No abstract

Ruminant husbandry contributes to global methane (CH4) emissions and beside its negative impact on the environment, enteric CH4 emissions cause a loss of gross energy intake in cows. The study is aimed to estimate CH4 emission and metabolic status in dairy cows via the methane concentration profile as a tool for analyzing the CH4 production pattern. The study included eighteen cows whose enteric CH4 emission was measured during three consecutive days in three periods: 2 hours before (P1), 2–4 hours (P2) and 6–8 hours (P3) after the morning feeding. Based on CH4 enteric emissions, cows were divided into two groups (n=6, respectively): HM (average CH4 concentration: 5430.08 ± 365.92 ppm) and LM (average CH4 concentration: 1351.85 ± 205.20 ppm). Following CH4 measurement, on day 3, venous blood was sampled to determine the indicators of the metabolic status. HM cows had significantly higher average CH4 concentrations, maximum and average CH4 peak amplitude than LM cows in all measuring periods (P1-P3), while the number of CH4 peaks tended to be higher in HM than in LM cows in P2. There were no differences in the maximum and average CH4 peak width and average distance among two CH4 peaks between examined groups of cows. HM cows had significantly higher total protein concentrations and significantly lower total bilirubin and NEFA concentrations than LM cows. In conclusion, HM cows have a greater number of eructations and release more CH4 per eructation than LM cows, hence the differences in metabolic status are most likely related to the differences in their liver function.

Previous studies in the field of acid-base and oxidative status in cows have mainly focused on the transition period (three weeks before and three weeks after calving). The aim of this study was to determine the differences in the parameters of acid-base and oxidative status and electrolyte balance in cows not only during the transition period, but also at other stages of the production cycle. Holstein-Friesian cows were divided into four numerically equal groups (n = 6): early lactating cows (9?2 days in milk - DIM), peak lactating cows (50?5 DIM), late lactating cows (170?10 DIM) and dry cows (10?1 days before calving). Venous blood samples were taken from the cows to analyze acid-base status, electrolyte concentrations and oxidative stress parameters, and to compare group means. Significantly higher pH was observed in early lactating cows than in late lactating cows. Sodium (Na+) concentration was significantly lower in early lactating and peak lactating cows compared to dry cows, while chloride (Cl-) concentration was also lower in late lactating cows compared to dry cows. Plasma glutathione peroxidase (GSH-Px) activity was higher in early lactating cows compared to peak lactating cows. Thus, the highest blood pH, lowest Na+ and Cl- concentrations and highest serum GSH-Px activity were observed in early lactating cows compared to other groups, indicating the highest metabolic and oxidative stress during this period. In conclusion, it would be useful to consider the inclusion of these parameters in standard health assessment procedures in intensive dairy production.

The aim of the study was to determine the stability of the activity ofglutathione peroxidases 1 and 3 during storage at +40C and -180C. Blood sampleswere taken from eight sheep and the activity of the enzyme was determined in theplasma (GPx3) and erythrocytes (GPx1) on the first, third, fifth and seventh day insamples stored at +40C and after one and three months in samples stored at -180C.GPx3 activity decreased significantly during storage at both temperatures, whileGPx1 remained steady even after three months of storage at -180C. Obtained resultsindicate that GPx3 activity has to be determined in fresh sheep plasma samples,while the activity of sheep erythrocyte GPx1 can be determined even after 3 monthsof storage at -180C.