Serum vitamin D concentrations at dry-off and close-up predict increased postpartum urine ketone concentrations in dairy cattle.

Vitamin D is commonly supplemented to dairy cows as vitamin D3 to support calcium homeostasis and in times of low sunlight exposure. Vitamin D has beneficial immunomodulatory and anti-inflammatory properties. Serum 25-hydroxyvitamin D [25(OH)D] concentrations fluctuated during lactation, with the lowest concentrations measured in healthy cows within 7 d of calving. However, it is unknown if serum 25(OH)D concentrations measured during the previous lactation are associated with transition diseases or health risk factors in dairy cattle. We collected serum samples from 279 dairy cattle from 5 commercial dairy herds in Michigan at dry-off, close-up, and 2-10 d in milk (DIM). Vitamin D concentrations were determined by measuring serum 25(OH)D by radioimmunoassay. Total serum calcium was measured by colorimetric methods. Body condition scores (BCS) were assigned at the time of blood collection. Clinical disease incidence was monitored until 30 d postparturition. Separate bivariable logistic regression analyses were used to determine if serum 25(OH)D at dry-off, close-up, and 2-10 DIM was associated with various clinical diseases including mastitis, lameness, and uterine disorders (classified as metritis, retained placenta, or both) and increased urine ketone concentrations at P < 0.05. Among all significant bivariable analyses, multivariable logistic regression analyses were built to adjust for potential confounding variables including parity, BCS, season, and calcium. Receiver operator characteristic (ROC) curve analyses were used to determine optimal concentrations of serum 25(OH)D. We found that higher serum 25(OH)D concentrations at dry-off and close-up predicted increased urine ketone concentrations in early lactation, even after adjustment for confounders. Alternatively, we found that lower serum 25(OH)D at 2-10 DIM was associated with uterine diseases. Optimal concentrations for serum 25(OH)D at dry-off and close-up for lower risk of increased urine ketone concentrations were below 103.4 and 91.1 ng/mL, respectively. The optimal concentration for serum 25(OH)D at 2-10 DIM for uterine diseases was above 71.4 ng/mL. These results indicate that serum 25(OH)D at dry-off and close-up may be a novel predictive biomarker for increased urine ketone concentrations during early lactation. Increased urine ketone concentrations are not necessarily harmful or diagnostic for ketosis but do indicate development of negative energy balance, metabolic stress, and increased risk of early lactation diseases. Predicting that dairy cattle are at increased risk of disease facilitates implementation of intervention strategies that may lower disease incidence. Future studies should confirm these findings and determine the utility of serum 25(OH)D concentrations as a predictive biomarker for clinical and subclinical ketosis.

Response of cattle with clinical osteochondrosis to mineral supplementation.

Since 1982, farmers in the North West province and other parts of South Africa have noticed an increase in the incidence of lameness in cattle. Macro- and microscopical lesions of joints resembled osteochondrosis. Pre-trial data indicated that cattle with osteochondrotic lesions recovered almost completely when fed a supplement containing bio-available micro- and macrominerals of high quality. In the present trial, 43 clinically affected cattle of varying ages (1-5 years) and sexes were randomly divided into three groups. Each group was fed the same commercial supplement base with differing micro- and macromineral concentrations to determine the effect of mineral concentrations on the recovery from osteochondrosis. Both supplements 1 and 2 contained 25% of the recommended National Research Council (NRC) mineral values. Additional phosphate was added to supplement 2. Supplement 3, containing 80% of the NRC mineral values, was used as the control. Results from all three groups indicated no recovery from osteochondrosis. Urine pH of a small sample of the test cattle showed aciduria (pH < 6). Supplement analysis revealed addition of ammonium sulphate that contributed sulphate and nitrogen to the supplement. Supplementary dietary cation anion difference (DCAD) values were negative at -411 mEq/kg, -466 mEq/kg and -467 mEq/kg for supplements 1, 2 and 3, respectively, whereas the pre-trial supplement was calculated at +19.87 mEq/kg. It was hypothesised that feeding a low (negative) DCAD diet will predispose growing cattle to the development of osteochondrosis or exacerbate subclinical or clinical osteochondrosis in cattle.

A nationwide survey of pathogenic leptospires in urine of cattle and buffaloes by Loop-mediated isothermal amplification (LAMP) method in Thailand, 2011-2013.

Leptospirosis is a worldwide distributed zoonosis which has long been endemic in Thailand. Cattle and buffaloes are important livestock species that live in close contact with humans, especially in rural areas. These animals may, therefore, act as long-term carriers of leptospirosis for humans and other livestock species. The present study employed loop-mediated isothermal amplification (LAMP) method to detect pathogenic leptospiral 16S rDNA in the urine of cattle and buffaloes for assessing associations between uroprevalence and species, sex, age and spatial distribution. A total of 3,657 urine samples were collected for laboratory diagnosis, and 312 of which turned positive to the test (true prevalence 5.90%; 95% CI 4.98-6.91). The highest true uroprevalence was found in lower northern region at 19.80% (95% CI 15.83-24.32) followed by upper and lower northeastern regions at 15.22% and 6.25%, respectively. However, the highest true uroprevalence in beef cattle, the majority of cattle in Thailand, was recorded in northeastern region which is the endemic area of human leptospirosis. The uroprevalence was not statistically different among species and types of examined animals. Male animals were over twice more likely to be infected compared to females. Excluding animals younger than one year of age due to small sample size, the uroprevalence upraised with increasing age. A collaborative investigation between veterinary and public health sectors is required to holistically explore the link between leptospirosis in humans and livestock, especially in high prevalent areas.

Urinary calcium excretion in non-lactating dairy cows in relation to intake of fat-coated rice bran.

At calving, many older cows fail to compensate the sudden demand of calcium by an adequate activation of intestinal absorption. This results in a variable degree of hypocalcaemia. Reducing intestinal availability of calcium during the close-up period can prevent milk fever. Fat-coated rice bran (FCRB) was investigated for its potential to reduce Ca availability in pre-calving cows. Fat-coated rice bran was incubated in situ to estimate ruminal degradation of dry matter and phytic acid. Also, seven dry multiparous dairy cows were used for a feeding trial in three periods of approximately 1 week each: P1: adaptation; P2: feeding of 2 kg of FCRB and P3: withdrawal of FCRB. Feed intake was recorded and daily urine samples were analysed for pH, Ca and creatinine. The bypass fraction of phytic acid (passage rate: 5%/h) was 30%. Fat-coated rice bran depressed dry matter intake in P2, resulting in a lower Ca intake. In P2 urine pH and calcium excretion were lower. Daily calcium excretion decreased after introduction of FCRB, peaked after withdrawal and dropped 2 days later. Changes in urinary Ca excretion by feeding FCRB indicate that FCRB affected Ca homeostasis in dry multiparous dairy cows.

Effect of intravenous calcium borogluconate and sodium phosphate in cows with parturient paresis.

Thirty cows with parturient paresis were divided into three groups of 10. All the cows were given 500 ml of a 40 per cent calcium borogluconate solution intravenously over a period of 10 minutes, and 20 were also given 500 ml of a 10 per cent solution of sodium phosphate intravenously; in 10 of the cows this solution was administered over a period of 10 minutes immediately after the calcium borogluconate solution, and in the other 10 cows 200 ml of the solution was administered rapidly and the remaining 300 ml was added to 10 litres of sodium chloride and glucose solution and infused slowly over six hours. There were no significant differences between the groups with respect to the outcome of the treatments; six or seven of the cows in each group stood within eight hours of the treatment. There were no significant differences between the changes in serum calcium concentrations among the groups. The mean concentrations of inorganic phosphorus in the groups given sodium phosphate were increased above the normal range initially, but after eight hours there were no significant differences between the groups in terms of the numbers of cows that were hypophosphataemic. There were no significant differences between the three groups with respect to changes after treatment in the serum concentrations of magnesium or parathyroid hormone.

Preventive effect of mildly altering dietary cation-anion difference on milk fever in dairy cows.

In the present study, we examined whether mildly altering dietary cation-anion difference (DCAD) contributes to the prevention of milk fever in dairy cows. Thirty multiparous cows and ten primiparous cows (heifer group) were used in this study and the multiparous cows were randomly divided into three groups of ten animals each (anion, non-anion and control groups). The cows in the anion group were given supplemental salts that slightly lowered DCAD. These salts consisted of 115 g of CaCO3, 42 g of CaHPO4, 65 g of MgSO4 x 7 H2O and 80 g of CaCl2 x 2 H2O as a daily dose for each cow, using a catheter from 21 days before the expected date of parturition until parturition. The cows in the non-anion group were given only the same Ca, Mg and ip supplement but no sulfate and chloride salts as that in the anion group. The cows in the control and heifer groups were not given any additional supplement. The incidence of hypocalcemia in the anion group decreased to approximately half of those in the non-anion and control groups, while the heifer group did not develop hypocalcemia at all. In addition, the number of days spent for the treatment of hypocalcemia and the number of drug bottles (calcium borogluconate solution) used for the treatment decreased to less than half in the anion group compared with those in the non-anion and control groups. At parturition, the serum Ca concentration in the control (6.2 +/- 1.9 mg/dl, mean +/- standard deviation) and non-anion groups (6.4 +/- 1.7 mg/dl) were significantly lower than that in the heifer group (8.3 +/- 0.4 mg/dl), and the level in the anion group was intermediate (7.3 +/- 1.3 mg/dl). The change in ionized Ca concentration was almost the same as that in serum Ca concentration, but only the concentration in the anion group tended to increase slightly from a week before parturition and was significantly higher than that in all other groups three days before parturition. Urinary pH in the anion group was maintained at a mildly acidic level (6.8-7.0) for the last two weeks before parturition, compared with those in the control (7.3-7.5) and non-anion groups (7.9-8.1), and similar to that in the heifer group (6.3-7.3). The urinary Ca excretion was the highest in the anion group among all groups during the prepartum period. There were no specific changes in the excretion of parathyroid hormone and 1,25-dihydroxyvitamin D in all groups of multiparous cows while the levels of these hormones remained low in the heifer group throughout the experimental period. The data in the present study indicates that the administration of anion salts that slightly lowered DCAD in the preparum period was effective for preventing milk fever in multiparous cows. Safe and mild metabolic acidosis induced by the anion salts could be evaluated by urinary pH (6.8-7.0), and might increase the responsiveness to Ca requirement at parturition through some complex mechanisms unrelated to the excretion of Ca-related hormones. In addition, it was clarified that primiparous cows have a high potential to respond to sudden Ca demand unrelated to hormone excretion, and their Ca metabolism was in some respects similar to that in multiparous cows fed anion salts. Therefore, manipulating mildly DCAD is expected to be an effective, safe and natural method for preventing milk fever in dairy cows.

Use of pre-partum urine pH to predict the risk of milk fever in dairy cows.

The objective of this study was to evaluate the correlation between serum calcium (Ca) and inorganic phosphorus (IP) values and urine pH of cows fed common rations without the addition of anionic salts in late pregnancy. One hundred and seven Holstein cows, having completed two or more lactations and with an expected calving date within the next seven days were selected from two herds. In order to determine levels of serum Ca and IP and urine pH, blood and urine samples were collected seven to one days before parturition. Of the 107 sampled cows, 17 developed recumbency after calving and were considered to be affected by milk fever. There were significant ( p<0.01 ) negative correlations between urine pH and serum Ca, IP and the ratio of Ca to IP, The urine pH, and levels of serum Ca and IP measured within 48 h prior to parturition differed significantly ( p<0.001 ) between recumbent and non-recumbent cows. The sensitivity, specificity, positive and negative predictive values of urine pH test 48 h prior to parturition, using a cut off level of above pH 8.25, were 100%, 81%, 55%, and 100%, respectively. These signify that monitoring urine pH within 48 h prior to parturition is a sensitive method to assess the risk of parturient paresis. The results of this study emphasize the importance of acid-base status of the animal in the pathophysiology of milk fever.

Drought associated poisoning of cattle in South Texas by the high quality forage legume Leucaena leucocephala.

Approximately 80 head of yearling cattle grazing on 680 acres exhibited signs of Leucaena leucocephala toxicosis, which was confirmed in 3 animals by detection of 3-hydroxy-4 (IH)-pyridone, the metabolite of the poisonous principle mimosine, in their urine. The animals had grazed leucaena almost exclusively due to lack of alternative forage resulting from drought conditions. Toxicosis from this otherwise high quality forage would likely not have occurred had animals consumed lower amounts of leucaena and could probably have been prevented, as it has been elsewhere, had the animals been colonized with Synergistes jonesii, a beneficial ruminal bacterium capable of degrading the toxic metabolites.

Development of an immunomagnetic antigen capture system for detecting leptospires in bovine urine.

A magnetic bead antigen capture system which combined the use of two evolving techniques - immunomagnetic separation (IMS) and time-resolved fluoroimmunoassay (TR-FIA) - was developed to detect Leptospira borgpetersenii serovar hardjo in bovine urine. The assay utilised monoclonal antibody coated magnetic beads to capture leptospiral antigen which was in turn detected using another monoclonal antibody (Indicator) labelled with biotin. Signal was generated by the binding of europium labelled streptavidin to indicator antibody. The sensitivity of the assay was improved from 10(3) to 10(2) leptospires per ml by using an ethanol precipitation procedure to treat each sample. The assay detected only 31 of 56 (55 per cent) urine specimens culture-positive for hardjo, but seven of 24 urine samples culture-negative for hardjo were identified as positive by the assay. These seven samples were from animals which were culture positive on at least one other occasion. These results suggest that this system should be further investigated as a complementary test to culture for the identification of hardjo carrier animals.

Orotate in milk and urine of dairy cows with a partial deficiency of uridine monophosphate synthase.

Cows with a partial deficiency of uridine monophosphate synthase have elevated orotate in their milk and urine. Variability of orotate was assessed in two such cows monitored biweekly for two complete lactations. Concentrations of milk and urinary orotate showed extensive variation during lactation, but coefficients of variation were similar for deficient and normal cows. Orotate averaged 500 micrograms/ml milk for deficient cows (versus a normal of 80 micrograms/ml), and a threshold of 200 micrograms/ml distinguished normal from deficient cows. Deficient cows had low milk orotate upon initiation of lactation and exhibited a latency of 1 to 7 wk to attain that threshold. The deficiency also resulted in a lactation-induced orotic aciduria. Orotate averaged 32.2 micrograms/ml urine for deficient cows (versus a normal of 7.3 micrograms/ml), and a threshold of 15 micrograms/ml urine differentiated the animals. Latency was 3 to 18 wk for deficient cows to exceed that threshold. Total orotate output and orotate concentration were elevated in milk and urine of lactating cows deficient for uridine monophosphate synthase. The output of orotate was predominantly in milk rather than urine for both deficient and normal cows. Additionally, orotate was elevated in blood of deficient cows when they were lactating.