The aim of this study was to investigate the relationship between concentration of non-esterified fatty acid and ketone bodies in blood of dairy cows, and to evaluate these concentrations for the detection of prevalence of subclinical ketosis. The second aim was to compare the concentration of β-hydroxybutyric acid determined by an electronic handheld meter Precision Xtra ® with serum concentration of β-hydroxybutyric acid analysed in laboratory with izotachometric and photometric method, respectively. Blood samples were collected from jugular vein 4-6 h after morning feeding in three groups of Holstein cows (n = 909) according to the lactation phase from 51 different herds with similar husbandry characteristics. High lipomobilization (non-esterified fatty acid ≥ 0.35 mmol·l -1 , mean concentration 0.34 ± 0.15 mmol·l -1 ) was detected in 30.3% of antepartum cows, while increased concentrations of β-hydroxybutyric acid (≥ 1.0 mmol·l -1 , prevalence of subclinical ketosis) were detected in 18.5% and 14.1% of the early lactation and mid lactation cows, respectively. The correlation coefficient (r = 0.84, P < 0.001; r = 0.93, P < 0.001) was found between measurements of whole blood β-hydroxybutyric acid of 60 and 38 dairy cows determined with the Precision Xtra ® test and plasma or serum β-hydroxybutyric acid concentration determined by isotachophoresis and photometrical method, respectively. Our results show that the monitoring of changes in the blood concentration of β-hydroxybutyric acid in high-yielding cows in the early postpartum period by the electronic handheld meter Precision Xtra ® may be effective in reducing the incidence of ketosis and health problems associated with ketosis in dairy cattle herds. Peripartal period, non-esterified fatty acid, β-hydroxybutyric acid, laboratory and farm diagnostic test
The effects of intraperitoneal and intravenous administration of serotonin on cardiac output, blood pressure, and organ distribution of blood flow (Rb86) were studied in the rat. Fifteen to thirty minutes after intraperitoneal injection (10 mg/kg) cardiac output was unchanged, while blood pressure was significantly reduced. Increase in blood flow was noted in the myocardium, pulmonary parenchyma and "carcass" (skeletal muscle, bone, CNS), with decrease in the kidney and the skin. Splanchnic blood flow was unchanged. Conversely, intravenous infusion of serotonin produced an increase of cardiac output, blood pressure, and cutaneous blood flow.
The experiment was conducted to evaluate the effect of different types of available nutrients of total mix rations on fermentation and synthesis capacities of the rumen in Holstein dairy cows divided into groups in the transition period (± 3 weeks after parturition) and early lactation (60-80 days in milk). The diets were fed as a total mixed ration. Results obtained with feeding Diet C (high concentration of available nutrients) to dairy cows confirmed a significant increase in 2,6-diaminopimelic acid from the initial mean 2.2 μg/ml at 21 days before calving to 6.2 μg/ml (P < 0.01) at 21 days after calving or 7.6 μg/ml (P < 0.01) at early lactation, and a parallel significant increase in the concentration of volatile fatty acids (P < 0.01). The concentration of propionic acid increased from the initial mean 25.3 to 39.3 mmol/l (P < 0.01) in the transition period, and to 43.1 mmol/l at early lactation (P < 0.01). All indicators of rumen fermentation and synthesis determined in dairy cows with Diet B (low concentration of available nutrients) of the total mix ration according to productive phases were not significant. High regression coefficients of examined indicators of 2,6-diaminopimelic acid to volatile fatty acid (r = 0.813), propionic acid (r = 0.780) and acetic acid (r = 0.635) indicate direct correlation between fermentation and synthesis activities of the rumen. Our results show that 2,6-diaminopimelic acid appears as a perspective marker for the monitoring and evaluation of the synthesis function of the rumen and production of bacterial biomass under breeding conditions. VFA, DAPA, feeding and nutrition, microflora, fermentationRumen fermentation of the feed's organic matter and microbial biomass synthesis are reported to have the potential to meet 70-85% of the energy requirements and 70-100% of the protein needs of ruminants, even at higher levels of production. Microbial proteins synthesized in the rumen cover 80% of daily amino acid needs and constitute 50-80% of total absorbable amino acids (Bach et al. 2005). Synthesis of microbial proteins is affected by usability of fermentable carbohydrates (Ahvenjarvi et al. 2002), nitrogen (Verbic 2002) and minerals (Broudiscou et al. 1999). Optimum production of rumen microflora and synthesis of microbial proteins at the level of 12.6 g/100 g fermentable organic matter is ensured when the concentration of NH 3 in the ruminal fluid varies in the range 8.8-14.7 mmol/l which is an accepted reference value for assessment of the level of protein saturation in ruminant rations (Vajda et al. 1994; NRC 2001). Microbial efficiency expressed as g of microbial nitrogen per kg of dry matter, organic matter, total carbohydrate, and 100 g N digested, ranged from 20.8 to 26.6; 34.7 to 44.3; 35.1 to 50.3 and 89 to 95 g, respectively (Sniffen et al. 2006). Multiplication and growth of rumen microflora is affected by nutritional (quantity and ratio of carbohydrates and proteins) and dietetic factors (structure of total mix ration, dry matter intake, production of sal...
The aim of this study was to evaluate the buffering capacity of some fermented feedstuffs and the effect of dietary acid-base status on ruminal fluid pH. The first experiment was performed with different types (n = 24) of wet and dry fermented feedstuffs to determine the buffering capacity and buffer value index. The buffer value index of wet corn silages was more negative than for dry corn silages account on acid loss during drying. In the second experiment, the effects of different concentrations of lactic acid on base-buffering capacity, buffer value index and indicators of fermentation process were studied in two groups of corn silages (n = 21). Two groups of analyzed values were compared using unpaired t-test. Differences among the groups in base-buffering capacity (P < 0.001) and buffer value index (P < 0.01) were significant. In the third experiment, rumen fluid pH was measured using 8 total mixed rations on 48 lactating dairy cows. In the present study no significant (P > 0.05) correlation was found between ruminal pH and dietary buffer value index. These results confirmed that dietary acid-base status alone is not adequate as a predictor of the need for buffers in the diet of lactating cows. It is the first report about using of buffering capacity determination methods for evaluation of feedstuffs and dietary acid-base status in dairy cows. Buffer, ruminal pH, silages, total mixed rationsThe cow has three primary means of buffering acid ingested from silage or acid produced by rumen fermentation. These include buffer naturally occurring in saliva, buffering capacity of ingested feed and added dietary buffers. Buffers in dairy rations are compounds that neutralize excess acid within the ruminant's digestive system and help to resist changes in rumen pH when high grain or fermented forage are fed. They supplement the cow's natural buffers that occur in saliva. Ruminants are generally able to maintain ruminal pH within physiological limits by their own regulation of intake, endogenous buffer production, microbial adaptation and volatile fatty acids (VFA) absorption.Buffering capacity (BC) of forages can be defined as the degree to which forage material resists changes in pH. All forages have different buffering capacities. Fresh forage with a high buffering capacity will require more acid to reduce its pH than forage with a low buffering capacity. Moharrery (2007) reported that BC in forage and protein concentrate are 5.6 and 4.1 times higher than BC in grains. Buffer value index (BVI) is related directly to BC but inversely to H + (acidity) . Feedstuffs influence the ruminal acid-base status through their pH, BC and stimulation of salivation (Le Ruyet et al. 1992). The buffer value index can account for alterations in both of measures (pH, BC) and it provides a more complete evaluation of diet-induced changes in ruminal acid-base status.The aim of the study was firstly to find base-buffering capacity and buffer value index of some fermented feedstuffs and investigate the effect of dietary base-BC ...
Experiments were conducted on calves divided into three groups, 6 animals in each, to determine the influence of the intake of non-acidified and acidified milk replacer on the level of acid-base homeostasis in venous blood. The milk replacer was supplied at a dose of 700 g dry matter in 8 l of the liquid in two feedings. The milk replacer was acidified by adding formic acid to ensure the concentration of 0.2% in milk replacer. Venous blood was collected before feeding and 1, 2, 4, and 6 hours after feeding. The samples were analyzed for blood pH, actual bicarbonate HCO<sub>3</sub><sup>-</sup> (mmol/l), base excess BE (mmol/l), partial pressure of carbon dioxide pCO<sub>2</sub> (kPa) and partial pressure of oxygen pO<sub>2</sub> (kPa). Significant changes were observed in calves fed acidified milk of albumin type. The mean daily values of acid-base parameters in these calves were significantly lower in comparison with animals fed non-acidified milk replacer and reached the following levels: pH 7.343 ± 0.032 (<i>P</i> < 0.05), HCO<sub>3</sub> 24.49 ± 2.13 mmol/l (<i>P</i> < 0.01), BE 1.11 ± 1.97 mmol/l (<i>P</i> < 0.001). A similar tendency but of a more pronounced decrease in values was recorded in the group of calves fed acidified milk replacer of casein type: pH 7.312 ± 0.022 (<i>P</i> < 0.01), HCO<sub>3</sub><sup>-</sup> 21.73 ± 0.75 mmol/l (<i>P</i> < 0.001), BE 96 ± 0.86 mmol/l (<i>P</i> < 0.001). In relation to the time after feeding the group of calves fed non-acidified milk replacer showed a rising tendency in the level of metabolic components (HCO<sub>3</sub><sup>-</sup>), compensated by respiratory regulating mechanisms (rise in pCO<sub>2</sub>) conducive to the maintenance of optimum blood pH level. The group of calves fed acidified milk replacer (formic acid 2 ml/l) of the albumin type showed metabolic acidosis with subsequent gradual adjustment and compensation by means of metabolic (HCOHCO<sub>3</sub><sup>-</sup>) rather than respiratory regulation mechanisms. The calves fed acidified casein type milk replacer displayed metabolic acidosis with insufficient metabolic regulation and more intensive respiratory compensation (decrease in pCO<sub>2</sub>). Concurrent investigations of the abomasum acidity and blood acid-base homeostasis reflected the joint action of both the acidifying effect of formic acid and significantly lower production of bicarbonate (HCO<sub>3</sub><sup>-</sup>) related to the intake of acidified milk and the tendency to the development of metabolic acidosis.
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