Compensatory growth in Atlantic halibut: Effect of starvation and subsequent feeding on growth, maturation, feed utilization and flesh quality

A group of juvenile Atlantic halibut (mean, SD, 199.5 g, 44.7) was split into two experimental groups: one group was fed in excess twice a day and later five days a week (i.e. Control group), and the other group was starved for 5 weeks and then subsequently re-fed for 10 weeks (i.e. 5/10 starvation/re-fed group). This treatment was repeated for three years until the fish were harvested (mean final weight, 4.4 kg). A size +specific compensatory response was seen; partial compensation was observed in halibut weighing less than 500 g whereas full recovery growth was seen in halibut over 2 kg. Food consumption and feed conversion efficiency was measured during two full 5/10 starvation/re-fed cycles. The Control group consumed 86% more food in the measurement period, whereas the FCE 40% higher in the 5/10 starvation/re-fed group (FCE = 0.95) compared to the Control group (FCE = 0.68). In males lower gonadosomatic index (2.2 vs. 3.0) and plasma 11-ketotestosterone (0.22 vs. 1.26 ng ml^− 1) levels in the 5/10 starvation/re-fed group were observed during late winter and spring of 2006 (age 3 years) indicating higher age at 1st maturity. Starvation had a significant effect for improving the quality as starved fish had higher muscle pH (6.4 vs. 6.2), less gaping (0.1 vs. 0.3) and harder texture (61.4 vs. 57.6 N). Overall, the rearing on a repeated 5/10 starvation/re-fed regime for 3 years led to full growth compensation, higher feed conversion efficiency, lower male maturation and improved flesh quality.     

Endotoxins in animal feedstuffs

Microbial heat stable endotoxins comprise part of most animal feedstuffs. These components have become the subject of considerable interest in later years because of the demonstration of acute toxicity, intravascular coagulation and generalized Shwartzman’s reaction in connection with intravenous injections of endotoxins (Nordstoga 1976). Endotoxins are normally present in the intestine of man and animals, but seem only to be absorbed under special conditions. Of particular interest is the “sudden infant death syndrome” which has been described for infants receiving cow milk (Di Luzio & Friedmann 1973). Absorption of endotoxins may also occur in adults e.g. in connection with γ-irradiation, immunosuppression, transplantations, severe traumatic lesions and burns (Nordstoga). It is supposed that endotoxins play an important role in the development of shock under these conditions (Nordstoga). Fine (1972) reported that exogenously administered endotoxins may break down the defence mechanisms and lead to continuous absorption of endotoxins from the intestine.     

Genetic typing of bovine viral diarrhoea virus: most Slovenian isolates are of genotypes 1d and 1f

A selection of 43 bovine viral diarrhoea viruses isolated from mainly persistently infected cattle on 23 Slovenian farms between 1997 and 2001 were characterised genetically. Viral RNA was extracted from infected cell cultures, reverse transcribed and amplified by PCR with primers targeting the 5'-UTR and the N(pro) gene, followed by direct sequencing of purified PCR products obtained for both genomic regions. The N(pro) sequences provided the best genetic resolution, and gave also higher statistical support for phylogenetic classification of the viruses. Thirty-eight of the Slovenian isolates were of genetic subtypes 1d and 1f, four were 1b, and one subtype 1g. No BVDV type 2 viruses were found. This genetic prevalence matched those previously reported for neighbouring countries, as opposed to findings reported for more distant European countries, e.g. France, Spain and the UK. From eight cattle herds several virus isolates were analysed; with one exception all isolates from each herd were of the same genetic group. Extended sequencing of the N(pro) and part of the C gene of virus isolates with identical 5'-UTR sequences allowed differentiation between isolates obtained at different times from one herd.     

Long-term effect of photoperiod manipulation on growth, maturation and flesh quality in Atlantic halibut

The aim of this study was to investigate the effect of continuous light at different stages during the production cycle of Atlantic halibut Hippoglossus hippoglossus L. on growth, age at first maturity, endocrine parameters and flesh quality. A group of juvenile halibut [mean (SD), initial weight 191.3 g (44.7)] was reared in indoor tanks under ambient temperature conditions for 38 months until harvesting (mean final weight, 4.6 kg). The entire photoperiod experiment was divided into four phases, where the fish in each phase were exposed to either natural photoperiod (62°33'N) or continuous light (L). Thus, the following five photoperiod combinations were tested: (a) Control group (NNNN), (b) Group 2A (NLNN), (c) Group 2B (NNLN), (d) Group 2C (NNNL) and (e) Production group (LNNN). Exposure to continuous light stimulated growth, and the final mean weights of Groups 2A and 2B were 23% and 11% higher than those of the Control group (NNNN). The final plasma 11-ketotestosteron levels were lower in Groups 2A (2.94 ng mL⁻¹) and 2B (2.46 ng mL⁻¹) compared with the Control (5.29 ng mL⁻¹), Group 2C (5.09 ng mL⁻¹) and the Production group (4.78 ng mL⁻¹) during spring 2007 (age 4 years), indicating higher age at first maturity in Groups 2A and 2B. Photoperiod regime had only a minor, and transient, effect on flesh-quality traits of the fish, whereas a significant seasonal effect was seen with a tendency towards increased gaping, lower pH, lower hardness and lower shear force in July compared with December and March.     

Nutrient balance in Scots pine (Pinus sylvestris L.) forest. 2. Effects of plant growth and N-deposition on soil solution and leachate chemistry in a lysimeter experiment

Three years of N application to a Cambic arenosol (Typic Udorthent) in two lysimeter series, one with and one without young saplings of Pinus sylvestris L. have produced significant changes in soil solution and leachate chemistry. An application of 30 kg N/ha^*yr^?1 significantly increased NO₃ ^? leaching from the soil. This N load was also sufficient to significantly increase the mobility of the phyto-toxic elements Al³⁺ and Mn²⁺, likewise to increase leaching of the important plant nutrients Ca²⁺, Mg²⁺ and K⁺. At a N load of 90 kg N/ha^*yr^?1 significant increase in NH₄ ⁺ leaching was observed, but total leaching of NH₄ ⁺ was still very low compared to NO₃ ^? leaching. No significant treatment effects were found for SO₄ ^2?, Fe²⁺ and Cl^? in the leachate. Trees grown in the lysimeters buffered the acidifying effect of N application and increased the leachate pH by 0.2 pH units compared to lysimeters without trees.     

Factors neutralizing the bacteriocidal effect of lysolecithin

The investigations indicate that a variety of non-dialyzable proteins and peptides, including hemoglobins, blood serum proteins, casein, soy protein and hydrolyzed proteins (peptones) are able to neutralize the bacteriocidal effect of lysolecithin.A number of lysolecithin-resistant bacteria are shown to produce lysolecithin-inhibiting metabolites that also promote growth of sensitive organisms in lysolecithin-containing media. On lysolecithin-con- taining agar this can result in a characteristic satellite growth of sensitive organisms around resistant “mother colonies”. Stable resistant mutants were easily selected from a wild type of Staphylococcus aureus after heavy inoculation on lysolecithin-containing nutrient agar.The bacterial lysolecithin-neutralizing factors examined are not considered to be of enzymatic nature. The factors in culture filtrate of Escherichia coli were separated into two active fractions by gel filtration. Due to extremely small amounts of the substances responsible for the neutralizing activity, chemical analyses of these fractions proved problematic, and only a few amino acids could be demonstrated.The neutralizing activity of the bacterial factors, and some of the proteins and peptides, resisted 100° C, or more, for several min.Some aspects of the lysolecithin-inhibitor-interaction are discussed.