Interactions of aflatoxin and the antioxidant butylated hydroxytoluene in two-week-old chicks

Two-week dietary administration of 2500 ppb aflatoxin was sufficient to cause a decrease in bursal weights and a reduction in the number of splenic leukocytes in chicks. No significant effects on weight gain or feed efficiency were evident. The chicks also had elevated heterophil-to-lymphocyte ratios, suggesting a heightened reaction to stress. This effect could be blocked by dietary administration of the antioxidant butylated hydroxytoluene (BHT) at a concentration eight-fold over that normally present to preserve control feed. The BHT treatment increased the activities of the enzymes glutathione-S-transferase, aniline hydroxylase and O-demethylase, which metabolize aflatoxins in the liver.     

Immune function in dairy cows related to energy balance and metabolic status in early lactation

Two feeding experiments were carried out in 2 successive years with 28 cows of the Norwegian Red Cattle (NRF) in each experiment. The cows were randomly distributed into 4 groups and subjected to different feeding regimens from 1 month prior to calving until 12 weeks after calving. The experimental design was factorial (2 x 2) with respect to protein content of the concentrate (17.5% digestible crude protein (DCP) v.s. 12.5% DCP) and concentrate allowances (standard v.s. substandard allowances after calving). Silage was offered ad libitum. Samples for estimation of serum immunoglobulin-G, white blood cells and lymphocyte responses to the mitogens phytohemagglutinin, concanavalin A and pokeweed mitogen were collected 4 weeks prior to expected calving, and 2, 4 and 8 weeks after calving. The levels of milk immunoglobulin-G were estimated at calving and 2, 4 and 8 weeks after calving. A significant positive relationship was found between the estimated energy balance and the lymphocyte response to mitogens. Little evidence was found for the existence of a significant relationship between the immunologic parameters and plasma indicators of metabolic status. The lymphocyte response to phytohemagglutinin and levels of serum immunoglobulin-G increased, while levels of milk immunoglobulin-G decreased during the period from calving to 8 weeks after calving. Increased milk somatic cell counts were associated with a significant decrease in the lymphocyte responses to mitogens.     

Effect of selenium on sheep lymphocyte responses to mitogens

The effect of selenium (Se) on sheep lymphocyte response to mitogens was studied. In an indoor experiment lambs were fed a basal diet containing 0.13 mg Se kg-1, and supplemented with, respectively, 0.1 or 0.5 mg Se kg-1, either as sodium selenite or as selenomethionine. Enhancement of the proliferative response of lymphocytes to phytohaemagglutinin (PHA), pokeweed mitogen (PWM) and concanavalin A was found in lambs following selenium supplementation at the lower levels. The highest dietary selenium content, however, induced decreased mitogen response. Transient increases in lymphocyte response to PHA and PWM by ewes supplemented with selenium was demonstrated in one field study and a combined effect of selenium and vitamin E was seen in another. There was no stimulatory effect on the mitogen response of lymphocytes from sheep supplemented with dietary vitamin E alone.     

Effect of subinhibitory concentrations of tiamulin on the haemagglutinating properties of fimbriated Escherichia coli (K88, K99)

The haemagglutinating properties (HA) of Escherichia coli possessing the fimbrial antigens K88 and K99 were significantly affected by tiamulin. HA for K88-positive strains was reduced at 1/10 to 1/40 minimum inhibitory concentration (MIC), while the corresponding values for the K99 strains were 1/2 to 1/10 MIC. Tiamulin concentrations of 3 to 12 micrograms ml-1 increased salt aggregation test values from between 1.4 and 1.5, to more than 2.     

Carbonic anhydrase polymorphism in cattle and swine

Two electrophoretically different carbonic anhydrase (Ca) isoenzymes have been demonstrated in cattle where their presence is presumed to be controlled by codominant allelic genes (Sartore & Bernoco 1966). Previous reports of Ca polymorphism in swine are not available.