Effect of the addition of Vemozim F to diets with decreased content of phosphorus on the microstructure of tibia in broiler chickens

The subject of the study was to investigate the effect of the addition of different doses of the new Bulgarian enzyme preparation – VemoZim F - activity 5000 FТU/g to wheat-corn-soyabean meal diets, with 30% decreased content of available phosphorus on the microstructure of tibia in broiler chickens. The experiment was performed with 180 one-day-old male chick broilers - Ross 308, up to the age 38 days, bred in battery cages, distributed in 5 groups, with 36 numbers in each one, equalized by body weight. The chicks from the control group obtained balanced diet, according to the requirements of the used hybrid, and these from the experimental groups, with 30% deficit of phosphorus diets - 0,35, 0,32 and 0,30% in the starter, grower and finisher, respectively. The compound feed of II nd group of chicks was without addition of VemoZim F, compared to ІІІ rd, ІV th and V th experimental groups, in whose diets, 150 g/t of VemoZim F was added correspondingly - recommended dose, providing 750 FТU/kg feed, 1500g/t of the investigated additive - 10 times higher dose of phytase and in the chicks from V th group 100 times more phytase than the recommended dose via the addition of 1500 g/t concentrate of phytase in VemoZim. The results of the histological analysis of tibial bone epiphysis showed, that in chickens that received 30% reduced content of available phosphorus without addition of VemoZimF, diversions in the ossification processes were observed, characteristic of phosphorus deficiency compared to the control. Remarkable differences in the chicken tibial microstructure from the control group and those that obtained 150 g/t VemoZimF recommended dose, providing 750 FTU/kg feed were not found. The increased level of phytase 10 and 100 times - respectively, 7 500 and 75 000 FТU/kg feed in the chicken diet compared to the experimental group led to different degree of structure alterations, with identical kind and localization in the epiphyseal cartilage of the tibial bones.