The effect of phytase-containing feed supplements of fungal and bacterial origin on the biochemical blood features of Japanese quail (Coturnix japonica)

Recently, the use of various phytase preparations in the poultry has drawn more attention. The modern market offers a wide range of phytase preparations, mainly phytases of microbial origin, namely class A (PhyA) and class C (PhyC). However, the enzymes upon passing along the gastrointestinal tract of the birds, significantly lose their activity due to acid denaturation and proteolysis. The technology of phytase encapsulation in yeast cells as microcontainers can reduce much enzyme losses, and increase its thermal stability. The extremophilic Yarrowia lipolytica yeast is a promising object for current biotechnology, in particular for the production of encapsulated phytase. The study first shows the evidence of high digestibility of phytate-containing products by Japanese Manchurian golden quails upon application of the encapsulated phytase of bacterial origin, compared to the control and commercial phytase of Ladozim proxy. The study was aimed at assaying the effect of feed supplements containing the phytases of fungal and bacterial origin on some biochemical features of Japanese quails. The experiment was performed in the Zagorskoe EPH Research Center, a branch of the VNITIP Scientific Research Center of the Russian Academy of Sciences (Sergiev Posad, Moscow Province) using quails (Coturnix japonica), the Manchurian golden breeds. In the diet of quails, there were used the cultivated pilot batches of a feed additive containing microencapsulated phytase of Obesumbacterium proteus and the commercial phytase of Ladozim proxy from Aspergillus ficuum (Biopreparat LLC, Russia) with an activity of 500 and 4,500 units of phytase/g, respectively. To obtain a feed additive of microencapsulated phytase from O. proteus , the modified method for obtaining the Yarrowia lipolytica Po1f pUV3-Or cells transformed with the phytase gene from O. proteus based on the pUVLT2 vector with a mitochondrial porin promoter VDAC (Voltage Dependent Anion Channel) was used. Six groups of one-day-old quails with 25 heads each were formed with different types of feed, namely group I (control+) got feed with a total phosphorus content of 0.45 % of available phosphorus without any additives; group II (control-) got the feed with a total phosphorus content of 0.35 % of available phosphorus without any additives; group III got the feed with the addition of O. proteus microencapsulated phytase at a dose of 500 units of phytase/kg of feed with a total phosphorus content of 0.35 % of available phosphorus; group IV got feed with the addition of O. proteus microencapsulated phytase at a dose of 500 units of phytase/kg with a total phosphorus content of 0.45 % of available phosphorus; Group V got the feed with an additive containing the commercial phytase Ladozim proxy from A. ficuum at a dose of 4,500 units of phytase/kg of feed with a total phosphorus content of 0.45 % of available phosphorus; group VI got the feed with an additive containing commercial phytase Ladozim proxy from A. ficuum at a dose of 4,500 units of phytase/kg of feed and a total phosphorus content of 0.35 % of available phosphorus. Upon removing quails from the experiment on the 42nd and 60th days, blood and tissue samples were taken from four heads of each group and some hematological parameters were assayed using an automatic URIT-3020 analyzer No. 3020E01663 (China). Tissue samples (pectoral and femoral muscles) were used to get histological preparations. Cryosections were analyzed using an Axio Imager D2 microscope at a 400½ magnification (Zeiss, Germany). At the first stage of life (42 days), the application of phytases in the diet decreased liver aminotransferase, alkaline phosphatase, and glucose levels, increased serum protein amount. When a commercial phytase was applied to the poultry diet with phosphorus deficiency at the age of 60 days, the level of aspartate aminotransferase, alkaline phosphatase, cholesterol, and triglycerides increased, while application of the encapsulated phytase from O. proteus raised the total protein amount and reduced the liver enzymes level. At the age of 60 days, under the conditions of complete total phosphorus, the feed additive increased the phosphorus level in the blood serum by 60 and 40% for the bacterial and fungal phytase groups, respectively. Microstructural assay of histological sections of the pectoral muscles showed that in the muscles of the quails getting phytase myofibrils had more arranged architecture with pronounced sarcomeres, stained myocyte nuclei, and transverse striation of fibers that indicated high quality and technological properties of meat.