Oxytetracycline (OTC) pharmacokinetic values in plasma and bile were ascertained after IV administration of the drug. At 6 hours after administration of 1 mg of OTC/kg of body weight, 2.15% of the dose was found in the bile and 37.6% was found in the urine. At 2 hours after administration, the peak bile-to-plasma OTC concentration ratio was 60:1. Bioavailability of OTC was 47.6% when it was administered orally to fasted turkeys and was 9.4% when administered to fed turkeys.

Pharmacokinetic variables of skeletal muscle creatine kinase (CK) activity after IV administration of a muscle extract; CK bioavailability after IM administration of the muscle extract; and effect of IM administration of saline solution, to appreciate the possible release of CK consecutive to muscle puncture, were determined in 6 cows. A general equation for the quantitative estimation of skeletal muscle damage also was derived. Administration of saline solution IM had no effect on plasma CK activity (ANOVA, P > 0.05) in any of the cows. After IV administration of the muscle extract (150 U/kg of body weight), mean volume of the central compartment, plasma half-life, and plasma clearance of CK were 0.027 +/- 0.007 L/kg, 520 +/- 109 minutes, and 6.43 +/- 2.29 ml/kg/h, respectively. After IM administration (150 U/kg), mean bioavailability of CK was 51 +/- 17% and maximal plasma CK activity (500 +/- 97 U/L) was observed at 454 +/- 131 minutes. The rate of CK activity entry into plasma was determined by use of deconvolution analysis. Two peaks were observed; the first appeared before the 30th minute after IM administration, and the second appeared at 3.3 +/- 1.1 hours. Amplitudes were 6.31 +/- 4.45 and 6.57 +/- 3.08 U/kg/h, for the first and the second peaks, respectively. The quantity of CK liberated from control muscle was 0.69 +/- 0.12 U/kg/h, corresponding to a normal daily catabolism of 5.8 +/- 1.0 mg of muscle/kg. From these results, the following equation can be proposed to determine the corresponding mean equivalent of destroyed muscle (Qmuscle, test article) after IM administration of a test article: Qmuscle, test article (g/kg) = 4.41 X 10(-6) AUC (U/h/L), with AUC being the CK plasma activity area under the curve.

An experiment was conducted to compare the bioavailability of dl-alpha-tocopherol acetate (TA) with that of dl-alpha-tocopherol nicotinate (TN) when administered to sheep, as a single dose, either into the rumen or the peritoneal cavity. A total of 16 sheep were used in a factorial design, with 4 sheep/treatment at the interaction level. In addition, 5 sheep that received no supplemental alpha-tocopherol, were euthanatized at the end of the trial to provide baseline data for tissue alpha-tocopherol concentrations. Curves were fitted to the plasma alpha-tocopherol concentration values, taken over 180 hours after administration of the esters. Availability of TA was greater than TN, as evidenced by the significantly higher curve parameter values (P < 0.05) and tissue concentrations (P < 0.05). Route of administration had a marked effect on availability of TA (P < 0.001), but not of TN.

The pharmacokinetics and bioavailability of rifampin were determined after IV (10 mg/kg of body weight) and intragastric (20 mg/kg of body weight) administration to 6 healthy, adult horses. After IV administration, the disposition kinetics of rifampin were best described by a 2-compartment open model. A rapid distribution phase was followed by a slower elimination phase, with a half-life (t1/2[beta]) of 7.27 +/- 1.1 hours. The mean body clearance was 1.49 +/- 0.41 ml/min.kg, and the mean volume of distribution was 932 +/- 292 ml/kg indicating that rifampin was widely distributed in the body. After intragastric administration of rifampin in aqueous suspension, a brief lag period (0.31 +/- 0.09 hour) was followed by rapid, but incomplete, absorption (t1/2[a] = 0.51 +/- 0.32 hour) and slow elimination (t1/2[d] = 11.50 +/- 1.55 hours). The mean bioavailability (fractional absorption) of the administered dose during the first 24 hours was 53.94 +/- 18.90%, and we estimated that 70.0 +/- 23.6% of the drug would eventually be absorbed. The mean peak plasma rifampin concentration was 13.25 +/- 2.70 microgram/ml at 2.5 +/- 1.6 hours after dosing. All 6 horses had plasma rifampin concentrations > 2 microgram/ml by 45 minutes after dosing; concentrations > 3 microgram/ml persisted for at least 24 hours. Mean plasma rifampin concentrations at 12 and 24 hours after dosing were 6.86 +/- 1.69 microgram/ml and 3.83 +/- 0.87 microgram/ml, respectively. We tested 162 isolates of 16 bacterial species cultured from clinically ill horses for susceptibility to rifampin. All strains of coagulase-positive staphylococci, Streptococcus zooepidemicus, Str equi, Str equisimilis, Rhodococcus equi and Corynebacterium pseudotuberculosis were highly susceptible to rifampin (minimal inhibitory concentration [MIC] less than or equal to 0.25 microgram/ml).

This study was conducted to investigate whether dietary enzymes alter the caecal microbial profile of broilers fed sorghum-based diets. Four sorghum-based diets (918 g sorghum/kg diet) were prepared. One was the control diet and three had enzymes (xylanase, phytase andprotease) added. Broilers, 35-day-old, were reared (8 birds/cage) in an environmentally controlled shed and randomly allocated to replicated (n=4) assay diets and free access to feed and water all time. On day-42, birds were euthanized and caecal contents collected, pooled on a per/pen basis and frozen (-20 °C). The DNA was extracted from caecal samples using a bead-beating protocol and the V2V3 regionof the bacterial 16S rRNA gene amplified by PCR. Amplicons were separated on sequence difference using Denaturing Gradient Gel Electrophoresis (DGGE) and microbial profiles generated and compared.The DGGE profiles, when analysed, indicated that there was approximately 80% similarity between caecal microflora in all types of the diet treatments. This suggests that there was no overalldifference between any of the profiles and therefore the addition of different types of feed enzymes in a sorghum-based diet had no impact on the overall composition of the broiler caecal microflora.

Napier grass (Pennisetum purpureum) has been the most promisingand high yielding fodder giving dry matter yields. This experiment was conducted to determine the effect of cutting intervals on the yield and nutrient composition of six cultivars of Napier grass (Pennisetum purpureum) which is 3rd Generation Napier, India Napier, Kobe Napier, Red Napier, Taiwan Napier and Zanzibar Napier. The grasses were cut close to the ground levelto get a uniform stand on day 70 after planting and the cutting intervals were at 35 and 42 days and carried out for 3 times.After each harvest, the rates of maintenance fertiliser used were 150 kg of nitrogen, 60 kg of phosphorus and 100 kg of potassium per hectare per year. Harvested plant material was weighed, pre-dried in a forced-air drying oven at 60 °C overnight before grinding. Ground samples were used to determine dry matter (DM), crude protein (CP), crude fibre (CF) and metabolised energy. The data were analysed using Statistical Analysis System (SAS™) followed by Tukey’s post-hoc test. AP value of less than 0.05 (p<0.05) are considered statistically significant. Results showed that increasing the cutting interval (i.e. advancing age of maturity) increased dry matter and crude fibre significantly.However, in terms of nutrient content, crude protein and metabolised energy percentage was markedly decreased as thecutting interval increased. From the results presented, it is clear that cutting a stand of Napier grass at 35 days will achieve greater yield and nutrient content.

In the conditions of the Republic of Belarus there were studied the productive and interior indexes of bull calves which were fed with dried distiller's grains. Inclusion into bull calves diets of the mixed fodder containing 33% of dried distiller's grains made it possible to increase the concentration of volatile fatty acids on 16-18%, albuminous nitrogen - on 4-7%, quantity of infusorians - on 16-17%, as well as to reduce the ammonia level in a ruminal liquid from 23,4 up to 17 mg%. Inclusion of 33% of dried distiller's grains into structure of mixed fodder and feeding the same quantity of fresh distiller's grains promoted increasing of nutrient digestibility on respectively 4,0-5,9% and 3,5-4,5%, nitrogen retention - on 13%. Increasing of level of dried distiller's grains in structure of grain forage up to 67% increased the digestibility of nutrients on 1,5-2% and nitrogen retention - on 4%. Substitution in mixed fodder for bull-calves of 33 and 67% of fodder grain by dried distiller's grains made it possible to increase daily average live weight gain of animals respectively on 10 and 4%. Feeding of dried and fresh distiller's grains at simultaneous introduction in rations of complex mineral additive promoted the activation of metabolic processes that was proved by increasing of crude protein of blood at 6-7% and 5-8%, as well as decreasing of concentration of urea - on 25 and 22% respectively. Use of 33% of dried distiller's grains as a part of mixed fodder for cattle young stock proved to be economically effective and allowed to lower the cost price of a live weight gain on 10-11%. Feeding with fresh distiller's grains allowed to lower the prime cost price on 7% and to receive additional profit.

In the conditions of the Republic of Belarus there was studied the yielding capacity and quality composition of nontraditional high-energy crops (sorghum and Sudan grass hybrid; millet (Panicum); white panicum (Japanese millet)) as well as there was developed a technology fodder conservation. In course of the study there was analyzed accumulation of nutrients in accordance with crop development phases and their quality composition; also there was determined a method of application of grass stands of the studied crops for their production use. It is established, that the most suitable for conditions of Vitebsk region from high-quality cultures is sorgho-sudan-grass hybrid which reaches phases of seed formation and provides productivity of dry matter more than 9 t/ha with humidity of green mass of 69% that is optimum for preparation of tinned forage. Sugar sorgho and grain is reached by phases of ear formation and have provided productivity of green mass of 25,9-25,7 t/ha, dry matter - 3,5 t/ha. To use double-cut sorgho-sudan-grass hybrid on a silo less effectively as the received green mass has high humidity (92%), and the general gathering of dry matter twice more low, than at single-cut use. At single-cut use the culture reaches phases of grain formation in which contains about 31% of dry matter that is favorable for conservation. Double-cut use of sorgho-sudan-grass hybrid is comprehensible at its cultivation in the green conveyor to use as green top dressing during the pasturable period. Japanese millet is better to use double-cut as it has provided the maximum productivity of green mass of high quality (63,9 t/ha) and dry matter (9,1 t/ha), it is in 2,3 and 1,6% of time above, than at single-cut use. Single-cut crops of sorgho-sudan-grass hybrid are expedient for using as a component at siloing of galega orientalis. In an early phase of development (7-8 leaves) the new-mown green mass of sorgho-sudan-grass hybrid possesses toxicity on the bottom border of average degree, but in 2 hours after mowing the forage becomes not toxic. In later phase of development there is an accumulation of sugars, and new-mown mass of sorgho is nontoxical. Sorghum cultures contain high percent of non-decomposed protein - 58,3-84,6% that is very important in feeding of highly productive cows.

Belarus is included into number of the leading countries of the world which provide the increasing of the expansion rates of milk production and dairy products on a per capita basis. However, the agricultural enterprises of the Republic of Belarus annually spend approximately 800 thousand tons of whole milk that makes about 20% from the general milk yield for manufacturing expenditures in the process of livestock operation. The purpose of research was working out of a new premix structure and zootechnic requirements to its use in structure of milk replacer, produced on hydrodynamic installation. The optimum doses of amino acids, vitamins and mineral substances promoted the increasing of calves daily average weight gain during the dairy period on 5,4% (788,5 g instead of 748,1 g), reducing of expenses for forages per 1 kg of weight gain - on 6,5% (2,9 fodder units against 3,1 fodder units) and the decreasing of the prime cost production for fodder expenses - on 4,7%. There was presented the composition and nutritive value of the analysed whole milk replacer. Usage of local sources of protein-fatty raw materials of plant origin, and also secondary resources of processing of whole milk in the content of milk replacer for young cattle allows to completely refuse from expensive components delivered from abroad and to lower their cost

Research was directed towards selection of national, accessible and cheap ingredients of whole milk replacers in the conditions of the Republic of Belarus. The efficiency of compounding preparation and its use in calves feeding at an early age was analysed. There was developed the technological scheme of application of hydrodynamic installation which operates according cavitating principle and makes it possible to receive the homogeneous and finely divided mass directly from grain forage that is very important for preparation of milk replacer. New equipment gives the chance to lower power consumption on 17%, to receive economic benefit. During testing of developed of milk replacer-1 (used for calves feeding since one month old) and milk replacer-2 (used for calves feeding since two months old) and their comparison with the whole milk replacer Kalvolak (the Netherlands) it was revealed, that indices of a daily average weight gain in calves of the first group fed with foreign milk replacer, and in calves of the second groups, which were fed with the national milk replacer, did not show authentic differences (806 and 816 g). However, the prime cost of 1kg of live weight gain in the second case was on 43% cheaper than in the first one. The cost price of 1kg of live weight gain of calves on expenses for fodder units in trial group was on 33% cheaper in comparison with the control group