Combined analysis of group recorded feed intake and individually recorded body weight and litter size in mink.

In the mink industry, feed costs are the largest variable expense and breeding for feed efficient animals is warranted. Implementation of selection for feed efficiency must consider the relationships between feed efficiency and the current selection traits BW and litter size. Often, feed intake (FI) is recorded on a cage with a male and a female and there is sexual dimorphism that needs to be accounted for. Study aims were to (1) model group recorded FI accounting for sexual dimorphism, (2) derive genetic residual feed intake (RFI) as a measure of feed efficiency, (3) examine the relationship between feed efficiency and BW in males (BWM) and females (BWF) and litter size at day 21 after whelping (LS21) in Danish brown mink and (4) investigate direct and correlated response to selection on each trait of interest. Feed intake records from 9574 cages, BW records on 16 782 males and 16 875 females and LS21 records on 6446 yearling females were used for analysis. Genetic parameters for FI, BWM, BWF and LS21 were obtained using a multivariate animal model, yielding sex-specific additive genetic variances for FI and BW to account for sexual dimorphism. The analysis was performed in a Bayesian setting using Gibbs sampling, and genetic RFI was obtained from the conditional distribution of FI given BW using genetic regression coefficients. Responses to single trait selection were defined as the posterior distribution of genetic superiority of the top 10% of animals after conditioning on the genetic trends. The heritabilities ranged from 0.13 for RFI in females and LS21 to 0.59 for BWF. Genetic correlations between BW in both sexes and LS21 and FI in both sexes were unfavorable, and single trait selection on BW in either sex showed increased FI in both sexes and reduced litter size. Due to the definition of RFI and high genetic correlation between BWM and BWF, selection on RFI did not significantly alter BW. In addition, selection on RFI in either sex did not affect LS21. Genetic correlation between sexes for FI and BW was high but significantly lower than unity. The high correlations across sex allowed for selection on standardized averages of animals' breeding values (BVs) for RFI, FI and BW, which yielded selection responses approximately equal to the responses obtained using the sex-specific BVs. The results illustrate the possibility of selecting against RFI in mink with no negative effects on BW and litter size.

Inbreeding affects fecundity of American mink (Neovison vison) in Danish farm mink.

Inbreeding is an increasing problem in farmed mink, because of limited exchange of individuals between farms. In this study, genetic relatedness within seven American mink (Neovison vison) colour strains originating from 13 different mink farms in Denmark was analysed using 21 polymorphic microsatellite loci. We detected large differences in the level of relatedness (range 0.017-0.520) within colour strains. Moreover, a very strong and highly significant negative correlation between the level of relatedness and fecundity was observed (r = 0.536, P < 0.001) [Correction added after online publication on 9 March 2011: r(2) has been changed to r]. To our knowledge, this is the first time that such a correlation has been demonstrated for commercially farmed mink.

Genetic variation in litter size and kit survival of mink (Neovison vison).

The aims of this study are to estimate variance components of litter size and kit survival rate and estimate genetic correlations of litter size and kit survival rate with dam's juvenile body weight and pregnancy length. Variance components for litter size and kit survival were analysed using an AI-REML approach, based on data from 1940 litters of the black colour type mink from 1996 to 2001. The models included (i) additive genetic effect of dam; (ii) dam and sire genetic effects; (iii) additive genetic effect of dam in relation to litter size and dam and sire genetic effects in relation to survival rate; (iv) additive genetic effect of dam to estimate the correlations of litter size or kit survival with dam juvenile body weight and pregnancy length on yearling dams (1357 litters). The dam heritabilities were of litter size (0.02-0.08) and survival rate (0.05-0.10). The permanent effects of dam were important for litter size (0.15-0.19) but not for survival rate. A positive dam genetic correlation between litter size and survival rate was found at 1 week postpartum (0.42), and a positive sire genetic correlation between number of weaned kits and survival rate at the age of 6 month (0.72). Litter size and survival rate were genetically antagonistically related to dam's juvenile body weight (-0.34 to -0.53). These results indicate the following: (i) it is possible to improve litter size and kit survival by selection, (ii) effective improvement of kit survival rate in the suckling period requires selection for maternal effect on kit survival and kit's own capacity to survive and later in the growth period for kit's own ability to survive and (iii) antagonistic genetic correlation of dam juvenile body weight with litter size and survival rate should be taken into consideration in mink breeding programs.

Stereotypic behaviour in farm mink (Neovison vison) can be reduced by selection.

In this article we present the first estimation of genetic variation of stereotypic behaviour (SB). Stereotypic behaviour is defined as an unvarying behaviour without any specific goal or function repeated at least five times. All types of SB were included in the analyses. Altogether 1484 adult mink females of the brown colour type were assessed for behaviour traits: SB, active or inactive behaviour, staying in nest box. Genetic correlations were based on estimates of additive genetic (co)variances obtained from a trivariate linear animal model fitted to behaviour traits, body weight and litter size. The SB has an intermediate genetic variation (h(2) approximately 0.3) and divergent selection for SB confirmed that the frequency of SB can be altered by selection. The results confirmed the hypotheses of negative genetic correlation between SB and body weight and negative genetic correlation between body weight and litter size. The hypotheses of positive correlation between SB and active behaviour and SB and litter size were not confirmed. Consequences of selection for reduced SB can be changes in other behaviour traits, body weight and litter size, depending on the genetic correlation between the traits.

Effect of supplemental roughage on behavior, physiological stress response, and egg production parameters of farmed partridges (Perdix perdix).

The objective of the present experiment was to test the hypothesis that supplemental feeding of roughages (maize silage, rucola salad, or wheat sprouts) would reduce behavioral and physiological signs of stress and increase egg production. A total of 160 adult partridge breeder birds were housed in pairs of 1 male and 1 female/cage during the egg-laying period from April to June. Birds fed on maize silage spent more time laying and less time foraging than birds in the wheat sprout treatment (P < 0.05). Birds fed wheat sprouts were more active than control birds (active 57 vs. 43% of the time, P < 0.05). Birds on the western side of the shed spent more time eating (3.9 vs. 1.24%, P < 0.01). Aggression and dustbathing were rarely seen, and feather pecking was never observed. The basal level of corticosterone (SD) was, on average, 11.4 (6.0) ng/mL of plasma and was not affected by treatments. After 15 min of crating, the average level of corticosterone was 50.0 (20.5) ng/mL of plasma, and strongly tended (P = 0.066) to be higher in the birds on the wheat sprout treatment compared with those on the control or other treatments. Fewer eggs (P < 0.05) were produced by birds on the wheat sprout treatment compared with those on the control treatment (on average, 45.9 vs. 52.1 eggs in total and 40.9 vs. 47.3 eggs for setting). Treatments did not affect egg fertility, egg hatchability, or the number of hatched chicks. In conclusion, we cannot recommend supplementing partridge diets with wheat sprouts during the egg-laying period because this seems to cause behavioral and physiological stress responses and impaired egg production. In general, partridge breeders in the production system investigated here did not show overt signs of maladaptive behavior or physiological stress when fed pelleted concentrate only or concentrate with supplements of maize silage or fresh rucola salad.

Clinical short term study of marginal integrity of resin restorations.

The marginal adaptation of 649 Durafill and Silux fillings in beveled and acid etched enamel cavities was assessed in a clinical study. The investigation included Class III with and without lingual extension, Class IV and Class V. The frequency of marginal discoloration and marginal gaps after 15 months was markedly reduced in all Classes when a low-viscous resin was used prior to application of the restorative.