Uptake of selenium and mercury by captive mink: Results of a controlled feeding experiment.

Captive, juvenile, ranch-bred, male mink (Neovison vison) were fed diets containing various concentrations of methyl-mercury (MeHg) and selenium (Se) for a period of 13 weeks and then sacrificed to determine total Hg levels in fur, blood, brain, liver and kidneys and total Se concentrations in brain tissue. As MeHg concentrations in the diet increased, concentrations of total Hg in the tissues also increased with the highest level occurring in the fur > liver = kidney > brain > blood. Concentrations of Hg in the fur were correlated (r(2) > 0.97) with liver, kidney, blood and brain concentrations. The addition of Se to the mink diet did not appear to affect most tissue concentrations of total Hg nor did it affect the partitioning of Hg between the liver:blood, kidney:blood and brain:blood; however, partitioning of Hg between fur and blood was apparently affected.

Evaluation of four serological techniques to determine the seroprevalence of Neospora caninum in foxes (Vulpes vulpes) and coyotes (Canis latrans) on Prince Edward Island, Canada.

The objectives of this study were (1) to evaluate the performance and agreement of serological assays (ELISA, IFAT, Neospora caninum agglutination test and immunoblot) using reference sera and field sera from foxes and coyotes and (2) to estimate the N. caninum seroprevalence in foxes and coyotes on Prince Edward Island, Canada. With fox and coyote reference sera the test performance of the ELISA, IFAT and IB was excellent (100% sensitivity and specificity). NAT showed a low sensitivity (50%). Serum was collected from 201 coyotes and 271 foxes. The seroprevalence observed in the different assays ranged from 0.5 to 14.0% in coyotes and 1.1 to 34.8% in foxes. The seroprevalence, when taking more than one test positive as cut-off value was 3.3 and 1.1% for coyotes and foxes, respectively. From the N. caninum-positive group, all coyotes were older than 3 years. Agreement among assays (measured as prevalence-adjusted bias-adjusted kappa) using the field sera ranged from 0.17 to 0.97. Best agreement was observed between ELISA and IFAT, poor agreement was observed between NAT and the other assays. Positive agreement was moderate to poor among all assays utilized in this study. Although the seroprevalence observed was low, N. caninum antibodies are present in foxes and coyotes on Prince Edward Island (PEI) and their role in the N. caninum epidemiology needs further study.

Growth performance and ileal and total tract amino acid digestibility in broiler chickens fed diets containing bacterial protein produced on natural gas.

A total of 180 broiler chickens were fed 1 of 3 diets from day-old to slaughter at 35 d: a control diet with 35% soybean meal (SOY) or diets in which either 6% basic bacterial protein meal (BBP) or 6% autolysed bacterial protein meal (AUT) partially replaced soybean meal protein. Ileal and total tract apparent amino acid digestibility were examined in 5 chickens per diet using TiO(2) as an inert marker. Chickens fed the diets with bacterial protein had higher weight gain and feed consumption than control chicks during the first 3 wk, but there were no differences in growth or feed intake during the last 2 wk or during the total experimental period. The birds fed the BBP diet showed more efficient feed conversion compared with chickens fed the SOY and AUT diets. Litter quality at 5 wk was poorer in pens where the chickens were fed the AUT diet compared with the other 2 treatments. There were no differences among diets in the dressing percentage. Ileal amino acid digestibility at 5 wk of age revealed only minor differences between diets. There was a tendency toward lower ileal digestibility (0.12 > P > 0.07) of Arg, Lys, Met, and Phe in the AUT diet compared with the SOY diet, whereas there were no differences between the SOY and BBP diets. Total tract amino acid digestibilities at 5 wk were similar or slightly lower than the ileal digestibilities within diets. Total tract amino acid digestibility at 2 wk was similar to the total tract amino acid digestibility at 5 wk. The diets containing bacterial protein showed lower total tract digestibility of most amino acids compared with the SOY diet. It was concluded that 6% of either basic or autolysed bacterial protein can replace soybean meal in diets for broiler chickens without impairing growth performance, and the basic bacterial protein seemed to be a slightly better substitute than the autolysed bacterial protein.

Observations on thermoregulatory ontogeny of mink (Mustela vison).

(1) We measured cooling rate for neonatal mink during a 10min coldroom (3.9 degrees C) exposure and subsequent warming rate during a 20min incubator (37.2 degrees C) exposure, the behaviour of the kits and the changes in their pelage between 1 and 46d of age, in an attempt to monitor the ontogeny of their thermoregulatory capacity. (2) Body weight of the 1d old kits averaged only 12.8+/-2.3g (n=4), but they gained weight rapidly reaching 226.1+/-28.3g (males, n=4) and 207.6+/-16.1g (females, n=4) at 30-31d of age, and 562.3+/-43.2g (males, n=3) and 435.7+/-35.5g (females, n=4) at 45-46d of age. (3) Body cooling rate (C(rate) ( degrees C/min); n=80) was affected by the age (between 1 and 31d), BW, initial rectal temperature (T(r0)), and sex of the kits, in addition to their body posture (P(cold), 1=extended, 2=curled-up) during coldroom exposure. C(rate) ( degrees C/min)=-0.34-0.02age-0.002BW+0.05T(r0)-0.06sex-0.20P(cold) (R(2)=0.75). (4) Body warming rate (W(rate) ( degrees C/min); n=80) was influenced by the age(2) and rectal temperature of the kit after the coldroom exposure (T(r10)). W(rate)( degrees C/min)=1.24+0.0002age(2)-0.04T(r10) (R(2)=0.76). (5) Kit fur fibre length increased from 5.45+/-0.63mm (males, n=2) and 6.20+/-0.20mm (females, n=3) at 22-23d of age to 9.43+/-1.44mm (males, n=4) and 8.70+/-1.89mm (females, n=4) at 30-31d of age, and to 12.93+/-0.47mm (males, n=3) and 11.38+/-0.41mm (females, n=4) at 45-46d of age, the growth averaging about 0.26mm per day. (6) Under normal circumstances newborn mink kits are hypothermic.Their thermoregulation develops only gradually and is dependent on increase in body mass, insulation and behavioural thermoregulation. Their strategy of survival is based on the ability to withstand hypothermia and on the nutrition and warmth provided by the dam.

Body composition in mink (Mustela vison) kits during 21-42 days postpartum using estimates of hydrogen isotope dilution and direct carcass analysis.

We compared carcass analysis and hydrogen isotope dilution methods to measure total body water (TBW) and body composition in a small altricial carnivore, the mink. Dilution space (D) of mink at 21-42 days of age (n=20), was determined after subcutaneous administration of tritiated water. The same animals were then used to determine TBW and body composition by carcass analysis and to derive predictive empirical relationships between TBW and total body fat, protein and energy. A separate validation set of 27 kits was used to test the accuracy of predicting body composition from TBW. D overestimated TBW by a consistent and predictable 4.1% (R(2)=0.999, P<0.001). Our estimates of fat, protein and energy content, using equations derived from TBW, were not significantly different than those obtained from direct carcass analysis (P>0.980) in either the initial or validation set of mink. TBW was shown to decrease from 81 to 76% and total body protein to increase from 14 to 19% of LBM of the kits from 21 to 42 days of age. Although a rapidly changing hydration state was apparent in neonates, we conclude that when this is taken into account, accurate estimates of body composition can be obtained from hydrogen isotope dilution.