Commercial‐scale Validation of Temperature‐step Rearing on Growth Physiology in Turbot,Scophthalmus maximus

The aim of this study was to investigate the possible benefit of “temperature‐steps” (T‐steps) rearing for juvenile turbot (initial weight 15.1 g) under realistic production scale and to determine whether initial growth advantage is maintained throughout the rearing period to market size. One group (called T‐step 22‐19‐16) of juvenile turbot was reared at three different temperatures, that is, 22 C (from 17 to 60 g) followed by 19 C (from 60 to 100 g) and 16 C (>100 g); another group (called T‐step 19‐16) at two temperatures, that is, 19 C (from 17 to 100 g) and lowered to 16 C (>100 g); and the third group (called C16) at one constant temperature, that is, 16 C. Relative growth was significantly higher in the two T‐step groups, with the T‐step 19‐16 showing the highest overall growth. Feed conversion efficiency was highest in the 19‐16 group. Only minor effects of the experimental rearing on blood physiology were found, with one notable exception of inverse relationship between plasma glucose and growth. Overall, these findings indicate that a short interval of rearing fish at high temperature during the early juvenile phase may have a long‐term effect on biomass increment in turbot. This is an important finding for the turbot industry.     

Haemophilus somnus-induced interference with bovine neutrophil functions

The effect of Haemophilus somnus on bovine polymorphonuclear leukocyte (PMN) function was examined in vitro with whole cells and fractions extracted from the surface of this bacterium. The ability of PMNs to iodinate protein and ingest Staphylococcus aureus was significantly inhibited in the presence of live cells, heat-killed whole cells or supernatant fluid from heat-killed cells, but not in the presence of washed, heat-killed cells. None of the fractions inhibited nitroblue tetrazolium (NBT) reduction by PMNs. The PMN inhibitory factors were further characterized. The material that inhibited S. aureus ingestion was found to be a heat-stable cell surface material of greater than 300 000 MW. The fraction inhibiting iodination of protein was found to be less than 10 000 MW.     

Corticosteroid-induced suppression of in vitro lymphocyte proliferation in four captive rhinoceros species.

Captive African black rhinoceroses (Diceros bicornis) are unusually susceptible to several diseases not commonly observed in any of the other three rhinoceros species maintained in captivity. The potential role of corticosteroids (either endogenously produced or exogenously administered) in the development of these sometimes fatal diseases has been questioned. In this study, the suppressive effects of two therapeutic corticosteroids (dexamethasone and hydrocortisone) on in vitro lymphocyte proliferation was examined in four rhinoceros species, including the Sumatran rhinoceros (Dicerorhinus sumatrensis, n = 3), Indian rhinoceros (Rhinoceros unicornis, n = 4), African black rhinoceros (n = 10), and African white rhinoceros (Ceratotherium simum, n = 5). Three blood samples collected from each rhinoceros 1 mo to 1 yr apart provided replicates for the study. Both dexamethasone and hydrocortisone suppressed (P < 0.05) lymphocyte proliferation stimulated by B-cell mitogens (pokeweed and lipopolysaccharide) and T-cell mitogens (phytohemagglutinin and concanavalin A). Suppressive effects of the glucocorticoids differed (P < 0.05) depending on the mitogen used to stimulate the lymphocytes. Overall, dexamethasone was a more potent suppressor of cell proliferation when compared with hydrocortisone (P < 0.05). However, black rhinoceros cell proliferation in response to any of the four mitogens was never completely suppressed, even in cultures containing the highest steroid concentration tested (10(-3) M). The effect of the two corticosteroids differed slightly among the rhinoceros species and subspecies tested, but there was no evidence that eastern or southern black rhinoceros lymphocytes were more sensitive to the suppressive effects of corticosteroids than the other rhinoceros species.