Effects of dietary <Emphasis Type="Italic">n</Emphasis>-3 fatty acids on Toll-like receptor activation in primary leucocytes from Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>)

The shortage of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the international markets has led to increasing substitution of fish oil by plant oils in Atlantic salmon (Salmo salar) feed and thereby reducing the EPA and DHA content in salmon. However, the minimum required levels of these fatty acids in fish diets for securing fish health are unknown. Fish were fed with 0, 1 or 2% EPA or DHA alone or in combination of both over a period, growing from 50 to 400 g. Primary head kidney leucocytes were isolated and stimulated with Toll-like receptor (TLR) ligands to determine if EPA and DHA deficiency can affect expression of important immune genes and eicosanoid production. Several genes related to viral immune response did not vary between groups. However, there was a tendency that the high-level EPA and DHA groups expressed lower levels of IL-1β in non-stimulated leucocytes. These leucocytes were also more responsive to the TLR ligands, inducing higher expression levels of IL-1β and Mx1 after stimulation. The levels of prostaglandin E2 and leukotriene B4 in serum and media from stimulated leucocytes were lower in both low and high EPA and DHA groups. In conclusion, leucocytes from low EPA and DHA groups seemed to be less responsive towards immunostimulants, like TLR ligands, indicating that low levels or absence of dietary EPA and DHA may have immunosuppressive effects.     

Effect of hCG Stimulation on Plasma Androstenone Concentrations and Cytochrome b5 Levels in Testicular Tissue

The effect of Human chorionic gonadotropin (hCG) stimulation on the concentrations of free and conjugated androstenone in plasma was studied in 34 crossbred entire male pigs (Landrace x Swedish Yorkshire). Seventeen pigs were treated with hCG 4 days prior to slaughter and the remaining pigs were treated with sterile saline and served as controls. Blood samples were taken prior to hCG or saline injection and on the day before slaughter and analysed for concentrations of free and conjugated androstenone. Testicular tissue samples were taken at slaughter and analysed for the levels of cytochrome b5 (cyb5) protein. Here we have demonstrated for the first time that hCG stimulation causes an increase in the plasma levels of both free and conjugated androstenone. Not all animals responded in the same way to hCG treatment regarding levels of free and conjugated androstenone demonstrating that individual animals can have differences in their capacity to produce free and conjugated androstenone. We suggest that hCG treatment is a good way to determine the potential for androstenone conjugation when androstenone synthesis in the testis is high. The levels of cyb5 protein in the testis were slightly related (r=0.41, p < 0.10) to free androstenone levels in the pigs after hCG administration, although levels of cyb5 protein were not affected by hCG treatment.     

Blood groups of the I system in pigs: association with variants of serum amylase

The Am I variant of porcine serum amylase was detected only in pigs having the red-cell antigen I(b), whereas several I(b) positive pigs were found without Am I. Family and population studies show that the chromosomal loci, I and Am, are identical or closely linked. The phenotype of one exceptional progeny from a double backcross mating possibly was a result of paternal irradiation or genetic recombination during o?genesis.     

The effect of active immunization of ewes against androstenedione on lambing rate and production

Active immunization of sheep of the Dala breed against androstenedione caused a mean increase in number of lambs born (live-born and stillborn) of 0.29 (p less than 0.01). In yearlings the difference was 0.43 lambs (p less than 0.01) and in older ewes 0.23 lambs (p less than 0.1). Five of the older immunized ewes gave birth to quadruplets while none in the control group gave birth to more than 3 lambs. In older ewes there was an increase in the number of stillborn lambs. In young immunized ewes the mean ewe production, registered as total live weight of lambs in the autumn, was 11.3 kg higher than in control animals. This difference was however not significant (p less than 0.1).     

A rapid radioimmunological evaluation of the androstenone content in boar fat

Fat from boars containing androstenone is absorbed to a piece of filter paper. The filter paper is then placed in a tube and a buffer containing antibodies against androstenone is added. Following incubation the filter paper is removed, and by measurement of the residual binding capacity for androstenone in the buffer a relative value for androstenone content in the fat is obtained.The coefficient of correlation between the results obtained by this rapid method and the ordinary radioimmunoassay was −0.95.