Rudolf Staufenbiel

Performance and metabolic and endocrine changes with emphasis on glucose metabolism in high-yielding dairy cows with high and low fat content in liver after calving.

Elevated liver fat content occurs in high-yielding dairy cows during the transition from pregnancy to lactation after fat mobilization and may affect hepatic glucose metabolism, but the degree of liver fat storage is highly variable. Therefore, we studied metabolic and endocrine changes and hepatic glucose metabolism in cows that markedly differ in liver fat content. Multiparous cows from the same herd with high (HFL; n = 10) and low (LFL; n = 10) liver fat contents (mean of d 1, 10, and 21 after calving for each cow, respectively) were studied from 60 d before expected calving to 56 d in milk. Cows were fed ad libitum and all cows received the same diets. Liver samples were taken on d 1, 10, and 21 after calving; mean fat content (+/-SEM) in liver of HFL cows was 174 +/- 9.6 mg/g, whereas mean liver fat content in LFL cows was 77 +/- 3.3 mg/g. Blood samples were taken 20 and 7 d before expected calving and 0, 7, 14, 28, and 56 d after calving to measure plasma concentrations of nonesterified fatty acids, beta-hydroxybutyrate, glucose, insulin, glucagon, insulin-like growth factor-I, and leptin. In liver, glycogen content as well as mRNA levels of phosphoenolpyruvate carboxykinase, pyruvate carboxylase, glucose-6-phosphatase, and glucose transporter were measured by quantitative real-time PCR. Back fat thickness decreased and dry matter intake increased with onset of lactation, and back fat thickness was higher but dry matter intake was lower in HFL than in LFL. Energy-corrected milk yield did not differ between groups, but milk fat content was higher and lactose content was lower in HFL than LFL at the beginning of lactation. Energy balance was more negative in HFL than in LFL. Plasma nonesterified fatty acids and beta-hydroxybutyrate concentrations increased and plasma glucose concentration tended to decrease more in HFL than LFL with onset of lactation. Glucagon to insulin ratios increased more in HFL than LFL with onset of lactation. Hepatic glycogen content was higher in LFL than HFL, whereas mRNA levels of glucose-6-phosphatase and pyruvate carboxylase were higher in HFL than in LFL, and cytosolic phosphoenolpyruvate carboxykinase mRNA level increased similarly after parturition in both groups. In conclusion, an elevated liver fat content was related to greater fat mobilization and reduced feed intake and was associated with effects on hepatic glucose metabolism. As environment and feeding management were the same, individual cow factors were responsible for differences in energy metabolism during the transition period.

Phosphorus Homeostasis in Dairy Cows with Abomasal Displacement or Abomasal Volvulus

Abnormal phosphorus homeostasis occurs in dairy cows with an abomasal displacement or volvulus. The goal of this study was to identify potential mechanisms for hypophosphatemia and hyperphosphatemia in cows with a left displaced abomasum (LDA), right displaced abomasum (RDA), or abomasal volvulus (AV). Accordingly, the results of preoperative clinicopathologic analyses for 1,368 dairy cows with an LDA (n = 1,189), RDA, or AV (n = 179) (data set 1) and for 44 cows with an AV (data set 2) were retrieved. Laboratory values were compared by Students t-tests, and correlation and regression analyses were performed. Thirty-four percent of the animals from data set 1 (463/1,368) were hypophosphatemic (serum phosphorus concentration ([Pi]) < 1.4 mmol/L), and 9% (122/1,368) were hyperphosphatemic ([Pi] >2.3 mmol/L). Serum [Pi] was significantly lower (P < .05) in cows with an LDA (1.60 +/- 0.53 mmol/L; mean +/- SD) than in cows with an RDA or AV (1.85 +/- 0.68 mmol/L). For cows with an LDA, [Pi] was correlated with serum urea nitrogen concentration ([SUN]) (r = 0.34) and serum concentration of magnesium ([Mg]) (r = 0.20). For cows with an RDA or AV, linear correlations existed between [Pi] and [SUN] (r = 0.45), [Mg] (r = 0.43), and serum chloride concentration ([Cl]) (r = -0.27). Stepwise logistic regression analysis indicated that low [SUN] and the diagnosis of an LDA had the strongest associations with hypophosphatemia. In cows with hyperphosphatemia, [Pi] was most strongly associated with azotemia. In cows with an AV, the strongest correlations with [Pi] were found for [SUN] and serum creatinine. We conclude that hypophosphatemia in cows with an LDA is primarily due to decreased feed intake. In contrast, hyperphosphatemia in cattle with an RDA or AV appears to result from dehydration and decreased renal blood flow.

Clinicopathologic variables associated with hypokalemia in lactating dairy cows with abomasal displacement or volvulus

OBJECTIVE To identify potential mechanisms for hypokalemia in dairy cows with left-displaced abomasum (LDA), right-displaced abomasum (RDA), or abomasal volvulus (AV). DESIGN Retrospective analysis of clinicopathologic data from 2 convenience samples of cows. SAMPLE 112 lactating dairy cows with AV (group 1); 1,332 lactating dairy cows (group 2) with LDA (n = 1,160) or RDA or AV (172). PROCEDURES Data were analyzed via Spearman ρ and multivariate stepwise regression. RESULTS 78 of 112 (70%) group 1 cows were hypokalemic (mean serum potassium concentration, 3.5 mEq/L; reference range, 3.9 to 5.8 mEq/L). For group 1 cows, serum chloride concentration had the strongest positive association with serum potassium concentration, and serum potassium concentration was negatively associated with plasma bicarbonate and serum glucose, creatinine, and urea concentrations. Six hundred thirty-six of 1,160 (55%) of group 2 cows with LDA were hypokalemic (mean serum potassium concentration, 3.7 mEq/L). Ninety-two of 172 (53%) group 2 cows with RDA or AV were hypokalemic (mean serum potassium concentration, 3.8 mEq/L). For group 2 cows, serum chloride concentration had the strongest positive association with serum potassium concentration, and serum potassium concentration was negatively associated with indices of feed intake (serum bilirubin concentration) and hydration status. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested hypokalemia was associated with hypochloremia, alkalemia, low feed intake with high amount of milk produced, hypovolemia, and hyperglycemia in lactating dairy cows. Treatment of hypokalemia should include surgical correction of abomasal displacement, increased dietary potassium intake via dietary dry matter intake or oral administration of KCl, and correction of hypochloremia, alkalemia, metabolic alkalosis, and dehydration.

Liver phosphorus content in Holstein-Friesian cows during the transition period

Hepatic lipidosis and hypophosphatemia are frequently observed in high-yielding periparturient dairy cows. Objectives of this study were to investigate the association of the liver P content with the degree of liver fat accumulation and serum P concentration and to characterize the change in liver P content throughout the transition period. In a cross-sectional study, liver biopsies obtained from 33 Holstein-Friesian cows 14 d postpartum (p.p.) were assayed for total lipid (TLip), triacylglycerol, DNA, P, Mg, K, Na, and Ca content. Serum samples obtained at the time of biopsy were analyzed for indices of liver function and injury and the serum P concentration was determined. From this cross-sectional study, 6 cows were selected for a longitudinal study and liver tissue obtained from the 6 cows on d -65, -30, -14, 1, 14, 28, and 49 relative to calving was assayed. The amounts of P, K, Mg, Na, and Ca were expressed as amount in dry weight (DW), wet weight (WW), nonfat wet weight (NFWW), and indexed to DNA. In the cross-sectional study, P(DW) and P(WW) decreased with increasing TLip, whereas P(NFWW) and P(DNA) were independent of TLip. Values for P(DNA) varied widely, whereas P(NFWW) varied within a narrow range. Stepwise regression analysis revealed the strongest associations between P(DW) and the amount of tissue water (partial R2 = 0.74) and the log to the base 10 of triacylglycerol (partial R2 = 0.05). The P(WW) was associated with the log to the base 10 of triacylglycerol (partial R2 = 0.20), but no associations were found for P(NFWW). These findings indicate that decreased electrolyte content in dry and wet liver tissue with increased liver lipid content is predominantly due to the decrease in tissue water and therefore the distribution volume of electrolytes. In the longitudinal study, P(DW), P(WW), and P(NFWW) were decreased on d 14 p.p. Similar directional decreases were found for K, Mg, and Na, but P was the only electrolyte that was significantly decreased in liver tissue at d 14 p.p. This finding indicates that the P content of liver tissue decreases in early lactation due to a reduction in hepatocellular cytosol volume as well as a decrease in cytosolic P concentration, with the latter having biological relevance. The clinical significance of decreased cytosolic P concentration in the hepatocytes of dairy cows in early lactation remains to be determined.

Plasma potassium-lowering effect of oral glucose, sodium bicarbonate, and the combination thereof in healthy neonatal dairy calves

Hyperkalemia is a common complication in neonatal diarrheic dairy calves and is corrected by administration of glucose or sodium bicarbonate. Although the hypokalemic effect of glucose is well established in other species, controversial results are reported for sodium bicarbonate. Our objective was to study the effect and mechanism of action of glucose and sodium bicarbonate on the potassium homeostasis of healthy neonatal dairy calves. Nine healthy neonatal Holstein-Friesian calves underwent 3 oral treatments with 2L of NaHCO(3) (150 mmol/L), glucose (300 mmol/L), and glucose+NaHCO(3) solution (300 mmol/L+150 mmol/L) in randomized order. Blood was obtained before treatment (T(0)) and at 30-min intervals thereafter. Changes between each time point and T(0) were determined for all parameters. Urine was collected volumetrically to determine total renal potassium excretion over an 8-h posttreatment period. Plasma volume changes were extrapolated from changes in plasma protein concentration. Treatment and time effects were tested with repeated-measures ANOVA. Multivariate stepwise regression analysis using dummy variable coding was conducted to identify associations between changes in plasma potassium concentration ([K]) and changes in plasma glucose concentration ([glucose]), blood base excess, and plasma volume. Oral glucose and sodium bicarbonate treatments decreased [K] by 25 and 19%, respectively, whereas the combination of both compounds caused an intermediate [K] decline (22%). For the glucose treatment, the decline in [K] was only associated with changes in plasma [glucose] (partial R(2)=0.19). In NaHCO(3)-treated calves, [K] decline was associated with change of extracellular volume (partial R(2)=0.31) and blood base excess (partial R(2)=0.19). When glucose and NaHCO(3) were combined, [K] decline was associated with changes in plasma volume (partial R(2)=0.30), BE (R(2)=0.22), and [glucose] (partial R(2)=0.03). Our results indicate that glucose lowers plasma [K] mainly through an insulin-dependent intracellular translocation of K, whereas NaHCO(3) causes hypokalemia through hemodilution followed by intracellular translocation of K caused by the strong ion effect. The combination of glucose and NaHCO(3) at the dosage used in this study does not have an additive hypokalemic effect. When combined, hemodilution and strong ion effect have the strongest effect on plasma [K], whereas the insulin-dependent effect of glucose appears to be blunted.

Evaluation of the use of nonesterified fatty acids and β-hydroxybutyrate concentrations in pooled serum samples for herd-based detection of subclinical ketosis in dairy cows during the first week after parturition

OBJECTIVE To evaluate the use of nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) concentrations in pooled serum samples for herd-based detection of subclinical ketosis (SCK) in dairy cows after calving. DESIGN Cross-sectional study. ANIMALS 1,100 dairy cows from 110 herds. PROCEDURES Blood samples were collected from 10 healthy cows/herd in the first week after parturition. Aliquots of serum were mixed to create a pooled sample. Concentrations of NEFA and BHBA were measured to estimate prevalence of SCK. Pooled sample test results were compared with those obtained for individual samples. Linear regression and receiver-operating characteristic curve analysis were performed; Bland-Altman plots were used to evaluate agreement between methods. RESULTS Overall prevalence of SCK was 30.7%, 19.3%, and 13.6%, as determined by use of BHBA threshold concentrations of 1,000, 1,200, and 1,400 μmol/L, respectively. Pooled sample concentrations of NEFA and BHBA were significantly correlated (r = 0.98 and 0.97, respectively) with individual sample means and with the number of cows that had NEFA (R(2) range, 0.81 to 0.84) or BHBA (R(2) range, 0.65 to 0.76) concentrations above predefined thresholds. Pooled sample concentrations of NEFA and BHBA were very accurate to highly accurate for herd-based detection of SCK. CONCLUSIONS AND CLINICAL RELEVANCE Analysis of NEFA and BHBA concentrations in pooled serum samples was useful for herd-based detection of SCK. A sample size of 10 cows/herd was deemed adequate for monitoring dairy herds for SCK. Reference criteria specific to pooled samples should be used for this type of herd-based testing.

Short Communication: Prepartal Concentration of Estradiol-17β in Heifers with Stillborn Calves

This study was conducted to investigate hormonal imbalances preceding stillbirths and dystocia in primiparous heifers. The study was conducted between 2003 and 2004 on a German dairy farm, including 433 heifers. Starting 3 wk before calving, a weekly blood sample was collected. At calving, another blood sample was obtained, and the calving ease (grade 0 = unassisted to grade 2 = heavy pull with mechanical calf puller), sex, birth weight, as well as vitality status (stillborn, alive) of the calf were recorded. The blood serum was analyzed for estradiol-17beta and progesterone concentration. At parturition, the measured estradiol-17beta concentration was greater in heifers delivering bulls than in those with female calves and was increasing with greater birth weight of the calf and increasing calving difficulty score. Already 2 wk before calving, the serum estradiol-17beta concentration was significantly smaller in heifers with stillborn than live calves. On the other hand, the progesterone concentration was greater 2 wk before calving in heifers with stillborn calves, but it was unaffected by the birth weight or sex of the calf or the calving difficulty score. Stillborn and live calves did not differ in birth weight or pregnancy duration. The smaller estradiol-17beta concentrations of the heifers with stillborn calves could indicate an abnormality of the placenta or an abnormality of hormonal signals from the calf to the placenta in the weeks before the calving.

The impact of dietary cation anion difference (DCAD) on the acid-base balance and calcium metabolism of non-lactating, non-pregnant dairy cows fed equal amounts of different anionic salts

We evaluated the impact of the dietary cation-anion difference (DCAD) on the influence of anionic salts (AS) on the metabolism of dairy cows using a study-design that included control of feed intake. Ten mature, non-lactating, non-pregnant, Holstein-Friesian-crossbreed cows received 2000 mEq of either one of the seven anionic salts tested, two combinations of the anionic salts or water as control via a rumen cannula. Salts and controls were assigned in a 10x10 Latin square design. Whole blood, serum and urine samples were taken during treatment (TP) and washout period. Samples of whole blood were tested for pH, base-excess and bicarbonate concentrations. In urine, pH and net acid-base excretion (NABE) were analysed. Calcium was measured in serum and urine. According to the different batches of hay, five groups of DCAD were created regarding cluster analysis. Changes in urine and blood parameters were statistically analysed for each DCAD group separately. The different DCAD had an impact on the amount of change in acid-base balance (ABB) and calcium metabolism and for how long these changes lasted. In the DCAD group receiving the highest amount of AS (239 mEq/kg dry matter with AS), changes of ABB were only noticeable in urine and these changes only differed from day zero in the first week of TP (P<0.05). In the other four groups changes of ABB were also visible in blood parameters, but only on a few days of TP did the deviations differ significantly (P<0.05) from day zero. Changes of ABB parameters in urine samples were more pronounced than those in blood and differed clearly from day zero (P<0.05). Parallel to the changes of ABB, calcium concentrations in these samples were significantly increased (P<0.001) in all DCAD groups. Except for the highest DCAD group, ionized calcium concentrations changed over time (P<0.020). However, the differences were very small and only differed from day zero on a few TP days. We conclude that the DCAD of a dairy cows diet has an important impact on the effect of AS on ABB and calcium metabolism with respect to the duration and amount of change. The target regions of DCAD should be clearly below 100 mEq/kg dry matter to ensure the desired effect on ABB and calcium metabolism. Extremely negative DCAD should be avoided to minimize the risk of clinical acidosis induced by AS.

Relationship between body condition score and ultrasound measurement of backfat thickness in multiparous Holstein dairy cows at different production phases

BACKGROUND The validity of the body condition score (BCS) for evaluating subcutaneous fat has been questioned because of its subjectivity. With the advent of ultrasonography, backfat thickness (BFT) can be objectively measured and used to assess the energy status of dairy cows in conjunction with BCS. OBJECTIVE Determine the relationship between BCS and ultrasound measurements of BFT throughout the lactation cycle. METHODS Cows (n = 1123) were selected randomly and classified according to their lactation stage into four different groups. BCS was determined using a 5-point scale and BFT measurements were obtained using a 5-MHz linear transducer. RESULTS The correlation coefficient (r) for the relationship between BCS and BFT varied according to the stage of lactation. There was a high correlation (r = 0.96-0.98) and relationship (r(2) = 0.92-0.96) between BCS and BFT. The highest correlation was found at BFT values of 10-35 mm and BCS of 2-4.5 units. CONCLUSION BCS is a practical tool for evaluating body condition; furthermore, it may be as valid as BFT for the estimation of subcutaneous fat in Holstein dairy cows over time.

Alkalinizing effect of NaHCO3 with and without glucose when administered orally to euhydrated neonatal dairy calves

The use of oral rehydration solutions (ORS) is well established as an effective treatment to correct water-, electrolyte-, and acid-base balance in diarrheic calves. The main ingredients of a commercial ORS are Na, glucose, and alkalinizing agents, such as NaHCO3. Particular importance is attributed to the combination of glucose and Na at a specific ratio to optimize intestinal sodium, and thereby water uptake, through the sodium-glucose co-transport. Enhancing intestinal Na absorption by combining glucose and Na in an ORS has the potential to improve the alkalinizing effect of an ORS according the strong ion theory. The objective of this study was to investigate the effect of glucose on the alkalinizing effect of NaHCO3 when administered orally. Nine healthy neonatal Holstein-Friesian calves underwent 3 oral treatments with 2-L solutions of NaHCO3 (150 mmol/L), glucose (300 mmol/L), and glucose + NaHCO3 (300 mmol/L + 150 mmol/L, respectively) in randomized order. Arterial and venous blood was obtained before treatment and in 30-min intervals thereafter for blood gas analysis and determination of plasma protein and electrolyte concentrations. Urine was collected volumetrically to determine urine volume, osmolality, pH, net acid excretion, and renal Na excretion after treatment. Plasma volume changes were extrapolated from plasma protein concentration changes. Treatment and time effects were tested with repeated measures ANOVA. Only subtle differences between oral administration of NaHCO3, with and without glucose, were observed for the change of the standard HCO3 concentration relative to baseline. No differences in plasma Na, plasma volume expansion, renal Na, net base excretion, urine volume, or pH could be identified between animals treated orally with NaHCO3 with and without glucose. Similarly, no differences in blood glucose concentration, plasma volume expansion, urine volume, or renal glucose excretion were observed in the 8h after treatment when comparing oral glucose treatment with and without NaHCO3. Our results indicate that combination of NaHCO3 with glucose in a hypertonic ORS only had a minor effect on the alkalinizing effect of NaHCO3, which is unlikely to be of clinical relevance. The combination of NaHCO3 and glucose neither improved Na, glucose, nor water absorption in euhydrated neonatal dairy calves, questioning the relevance of a specific ratio between Na and glucose in ORS for calves.