Serum free amino acid concentration in hepatic lipidosis of dairy cows in the periparturient period

Blood samples were taken from eight multiparous cows at a dairy farm on eight occasions between the prepartum period and peak lactation to study the serum concentrations of amino acids and biochemical constituents. The cows were classified as having either severe hepatic lipidosis (HL) or non-hepatic lipidosis (non-HL) according to their clinical condition after calving and changes in serum biochemical parameters. The serum concentrations of beta-hydroxybutyric acid were higher in the HL group than in the non-HL group (ANOVA: p<0.01). The serum concentrations of methionine (Met), phenylalanine, and arginine were significantly different between the two groups (ANOVA: p<0.05). In particular, the Met levels were significantly low for 14 days after calving in the HL group (p<0.05), although Met levels in the HL group tended to be lower than the values in the non-HL group until 30 days after calving, starting 14 days before calving. The results suggest that an insufficiency of Met during the periparturient period is related to the development of hepatic lipidosis.     

Biomarkers for the activation of calcium metabolism in dairy cows: elevation of tartrate-resistant acid phosphatase activity by lowering dietary cation-anion difference is associated with the prevention of milk fever

In our previous study, it was demonstrated that the administration of anion salts, which slightly lower the dietary cation-anion difference (DCAD), in the prepartum period is safe and effective for preventing milk fever in multiparous cows. In the present study, several biomarkers, which might show activation of Ca metabolism, were analyzed using stored samples in the previous study to investigate the mechanism of the preventive effect on milk fever by lowering DCAD. Changes in bone-specific alkaline phosphatase activity, osteocalcin and insulin-like growth factor I concentrations in serum were almost the same among the three groups of multiparous cows with or without the oral administration of anion salts, while the levels of these serum biomarkers in the group of primiparous cows (heifer group) were much higher compared with those in the three multiparous groups throughout the experimental period. Urinary deoxypyridinoline excretion was not a useful biomarker for dairy cows because it hardly changed during the peripartum period in all groups. However, serum tartrate-resistant acid phosphatase (TRAP) activity, which is known as a biomarker of osteoclast activity, was well associated with the administration of anion salts lowering DCAD because among the three multiparous groups, only the group of multiparous cows fed the anion salts (anion group) showed an increased level, which rose to the level in the heifer group, and was markedly higher than those in the other control groups of multiparous cows. The increased activity of serum TRAP in the anion group suggested that Ca in the plasma pool was mobilized smoothly from bone-bound Ca via mature osteoclasts at parturition, which might be due to prior activation under mild acidosis induced by slightly lowering DCAD. Therefore, TRAP was the best biomarker to monitor the activation of Ca metabolism in dairy cows fed anion salts.     

Serum osteocalcin in dairy cows: age-related changes and periparturient variation

We evaluated age-related changes in serum osteocalcin concentrations in non-periparturient cows and variations in serum osteocalcin concentration in periparturient primiparous and multiparous cows. The serum osteocalcin levels were evaluated in 144 non-periparturient Holstein dairy cows aged 11 days to 10 years; these levels were the highest in the youngest cows, appeared to steadily decrease with age until the time of the first calving, and were subsequently maintained at low levels. Between 14 days before calving and 21 days after calving, the serum osteocalcin levels were significantly higher in the primiparous cows than in the multiparous cows. A comparison between age-matched non-periparturient and periparturient cows showed that serum osteocalcin levels were significantly lowered during late gestation in both primiparous and multiparous cows. These results suggest that serum osteocalcin measurement might be useful for the detection of mineral imbalances at the time of parturition in cows.     

Peripartal changes in serum alkaline phosphatase activity and lactate dehydrogenase activity in dairy cows.

Peripartal serum alkaline phosphatase activity and lactate dehydrogenase activity were measured in 30 dairy cows in order to examine the association between retained fetal membranes and enzyme activity. Daily blood samples were obtained from pregnant cows, starting 15 days before the expected day of calving until eight days after parturition. Sera from 15 cows which retained fetal membranes longer than 24 hours and 15 cows which shed fetal membranes within six hours after parturition were analyzed for alkaline phosphatase and lactate dehydrogenase enzyme activities. Mean alkaline phosphatase enzyme activities ranged from 15.93 to 32.6 U/L in retained and nonretained placenta cows. There was a trend towards higher serum alkaline phosphatase activities in retained placenta cows but the differences were not significant among the groups (P greater than 0.05). Mean lactate dehydrogenase activities ranged from 307.2 to 438.86 U/L in nonretained and retained placenta cows. Lactate dehydrogenase enzyme activities in nonretained and retained placenta cows were similar (P greater than 0.05). The alkaline phosphatase and lactate dehydrogenase enzyme activities peaked at the time of parturition in both groups. However, the differences in alkaline phosphatase and lactate dehydrogenase activities on different days within non-retained and retained placenta cows were significant (P less than 0.05). Results indicate that prepartal changes in alkaline phosphatase and lactate dehydrogenase enzyme activities are not predictive of placental retention postpartum.     

Effectiveness of calcium chloride in increasing blood calcium concentrations of periparturient dairy cows.

Calcium chloride supplements such as gels and drench were studied to determine their effectiveness for increasing blood serum Ca concentrations in periparturient dairy cows. Multiparous, pregnant Holstein dairy cows (n = 36) were assigned to one of four treatments. After calving, cows in four treatments received basal diet and two doses of either control inert gel (CON), gel containing CaCl2 and vitamins (CVG), gel containing CaCl2 and minerals (CMG), or CaCl2 as drench containing vitamins (CVD). The first dose was given within 2 h after calving and the second dose 12 h after the first dose. Each dose provided .07, 54.5, 56.0, and 33.2 g of elemental Ca in CON, CVG, CMG, and CVD treatments, respectively. Blood samples were collected at 0, 15, 30, 60, 180, and 360 min after each oral dose. The blood serum Ca concentrations were 6.26, 7.56, 6.20, and 5.96 mg/dL during the pretreatment period and deviated -13.5, 7.1, 9.3, and 18.1% from pretreatment levels at 18 h after the first dose in CON, CVG, CMG, and CVD treatments, respectively. The average changes in serum P from pretreatment levels were not different among treatments. Serum Mg concentrations remained below the pretreatment levels in all four treatments. Blood serum beta-hydroxybutyrate during the first 2 wk and milk yields during the first 4 wk of lactation were the same in all treatments. Three cases of clinical milk fever were observed in CON treatment and one case in CVD treatment. The oral supplements of CaCl2 as gel or drench increased the blood Ca levels in periparturient dairy cows. Increased supply of Ca through oral supplements of CaCl2 may prevent milk fever in cows that are marginally hypocalcemic.     

The effect of concentrate feeding on calcium metabolism and plasma gastrin concentration in parturient cows

The effect of concentrate feeding on calcium metabolism was studied in pregnant cows. The concentrate (5 kg/day) was added to the diet about three weeks before expected calving. A control group was fed only hay during the whole dry period. It was earlier observed in sheep that concentrate feeding was followed by a disturbance in calcium homeostasis, but no such disturbances were observed in the cows. The concentrate fed cows consumed 50 % more calcium than the controls and were found to mobilize less calcium from the skeleton immediately after calving. There was no evidence for the theory that the gastro-intestinal hormone gastrin is involved in calcium homeostasis in the parturient cow.     

Associations between periparturient disorders and reproductive efficiency in Holstein cows in northern Mexico

Interrelationships among parity, twinning, retained placenta, abortion, metritis, cystic ovaries, milk fever and postpartum reproductive events were investigated in Holstein cows in northeast Mexico. Data were from 6565 lacations from a large commercial dairy herd. Path analysis was used to model the direct and indirect effects of these variables. The risk of reproductive disorders in cows having a particular periparturient complication was assessed by odds ratio analysis. Milk fever was dropped out of the restricted model, mainly because of the low lactational incidence of this disease (0.5%).

The most important implied cause and effect relationships among the periparturient events were twinning causing retained placenta and retained placenta causing metritis (odds ratio = 5.2 and 4.7, respectively; P * 05). Excluding abortion, most reproductive disorders and twinning increased the days from parturition to first estrus (from 4.4 to 9.2 days), the days from parturition to conception (from 1.3 to 21.4 days), the services per conception (from 0.28 to 0.5) and the calving interval (from 14.7 to 21.3 days). Only in associations between retained placenta and reproductive parameters were the indirect components an important part of the total causal association.     

Evaluation of tartrate-resistant acid phosphatase and cathepsin K in ruptured cranial cruciate ligaments in dogs

OBJECTIVE: To determine localization of tartrate-resistant acid phosphatase (TRAP) and cathepsin K in ruptured and healthy cranial cruciate ligaments (CCL) in dogs. ANIMALS: 30 dogs with ruptured CCL, 8 aged dogs without ruptured CCL, and 9 young dogs without ruptured CCL. PROCEDURE: The CCL was examined histologically and cells containing TRAP and cathepsin K were identified histochemically and immunohistochemically, respectively. RESULTS: Cathepsin K and TRAP were detected within the same cells, principally within the epiligamentous region and to a lesser extent in the core region of ruptured CCL. Numbers of cells containing TRAP and cathepsin K were significantly greater in ruptured CCL, compared with CCL from young or aged dogs, and numbers of such cells were greater in CCL from aged dogs, compared with those of young dogs. In aged dogs, small numbers of cells containing TRAP and cathepsin K were seen in intact CCL associated with ligament fascicles in which there was chondroid transformation of ligament fibroblasts and disruption of the extracellular matrix. CONCLUSIONS AND CLINICAL RELEVANCE: Ruptured CCL contain greater numbers of cells with the proteinases TRAP and cathepsin K than CCL from healthy, young, or aged dogs. Results suggest that cell-signaling pathways that regulate expression of these proteinases may form part of the mechanism that leads to upregulation of collagenolytic ligament remodeling and progressive structural failure of the CCL over time.     

The effect of dietary calcium and phosphorus supplementation in zeolite a treated dry cows on periparturient calcium and phosphorus homeostasis

Previous studies have proved the possibility of preventing parturient hypocalcaemia by zeolite A supplementation during the dry period, and a recent in vitro study has indicated a marked calcium (Ca) as well as phosphorus (P) binding effect of zeolite A in rumen fluid solutions. Because of the connection between the Ca and P homeostatic systems, the preventive effect against parturient hypocalcaemia may arise from zeolite induced decreased availability of dietary Ca as well as P. In the present study, the expected Ca and P binding capacity was challenged by feeding high and low levels of dietary Ca and/or P to zeolite A treated dry cows. Twenty-one pregnant dry cows were assigned to four experimental groups receiving a dry cow ration unsupplemented or supplemented with extra Ca and/or P. During the last 2 weeks of the dry period all cows additionally received 600 g of zeolite A per day. A high level of dietary P prepartum significantly decreased the plasma Ca concentration before as well as immediately after calving (day 0-3). Conversely, the plasma inorganic phosphate concentration was higher among these cows than among cows receiving no supplemental P. The prepartum dietary Ca level significantly affected the serum 1,25-dihydroxyvitamin D concentration during zeolite supplementation, whereas the periparturient plasma Ca concentration was apparently not affected by the dietary Ca level. During zeolite A supplementation plasma parathyroid hormone was significantly higher among cows receiving additional P. The urinary deoxypyridinoline/creatinine ratio was not affected by the prepartal dietary Ca or P level. Serum aluminium (Al) was significantly higher during zeolite A supplementation than during the preceding period, indicating partial destruction of the zeolite in the intestinal tract with subsequent release and absorption of Al. It is suggested that the effect of prepartum zeolite supplementation on the periparturient Ca homeostasis depends on the level of Ca as well as P in the dry cow ration.     

Relationship between parity and mineral status in dairy cows during the periparturient period

Data from 65 cows were collected to clarify the relationship between parity and mineral status in Holstein cows during the periparturient period. Milk fever occurred in a second‐ and a fourth‐lactation cow at parturition. Bodyweight of cows decreased immediately after parturition, and the decreased weights of cows from 1 to 6 days after parturition ranged from 11 to 27 kg. Milk yield of multiparous cows was higher than that of primiparous cows, but Ca and P concentrations in colostrum were not affected by the parity. Plasma glucose of primiparous cows was higher than that of multiparous cows, and plasma nonesterified fatty acids of fourth‐and‐more‐lactation cows at parturition was highest. Plasma Ca concentration of cows at parturition decreased with advancing parity, and plasma inorganic P concentration of third‐and‐more‐lactation cows was lowest at parturition. Plasma parathyroid hormone of fourth‐and‐more‐lactation cows at parturition was highest, but plasma hydroxyproline and alkaline phosphatase was lowest. These results suggest that the large transfer of Ca and P to colostrum is a factor in the development of milk fever in third‐and‐more‐lactation cows.     

Serum activities of tartrate-resistant acid phosphatase and bone specific alkaline phosphatase as indices of bone metabolism in the cow

The correlation between the serum hydroxyproline concentration and serum activity levels of TRAP and BALP was examined in 41 cows. The correlated coefficient (r) was 0.6391 for TRAP and 0.3147 for BALP, respectively. Judging from the significant correlation to the serum hydroxyproline concentration, serum TRAP activity is an index for bone metabolism in cows. Serum TRAP activity was therefore measured in 205 healthy cows (2-9 years old) in order to observe the changes in bone resorption with aging and milk production. TRAP levels differed slightly between group A (< or =4 yrs) and B (5 yrs< or =) at the same stage of lactation. The activity levels rose slightly at the height of lactation stage and during the dry stage.     

The concentration of ionized magnesium in serum during the periparturient period of non-paretic dairy cows

Ion-selective electrodes have recently been designed for determining the ionized concentration of magnesium (Mg²⁺) in serum. This development may allow new insights into some metabolic diseases of cattle. For this report, the concentrations of Mg²⁺, total magnesium (Mg_tot), ionized calcium (Ca²⁺), total calcium (Ca_tot), and inorganic phosphate (P_i) were determined in sera from seventeen 3-to 16-year-old Brown Swiss and crossed Simmental/Red Holstein cows during the periparturient period. In each animal, a transient increase of Mg²⁺ and Mg_tot serum concentrations was observed in association with the transient decrease in serum concentrations of Ca²⁺, Ca_tot and P_i after parturition. On average, throughout the study, the serum Mg²⁺ concentrations were 68.5% of those of Mg_tot, whereas the serum Ca²⁺ concentrations were 52% of those of Ca_tot. The possible mechanisms involved in the transient increase of Mg²⁺ and Mg_tot serum concentrations are discussed.Abbreviations Ca²⁺ ionized calcium - Ca_tot total calcium - Mg²⁺ ionized magnesium - Mg_tot total magnesium - P_i inorganic phosphate - PTH parathyroid hormone - PTHrP parathyroid homrone related protein     

Prolactin, estradiol, and progesterone changes in paretic and nonparetic cows during the periparturient period

We studied the relationship of serum prolactin, estradiol-17 beta, and progesterone concentrations to plasma calcium, phosphorus, and free hydroxyproline concentrations, as well as to dry matter intake, in 14 aged dairy cows (mean of 4.5 parities), 7 of which became paretic, from 28 days before to 4 days after calving. Plasma calcium and phosphorus concentrations and dry matter intake decreased more at parturition in paretic cows than in nonparetic cows. Prolactin concentrations were not different between paretic and nonparetic cows, but were variable. Concentrations of estradiol were higher in paretic cows from 15 to 5 days before parturition, whereas hydroxyproline concentration was lower in paretic cows on days 10 through 3 before parturition. Progesterone concentration was lower in paretic cows and decreased earlier at parturition, compared with that in nonparetic cows. The findings suggested that high estradiol concentrations in late pregnancy inhibit bone resorption and predispose aged cows to parturient paresis. The earlier decrease in progesterone concentration at parturition and lower concentrations throughout late pregnancy might have contributed to the greater inappetence in paretic cows at parturition. The importance of prolactin in the pathogenesis of parturient paresis is not clear.     

Genetics and physiology of leptin in periparturient dairy cows

In dairy cattle, the increase in milk yield has been accompanied by a more negative energy balance (EB) during early lactation and a decrease in fertility. As the hormone leptin is involved in regulation of nutritional status and reproductive function this hormone is an interesting protein to investigate during the periparturient period in dairy cattle. This study was performed to get insight into the function of leptin during the periparturient period and to perform an association study between polymorphisms in the bovine leptin gene and leptin receptor gene and fertility as well as production traits. Leptin concentrations in the periparturient cow undergo remarkable changes; leptin concentrations were high during late pregnancy and declined to a nadir at parturition. Genetic analysis of the leptin gene indicated that a combination of three polymorphisms located at a 135 bp region of the leptin promoter explained most of the variance in prepartum leptin concentrations. The two extreme genotype combinations could be used to investigate the function of leptin concentrations in pregnant cows. A polymorphism located on intron 2 of the leptin gene explained a significant part of the variation in milk yield. On the promoter region of the leptin gene an SNP was detected that was associated with first postpartum luteal activity (FPLA). This SNP could be a candidate marker for fertility in dairy cows. Another SNP on the leptin promoter was associated with energy balance and dry matter intake (DMI) where a higher dry matter intake occurred together with a higher energy balance. Two genotype combinations of the aforementioned three associated SNPs were defined which had a good milk yield together with a good energy balance and fertility. Calculations of an economical value per trait have to validate if one of these genotype combinations would be a possible candidate to be used in selection.     

Changes of serum alkaline phosphatase activity in dry and lactational cows

Serum alkaline phosphatase (ALP) activities were measured during dry and lactational periods to investigate the influence of lactation on serum ALP activity in cows. Higher levels of serum ALP activity were seen in lactational periods than in dry periods. The serum activities of bone-specific ALP (BALP), liver ALP (LALP), tartrate resistant acid phosphatase (TRAP) and aspartate aminotransferase also increased in lactational periods. ALP activities in the bone extract and in whey were decreased at similar rates by the addition of lectin. Moreover, since the ALP band in whey was observed to have the same migration in polyacrylamide gel (PAG) disk electrophoresis as that of the bone extract, analysis of ALP isoenzymes by lectin affinity or PAG disk electrophoresis could not distinguish ALP originating from the mammary gland from that of bone. In this study, it was clear that the increased level of serum ALP activity was due to increases of BALP and LALP in lactational periods. However, the extent of the influence of ALP originating from the mammary glands on serum ALP activity was unknown. Judging from changes of BALP and TRAP activities in the serum and the correlation between the both, it was guessed that ALP originating from the mammary glands influenced serum ALP activity.     

Influence of different calcium contents in diets supplemented with anionic salts on bone metabolism in periparturient dairy cows

At the initiation of lactation, Ca homeostatic mechanisms have to react to a tremendous increase in demand for Ca. Mobilization of Ca from bone and increased absorption from the gastrointestinal tract are required to re-establish homeostasis. It has been shown that dietary anions play an important role in the prevention of milk fever by mobilizing Ca from bone and by increasing Ca absorption in the GI tract. The purpose of the present study was to investigate the influence of different Ca contents in diets supplemented with anionic salts on bone metabolism of dairy cows. Twenty-four holstein cows (housed inside, second to fourth lactation) without a milk fever history were divided into four groups (A, B, C, D). Each group was fed a different diet which was given from day 263 of gestation till the day of parturition. Group A and B received a low calcium diet (4 g/kg DM) whereas group C and D received a high Ca diet (8 g/kg DM). In addition group B and D received anionic salts. The DCAD was calculated with the formula: DCAD (mEq/kg DM)=(0.2 Ca2++0.16 Mg2++Na++K+)-(Cl-+0.6 S2-+0.65 P3-). Blood and urine samples were collected on days 256, 270 and 277 of gestation, on the day of parturition as well as the following 5 days and on days 9, 14 and 19 after parturition. Serum Ca, P, Mg, ICTP, OC, VITD, PTH and urinary pH were analysed. The bone resorption marker ICTP showed a significant increase after parturition in all the groups. On the contrary, the bone formation marker OC decreased after parturition in all the groups. The VITD concentrations in group D and the urinary pH in group B were significantly lower compared to the other groups (p<0.05). The Ca concentrations tended to be higher in group B around parturition than in all the other groups. No significant influence of the four different diets on all the other parameters could be shown. In conclusion, this data showed that the addition of anions and the different Ca contents had no significant influence on bone resorption and bone formation markers. This may be because of the fact that the dietary cation-anion balance was not low enough (DCAD-group A: 181 mEq/kg DM, group B: -48 mEq/kg DM, group C: 210 mEq/kg DM and group D: 28 mEq/kg DM) to induce a metabolic acidosis with all its positive effects on calcium metabolism.     

Heat stress decreases plasma vitamin C concentration in lactating cows

Heat stress causes oxidative stress, which decreases plasma levels of vitamin C, an antioxidative vitamin in pigs and poultry. We investigated the plasma vitamin C concentration in lactating cows exposed to a hot environment temperature. In the first experiment, plasma vitamin C concentrations of 8 lactating cows were measured in summer and autumn. The concentration was found to be significantly lower in summer. The second experiment was performed using 4 lactating cows in a crossover design. The ambient temperature was set at 18 °C in the control treatment and at 28 °C in the heat-stressing treatment. Milk yields and feed intake tended to be lower in the stressing than control treatment. Rectal temperature and respiration rate were significantly (P < 0.05) higher in the heat-stressing treatment. The plasma vitamin C concentration was significantly (P < 0.05) lower in the heat-stressing period. These results indicate that heat stress decreases the plasma vitamin C concentration. Dietary supplementation with vitamin C may be beneficial for lactating cows in hot weather.