Bacteriological quality of ready-mixed mink feed in Finland

The occurrence of thermophilic Campylobacter in mink and an experimental oral infection of pregnant mink by Campylobacter jejuni

The occurrence of C. jejuni in the intestinal contents of mink and in the mink feed, prepared from fresh, untreated slaughter offal, was studied. The farms and the central feeding kichens, from where the intestinal and feed samples were collected, were situated in the northwestern part of Finland. All mink samples, originating from 9 farms, and feed samples, originating from 2 central feeding kichens were negative for C. jejuni and for C. coll The only positive faecal samples were obtained from a farm, being located in the southern part of Finland.

Experimental colonization of C jejuni was followed in 10 pregnant mink during their last trimester of pregnancy. The animals colonized only transiently with C. jejuni. Five of the animals shedded Campylobacters only for 1–2 weeks after inoculation. Two experimental animals aborted. These animals were colonized at the time of abortion with C jejuni. The association of C jejuni infection to abortion was not, however, confirmed. The uterine contents or the fetuses examined were negative for Campylobacters.

Seasonal changes in energy economy of farmed polecat as evaluated by body weight, food intake and behavioural strategy

An analysis of seasonal changes in energy budget of the farmed polecat (Mustela putorius) was performed in subarctic climate. Cyclical variations were found in the body weight of male polecats from maximum values in February (2.1 kg) to minimum values in June-July (1.5 kg). There were only minor seasonal changes in the body weight of females. There was a direct relationship between body weight and voluntary energy intake on one hand (r = 0.89) and an inverse relationship between body weight and locomotor activity (r = -0.88) on the other hand. Energy intake was significantly (p less than 0.05) higher during winter (224 kcal/animal/day) than during summer (142 kcal/animal/day). Total time spent outside the nest was at its maximum during the winter months (60 min/day). The results suggest that in male polecats, changes in absolute food intake induce seasonal changes in body weight. Seasonal changes in locomotor activity seem to be less important in energy balance regulation. The fact that the body weight of females showed only minor seasonal variation supports the role of sexual hormones in the control of the body weight.

Pathogenic, enterotoxin-producing staphylococci in mink feed and mink feed raw materials

Samples of 51 mink feeds and 101 raw material batches were analysed for pathogenic staphylococci. Of the feed samples 37 % were contaminated with pathogenic staphylococci, the mean count being 3.02 log CFU (colony forming units)/g and the highest count being 4.48 log CFU/g of feed. Of the raw materials investigated, slaughter-house offals were most frequently contaminated and contained highest counts of S. aureus, 60 % of the samples being positive with a mean log count of 3.86/g and a maximum of 5.70/g. Forty-eight staphylococcal isolates were tested for eniterotoxin production. Toxin A, B or G were produced by eight isolates, A being the most common. None of the isolates produced B or E toxins.

The effect of the bacteriological status of feed on some haematological and blood chemical data on mink

Blood samples from 100 minks from a research farm using bacteriologically high quality feed and from 55 minks from another farm supplying bacteriologically inferior feed, as well as from nine minks from Denmark from two farms providing still better quality feed than both Finnish farms – all minks apparently clinically healthy – were analyzed for some haematological and chemical data: total leucocyte count, haemoglobin, ornithine carba-moyltransferase (OCT), alkaline phosphatase (AP), alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), γ-glutamyl-transferase (Γ-GT), total bilirubin and creatinine. The Finnish minks supplied with high quality feed had more optimal values of total leucocytes, haemoglobin, OCT, AP and creatinine than minks receiving feed with higher bacterial contamination. The Danish minks had better blood values in the investigated parameters except for lower haemoglobin and total bilirubin, which showed no significant difference.

Experimental staphyloenterotoxicosis in mink

Experimental staphyloenterotoxicosis was produced in minks by oral administration of mink feed containing 5 or 200 µg of purified enterotoxin A per test animal. The animals became very exhausted after the ingestion of toxin. Vomiting was observed in two of seven minks of the lower toxin group with a latent period of 2.5 to 4.0 h. The higher toxin concentration caused vomiting in four of seven test animals with a latent period of 2.0 to 2.5 h. Vomitus was accompanied by strong salivation. Poor appetite was observed in four of seven minks having ingested 5 µg of SEA, and 200 µg caused total loss of appetite in all the test animals. After a test period of 22 h all the animals but one had normal appetite. Diarrhoea was prominent in three of seven minks with the low toxin concentration and in all with the high toxin concentration. Statistically significant haemato-logical changes compared to the control group were an increase in neutrophil count and a decrease in lymphocyte count in the high toxin group. Significant changes in the blood chemical data were an increase in blood urea nitrogen with 200 µg of SEA and a decline in the cholesterol level in both toxin groups.

Bacteriological quality of raw materials used in Finnish mink feed

Mink feed raw materials were analyzed for total bacterial count, the number of faecal streptococci, the coliform count, the number of haemolytic bacteria and the number of sulphite reducing bacteria. The investigation comprised samples from the following raw materials: four slaughter-house offal products, preserved and unpreserved slaughter blood, Baltic herring, cod filletting offal, fish silage, blood meal, fish meal, meat-bone meal, protein concentrate, brewer’s yeast and cereal feed.

The slaughter-house offals and unpreserved slaughter blood had the poorest quality, in terms of all the bacterial types for which the samples were analyzed. There were statistically significant differences in bacterial contents between slaughter-house offals from different sources. The preserved slaughter blood had significantly lower bacterial contents as compared to the unpreserved slaughter blood. Single samples of the cod filletting offal, Baltic herring and the blood meal had relatively high total bacterial counts, but the specified mean bacterial counts were relatively low. The bacterial counts for the rest of the investigated raw materials were relatively low.