For increase of efficiency and natural resistance, decrease in the cost price and increase of poultry efficiency the big attention is given to questions of bird mineral food. Now for balancing of bird rations on mineral substances, especially on calcium, the poultry-farming enterprises apply an expensive cockleshell which is delivered from Azov. During too time in our country there are enough of local sources of the mineral raw materials which use in bird feeding can be effective enough. Dolomite in the form of flour which stocks are great enough can serve one of sources of bird mineral food. As a result of the spent research it is established, that use of the local mineral additive dolomite in feeding of hens-layers probably as a substitute of an expensive import cockleshell. For an optimum dose it is possible to accept 3% of dolomite from forage mass. At use of the given dose the best results of egg efficiency, livestock safety and the expense of forages have been received. | Для повышения продуктивности и естественной резистентности, снижения себестоимости и повышения эффективности отрасли в целом большое внимание уделяется вопросам минерального питания птицы. В настоящее время для балансирования рационов птицы по минеральным веществам, особенно по кальцию, птицеводческие предприятия применяют дорогостоящую ракушку, завозимую с Азовского моря. В тоже время в нашей стране имеются достаточные количества местных источников минерального сырья, использование которых в кормлении птицы может быть достаточно эффективным. Одним из источников минерального питания птицы может служить доломит в виде муки, запасы которого достаточно велики. В результате проведенных исследований установлено, что использование местной минеральной добавки доломита в кормлении кур-несушек возможно в качестве заменителя дорогостоящей импортной ракушки. За оптимальную дозу можно принять 3% доломита от массы корма. При использовании данной дозы были получены лучшие результаты яичной продуктивности, сохранности поголовья и расхода кормов.

Determination of influence of polymorphic variants of genes of kappa casein, beta-lactoglodulin and alpha-lactoalbumin on indexes of milk producing ability (milk yield, fat and protein content) of brood cows of Belarusian white-and-black breed was studied in the conditions of the Republic of Belarus. In course of analysis of polymorphism of kappa casein gene there was revealed the exceeding of frequency index of allel CSN3**a over the index of allel CSN3**b (0,795 and 0,205 respectively). Studying of polymorphism of beta-lactoglodulin gene showed that the frequency indexes of allel variants formed in the following way: BLG**a - 0,489 and BLG**b - 0,511. There were revealed three genotype variants of alpha-lactoalbumin among which the highest frequency indexes were stated for heterozygous genotype LALBA**aa *(32%) and LALBA**bb (14%). There was calculated the genetic equilibrium for loci of studied genes: x2 value for all studied loci was 0,008 – 1,96. Analysis of milk producing ability data in groups with different genotypes by locus of CSN3 gene showed that the highest indexes of milk yield were stated for group of cows with genotype CSN3**aa. Animals with genotype CSN3**bb had the highest fat percent, animals with genotype CSN3**aa - the lowest. Analysis of milk yield indexes showed that animals with homozygous genotypes BLG**aa and BLG**bb showed lower average milk yield than animals with genotype BLG**ab on 130 and 570 kg, respectively