In the conditions of the Republic of Belarus there were analyzed indices of impregnating ability and efficiency of stud bull mothers of various genotypes on a kappa-casein gene (CSN3). As a result of genotyping of kappa-casein gene by DNA-diagnostics method it is revealed three genotypes - CSN3АА, CSN3AB, CSN3BB. Frequency of occurrence of homozygous genotype CSN3AA at stud bulls - 87,3%; heterozygotic CSN3AB - 20,5%; homozygous CSN3BB - 1,2%. Statistically authentic difference between these indices depending on a genotype it is not established. Thus, authentic connection between indices of impregnating ability and efficiency of stud bull mothers and their genotype on a locus of a kappa-casein gene that specifies in absence of influence of the last on the given indices is not established and gives the chance to conduct selection on gene CSN3 without decrease in breeding value of stud bulls on reproductive qualities.

In the conditions of the Republic of Belarus as a result of task-specific selection and breeding work there was developed and approbated Berezinsky breed type of Belarusian meaty breed. Sows of the studied breed type were notable for high indices of reproductive signs: the average multiple pregnancy in three breeding swine herd was 11,1 pigs per farrowing; milkability - 55 kg, litter size at weaning stage at 35-day age - 87,1 kg. The predominancy over the forecast exponent indices made 4,7-5,7%. In course of the study there were analyzed the forecasted indexes of the basic breeding signs of Berezinsky breed type of Belarusian meaty breed for 2005-2010; productivity indices of the experimental sows; coefficient of variations of sow productivity.

In the conditions of the Republic of Belarus there was realized a complex evaluation of producer bulls of different genotypes of origin for the further correction and breeding in different categories of agricultural enterprises. In course of the study there was conducted a preliminary (without quality evaluation of daughters) estimation of bulls which gave a precise performance of each bull, made it possible to correct its type and direction of breeding. Research made it possible to considerably increase the genetic trend in accordance with indexes of milk productivity which would make it possible to form a regional type of black-and-white cattle with the given indexes of productivity and reproduction. In course of the study there were analyzed the following breeds: black-and-white, Holstein, Hungarian breeding, Swedish breeding. Comparative evaluation of reproductive qualities of bulls in accordance with age-specific and breed types was presented. Body conformations of bulls of Holsten and Black-and-white of different ae-specific groups were stated. Results of complex evaluation of full-grown, under 5 year-old and replacement producing bulls of Holstein and Black-and-white breeds were presented.

Analysis of synchronization of oestrus of cows by means of Ovsynch and Pre-Synch methods was realized in the conditions of the Republic of Belarus. Research results showed that estrus synchronization by means of Pre-Synch method proved to be more efficient by means of higher percentage of fertilization after the first and second insemination in comparison with Ovsynch method. Treatment of cows with the substances Surfagon and Tetravit for synchronization of oestrus did not render negative effect on milk quality and safety.

Results of studying the efficiency of iodine containing preparation Jodon which was applied to highly productive cows with hypovarianism and to servicing bulls in order to increase their reproductive function realized in the Republic of Belarus were presented. On the basis of realized studies there was proved the considerable efficiency of Jodon preparation.

Beef production in the Republic of Belarus could be competitive only in case of development of the specialized beef cattle breeding. Therefore, for the increasing of beef production and improvement of its quality in Belarus there was noted the necessity to use cattle beef breeds both in case of straightbred breeding, and in crossing with low income-earning Black-and-White cow stock. Research results showed that hybrid Gereford x Black-and-White breeds of the first and second filial generations showed higher reproductive abilities which were manifested in 105-120 days age reduction at the stage of the first insemination, 18-44 days reduction of service period, 0,07-0,1 times increasing of breeding efficiency index, 9,8-14,4% increasing of calf crop per 100 dams, and 14,4-16,4% increasing of young stock livability in comparison with the Black-and-White breeds calves. Research results showed that the non-heating season of the mongrel Gereford x Black-and-White heifer breeds of the first and second filial generations was 396-400 days, breeding efficiency index (rate of fertilization) - 1,29-1,32, breeding performance index - 85,4-90,0%, while for the at Black-and-White heifer breeds the same indices were 425 days, 1,29 and 75,6%, respectively

The organizational aspects of reproduction in a swine heard were featured, the productivity indices of the crossbred sows obtained through the crisscrossing of the Belarusian Large White, Belarusian Black and White and Estonian Bacon pig breeds were given. The duration of the gestation period for the sows of different origin was shown. The results of the realized experiment showed that at all stages of reproduction there was required the full-value feeding and the maintenance of animals, observance of terms of revealing of sexual hunting and timely insemination of sow. For the systematic increase of swine productivity for selection of replacement pigs for reproduction besides the standard indicators it was necessary to consider the duration of gestation period. In course of study there was stated the well-defined consistent pattern of increasing of pig average weight which were born from sows with the lengthened gestation period. Piglets with the standard and extended term of prenatal growth showed higher indices of body weight at a birth and surpassed their herd mates with the shortened duration of prenatal development on 8,6-10,5% (Р less 0,001). Heavy litter of pigs affected the intensity of their subsequent development. At the weaning stage the weight of 1 pig with the shortened prenatal development was 6,25 kg, and the weight of pigs with the standard and extended periods - 6,62 kg (Р less 0,001) and 6,89 kg (Р less 0,001), respectively and exceeded on 5,9% and 10,2%. The 3-month age pigs with the shortened prenatal development lag behind herd mates with the standard and extended period of prenatal development in the indices of growing capacity on 1,2-1,4 kg (4,0-4,6%). The same tendency was noted after fattening period

Research of the reproductive qualities of sows of different genotypes depending on duration of gestation period was realized in the conditions of an industrial pig complex of the Republic of Belarus. In course of research there were analysed 500 sows and 1991 farrowings and was stated that only 61,4% sows had gestation period in the range of physiological standards (at the average -11,5 days). In 17,8% of sows the mentioned above parameter was on 1,6 days shorter and in 1/5 of all sows under investigation it was 0,6 days longer. A higher productive performance was marked in double-breed sows of a genotype (White Large x Belarusian Meaty) with the average gestation period of 114,2 days. There were no essential deviations marked in the duration of the gestation period depending on the ordinal number of farrowing, though for the third farrowing the duration of the gestation period made 114,8 days and was 0,2-0,4 days longer as compared with the first and the second farrowings

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%.