Economic losses and decontamination.

Mycotoxin contamination of crops may cause economic losses at all levels of food and feed production including crop and animal production, and crop distribution and processing. The national economy would be affected adversely by losses incurred by crop and livestock producers and the multiplier effect this has on other industries as a result of the reduced spending power of producers. Costs of chemical analyses, quality control and regulatory programs, research and development, extension services, law suits, and the cost of human illnesses must all be borne by the national economy. The value of the losses encountered depends on grain, animal, and animal product prices, interest rates, degree of contamination, and other economic variables. Even during favourable seasons it is likely that millions of dollars are lost as a result of the contamination of crops with mycotoxins. Many compounds and treatments have been tested in order to reduce mycotoxin concentrations in food and feed or to alleviate their adverse effects on animals. Some of these treatments show promising prospects for commercial application, while others have had commercial applications already. However, until reliable, cost-effective, commercially applicable methods are more widely available, problems associated with mycotoxin contamination and the economic losses resulting, will continue to be seen in food and agriculture industries.

Influence of level of deoxynivalenol in the diet of dairy cows on feed intake, milk production, and its composition.

Eighteen primiparous Holstein cows were used in a 10-wk lactation study, preceded by a 2-wk covariate period, to determine the effect of concentration of deoxynivalenol in the diet on cow performance and transfer of deoxynivalenol and its metabolite, deepoxydeoxynivalenol, to milk. Diets were formulated to contain deoxynivalenol at 0, 6, and 12 mg/kg of concentrate DM, and daily intake of deoxynivalenol was .59, 42, and 104 mg, respectively. Increasing deoxynivalenol in the diet did not affect intake of concentrate or forage. Total milk output was not affected; however, milk fat responded quadratically; cows given deoxynivalenol at 6 mg/kg of concentrate DM had the lowest milk fat content and fat output. Overall energetic efficiency was not influenced because reduced energy output in milk was compensated by increased BW gains. No transfer of deoxynivalenol or deepoxydeoxynivalenol to milk was observed; concentrations were below detectable limits (1 microgram/ml) using HPLC-mass spectroscopy. We concluded that diets containing deoxynivalenol up to 6 mg/kg of dietary DM did not reduce feed intake of cows in this study and that deoxynivalenol or deepoxydeoxynivalenol was not transferred to milk. Further studies are required to confirm the apparent lack of effect of deoxynivalenol on milk production.

Metabolic changes in the rumen following protozoal inoculation of fauna-free sheep fed a corn silage diet supplemented with casein or soybean meal.

Fauna-free wethers were fed bi-hourly a corn silage diet containing casein or soybean meal as a protein supplement. The wethers were inoculated via rumen cannula with a mixed population of ruminal ciliate protozoa. Ruminal fluid was sampled daily for 4 d before and for 13 d (and on d 28) after inoculation. Protozoal populations reached peak numbers on d 8 and decreased to new levels after d 9 for wethers on both supplements. Protozoa decreased (P less than 0.01) the concentrations of total volatile fatty acids, increased (P less than 0.01) the pH and decreased (P less than 0.01) he concentrations of total and non-ammonia nitrogen in ruminal fluid. The concentrations of ammonia nitrogen increased with increasing numbers of protozoa for wethers on both supplements, but the concentrations decreased after d 7 to approximately pre-inoculation levels for the casein-supplemented diet. The increasing numbers of protozoa were associated with the increased concentrations of total and free alpha-amino nitrogen (P less than 0.01) and sulfide (P less than 0.05) and with the decreased concentrations of soluble Cu (P less than 0.05) in the ruminal fluid in soybean meal-supplemented wethers but not in those receiving casein. It was concluded that dietary proteins with differing physical characteristics are metabolized to a different extent by ruminal ciliate protozoa, which in turn can affect the metabolism of other dietary nutrients such as nitrogen and sulfur and contribute to copper-sulfur interaction.

A surgical technique for the long term collection of bile in the pig and measurement of the biliary excretion of copper and zinc.

A method is described for surgically modifying the gastrointestinal tract of the pig which enables the long term collection of bile and measurement of bile flow and allows the pig to be kept unrestrained in a large pen. Three surgically prepared gilts grew at an average of 0.79 kg d-1. Bile flow increased with bodyweight from 1.6 ml min-1 at 45 to 50 kg to 3.5 ml min-1 at 124.5 kg bodyweight. Mean output in bile of copper and zinc by the three gilts during the period 08.00 to 12.30 was 161.0 +/- 11.1 and 3.94 +/- 0.41 nmol min-1, respectively. The calculated output during 24 hours represented approximately 5.8 and 0.13 per cent of the daily intake of copper and zinc, respectively.