A series of coupled differential equations was used to model the temporal dynamics of rabies in raccoons in the mid-Atlantic region of the United States. The model takes explicit account of the development of natural immunity to rabies and was used to evaluate culling and vaccination elimination strategies. For habitats typical of the mid-Atlantic states, and given the assumptions of the model, it was estimated that elimination of rabies in raccoons by culling may involve the annual removal of over 32% of the raccoon population or the yearly vaccination of up to 99% of the susceptible fraction. Assuming a constant marginal cost for both culling and vaccination, the model suggests that, whatever the actual cost of each method, the cheapest strategy will always involve either culling or vaccination alone. A combined strategy of culling and vaccination will be cheaper than culling alone only when the per capita cost of vaccination is around one-fifth or less the per capita cost of culling.

In the conditions of the Republic of Belarus there were analyzed productivity indexes of sows of different families and family groups and their compatibility with male pigs of different lines of Belarusian meaty breed and Landras. On the basis of the realized research it was marked, that according to the number of piglets in a litter and multiple pregnancy distinctions between breeding sows of Landras breed and Belarusian meaty there was not observed. From sows of both breeds in average per farrowing there was obtain 11,0 - 11,2 piglets, including 10,4 - 10,5 live piglets, that exceeded requirements of the first class of the instruction on evaluation of pigs on 4,0 - 5,0%. At the same time, sows of the Belarusian meaty breed had litter weight at weaning in 40 days of 104 kg, that was authentically higher on 8 kg or on 8,3% (Р less than 0,001), than sows of Landras breed. In each breed there were some distinctions in sow productivity by families and in breeding with boars of different lines.

In the conditions of the Republic of Belarus there were analyzed the doses and efficiency of application of selenium in composition of a mixed fodder KP-2 in diets of bull calves of at their breeding for meat. In course of the study the was developed a formula of a mixed fodder with various doses (0,1; 0,2; 0,3 mg per 1 kg of a dry matter of a ration) of selenium; there was studied the influence of different selenium doses in mixed fodders on palatability of diets, their digestibility, use of nutritive elements and hematological indexes of animals. Also, there was analyzed the influence of different doses of selenium on bull calves growing intensity. There was given the zootechnical and economic evaluation of usage of selenium for bull calves. Selenium dose of 0.2 milligram per 1 kilogram of dry matter proved to be the most efficient and promoted the increasing of average daily body weight gain on 10.9%.