Scientific Information in Fur Animal Production

s 49 Genetic variation in litter size and kit survival of mink (Neovison vison) B.K. Hansen, G. Su, P. Berg 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 AIREML 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. J. Anim. Breed. Genet, 2010:127(6),442-51. Mapping Loci for Fox Domestication: Deconstruction/Reconstruction of a Behavioral Phenotype A.V. Kukekova, L.N. Trut, K. Chase, A.V. Kharlamova, J.L. Johnson, S.V. Temnykh, I.N. Oskina, R.G. Gulevich, A.V. Vladimirova, S. Klebanov, D.V. Shepeleva, S.G. Shikhevich, G.M. Acland, K.G. Lark During the second part of the twentieth century, Belyaev selected tame and aggressive foxes (Vulpes vulpes), in an effort known as the "farm-fox experiment", to recapitulate the process of animal domestication. Using these tame and aggressive foxes as founders of segregant backcross and intercross populations we have employed interval mapping to identify a locus for tame behavior on fox chromosome VVU12. This locus is orthologous to, and therefore validates, a genomic region recently implicated in canine domestication. The tame versus aggressive behavioral phenotype was characterized as the first principal component (PC) of a PC matrix made up of many distinct behavioral traits (e.g. wags tail; comes to the front of the cage; allows head to be touched; holds observer's hand with its mouth; etc.). Mean values of this PC for F1, backcross and intercross populations defined a linear gradient of heritable behavior ranging from tame to aggressive. The second PC did not follow such a gradient, but also mapped to VVU12, and distinguished between active and passive behaviors. These data suggest that (1) there are at least two VVU12 loci associated with behavior; (2) expression of these loci is dependent on interactions with other parts of the genome (the genome context) and therefore varies from one crossbred population to another depending on the individual parents that participated in the cross. Behav. Genet. 2010: [Epub ahead of print] doi: 10.1007/s10519-010-9418-1 Changes in digestive enzyme activity, intestine morphology, mucin characteristics, and tocopherol status in mink kits (Mustela neovison) during the weaning period M.S. Hedemann, T.N. Clausen, S.K. Jensen Weaning of livestock mammals is often associated with digestive problems related to profound changes in the physiology of the gastrointestinal tract. Knowledge on the changes occurring in the gastrointestinal tract of mink kits during the weaning period is scarce. Such knowledge is important in order to understand the increased occurrence of gastrointestinal disorders around the time of weaning and the reduced growth rates often Scientifur, Vol. 34, No. 4, 2010 50 observed. The present study was undertaken to investigate the developmental changes in the gastrointestinal tract of mink kits during the period 34-59 days of age. Twenty-four mink kits from 8 litters were included in the experiment. The dams and their litters were kept under standard farm conditions. The dams and the kits were fed a diet consisting of 48.1 % protein, 40.7 % fat, and 11.1 % carbohydrate of ME. The mink kits were weaned at 42 days of age. At 34, 47, and 59 days of age one male mink kit from each litter was euthanized, a blood sample was taken and samples were collected from the digestive tract (pancreas and intestinal tissue at 25 % and 75 % of the small intestinal length) and the liver (tissue and bile). The total activity of the pancreatic enzymes amylase, trypsin, chymotrypsin, lipase, and carboxyl ester hydrolase (CEH) per gram metabolic weight increased during the experimental period. When the activities were compared to the levels observed in adult mink in other studies it was found that amylase and CEH are fully developed at the age of 8 weeks whereas the activities of trypsin and chymotrypsin were 2-3 times higher in adult mink. The activity of lipase is 20-35 times lower in mink kits than in adult mink and hence the digestibility of fat is anticipated to be low in mink kits. The vitamin E concentration in plasma was stable from 34 to 59 days of age, while the concentration decreased in the liver. The stereochemical composition of α-tocopherol showed a steep decrease in the concentration of the biologically most active natural isomer in both plasma and liver through the whole weaning period, while the biologically less active 2S isomers showed a clear increase. This indicated that some αtocopherol acetate was hydrolysed and made available for absorption but the vitamin E status observed prior to weaning was not maintained. The villus height increased in the proximal part of the small intestine and decreased in the distal part whereas the crypt depth was doubled in both the proximal and distal part of the small intestine. This is probably a sign of a high proliferative activity in the crypts reflecting the rapid growth of the small intestine during the experimental period. The intestinal lining is covered by a protective mucus layer, and the backbone of this mucus layer is mucin secreted by the goblet cells found in the intestinal lining. The mucin staining area on the villi was markedly reduced during the experimental period but no change in the mucin staining area in the crypts was observed. A reduction in the mucin staining area may correlate to a decrease in the thickness of the mucus layer which may render mink kits more susceptible to infections during the weaning period. In conclusion, the present study demonstrates that the enzymatic capacity is not reduced during the weaning period but the low activity of lipase in mink kits compared to the activity found in adult mink implies that the digestibility of fat is low in mink kits, however, this warrants further investigation. The reduced mucin staining area and the lower vitamin E status suggests that the mink kits may be more susceptible to infections during the immediate postweaning period. Published in Animal, 2010, doi: 10.1017/S1751731110001990 Evaluation of methane-utilising bacteria products as feed ingredients for monogastric animals M. Øverland, A.H. Tauson, K. Shearer, A. Skrede Bacterial proteins represent a potential future nutrient source for monogastric animal production because they can be grown rapidly on substrates with minimum dependence on soil, water, and climate conditions. This review summarises the current knowledge on methane-utilising bacteria as feed ingredients for animals. We present results from earlier work and recent findings concerning bacterial protein, including the production process, chemical composition, effects on nutrient digestibility, metabolism, and growth performance in several monogastric species, including pigs, broiler chickens, mink (Mustela vison), fox (Alopex lagopus), Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), and Atlantic halibut (Hippoglossus hippoglossus). It is concluded that bacterial meal (BM) derived from natural gas fermentation, utilising a bacteria culture containing mainly the methanotroph Methylococcus capsulatus (Bath), is a promising source of protein based on criteria such as amino acid composition, digestibility, and animal performance and health. Future research challenges include modified downstream processing to produce value-added products, and improved understanding of factors contributing to nutrient availability and animal performance. Arch. Anim. Nutr. 2010:64(3),171-89