average, 60% of adult mink females were characterised as exploratory in August, but the percentage differed between farms. After 30 minutes of training, the farmers were able to perform the stick test with 74–100% agreement in results with an experienced tester. In order to improve welfare at farm level, a selection line of 200 exploratory females is established on each farm for the mating season in March 2000. During the first three years of selection, the effects of the behavioural selection on other welfare indicators, such as health, behaviour and production, will be monitored.

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.

Response to selection and genotype–environment interaction in mink (Neovison vison) selected on ad libitum and restricted feeding

Nielsen, V. H., Møller, S. H., Hansen, B. K. and Berg, P. 2011. Response to selection and genotype-environment interaction in mink (Neovison vison) selected on ad libitum and restricted feeding. Can. J. Anim. Sci. 91: 231-237. Mink were selected for high November weight (AL line) and low feed conversion ratio (FC line) on ad libitum feeding and for high November weight on restricted feeding (RF line). After three generations of selection, the average estimated breeding value for November weight was 533, 326, and 150 g in males and 168, 82, and -85 g in females in the AL, RF, and FC lines. The breeding value for feed conversion ratio was -1.39, -0.84 and -0.68 kg feed kg-1 gain in males and -0.39, -0.31 and -0.23 kg feed kg-1 gain in females in the selection lines. In generation 4, the AL, RF and FC lines were tested on both ad libitum and restricted feeding. The estimated breeding value for November weight in males in the AL line (533 g) was significantly greater than that in the RF line (384 g) on ad libitum feeding. The corresponding values on restricted feeding were 297 and 326 g, respectively, which were not significantly different. This indicates genotype×environment interaction. In the AL line, selection improved feed conversion ratio by increased appetite. In the RF line, it was improved by increased feed utilization. Environmental sensitivity in males, estimated from breeding values for November weight was 236 g in the AL line and 58 g in the RF line suggesting that the RF line was more robust to changes in feeding conditions. A smaller litter size in the AL line (4.1) than in the RF line (5.6) indicates that selection for large weight affects reproduction.

Longitudinal analysis of residual feed intake and BW in mink using random regression with heterogeneous residual variance

The aim of this study was to determine the genetic background of longitudinal residual feed intake (RFI) and BW gain in farmed mink using random regression methods considering heterogeneous residual variances. The individual BW was measured every 3 weeks from 63 to 210 days of age for 2139 male+female pairs of juvenile mink during the growing-furring period. Cumulative feed intake was calculated six times with 3-week intervals based on daily feed consumption between weighings from 105 to 210 days of age. Genetic parameters for RFI and BW gain in males and females were obtained using univariate random regression with Legendre polynomials containing an animal genetic effect and permanent environmental effect of litter along with heterogeneous residual variances. Heritability estimates for RFI increased with age from 0.18 (0.03, posterior standard deviation (PSD)) at 105 days of age to 0.49 (0.03, PSD) and 0.46 (0.03, PSD) at 210 days of age in male and female mink, respectively. The heritability estimates for BW gain increased with age and had moderate to high range for males (0.33 (0.02, PSD) to 0.84 (0.02, PSD)) and females (0.35 (0.03, PSD) to 0.85 (0.02, PSD)). RFI estimates during the growing period (105 to 126 days of age) showed high positive genetic correlations with the pelting RFI (210 days of age) in male (0.86 to 0.97) and female (0.92 to 0.98). However, phenotypic correlations were lower from 0.47 to 0.76 in males and 0.61 to 0.75 in females. Furthermore, BW records in the growing period (63 to 126 days of age) had moderate (male: 0.39, female: 0.53) to high (male: 0.87, female: 0.94) genetic correlations with pelting BW (210 days of age). The result of current study showed that RFI and BW in mink are highly heritable, especially at the late furring period, suggesting potential for large genetic gains for these traits. The genetic correlations suggested that substantial genetic gain can be obtained by only considering the RFI estimate and BW at pelting, however, lower genetic correlations than unity indicate that extra genetic gain can be obtained by including estimates of these traits during the growing period. This study suggests random regression methods are suitable for analysing feed efficiency and BW gain; and genetic selection for RFI in mink is promising.

Genetic parameters and effect of selection for body weight in lines of mink (Neovison vison) on ad libitum and restricted feeding

Abstract Selection was performed for high November weight on ad libitum (AL) and restricted feeding (RF) in mink in two generations. A farm fed line (FF) was maintained as a control. The estimates of heritability for November weight were large (0.62, 0.52, and 0.73 in males and 0.68, 0.51, and 0.60 in females in the FF-, AL-, and RF-line). The results indicate that selection on AL feeding increased appetite and thereby improved feed conversion ratio while selection on RF improved feed utilization. Furthermore, the results suggest that selection for August weight produces lean mink while selection for November weight produces fat mink.

WelFur – mink: development of on-farm welfare assessment protocols for mink

European Fur Breeders’ Association initiated the ‘WelFur’ project in 2009 in order to develop a welfare assessment protocol for mink and fox farms after the Welfare Quality® standards. The assessment is based on four welfare principles (Good feeding, Good housing, Good health and Appropriate behaviour) and 12 underlying criteria, to be measured on-farm. The major steps in the development of the WelFur mink protocols are described: (1) Writing literature reviews and listing potential measures. (2) Identifying valid, reliable and feasible welfare measures. (3) Developing registration protocols, descriptions, and schemes. (4) Testing preliminary protocols in relevant seasons of the annual production. This paper focus on the evaluation of validity, reliability and feasibility of the 22 measures that have been selected for the WelFur assessment protocols. These protocols have been tested in the three mink production seasons: Winter, spring, and autumn, in order to cover the life cycle of mink and proved feasible for a one-day visit.

Classification of animal welfare on mink farms differs between three annual production periods

According to the WelFur assessment protocol for mink, welfare is assessed via three one-day visits; one during each of the three main annual production phases. If one of these three assessments could provide a representative description of the welfare on a mink farm throughout the year, not only would much time and money be saved, it would also provide the farmer with an immediate result. As the same manager is usually in place for all three production phases and as most of the welfare problems associated with mink production are related to management, we hypothesise that assessment in one of the three phases should be sufficient for predicting the overall annual classification of welfare on a farm. Based on the WelFur protocol for mink, data from 19 farms were collected in each of the three production phases: breeders during winter (assessment period one); females and kits in lactation (assessment period two); and juveniles during late growth (assessment period three). The data were recorded by two external assessors per farm, on nine farms in 2011 and ten other farms in 2013, and an aggregated welfare assessment at farm level was calculated for each of the three visits. Data from the three assessments per farm were compared both at criteria, principle, and at overall classification level according to the Welfur mink concept. It appears that the estimated WelFur classification of farms differs between assessment periods, especially as regards to low score-value of the principal ‘Good Feeding’ in the summer period. Scores from periods two and three are needed to predict the full annual score of the four WelFur principles. Based on the results found, we reject the hypothesis that the overall annual classification of welfare of a farm in the WelFur system can be based on one period. A simplification of the WelFur-assessment system may be possible, with the exclusion of the welfare assessment in period one.

The reliability of welfare assessment according to the WelFur-protocol in the nursing period of mink ( Neovison vison ) is challenged by increasing welfare problems prior to weaning

The objective of this study was to test the hypothesis that the body condition of the mink dam, the frequency of dirty nests, frequency of injuries and diarrhoea change significantly with the day of assessment, post-partum, within the data collection period from parturition to weaning, influencing the scores of WelFur at criteria level, but not at principal level or the overall category of mink (Neovison vison) welfare according to the WelFur-Mink protocol. Data from a representative sample of around 120 dams and litters on four farms were collected three to four times in the period stipulated by the WelFur-Mink protocol. WelFur-scores between 0 (worst) and 100 (best) were calculated, aggregated and compared at criteria and principal level. The score for the criterion, ‘Absence of prolonged hunger’ dropped from 86 to 38 after about five weeks of lactation, affecting the principal score ‘Good feeding’, but not by enough to affect the estimated welfare classification. The score for the three other measures also varied with date of assessment but not enough to affect the classification. However, the observed change in the four measures we focused on indicates that a change in the overall WelFur classification can occur if these or other measures change a little more for the better or worse. Possible solutions to this could be reducing the time window for assessment, development of a valid correction factor or to stratify the visits into an early, middle and late visit on a farm within the three registration periods.