Anne-Helene Tauson

Postnatal Development in Mink Kits

Abstract The relative growth rate of mink kits during the 42 day lactation period was evaluated. Postnatal development, including chemical composition of the body, relative weights of liver and digestive tracts, liver glycogen, plasma glucose and cortisol, was studied from birth until 5–6 days of age. A maximum relative growth rate of 23%/d was recorded between 1 and 2 days of age. The average over 42 days was 9%/d. Body fat content increased from 1.4% at birth to 4.4% at 5 days of age. Stillborn kits tended to have a lower fat content than live born. Nutrient and energy retention data indicated a ten-fold increase in fat, a doubled protein content, and a three-fold increase in energy retained from birth until 5 days of age. The liver and digestive tract made up 3.5 and 5.6% of body weight at birth, respectively, a ratio that increased to 5% (liver) and 6.5% (digestive tract) from 3 and 2 days of age. Liver glycogen tended to be lower in dead than in live kits and tended to increase from 1 to 2 and 3 days...

Pre-Mating Body Weight Changes and Reproductive Performance in Female Mink

Abstract Reproductive results of one-year-old mink females are often inferior to what could be expected when compared with older females. In practice the females are often raised on a high feeding intensity followed by slimming to reduce the weight in the winter. In a field experiment for two consecutive years and in a station experiment for one year, two groups of each 50 and 15 one-year-old standard females respectively were fed according to the following model prior to their first reproductive cycle. Group I was raised on a high feeding intensity in the autumn and after that slimmed until late February. Animal live weights were reduced by on average more than 300 g. Group 2 animals were kept in a moderate condition throughout the autumn and winter resulting in a weight reduction less than 30 g. In the field experiment, the number of live born kits per litter as well as per mated female were statistically significant better for the non-slimmed females. There was also a tendency towards lower barren perc...

Effects of Flushing on Reproductive Performance, Ovulation Rate, Implantation Rate and Plasma Progesterone Levels in Mink

Abstract In three experiments with a total of 585 standard mink females, four main flushing models were investigated in relation to unflushed control groups. Flushing by ad libitum feeding followed a period of restricted feeding and started either 18 or 4–5 days before the start of the mating season, 3 days after the matings had started, or was carried out individually when the females mated. Flushing of non-restricted versus restricted animals was also compared in one experiment. To evaluate the effects on ovulation and implantation rate and plasma progesterone levels a limited number of animals per treatment was sacrificed. Flushing, following a period of restricted feeding, improved reproductive performance in yearling females when commenced 4–5 days before the start of the mating season. Litter size increased, but the frequency of barren females was not clearly affected. In yearling females mated at least twice, a quadratic regression of litter size on weight change in the flushing period was found. I...

Varied Energy Concentration in Mink Diets

Abstract Effects of varied dietary energy concentration at almost constant protein level and fat: carbohydrate ratio on kit growth performance, female weight changes in the lactation period and water turnover were studied in a 2-year project with mink. The studies reported here were preceded by a series of digestibility trials. In one experiment (II) 4 treatment groups of each 9 females and 54 kits and in the other (III) 3 treatment groups of each 15 females and 90 kits were used. Litter sizes were 5–7 kits and litter size ditribution was equal in all groups. In Expt. II, 3 females per group were used for collection of data regarding water turnover during lactation. The experimental feeding started within the first week of lactation and was terminated 42 days after parturition for the females and at the age of 56 days for the kits. The variation in energy concentration of the diets was achieved by dilution of a basic diet with cod offal and wheat and oats bran. Kit growth performance was positively affect...

Flushing of mink. Effect on plasma progesterone, plasma estradiol, implantation rate and reproductive performance.

Abstract Flushing by ad libitum feeding following a period of restriction has resulted in improved litter size in mink. In this investigation effects of 4 different flushing models on plasma estradiol-17β, plasma progesterone, number of corpora lutea, implantation sites and litter size were studied. Flushing from March 4, preceded by moderate restriction, resulted in superior estimated numbers of corpora lutea and a tendency for increased number of implantation sites and litter size. Plasma estradiol-17β tended to increase from February 25 to March 8 but was not affected by the experimental treatment. Plasma progesterone levels started to increase 4.0–7.7 days before the estimated day of implantation (34.0–37.7 days before parturition). The interval between day of increase in plasma progesterone and recorded day of peak plasma progesterone was shorter in three of the flushed groups compared with the control group. The level of plasma progesterone was not affected by the experimental treatment, estimated n...

Flushing of mink. Effects of level of preceding feed restriction and length of flushing period on reproductive performance

Abstract In an experiment with 200 standard mink females (five groups of 40 females) the effect of flushing (a period of restriction followed by refeeding preceding the mating season) on reproductive performance was evaluated. The results of a non-flushed control group were compared with flushing from 20 February or 4 March until mating. For each date for start of flushing, the flushing period was preceded by a 2-week period of either moderate or severe restriction. Reproductive results confirm earlier data in that flushing from March 4, preceded by a 2-week period of moderate restriction, resulted in improved litter sizes (with 1.2 kits on average). Flushing from February 20 was less efficient. When comparing level of restriction, severely restricted females responded less to flushing than did moderately restricted females. The experimental treatment did not affect readiness to mate and the frequency of barren females was not conclusively affected. The rate of stillborn kits was not significantly affected but the highest rate was recorded in the group with superior litter size. In this investigation, both yearlings and adult females responded similarly to flushing.

Water intake and excretion, urinary solute excretion and some stress indicators in mink ( Mustela vison ): effect of ambient temperature and quantitative water supply to lactating females

Lactation is a physiologically demanding period in mink production, during which kit and dam losses may occur. Ambient temperature and quantitative water supply are thought to affect animal performance and well-being, but conclusive data in the literature are sparse. Therefore, effects of ambient temperature (Ta; low, about 5 degrees; medium, about 15 degrees; high, average 20-25 degrees) and water supply (ad libitum (N), or 10% extra supplementation in the food (E)) were investigated regarding effects on quantitative water intake and excretion, urine osmolality and solute excretion, and urinary cortisol and catecholamines as stress indicators in an experiment with twelve lactating mink with litters of three to seven kits in three consecutive periods, lasting 3, 3 and 2 d respectively. Kit ages ranged from 15 to 20 d at the end of the experiment. Water requirement for milk production (factorial calculations) and water available for evaporation (balance component) were estimated. Period, and hence mainly Ta, had a significant influence on intake of metabolizable energy, quantitative water intake and excretion, but there was less effect of water supply. The total water intake and excretion were very high in relation to the weight of the animals as an effect of lactation. Water intake and excretion, and urinary Na excretion, seemed to be less accurately regulated compared with corresponding functions in non-lactating animals. Rectal temperature increased with increasing Ta, possibly as a means of decreasing evaporative water loss. Water output in milk was estimated to increase from 118 g/d at low Ta to 134 g/d at high Ta. The amounts of water available for evaporation were estimated to be 42, 58 and 69 g/kg0.75 at low, medium and high Ta. Cortisol data did not indicate that the animals experienced negative stress. It was concluded that prolonged periods of high Ta may be hazardous for lactating mink because of decreased intake of metabolizable energy resulting in energy deficit and excessive mobilization of body reserves simultaneously as the requirement for intake of water increases considerably.

Effect of Flushing on Embryos in Early Developmental Stages in Mink (Mustela vison)

Abstract Nutritional flushing of mink females by ad lib. feeding from March 3 or 5, following a two week period of restricted feeding, was evaluated with respect to effects on the number and early development of the eggs shed in females mated once on March 7, 10, 14, 17, 20 and 24. Plasma oestradiol-17β was recorded at mating and at killing 3 or 4 days after mating. The average number of eggs recovered increased for females mated from March 7 to 17, after which time it declined. The number of early embryos was not significantly affected by flushing, but the early development of the eggs was enhanced, documented by a significantly higher percentage of eggs having reached the four-cell stage or more at killing. The effect was most pronounced for females mated early in the breeding season, and then levelled off.

Plasma thyroxine concentration in non-pregnant and lactating mink, and effect of dietary rapeseed oil in the reproduction period.

Effect of dietary rapeseed oil from 00-varieties of rapeseed (0, 1.5% or 3% respectively in the wet compounded diets) on plasma thyroxine (T4), reproductive performance and kit weight gain during lactation was investigated with 3 groups of each 20 mink females. Plasma T4, which has not previously been reported for female mink, was significantly lower in lactating than in non-pregnant females. Unlike in an earlier experiment with growing male mink, it was not affected by dietary rapeseed oil. Reproductive performance, female weight development, feed consumption, and kit weight gain was normal in all treatment groups and there were no significant effects of the experimental treatment.

Vitamin B12 Supplementation to Mink (Mustela vison) in the Prevention of Feed-Induced Iron Deficiency Anaemia: II. Effect on Haematological Parameters and Mineral Content of the Liver

Abstract An effect of oral vitamin B12 administration on growth performance and fur quality characteristics in mink kits fed an anaemiogenic diet has earlier been found. The present data confirmed that kits fed the unsupplemented anaemiogenic diet developed anaemia with low haemoglobin, haematocrit and erythrocyte counts, microcytosis, anisocytosis, and low iron and cobalt contents in the liver. Oral vitamin B12 supplementation, but not injections, partly restored iron status, documented by haemoglobin and haematocrit values not being significantly different from the control group, and increased liver cobalt content. Iron therapy alone or combined with vitamin B12 resulted in normal iron status. A mechanism for the effect of vitamin B12 in preventing anaemia is suggested.