Lactate dehydrogenase (LDH) is widely distributed enzyme in cells of various living systems where it is involved in carbohydrate metabolism catalyzing interconversion of lactate and pyruvate with NAD⁺/NADH coenzyme system. Cells of tissues are direct source of lactate dehydrogenase isoenzymes that are naturally distributed in blood plasma/serum of animals and humans producing characteristic profile. This profile depends on intracellular isoenzyme concentration in all tissues that contribute to the common pool of lactate dehydrogenases in plasma/serum as a consequence of natural cell degradation. LDH is widely distributed in the body, high activities are found in the heart, liver, skeletal muscle, kidney, and erytrocytes, whereas lesser amounts are found in the lung, smooth muscle, and brain. Because of its widespread activities in numerous body tissues, LDH is elevated in a variety of disorders. There are many conditions that contribute to increased activity of LDH. An elevated total LDH value is a rather nonspecific finding. Therefore, LDH assays assume a more clinical significance when separated into isoenzyme fractions. The activity of LDH and its serum and tissue patterns and composition show great variations between the species. These differences do not allow using catalytic activities of LDH isoenzymes from one species to another. Instead, the pattern of serum LDH isoenzymes should be interpreted in respect to its species origin that is important in particular in veterinary medicine. Determination of total LDH activity and its isoenzyme pattern in serum of mammals had become one of the biochemical indicators in the assessment of organ disorders. When the content of cells is released from tissue to plasma, as on cell injury, the LDH isoenzyme pattern of the serum changes in favour of the profile of the affected organ (tissue) that can be used in the diagnostic practice.

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Background and Aim: Blood proteins in birds serve as an important indicator in the evaluation of health status and represent a basis in general biochemistry allowing the identification of metabolic alterations. The objective of this study was to evaluate the protein profile in broiler chickens extended by the concentrations of serum protein fractions at different periods of fattening. Materials and Methods: Into the evaluation, we included 24 clinically healthy Ross 308 line meat-type chickens at the age of 2 days. Blood samples were taken on day 4, 18, 32, and 46 of fattening always from six randomly selected chickens. Chickens were fed with a commercial starter, grower, and finisher feeds. The concentrations of total serum protein and protein fractions were evaluated. Results: Various significant changes in the proportion of the individual protein fractions were found during the observed period except for the beta-globulins in all protein fractions and the albumin/globulin (A/G) ratio. At the beginning of the fattening period, the relative concentrations of albumin, α1-globulins, and A/G ratio were significantly lower and the values of α2- and γ-globulins significantly higher (p<0.05). The values of pre-albumin fraction were found as a small band preceding the albumin fraction differed significantly between the different age groups of chickens (p<0.05). The total serum protein concentrations showed higher values in older broilers; the significantly highest mean value was recorded on day 32 of fattening. Conclusion: The results suggest that fattening and age of broilers influences not only the production patterns, metabolic processes, and lipid and mineral profile but also the parameters of protein profile. However, seeing that some contradictory data exist regarding the number and size of globulin fractions in chickens, further analyses are needed.

The objective of this study was to describe the physiological changes in serum protein profile in calves during the first month of life. Seven clinically healthy calves were used in this study. Calves received colostrum and whole milk from their dams by voluntary sucking. The first blood sampling was performed within one hour after birth before colostrum intake (day 0) and then at 1, 2, 7, 14 and 30 days of age. Serum was analysed for total protein concentrations, and for the relative and absolute values of serum protein fractions – albumin, alpha₁-(α₁), alpha₂-(α₂), beta₁-(β₁), beta₂-(β₂) and gamma-(γ) globulins. The results showed a significant effect of age on total protein concentrations and for all the analysed protein fractions. The concentrations of total proteins, β₂- and γ-globulins increased significantly one day after colostrum intake (P < 0.001) and then significantly decreased gradually till the end of the first month of age. An opposite trend was observed in the relative concentrations of albumin (P < 0.001). Significant decrease of values was found for relative concentrations of α₁-globulins (P < 0.001) and increase of the relative values of α₂- and β₁-globulins from birth till the end of the monitored period (P < 0.001). The above mentioned changes are also reflected in changes of albumin/globulin ratio (P < 0.001). The results suggest that the serum protein profile in calves is significantly influenced by colostrum intake and the age of calves. This should be taken into consideration when interpreting the serum protein profile in young animals.

Respiratory diseases of cattle, particularly in young animals, represent the most important health and economic problem of cattle rearing. The aim of the present study was to evaluate the changes of selected blood indices in 25 calves aged 2–9 months suffering from etiologically undifferentiated chronic respiratory diseases. Blood samples were analysed for haematological indices and selected serum biochemistry variables. The results found in sick animals were compared with results from 25 healthy animals of the same age, housing and feeding system. Significant differences in means between the groups of clinically healthy and sick calves were found in 13 out of 24 evaluated indicators. In sick animals we found significantly higher mean concentrations of haemoglobin and total number of white blood cells ( P < 0.05 and P < 0.01, respectively), as well as higher mean activity of AST and LDH ( P < 0.01), concentrations of total proteins and total immunoglobulins ( P < 0.001). Significantly lower mean values were recorded in the serum concentrations of albumin, creatinine and glucose ( P < 0.001), as well as in the concentration of Mg ( P < 0.01), P ( P < 0.001), Fe and Zn ( P < 0.05). The presented results suggest the effect of respiratory diseases in calves on several changes of haematological and selected serum biochemical indicators. They indicate that respiratory diseases did not lead only to direct disturbance of gas exchange and acid-base balance, but they also indirectly affect some other variables of blood biochemistry.