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Abstract. The influence of age and the reproductive status has been researched in the blood serum of 75 Merinolandschaf ewes. We have detected statistically very high concentrations of Ca in the blood serum of pregnant and non- pregnant ewes comparing to those in lactation, while the opposite way has been noticed for the concentrations of P-inorganic and Na. Statistically much higher concentrations of K have been found in the lactating and non-pregnant ewes comparing to the pregnant ones. Statistically much higher concentrations of albumin and cholesterol have been detected in the blood of pregnant ewes comparing to the non-pregnant ones, while the opposite way has been noticed for the concentrations of total proteins. GGT activity was statistically much higher in the blood of ewes in lactation comparing to the non-pregnant ones and the CK and ALT activity in the pregnant ones comparing to those in lactation. The ewes up to one year old had statistically very significant high concentrations of P-inorganic, Na, Fe, glucose, AP, GGT, CK activities and in the older ewes the concentrations of cholesterol and total proteins. Due to that, it is necessary to, before the metabolic profile specification of ewes, take into consideration age and the reproductive status of the animals. For the age there have to be taken the concentrations of P-inorganic, Na, Fe, glucose, cholesterol and total proteins as well as AP, GGT, CK activities and for the reproductive status the concentrations of Ca, P-inorganic, Na, albumin, total proteins as well as the ALT, CK, GGT activities. These researches give basis for the regular therapy application and carrying out the prevention of the metabolic disturbances of ewes in the aim of reducing economy losses.

Increased animal productivity has reduced animal fitness, resulting in increased susceptibility to infectious and metabolic diseases, locomotion problems and subfertility. Future animal breeding strategies should focus on balancing high production levels with health status monitoring and improved welfare. Additionally, understanding how animals interact with their internal and external environment is essential for improving health, fitness, and welfare. In this context, the continuous validation of existing biomarkers and the discovery and field implementation of new biomarkers will enable us to understand the specific physiological process and regulatory mechanisms used by the organism to adapt to different environmental conditions. Thus, biomarkers may be used to monitor welfare and improve management and breeding strategies. In this article, we describe major achievements in the establishment of biomarkers in dairy cows and small ruminants. This review mainly focuses on the physiological biomarkers used to monitor animal responses to, and recovery from, environmental perturbations. We highlight future avenues for research in this field and present a timely positioning document to the scientific community.

Milk production intensification has led to several unwanted aspects, such as sustainability issues and environmental pollution. Among these, increased milk outputs that have been achieved over the last 70 years have led to several health and pathophysiological conditions in high yielding dairy animals, including metabolic diseases that were uncommon in the past. Increased occurrence of diverse metabolic diseases in cattle and other domestic animals is a key feature of domestication that not only affects the animals' health and productivity, but also may have important and adverse health impacts on human consumers through the elevated use of drugs and antibiotics. These aspects will influence economical and ethical aspects in the near future. Therefore, finding and establishing proper biomarkers for early detection of metabolic diseases is of great interest. In the present review, recent work on the discovery of fitness, stress and welfare biomarkers in dairy cows is presented, focusing in particular on possible biomarkers of energy balance and oxidative stress in plasma and milk, and biomarkers of production-related diseases and decreased fertility.

Abstract. The aim of this investigation is to determine changes in concentrations of biochemical and haematological parameters, as well as metabolic hormones in the blood of Tsigai ewes in the first third of lactation. The study included 10 ewes Tsigai breed monitored during three periods of lactation: 20 days, 40 and 60 days of lactation. Ewes were fed feed mixture (300 g/day) and meadow hay ad libitum. A significant decrease of concentrations of Ca and Na was recorded in the blood of sheep at the 40th day of lactation and later an increase at the 60th day of lactation. The opposite trend was determined for concentrations of P-inorganic. Also it was determined a significant decrease in Fe content and an increase in the concentrations of glucose, triglycerides and total protein in the first third of lactation. In the blood of ewes at 40th day of lactation it was found a significant decrease of the activity of AST and LDH in contrast to ewes at 20th day of lactation. Concentrations of T3 and T4 hormones were slightly increasing in the first third of lactation, but the differences were not significant. The blood insulin concentrations were significant increased in the first third of lactation. Haematological blood parameters in lactating ewes did not differ significantly and was within the reference values. Determining the concentration of biochemical and haematological parameters and concentrations of blood thyroid hormones and insulin in the first third of lactation are imposed as a precaution in order to better monitoring of Tsigai ewes during lactation.

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The influence of the reproductive status was tested in the blood serum of 30 sheep (10 pregnant sheep on the 15th day prior to lambing, 10 lactating sheep on the 20th day of the lactation and 10 non-pregnant sheep). The influence of age was determined in the blood serum of 20 sheep and 20 lambs. Analysis of the impact of age in sheep and lamb on the concentration of thyroid hormones showed that 30-day old lambs had significantly higher (P<0.01) concentration of T3 and T4 compared to the other age categories of sheep. At the same time, 100-day old lambs had significantly higher concentration of T4 if compared to the 1 and 3-year old sheep. Referring to the reproductive status, there was significantly lower (P<0.01) concentration of T3 determined in the blood of lactating sheep than of nonpregnant and pregnant sheep. These findings point out unsatisfactory energy supply in the older sheep, sheep during late pregnancy and sheep at the beginning of lactation

The aim of this research was to monitor the metabolic profile of blood and the quality of ewes' milk during lactation in organic farming. Biological investigations were carried out on 32 clinically healthy Merinolandschaf ewes during the 3 th lactation on the 20 th , 60 th and 100 th day of lactation. Ewes' milk was analyzed for the non fat dry matter, milk fat, protein, lactose, urea, the somatic cells count (SCC) and te total viable cell number (CFU), as well as for the concentration of fatty acids, atherogenic (AI), thrombogenic (TI) and Δ9-desaturase activity index. Concentrations of minerals (Ca-calcium, P-phosphorus-inorganic, Mg-magnesium, and Fe-iron), biochemical parameters (urea, glucose, cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, total protein, albumin, globulin, NEFA-non-esterified fatty acids, BHBA-beta-hydroxybutyrate) and enzyme activity (ALT-alanine aminotransferase, AST-aspartate aminotransferase, ALP-alkaline phosphatase, CK-creatine kinase and GGT-γ-glutamyl transferase) were analyzed in blood serum. Chemical composition of milk differed among different stages of lactation, which was marked by the increased content of milk fat, the decreased urea concentration, as well as by numeorus changes of fatty acid concentration observed along with lactation progression. Number of SCC and CFU in milk increased during lactation. AT and TI were appropriate in all stages of lactation, which resulted in satisfactory quality of ewes' milk from organic farming. Determined concentrations of certain biochemical parameters (NEFA, triglycerides, VLDL-cholesterol, Ca and Fe) in blood of ewes originating from organic farming indicated lower deficit of energy during the 20 th day of lactation, as well as a lack of Ca and Fe concentrations in blood, which most likely occurred due to higher loss through milk. Accordingly, the blood metabolic profile can be considered as an indicator for feeding and health status of ewes during lactation in organic farming.