Conception rates in farm mink (Neovison vison) in relation to first mating date,age and color variety

The aim of the study was to analyze the effects of the first mating date, age and color variety on the conception rates in farm mink. We analyzed female mink reproductive performance in 492 Sapphire and 463 Standard Black females over 3 or 4 years. The analysis included the number of inefficient matings, the interval between the first inefficient mating and the efficient mating (copulation) and the conception rates. The results show a significant effect of female's age and color variety on the conception rates. The youngest, yearling females of either color needed a higher number of matings per conception, as compared to older, 2‐ and 3‐year‐old females. Black females demonstrated a higher number of inefficient matings (1.066), as compared with Sapphires (0.730). Yearling females were most often mated from 1 to 10 March, and older females from 11 to 20 March. Older females achieved better conception rates than the yearlings. Dates between 11 and 25 March proved to be the optimum for the first mating, since the highest conception rates were observed if the females had mated during this period.     

Convergence of the robust Gaussian regression filter applied to sanded wood surfaces

The quality of a sanded wood surface is represented by its roughness, which can be separated from the originally measured data by a procedure of filtering. Past experience has shown that the robust Gaussian regression filter (RGRF) is suitable for wood surfaces because it does not introduce distortions into the roughness profiles. The filter works iteratively until a user-defined convergence condition is met. The iterations stop when the difference between two consecutive profile median values becomes smaller than a given tolerance. This paper examines the convergence of RGRF when applied to wood surfaces sanded with various grit sizes in order to establish the tolerance value, which leads to convergence with the minimum number of iterations. This study was based on monitoring the variation of roughness parameters with the number of iterations for a range of tolerance values. A tolerance of 0.01 μm was found acceptable for filtering sanded wood surfaces.     

Pregnancy detection in putatively unmated mink (Mustela vison) by serum progesterone level

The aim of this study was to determine whether blood plasma progesterone is a reliable indicator of pregnancy in mink at an early stage of gestation. We also attempted to establish the threshold value of progesterone as a pregnancy indicator. The analysis was carried out at a production farm on 42 standard female mink aged 1 year, which were grouped both according to the observed success of mating ("mated" and "unmated") and the level of blood serum progesterone measured afterwards ("pregnant" and "nonpregnant"). It was next verified whether a particular female had been assigned to the proper group in the first place. An analysis of accuracy of mating success assessment within the group of unmated females revealed that more than one-third of decisions were wrong, since some females that had been considered unmated ultimately whelped. This suggests that mating supervision by farm workers lacks reliability. A progesterone test for verification of such management decisions should limit the risk of err,or. We suggest that progesterone tests could be carried out using the threshold values 1.9 ng/ml and 20 ng/ml in blood sampled on 25 March and 8 April, respectively, although some level of uncertainty should be taken into account.     

Organophosphorus insecticides affect normal polyamine metabolism in amphibian embryogenesis

The objective of the present study was to evaluate the concentration- and time-dependent effects of the organophosphorus insecticides malathion and azinphos-methyl on polyamine metabolism, and relate them to normal and altered embryonic development of the common toad Rhinella arenarum. Control embryos showed that the higher polyamines spermidine and spermine acquired importance with respect to the diamine putrescine as embryonic development progressed. The activity of ornithine decarboxylase significantly decreased in complete operculum embryos. Continuous exposure to malathion caused a decrease in polyamine levels during embryonic development. However, there was an increase in putrescine levels in complete operculum embryos exposed to a sublethal concentration of the insecticide. Embryos exposed to malathion displayed a decrease in fresh weight and size, along with an increase in the number of malformed individuals. R. arenarum embryos exposed to a lethal concentration of azinphos-methyl showed an increase in putrescine levels and a decrease in spermidine and spermine levels, accompanied by an increase in ornithine decarboxylase activity. In conclusion, as the embryonic development of the toad R. arenarum progresses, polyamine metabolism shifts to higher polyamine levels with a more preponderant contribution of spermidine and spermine with respect to putrescine and involves a dramatic change in ornithine decarboxylase activity, one of the key regulatory enzymes of the pathway. Organophosphorus insecticides are capable of altering polyamine metabolism, slowing embryo development in parallel with a reduction in spermidine and spermine levels. An increase in the oxidative degradation of polyamines might be involved in the toxic action of organophosphorus insecticides and might also be related to other effects such as teratogenesis.     

An attempt to control <Emphasis Type="Italic">Cameraria ohridella</Emphasis> using an attract-and-kill technique

This study estimates the efficacy of an attract-and-kill (A&K) technique to control the horse chestnut leaf miner, Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae), an invasive insect pest of the horse chestnut, Aesculus hippocastanum L. (Hippocastanaceae). The A&K formulation was dispensed as 50 μl droplets of paste-like matrix, containing C. ohridella sex pheromone, (8E,10Z)-tetradeca-8,10-dienal (85% + pure; 0.16% w/w) and a fast acting contact toxicant, pyrocides (94% pure; 6% w/w), applied directly to the bark of the trees. It was tested in 2003 at rates of 30 and 45 droplets/tree at the Ostrobramska site and at rates of 30, 60 and 90 droplets/tree at the Woloska site in Warsaw, Poland, for the first insect generation. A set of untreated plots (0 droplets/tree) was established at each site as well. The treatment efficacy was estimated using two indices: (1) moth catches in pheromone traps and (2) the number of mines per leaf. Trap catches were significantly higher in the untreated plots than in the treated plots regardless of the application rate in all sites. However, there were no significant differences in leaf damage amongst all plots on each site. At the “Lazienki Krolewskie” park the attractiveness of two types of pheromone sources were compared: traps were baited with rubber septum lures or with A&K droplets. The catches of C. ohridella in traps baited with lures were lower than captures in A&K droplet-baited traps, but the difference was not significant. Possible reasons for the low efficacy of the A&K method in management of C. ohridella and reducing leaf damage are discussed.     

Potential of three new krill products for seabream larval production

The objective of this study was to evaluate three products derived from krill as sources of essential fatty acids, protein and, particularly, phospholipids in microdiets for larval gilthead seabream (Sparus aurata). Their effect on larval performance, biochemical composition and histological development was investigated. The addition of krill phospholipids, rich in highly unsaturated fatty acids, improved larval sea bream growth in terms of weight and length, enhanced hepatic utilization of dietary lipids and reduced the incidence of enterocyte injuries. These results confirm the higher nutritional value of marine phospholipids for the early development of marine fish larvae in comparison with soybean phospholipids.     

Effect of dietary canthaxanthin on the growth and lipid composition of red porgy (Pagrus pagrus)

A 24‐week feeding trial was conducted to study the possible effect of dietary canthaxanthin on red porgy growth and lipid composition. Two triplicate groups were established to test two experimental diets: (1) Control group fed a diet with no added carotenoids, and (2) canthaxanthin group (CTX100) fed a diet with 100 mg of synthetic canthaxanthin per kilogram of diet (CTX). Final and eviscerated weight were increased (P < 0.05) in the CTX100 treatment. The rest of growth performance parameters were not affected by the CTX diet. Whole‐fish total lipid content was decreased (P < 0.05) in CTX100 fish. In the liver, total lipids were not affected; however, saturated fatty acids in CTX100 treatment were significantly lower together with a higher n‐3 PUFA and a lower n‐6 PUFA, therefore increasing the n‐3/n‐6 ratio. Liver histology of CTX100 fish revealed decreased lipid vacuolization thus, significantly lowering hepatocyte area. In the muscle, total lipids were not affected. Similar to the liver, an increase of n‐3 PUFA and decrease n‐6 PUFA, led to a significant increase of the n‐3/n‐6 ratio. Concerning plasma, only total cholesterol (TC) was significantly affected by the CTX diet. Dietary canthaxanthin has an effect on red porgy lipid composition.