The stability and automatic determination of ketone bodies in blood samples taken in field conditions

Association between hyperketolactia and production in early-lactating dairy cows

Study aims were to investigate associations of hyperketolactia (HYKL) status of Holstein dairy cows between 6 and 60 d in milk (DIM), defined by milk acetone (mACE) and β-hydroxybutyrate (mBHB) content, with daily milk yield and composition. Milk samples (∼5.0 million) were collected over a 5-yr period (2014-2019) within the milk recording system in Poland. Concentrations of mACE and mBHB determined by Fourier-transform infrared spectroscopy were used to categorize samples into 4 ketolactia groups. Based on threshold values of ≥0.15 mmol/L mACE and ≥0.10 mmol/L mBHB, ketolactia groups were normoketolactia (NKL; mACE <0.15 mmol/L and mBHB <0.10 mmol/L), BHB hyperketolactia (HYKLBHB; mACE <0.15 mmol/L and mBHB ≥0.10 mmol/L), ACE hyperketolactia (HYKLACE; mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L), and ACE and BHB hyperketolactia (HYKLACEBHB; mACE ≥0.15 mmol/L and mBHB ≥0.10 mmol/L). To investigate ketolactia association with production outcomes, a linear model was developed, including ketolactia group, DIM, parity, their interactions, year-season as fixed effects, and random effects of herd and cow. Among all milk samples, 31.2% were classified as HYKL, and of these, 52.6%, 39.6%, and 7.8% were HYKLACEBHB, HYKLBHB, and HYKLACE, respectively. Ketolactia groups differed for all traits studied in all parities and DIM. Among HYKL groups, lowest milk yield was found in HYKLACEBHB cows, except for 6 to 30 DIM in first- and second-lactation cows. Milk yield of HYKLBHB cows was higher than that of NKL cows until 20 to 30 DIM, and then it was lower than NKL cows. Milk yield of HYKLACE cows was mostly lower than NKL cows. Energy-corrected milk (ECM) yield of HYKLACEBHB cows was higher than that of NKL cows until 30 to 35 DIM for second lactation and third lactation or greater, and in the whole study period for first lactation. The yield of ECM for HYKLBHB cows was mostly higher than that of NKL cows, whereas HYKLACE cows had higher ECM than NKL cows until 15 to 25 DIM and then was lower for the HYKLACE group. Milk composition differed among HYKL groups. Highest milk fat (MF) and lowest milk lactose (ML) contents were observed in HYKLACEBHB cows. Cows in HYKLACEBHB and HYKLBHB groups had higher MF and lower milk protein (MP; except in 6-8 DIM in first lactation) and ML content than NKL cows. Milk fat content was higher in HYKLACE than NKL cows in first lactation and during the first 30 to 40 DIM in older cows. Lactose content was lower in HYKLACE than in NKL cows within 30 to 40 DIM; afterward it was higher in NKL cows. Lower MP content was found in HYKLACE than in NKL cows, except during 6 to 9 DIM for cows in first lactation and third lactation or greater. In conclusion, HYKL is associated with altered milk production in all parities, but a range of these negative relations depends on ketone status addressing both ACE and BHB contents. Further research is needed to ascertain underpinning biochemical defects of HYKL from elevated ACE, alone or in combination with BHB, during early lactation.

Association of High Somatic Cell Counts Prior to Dry off to the Incidence of Periparturient Diseases in Holstein Dairy Cows

Intramammary infections (mastitis) of dairy cows, along with other periparturient diseases, have become problematic within the dairy industry as they lead to loss of milk production. The main objective of this study was to determine whether elevated somatic cell counts (SCC) in cows prior to drying off are related to the incidence of other periparturient diseases. Additionally, we determined whether milk composition and milk yield are affected by a high SCC prior to drying off. Somatic cell counts of milk samples were determined prior to dry off (n = 140) and were used to classify cows in the study as high (>200,000 cells/mL) or low (<200,000 cells/mL) SCC. The composition of milk was analyzed before drying off and at 1 and 2 weeks after calving. The results showed that an elevated SCC before drying off was related to the incidence of ketosis. Cows with a high SCC at drying off also showed an increased likelihood of retained placenta, metritis, and lameness postpartum; however, it was not statistically significant. Milk lactose was lower in cows with high SCC, whereas protein content was lower after parturition. Milk production was lower for cows with pre-drying elevated SCC, particularly for cows with retained placenta, ketosis, and mastitis. In conclusion, cows with pre-drying elevated SCC were more likely to develop disease after parturition and produce less milk and with lower lactose and protein content.

Comparison of two diagnostic methods through blood and urine sample analyses for the detection of ketosis in cattle

Background and Aim:

Several Ecuadorian farms use human test strips (cheaper than veterinary strips) to diagnose bovine ketosis; however, their reliability is unknown. This study aimed to determine the confidence level of human strips for the detection of ketosis in bovines by comparing two diagnostic methods for ketosis: one used in bovines (gold standard) to analyze blood samples and the other used in humans to analyze urine samples.

Materials and Methods:

The study was conducted on an Ecuadorian farm using 50 animals, ten from each of five categories: heifers, 4 months pregnant (4MP), 15 days prepartum (15DPRE), 15 days postpartum (15DPOST), and 42 days postpartum (42DPOST). Blood samples were collected through coccygeal venipuncture and urine samples were collected during spontaneous urination. BHBCheck™ assay was used to measure b-hydroxybutyrate (BHB) in the blood, whereas Combur10Test^® was used to measure acetoacetate (AcAc) in urine for the determination of ketosis.

Results:

BHB was detected in all animals. Based on a ketosis cutoff point of 0.8-1.2 mmol/L, 13 animals from the 15DPOST and 42DPOST categories had ketosis; AcAc was detected in the urine from nine animals originated from the two same categories. Metabolites, either BHB or AcAc, were not detected in heifers, 4MP, or 15DPRE individuals. Finally, the BHBCheck™ assay had better efficiency in detecting ketosis in animals (p<0.05) than the Combur10Test^®.

Conclusion:

Combur10Test^® urine strips reached 92% reliability for the detection of ketosis in dairy cattle, compared to BHBCheck™ assays.

Characterization of ketolactia in dairy cows during early lactation

Fourier transform infrared spectroscopy (FTIR) allows for the determination of milk acetone (mACE) and β-hydroxybutyrate (mBHB) concentrations, providing a potential herd monitoring tool for hyperketolactia, defined as elevated milk ketone bodies. The study aim was to characterize mACE and mBHB concentration dynamics during early lactation in Polish Holstein-Friesian cows. Milk samples (n = 3,867,390) were collected within 6 to 60 days in milk (DIM) over a 4-yr period (April 1, 2013 to March 31, 2017) from approximately 21,300 dairy herds (average 38.7 cows/herd). Fixed effects of parity, DIM, and their interaction on mACE and mBHB concentrations were determined using a mixed model with a herd-year-season fixed effect and random cow effect. Published hyperketolactic mACE (≥0.15 mmol/L) and mBHB (≥0.10 mmol/L) threshold concentrations were used to classify study milk samples into ketolactia groups of normal (mACE <0.15 mmol/L and mBHB <0.10 mmol/L) and hyperketolactic (HYKL; either mACE ≥0.15 mmol/L or mBHB ≥0.10 mmol/L). Additionally, HYKL samples were categorized into subpopulations as having elevated mBHB and mACE (HYKL_ACEBHB, mACE ≥0.15 mmol/L and mBHB ≥0.10 mmol/L), only elevated mBHB (HYKL_BHB; mACE <0.15 mmol/L and mBHB ≥0.10 mmol/L), or only elevated mACE (HYKL_ACE; mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L). Effects of parity, DIM, ketolactia group or subpopulation, and their interactions on mACE and mBHB concentrations were also determined using the mixed model that included ketolactia group or subpopulation as an independent variable. Across all data, mACE and mBHB concentrations were influenced by effects of parity, DIM, and their interaction as well as parity, DIM, ketolactia group or subpopulation, and their interactions. For all samples, mACE and mBHB concentrations decreased with increasing DIM, with mACE concentration declining more rapidly compared with mBHB. In the data set, 68% and 32% of all samples were defined as normal or HYKL, respectively. Among HYKL samples, mACE was elevated soon after calving and declined over time. In contrast, mBHB started lower after calving and increased reaching peak concentrations around 30 DIM, and then decreased. Within HYKL samples, 50.8, 41.3, and 7.9% were categorized as HYKL_ACEBHB, HYKL_BHB, and HYKL_ACE respectively. Between 6 and 21 DIM, 11.3% of HYKL were classified as HYKL_ACE. Primiparous cows had greater (14.8%) HYKL_ACE samples in this time period. In conclusion, this study has characterized mACE and mBHB concentrations during early lactation and determined effects of parity, DIM, and their interaction. Using published criteria interpreting mACE and mBHB concentrations, it was intriguing to identify a unique population of samples having elevated mACE without mBHB in early lactation, especially in primiparous cows. Further research is needed to determine if this sample population represents an unhealthy metabolic status that adversely affects cow health and performance.

Ketone bodies - causes and effects of their increased presence in cows' body fluids: A review

Ketosis is the most common metabolic disease in high-performance dairy cows during the first 6-8 weeks of lactation. Its main symptoms include an excessive amount of so-called ketone bodies in a cow's body fluids. Ketone bodies consist of β-hydroxybutyric acid (βHBA), acetoacetic acid, and acetone. βHBA is the main component with its share of the total volume of ketone bodies in the blood of about 70%. Clinical symptoms of ketosis in cows include loss of appetite, preference for forage to concentrated feed, and acetone odor in their mouth and urine. Those symptoms are accompanied by a production drop, an increase of concurrent illness (mastitis, metritis, and displaced abomasum), and poor reproductive performance. One of the ketosis characteristic effects is an increase in the level of fat in milk (>5%), while protein levels decrease (<2.9%). In the case of subclinical ketosis (SCK), the fat-protein ratio in milk is increased to above 1.4:1. The current consensus for SCK is to consider a cutoff point of βHBA to be at least 1.2 mmol/L in blood plasma. Ketosis prevention is based on keeping perinatal cows in good condition, that is, with around 3.5 points in the five-point body condition scoring, carefully balancing food doses during the first 2 months of lactation with the correct energy-protein ratio. Glucose precursor products should be administered orally, in particular to at-risk herds. Ketosis occurs in 7-14% on average of the total number of cows in a herd. In general, data on the prevalence of SCK vary considerably, depending on their source. Moreover, the problem is mostly observed in poorly-fed animals with high milk production potential. The objectives of this review are to reveal the current situation of ketosis prevalence, the possibility of diagnosis, consequences in dairy cows and to provide some recommendations for ketosis treatment and prevention.

Evaluation of some metabolic profile parameters in transition cows: thresholds for estimating postpartum diseases in Aydin province

This study aimed to evaluate non-esterified fatty acids (NEFA), beta hydroxybutyric acid (BHBA), magnesium (Mg2+), calcium (Ca2+) and lactate as biological tests for the detection of some metabolic diseases during transition period in selected dairy farms located in Aydın province. Cow-side analysis with body condition score evalutation were performed weekly in at least 12 dairy cattle from each farm from prepartum week 2 to postpartum week 2. According to the prepartum NEFA ≥0.4 mmol/L, postpartum BHBA ≥1.4 mmol/L and Ca2+ ≤ 2.0 mmol/L at parturition (day 0) in herd-based evaluation, it was observed that all farms were positively evaluated for negative energy balance and also at risk for subclinical hypocalcaemia. Regarding the threshold value of Mg2+ <0.61 mmol/L, subclinical hypomagnesaemia was observed at the Ist and IInd farms. It was concluded that prepartum NEFA threshold (0.68 mmol/L), obtained from the receiver operating characteristics statistical analysis could be used for observing some postpartum clinical diseases. It was suggested that it allowed planning and strategic interventions to prevent herd-based diseases in Turkey and will be a precedent for future studies and herd management.

Ketosis an Old Story Under a New Approach

Ketosis, characterized by high concentrations of ketone bodies in the blood, urine, and milk, affects a considerable number of cows immediately after calving. Although much is known about ketosis, dairy cows continue to be affected in every herd world-wide. Cows affected by ketosis are treated with palliative treatments after the disease is diagnosed. This is a very expensive approach and costs the dairy industry extra expenses, contributing to lower profitability of dairy herds. In this review article, we summarize the mainstream view on ketosis, classification of ketosis into three types, current diagnostic approaches to ketosis, and the economic impact of ketosis on dairy farms. Additionally, we discuss the most recent applications of the new ‘omics’ science of metabolomics in studying the etiopathology of ketosis as well as its contribution in identification of novel screening or diagnostic biomarkers of ketosis.

Dairy cows affected by ketosis show alterations in innate immunity and lipid and carbohydrate metabolism during the dry off period and postpartum

The objective of this investigation was to search for alterations in blood variables related to innate immunity and carbohydrate and lipid metabolism during the transition period in cows affected by ketosis. One hundred multiparous Holstein dairy cows were involved in the study. Blood samples were collected at -8, -4, week of disease diagnosis (+1 to +3weeks), and +4weeks relative to parturition from 6 healthy cows (CON) and 6 cows with ketosis and were analyzed for serum variables. Results showed that cows with ketosis had greater concentrations of serum β-hydroxybutyric acid (BHBA), interleukin (IL)-6, tumor necrosis factor (TNF), serum amyloid A (SAA), and lactate in comparison with the CON animals. Serum concentrations of BHBA, IL-6, TNF, and lactate were greater starting at -8 and -4weeks prior to parturition in cows with ketosis vs those of CON group. Cows with ketosis also had lower DMI and milk production vs CON cows. Milk fat also was lower in ketotic cows at diagnosis of disease. Cows affected by ketosis showed an activated innate immunity and altered carbohydrate and lipid metabolism several weeks prior to diagnosis of disease. Serum IL-6 and lactate were the strongest discriminators between ketosis cows and CON ones before the occurrence of ketosis, which might be useful as predictive biomarkers of the disease state.

Elevated non-esterified fatty acids and β-hydroxybutyrate and their association with transition dairy cow performance

Dairy cows pass through a period of negative energy balance as they transition from late gestation to early lactation. Poor adaptation through this period, expressed as excessively elevated concentrations of non-esterified fatty acids (NEFAs) pre- or post-partum and elevated concentrations of β-hydroxybutyrate post-partum, increases an individual animal's risk of post-partum disease, removal from the herd, reproductive difficulty, and reduced milk production. Field studies have shown that subclinical ketosis often affects 40% of cows in a herd although the incidence can be as high as 80%. Peak incidence occurs at 5 days in milk, and cows that develop subclinical ketosis in the first week of lactation have a higher risk of negative effects and reduced milk production than cows that develop subclinical ketosis in the second week of lactation. Herds with more than a 15-20% prevalence of excessively elevated concentrations of NEFAs and β-hydroxybutyrate in early lactation have higher rates of negative subsequent events, poorer reproduction, and lower milk yield than herds with a lower prevalence of negative energy balance. This paper reviews (1) strategies for testing of energy-related metabolites, (2) consequences of poor adaptation to negative energy balance (for individual animals and for herds), (3) treatment approaches for affected cows, and (4) economic considerations for testing and treating cows with poor adaptation to negative energy balance.

Metabolism of Silage Alcohols in Lactating Dairy Cows

Dairy cows fed silage are subjected to various alcohols and low molecular weight esters. Four lactating Holstein cows fitted with ruminal cannulas and permanent indwelling catheters in the hepatic portal vein, hepatic vein, mesenteric vein, and mesenteric artery were used to study the absorption of alcohols into portal blood and the metabolism of feed alcohols in the rumen and splanchnic tissues. The cows were allocated to 4 experimental treatments in a Latin square design. All treatments were formulated as total mixed rations with the same overall nutrient composition, differing by the source of corn silage. Treatments were a control silage and 3 qualities of problematic corn silage (silage with Fusarium toxin, Penicillium-infected silage, and silage with a high propanol content). Feeding was followed by a decreasing ruminal pH, as well as decreasing molar proportions of ruminal acetate and isobutyrate. The ruminal concentrations of total VFA, ethanol, propanol, 2-butanol, ethyl acetate, propyl acetate, glucose, and L-lactate, and molar proportions of propionate, butyrate, isovalerate, valerate, and caproate increased after feeding. Treatments affected ruminal concentrations of propanol, propyl acetate, and butyrate and a strong correlation was observed between ruminal propyl acetate and the molar proportion of butyrate (r = -0.79). Arterial concentrations of ethanol, propanol, propanal, acetone (sum of acetone and acetoacetate), 3-hydroxybutyrate, L-lactate, glutamate, and glutamine increased, and the arterial concentration of glucose decreased after feeding, but no effects of treatment were observed for arterial variables. The postprandial increase in arterial ethanol was maintained for 5 h. The net portal release of ethanol tended to decrease with the treatment with the lowest ethanol content, and the net splanchnic release of ethanol increased after feeding, but overall, the net splanchnic flux of ethanol was not different from zero, in agreement with the liver being the major organ for alcohol metabolism. The net portal flux and net hepatic flux of propanol were affected by treatment. All dietary ethanol and propanol were accounted for by absorption of the respective alcohol into the portal blood. The hepatic extraction ratios of ethanol and propanol were, on average, 63 to 66%, and no indications of saturation of hepatic alcohol metabolism were observed at any time. We concluded that typical amounts of alcohols in corn silage do not interfere with splanchnic metabolism of any of the measured variables and do not saturate hepatic pathways for alcohol metabolism. However, even low concentrations of alcohols in feed might affect ruminal metabolism and are followed by hours of elevated peripheral blood concentrations of alcohols.

Fluorometric Determination of β-Hydroxybutyrate in Milk and Blood Plasma

Determination of beta-hydroxybutyrate (BHBA) in blood and milk samples is an important tool in the diagnosis of ketosis in dairy cattle. Apart from semiquantitative cow-side tests, well-established laboratory methods exist for measurements in blood serum or plasma. These spectrophotometric methods are, however, neither convenient nor reliable when transferred to analyses of milk. Due to its nontransparent nature, milk needs extensive pretreatment if traditional analyses are to be used. This paper describes a fluorometric determination of BHBA that is useful without pretreatment in opaque matrices such as milk and in blood plasma. The method is easy to automate, saves labor expenses, and is inexpensive. The analytical accuracy and precision are reliable for intensive as well as large-scale analysis; for example, in-line sampling from automatic milking systems. Analysis of 2500 random milk samples showed a BHBA content ranging from 10 to 631 microM (mean 49 microM). Furthermore, selected samples (n = 295) from diagnosed ketotic animals taken on d -35 to +35 from peak level ranged from 10 to 684 microM (median 79 microM, mean 141 microM). Using the same 1240 blood plasma samples, the fluorometric method was closely correlated with a traditional spectrophotometric method (r = 0.987). Hemolysis of samples does not appear to affect the fluorometric determination of BHBA.

Monitoring and testing dairy herds for metabolic disease

Clinical impressions of metabolic disease problems in dairy herds can be corroborated with herd-based metabolic testing. Ruminal pH should be evaluated in herds showing clinical signs associated with SARA (lame cows, thin cows, high herd removals or death loss across all stages of lactation, or milk fat depression). Testing a herd for the prevalence of SCK via blood BHB sampling in early lactation is useful in almost any dairy herd, and particularly if the herd is experiencing a high incidence of displaced abomasum or high removal rates of early lactation cows. If cows are experiencing SCK within the first 3 weeks of lactation, then consider NEFA testing of the prefresh cows to corroborate prefresh negative energy balance. Finally, monitoring cows on the day of calving for parturient hypocalcemia can provide early detection of diet-induced problems in calcium homeostasis. If hypocalcemia problems are present despite supplementing anionic salts before calving, then it may be helpful to evaluate mean urinary pH of a group of the prefresh cows. Quantitative testing strategies based on statistical analyses can be used to establish minimum sample sizes and interpretation guidelines for all of these tests.

Adaptation of an automated assay for determination of beta-hydroxybutyrate in dogs using a random access analyzer

An automated method for measuring beta-hydroxybutyrate was adapted to the Ciba-Corning 550 Express trade mark random access analyzer. The assay was based on a kinetic reaction utilizing hydroxybutyrate-dehydrogenase. Beta-hydroxybutyrate concentration (mmol/L) was calculated ratiometrically using a 1.0 mmol/l standard. Canine serum, plasma, and urine were used without prior deproteinization and only a 30-microliter sample was required. The method demonstrated good linearity between 0 to 2 mmol/l of beta-hydroxybutyrate. Analytical recovery (accuracy) within these concentrations ranged from 85.8 to 113.3%. Both within-run and day-to-day precision were determined, as was specificity of the assay in the presence of a variety of interfering substances. The automated assay was rapid and economical, with reagent stability maintained for at least 2 weeks at 4 degrees C. This assay can readily be applied toward the assessment of ketoacidosis in dogs, and with further validation, other species.

Relationship between concentration of citrate and ketone bodies in cow's milk

The authors' hypothesis is that the members of the tricarboxylic acid cycle (TCA cycle) such as citrate decrease in association with increased ketone body formation. To prove this hypothesis the connection between ketone bodies and citrate formation of milk was studied. A fluorimetric method was used to determine citrate and a headspace sampling gas chromatographic (GC) method was developed for determination of ketone bodies. Under real conditions of milk sampling, transport and storage, preserved milk samples of 119 clinically healthy dairy cows obtained in the 48 hours after milking were investigated. A low level of acetoacetate (ACAC) was found in all samples. This fact can be explained by the spontaneous decarboxylation of acetoacetate during sample storage (previously decarboxylised acetoacetate = pdACAC) and, consequently, the majority of the amount of acetoacetate in the samples (AC + pdACAC) appeared in the measured acetone concentrations. Based on the measured acetone concentration of milk samples two groups were formed retrospectively: HA (high-acetone) group (n = 41) with an AC + pdACAC concentration of > 0.4 mmol/l and a LA (low-acetone) group (n = 78) with an AC + pdACAC level of < or = 0.4 mmol/l. In the milk of cows of Group HA a positive correlation (r = +0.623) and linear connection between acetone (AC + pdACAC) and beta-hydroxybutyrate (BOHB) levels was found [BOHB = 2.491 + 0.586 x (pdAC + ACAC)]. Furthermore, in this group a negative correlation between citrate and BOHB and AC + pdACAC was also established (r = -0.579). Focusing on the results of this group the authors found a significant drop of AC + pdACAC and citrate during the metabolically critical first 1-4 weeks of lactation. For this reason they suggest that simple, easy, automated methods (i.e. flow injection analysis, Fourier transformation infrared analysis) should be introduced for the simultaneous determination of acetone and citrate concentration in milk to make the evaluation of the energy status of high-producing dairy cows easier and more certain.

Ketone bodies in milk and blood of dairy cows: relationship between concentrations and utilization for detection of subclinical ketosis

The objective of this study was to investigate the relationship between the concentrations of the different ketone bodies in milk and blood and to evaluate these concentrations for the detection of subclinical ketosis. A total of 60 multiparous cows were used. Concentrations of acetone, acetoacetate, and beta-hydroxybutyrate were analyzed quantitatively in blood and milk, and the Ketolac strip test was used for semiquantitative determination of beta-hydroxybutyrate in milk. Cows were defined subclinically ketotic when their concentration of blood beta-hydroxybutyrate was over 1200 micromol/L. High correlation coefficients were observed between blood acetone and blood acetoacetate, and between blood and milk acetone. On the contrary, concentrations of milk and blood beta-hydroxybutyrate were poorly correlated with the other concentrations of ketone bodies. The Ketolac strip test overestimated the concentrations of beta-hydroxybutyrate in milk. For the detection of subclinical ketosis, the best sensitivity-specificity combination was obtained with the determination of acetoacetate in blood or milk, with threshold concentrations of 125 and 50 micromol/L, respectively. Determination of beta-hydroxybutyrate in the milk via an enzymatic analysis or via the Ketolac strip test provided valuable results, with threshold concentrations of 70 and 100 micromol/L, respectively. The simplicity of use of the Ketolac strip test makes it a valuable way to investigate subclinical ketosis.

Subclinical ketosis in lactating dairy cattle

Subclinical ketosis is an important and common condition of early-lactation dairy cattle. It is associated with losses in milk production and increased risk of periparturient disease. Prevention depends on several factors, including proper transition-cow nutrition, management of body condition, and the use of certain feed additives such as niacin, propylene glycol, and ionophores. All currently available cowside tests for subclinical ketosis have certain limitations in their use. Effective monitoring schemes for subclinical ketosis can be developed, however, and these may be useful in many herd health programs.

Suppression of feed intake after parenteral administration of D-beta-hydroxybutyrate in pygmy goats

The effect of intraperitoneal injection of D,L- or D-beta-hydroxybutyrate on feed intake and plasma metabolites was investigated in pygmy goats. The combined intraperitoneal injection of D,L-beta-hydroxybutyrate or D-beta-hydroxybutyrate (15 mmol/kg0.75) and 1,3-butanediol (6.6 mmol/kg0.75), a ketogenic substrate, decreased cumulative food intake while the same dose of 1,3-butanediol or DL-beta-hydroxybutyrate alone had no effect. The decrease in food intake after combined injection of D-beta-hydroxybutyrate and 1,3-butanediol was characterized by a significant decrease in meal frequency and a prolongation of the latency to eat. The hypophagic effect of the combined injection of D-beta-hydroxybutyrate and 1,3-butanediol was significant for 8 h, while the hypophagia after D,L-beta-hydroxybutyrate and 1,3-butanediol was significant for only 2 h after injection. Injection of D,L-beta-hydroxybutyrate increased plasma D-beta-hydroxybutyrate levels to 0.55 mmol/l and decreased plasma free fatty acids. Addition of 1,3-butanediol (6.6 mmol/kg0.75) to the injection increased plasma D-beta-hydroxybutyrate level up to 0.75 mmol/l. The results show that parenteral administration of D-hydroxybutyrate reduces feed intake in pygmy goats and that the hypophagia appears to be related to the amount of D-beta-hydroxybutyrate injected. The hypophagia seems to be related to elevated plasma D-beta-hydroxybutyrate concentration, and the threshold concentration appeared to be about 0.7 mmol/l under the experimental conditions of this study.

The association between selected metabolic parameters and left abomasal displacement in dairy cows

The objective of this study was to examine the association between selected metabolic parameters and subsequent left displaced abomasum (LDA) diagnosis in dairy cows. Forty-four LDA cows sampled in the third week ante partum (a.p.) which was at a median of 34 days prior to LDA diagnosis, 36 LDA cows sampled in the first week post partum (p.p.) which was at a median of 14 days prior and 28 LDA cows sampled in the second week p.p., which was at a median of 9 days prior to LDA diagnosis were used. Each case was matched to 3 controls by herd and calving date. Data were available from a large field study. Aspartate-aminotransferase (AST) activity, the concentrations of beta-hydroxybutyrate (BHB), glucose, calcium and urea in blood, and the body condition score (BCS) were studied. Logistic regression was used to analyse the association between these parameters and subsequent LDA, adjusting for the effects of parity and pretreatment. A separate model was used for each sampling week and each parameter. In the third week a.p. none of the parameters were significantly associated with LDA. AST and BHB sampled in the first week p.p. and in the second week p.p. were significantly associated with LDA diagnosis. The higher the AST and BHB, the higher the odds of being diagnosed subsequently with LDA. The lower glucose and Ca in the second week p.p. the higher the odds of subsequent LDA diagnosis. Urea and BCS were not significantly associated with LDA in any of the weeks examined. We conclude that AST and BHB in the first and second week p.p. might be used as tests for subsequent LDA. Glucose, calcium, urea and body condition were either not significantly associated with LDA or significantly associated only in the second week p.p.; this may limit their use as tests for LDA.

Evaluation of five cowside tests for use with milk to detect subclinical ketosis in dairy cows

The objective of this study was to evaluate the characteristics of five ketone tests for use with milk to detect subclinical ketosis [defined as > 1200 mumol of beta-hydroxybutyrate (BHBA)/L of blood] in dairy cows. The tests studied were the Ketolac BHB strip to detect BHBA (Hoechst, Unterschleissheim, Germany) and four tests based on sodium nitroprusside to detect acetoacetate (Rothera tests) [Ketostix strip (Bayer, Etobicoke, ON, Canada), Bioketone powder (Societé d' Analyses Biopharmaceutiques, Laval, QC, Canada), Ketocheck powder (Great States, St. Joseph, MO), and Utrecht powder (University of Utrecht, Utrecht, The Netherlands)]. Milk samples (n = 529) from 266 cows in 25 Ontario dairy herds were used for this investigation. The Ketolac BHB strip at 50 and 100 mumol of BHBA/L of milk showed sensitivities of 92 and 72%, respectively. This test was more sensitive for subclinical ketosis than were any of the Rothera tests. The sensitivities of the Rothera tests were 43, 33, 28, and 5%, respectively, for Utrecht powder, Bioketone powder, Ketocheck powder, and Ketostix strip. The Rothera tests were highly specific, as was the Ketolac BHB strip at 200, 500, and 1000 mumol of BHBA/L of milk (specificity, > 97%). The prevalence of subclinical ketosis was highest during the first 6 wk of lactation, and a peak was detected during the 2nd wk of lactation. Of the tests evaluated in this study, Ketolac BHB strip was the most useful to monitor subclinical ketosis in dairy herds.

Evaluation of two cowside tests for the detection of subclinical ketosis in dairy cows

The goal of this study was to evaluate the sensitivity and specificity of two cowside tests for subclinical ketosis in dairy cows. The tests utilize milk and urine samples, respectively. One hundred and eighty-five cows, one to sixty days postpartum, were sampled for milk, urine, and blood. Subclinical ketosis was defined with serum beta-hydroxybutyrate measurements. The sensitivity and the specificity of both tests at different beta-hydroxybutyrate levels were estimated. When subclinical ketosis was defined at beta-hydroxybutyrate levels of 1.4 mmol/L and higher, the milk test had sensitivity of 90% and specificity of 96%. The urine test lacked specificity (values < 67%), but sensitivity was 100% at beta-hydroxybutyrate levels of 1.4 mmol/L upward. Both the milk and urine test can be used to monitor subclinical ketosis in a herd. Milk testing is preferred, because of the easy obtainability of milk combined with the overall better test characteristics.

Plasma protein synthesis and serum amino acids in dry and lactating dairy cows

Blood serum concentrations of protein, albumin, prealbumin, transferrin, amino acids and urea were measured in 31 healthy cows 0 to 6 weeks before and 3 to 8 weeks after parturition. In comparison to the precalving values the concentrations of albumin, prealbumin and transferrin were all lower after parturition. Alanine, glutamine, leucine, methionine, serine, and urea concentrations were also lower after calving. Multiple correlation analysis between plasma protein and amino acid concentrations reveals that the synthesis of export proteins in liver may be reduced due to limitation in amino acid availability.

Influence of feeding intensity on blood concentrations of glucose, ketone bodies and free fatty acids in nutritionally adapted dairy cows fed 24 times daily

Concentrations of acetoacetate, D-3-hydroxybutyrate, glucose and free fatty acids were determined in blood from 3 Jersey cows during a 5-months period. The cows were fed an identical complete feed every hour, from ad libitum intake to maintenance level, for 28 days at each of the following levels of intake: 170, 138, 102, 53 and 37 g organic matter per kg bodyweight0.75 (metabolic bodyweight). Throughout the experimental period, the cows were in negative energy balance, which was reflected in an average weight loss of 640 g per day. None of the metabolites differed from reference values for healthy lactating cows. The concentration of D-3-hydroxybutyrate decreased linearly with the level of feeding and reflected a decreased ruminal production of butyrate. The high feeding frequency to lactating cows may be considered an essential factor in the prevention of ketosis.

Influence of feeding intensity on blood concentrations of glucose, ketone bodies and free fatty acids in nutritionally adapted dairy cows fed 24 times daily

Concentrations of acetoacetate, D-3-hydroxybutyrate, glucose and free fatty acids were determined in blood from 3 Jersey cows during a 5-months period. The cows were fed an identical complete feed every hour, from ad libitum intake to maintenance level, for 28 days at each of the following levels of intake: 170, 138, 102, 53 and 37 g organic matter per kg bodyweight0.75 (metabolic bodyweight). Throughout the experimental period, the cows were in negative energy balance, which was reflected in an average weight loss of 640 g per day. None of the metabolites differed from reference values for healthy lactating cows. The concentration of D-3-hydroxybutyrate decreased linearly with the level of feeding and reflected a decreased ruminal production of butyrate. The high feeding frequency to lactating cows may be considered an essential factor in the prevention of ketosis.

Metabolism of propionate, glucose, and carbon dioxide as affected by exogenous glucose in dairy cows at energy equilibrium

In vivo kinetic techniques were used to quantify changes in metabolism of propionate, glucose, and blood CO2 when glucose was infused intravenously at 0, 342, or 737 g/d into four lactating cows. Neither production of milk or milk fat nor composition of milk was changed. Production of milk protein increased for the high glucose treatment. Isotope dilution data were used to calculate irreversible losses of rumen propionate, plasma glucose, and blood CO2 and to determine a unique solution for flux of C in this three-pool system. Irreversible losses of propionate and CO2 were not changed. Infusions of glucose increased irreversible loss of glucose in proportion to amounts infused, thus indicating there was no change in endogenous production of glucose. For the control, 52% of the C flux of blood glucose was derived directly from rumen propionate and another 26% came from other gluconeogenic substrates. Flux of C into glucose from exogenous sources increased in proportion to amounts of glucose infused. Flux of C from rumen propionate remained constant. The rate of C leaving the glucose pool, other than as CO2, tended to increase with infusion of glucose, and oxidation of glucose tended to increase for the high glucose treatment. High producing cows adjusted to increased exogenous glucose by increasing glucose utilization and without decreasing endogenous glucose production.

Subclinical ketosis in dairy cows

Subclinical ketosis is defined as a preclinical stage of ketosis. The peak prevalence of subclinical ketosis occurs during the fourth week of lactation. Herd-related factors, breed, parity, and season are other important determinants. Subclinical ketosis can be revealed by determining levels of plasma glucose, plasma NEFA and blood, and milk or urine ketone body concentration. There are theoretical and practical advantages of using milk ketone bodies. Most authors are agreed on approximate lower and upper borderlines for subclinical ketosis. The risk of an outbreak of clinical symptoms has been evaluated by some authors. Most authors have found significant negative relationships between energy balance and ketone body concentration. Some disagreement may be attributable to the fact that the diets used in different experiments can have different glucogenic potential, even if the energy content is the same. This affects the relationship between energy balance and ketone body concentration, as the ketone body level is influenced by both the energy balance and plasma glucose. Feeding silage with high butyric acid content increases the risk of subclinical ketosis. There are indications that cows with the highest milk yield directly after calving are at greatest risk for developing ketosis. Increased ketone body level secondarily reduces milk production, a decrease that has been quantified by some authors. Subclinical ketosis causes delayed reproductive functions return to normal after calving, increased intervals from calving to first and last service, and an increased frequency of ovarian cysts. The routine determination of milk acetone levels in control programs can be used to evaluate the status of individual cows, to indicate the energy feeding in early lactation at a herd level, and to evaluate sires for breeding. The heritability and the tendency toward a positive genetic correlation between milk acetone and milk yield have also been discussed, as have aspects of nutritional prevention. Factors such as energy- and protein-rich roughage, tasty high-energy concentrates, suitable feeding during the dry period, and division of the concentrates into at least four meals are considered to be important.

Fat infiltration in the liver of Finnish Ayrshire cows during early lactation

The incidence and severity of fat infiltration in the liver of Finnish Ayrshire cows at 1 and 8 weeks after calving were studied. All multiparous (n = 88) and some primiparous (n = 17) cows that calved in 20 commercial milk recorded herds were investigated. The cows lost weight and a condition score decreased significantly (p < 0.05) during early lactation. Blood samples were taken at 1, 4 and 8 weeks after calving. Ketone body concentrations were highest at 4 weeks after calving. Albumin and total protein concentrations and ornithine carbamyltransferase activity in the blood increased significantly (p = < 0.05) from 1 to 8 weeks after calving. The percentage of liver fat (v/v) was significantly (p < 0.05) greater at 1 (3.9 ± 0.5 %) than at 8 weeks (1.2 ± 0.3 %) after calving. Eighty-nine of 102 cows had less than or equal to 9 % of fat in the liver (mean 2.3 ± 0.2 %), and 13 cows had more than 9% (mean 14.9 ± 1.2%) at 1 week after calving. Only blood acetoacetate and plasma aspartate aminotransferase differed significantly between the groups. In the fatty liver group the incidence rate of treated cases of ketosis was 30.8 ± 13.3 % and of parturient paresis 23.1 ± 12.2 %. In the non-fatty liver group the rates were 10.1 ± 3.2 % and 7.8 ± 2.9 %, respectively. The differences were not significant.

Effects of in vivo administration of growth hormone on milk production and in vitro hepatic metabolism in dairy cattle

Bovine growth hormone (50 IU/d) or placebo injections were administered for 11 consecutive d to Holstein cows (four per treatment) in midlactation. Growth hormone injections increased milk yield, efficiency of milk production, and concentrations of growth hormone and free fatty acids in plasma. Concentrations of beta-hydroxybutyrate and acetoacetate in whole blood and glucose in plasma were not affected by treatment. Liver biopsies were taken from both groups of cows 8 d prior to and on the last day of injection. Liver slices were used for in vitro incubations with carbon-14-labeled propionate, alanine, butyrate, and palmitate. Rates of substrate metabolism before and after placebo treatment were similar. Compared with pretreatment, however, liver slices from cows receiving growth hormone had significantly higher rates of propionate conversion to both glucose and carbon dioxide. There was also a nonsignificant increase in rate of alanine conversion to glucose and carbon dioxide. Growth hormone treatment did not change in vitro production of ketones or carbon dioxide from butyrate or palminate. Results indicate that growth hormone increases hepatic capacity for propionate metabolism and supports the concept that growth hormone partitions fatty acids for preferential use by mammary tissue.

Ultrastructural changes of the liver in spontaneously ketotic cows

The ultrastructure of the liver in normal, mildly ketotic and severely ketotic cows was studied using stereological methods. In the liver of severely ketotic cows there is: (1) a significant increase in the volume fraction of hepatocytes and a decrease in the volume fraction of sinusoids, and (2) an increase in the volume fraction of lipid and smooth endoplasmic reticulum and a decrease in the volume fraction of glycogen and Golgi in parenchyma. A decrease in the profile density of mitochondria per 1 mm2 field and an increase of the volume occupied by mitochondria were not significant nor was the decrease in the volume density of rough endoplasmic reticulum. The degree and duration of negative energy balance obviously affect the morphological changes of the fatty liver. However, additional work is needed to determine the significance of ultrastructural changes in liver function.

Treatment of bovine ketosis with invert sugar, glucocorticoids, and propylene glycol

Four different treatments of bovine ketosis, using 3 different pharmaceutical preparations, were monitored. The main antiketogenic and glucogenic ingredients of the preparations were as follows: invert sugar (Metabol), prednisolone and dexamethasone (Predasen), the former preparations combined (Metabol & Predasen) and propylene glycol and dexamethasone (Dexaprol). Blood samples were drained from the ketotic cows prior to the treatment. The animals were sampled again 2 and 7 days after the first sampling. The whole blood concentrations of acetoacetate (AA concn), β-hydroxybutyrate (BHB concn) and glucose (glue concn) were determined. The measures of the antiketogenic and glucogenic efficacy of the various treatments applied were their ability to reduce the AA concn and BHB concn and to elevate the gluc concn.

Invert sugar (Metabol) alone had no antiketogenic efficacy, although in some cases it led to a subjective clinical improvement as reported by the owners of the animals. Invert sugar and glucocorticoids (Metabol & Predasen) dexamethasone and prednisolone (Predasen) and dexamethason plus propylene glycol (Dexaprol) were equally effective in bringing the AA, BHB and glue concns to normal range. The mean glue concn of the cows treated with Dexaprol was higher than that of the cows in the other treatment groups at 2 days (P < 0.01). No other differences between the 3 antiketogenic treatments could be shown.

Fatty infiltration of liver in spontaneously ketotic dairy cows

The purpose of this study was to ascertain 1) fatty infiltration of the liver in spontaneously ketotic cows and 2) the most appropriate blood components to aid diagnosis of ketotic fatty liver. Liver biopsies and blood samples were obtained under field conditions. Cows were divided into three groups (healthy, mildly ketotic, and severely ketotic) by their blood ketone body concentrations. Severely ketotic cows had a greater percent fat in the liver than healthy cows. The mildly ketotic group fell between the other two groups and was significantly different from only the severely ketotic group. There was a positive correlation between fatty infiltration and blood ketone body concentrations but a negative correlation with glucose concentrations. Liver-specific enzymes were positively correlated with fatty infiltration. Only ornithine carbamoyltransferase and iditol (sorbitol) dehydrogenase could be used to separate healthy cows from those with severe ketosis. The best equation to explain the variation of percent fat in liver included concentration of beta-hydroxybutyrate (BHB) and logarithm of ornithine carbamoyltransferase concentration (Log-OCT): % Fat = -6.15 + 2.39 (BHB) + 11.7 (LogOCT) Although this equation explained 39.5% of the variation, it could not be used to predict reliably percent fat in the liver. Liver biopsy seems still to be the only reliable method of measuring of fatty infiltration in the liver.

Correlation of whole blood concentrations of acetoacetate, beta-hydroxybutyrate, glucose and milk yield in dairy cows as studied under field conditions

The whole blood concentrations of acetoacetate (AA concn), β-hydroxybutyrate (BHB concn) and glucose (gluc concn) of 662 Ayrshire and Friesian dairy cows were measured and their milk yield during the indoor-housing period was recorded. Simple correlations among these parameters were evaluated. The correlation between the AA concn and the BHB concn (r = 0.869) was statistically highly significant (P < 0.001), as were the correlations of the logarithmic value of the AA concn with the gluc concn (r = —0.471) and with the milk yield (r = 0.259), and the correlation between the BHB concn and the glue concn (r = —0.288). The milk yield was found also to be associated with the BHB concn and the glue concn (P< 0.001). The associations between each pair of blood parameters were highly significant, too (P < 0.001). The AA concn was taken to be at least as good an indicator of the energy status of dairy cows as the BHB concn and the gluc concn. The AA concn is not diet-derived like the BHB concn and not as stress-sensitive as the blood concentration of free fatty acids and its diurnal variation is not as wide as the BHB concn and the gluc concn in subclinically ketotic cows. Thus the AA concn may be used as a proxy of the energy status and the ketotic stage of dairy cows under field conditions.