THE AGE DYNAMICS OF BIOCHEMICAL BLOOD INDICES IN BROILER CHICKEN (<i>Gallus gallus </i>L.)
Biochemical blood indices are important characteristics of physiological and health status of agricultural animals and poultry. In the past decades, the advanced measuring methodology and equipment including the development of automatic biochemical analyzers with standardized reagent kits have led to the significantly faster procedures and higher accuracy of analysis. The reference values of the biochemical indices determined by classic methods should therefore be redefined. In this study we report for the first time the revised reference values of biochemical blood indices including circulatory activity of blood digestive enzymes in growing broiler chicks ( Gallus gallus L.) during early ontogenesis (1 to 35 days of age). In the study, the hybrid chicks of an experimental broiler cross Smena 8 (line B59) were compared to their parental lines (Cornish line B5 and Plymouth Rock line B9) selected at the Smena Center for Genetic Selection (60 birds per genotype).The hybrids were fed ad libitum; parental lines were restricted in feed since day 15 of age. Mortality and live bodyweight were determined at 1, 7, 14, 21, 28, and 35 days of age. Two replicates of 10 birds per genotype were randomly taken for biochemical blood analyses. Blood was sampled from the jugular vein of decapitated chicks. Biochemical blood indices were measured by a flow semi-automatic biochemical analyzer Sinnowa BS3000P (Sinnowa Medical Science & Technology Co., Ltd., China) using reagent kits DIACON-VET (Russia). At 1 day of age in all studied genotypes concentrations of total protein, triglycerides, and calcium in blood serum were lower while concentrations of total phosphorus and total cholesterol were higher as compared to all subsequent ages. The most substantial increase in biochemical blood indices occurred during the first 7 days of age. This was due, among other factors, to the intensive growth of the body and the functional formation of the digestive system for this age period. The total protein concentration in blood serum increased with age in all genotypes because of proceeded body growth and the enhanced ability of protein synthesis. Concentration of total cholesterol tended to decrease with age, especially after 21 days of age. Concentration of triglycerides in serum increased to 14 days of age by 41.6-57.1 % as compared to the previous ages. There were no significant differences between the genotypes in total blood protein until 35 days of age. The hybrid chicks and their parental lines differed in the blood concentration of calcium, total phosphorus, and total cholesterol at 14 and 28 days of age, and triglycerides at 7 days of age. The blood digestive enzyme activities per live bodyweight decreased from day 1 to day 35 of age, most notably for trypsin (501-fold in hybrids, 453-fold in the Cornish line, and 442-fold in the Plymouth Rock line). Blood amylase activity decreased 100-, 52-, 50-fold, and lipase activity decreased 31-fold, 33-fold, and 35-fold, respectively.