The effect of the plasma glucose level on the abomasal function in dairy cows

We have studied the effect of plasma glucose level on the abomasal outflow rate of fluid using a hyperinsulinemic glucose clamp technique in dairy cows. Four nonpregnant, nonlactating cows were subjected to one of the following treatments: hyperinsulinemic normoglycemic clamp; hyperinsulinemic hypoglycemic clamp; hyperinsulinemic hyperglycemic clamp; or, as a control, an intravenous infusion of .9% sodium chloride in a Latin square design. The cows were previously fitted with a permanent fistula in the abomasum and the outflow rate of abomasal fluid was determined using Co-EDTA as a marker assuming that the outflow followed first-order kinetics. The abomasal pH was also registered. Insulin was infused continuously through a jugular catheter at a rate of 4.8 mU. kg(-1)min(-1) for 2.5 h in the three clamp treatments. A glucose solution was infused through the catheter at a variable rate to achieve a circulating concentration, near the preinfusion glucose level (approximately 4.1 mmol/L), 2 mmol/L below the preinfusion level, and 2 mmol/L above the preinfusion level for the three hyperinsulinemic treatments, respectively. There was a significant effect of treatment on the rate of abomasal outflow (P < .001). The rate of abomasal outflow was highest for the control treatment (7.8%/min). The slowest outflow was observed in the hyperglycemic cows (3.40%/min). The hypoglycemic and normoglycemic cows showed intermediate rates (6.0%/min and 5.2%/min, respectively). The rate of outflow for the hyperglycemic cows was significantly lower than for all the other treatments (P < .01). Abomasal pH was affected by treatment (P < .05). The highest pH was observed in the hyperglycemic cows (pH 2.3). The values for the other three treatments ranged from pH 1.9 to 2.0. These results show that hyperglycemia reduced the rate of outflow and increased the pH of abomasal fluid in dairy cows. An elevated plasma glucose level thus can be considered as a potential risk factor in the pathogenesis of left-displaced abomasum.     

Effects of urinary excretion of nitrogen, potassium and sodium on urine volume in dairy cows

Data of 50 balance measurements were collected from dry and lactating Holstein cows to clarify the effects of urinary excretion of nitrogen (N), potassium (K) and sodium (Na) on urine volume in cows. In dry cows, orchardgrass silage, timothy hay, alfalfa silage and corn silage were offered to meet the TDN requirement. Orchardgrass silage or alfalfa silage diets were offered in switch back trials in lactating cows. There were no relationships between urinary excretion and plasma concentrations of K or Na in cows, but urinary N excretion increased with the increase of plasma urea nitrogen. There was positive correlation between urinary excretion and urinary content of Na, but urinary K contents increased rapidly by 1.3% with the increasing urinary K excretion and thereafter remained almost constant. The increasing urinary K and N excretion enhanced urine volume in cows, but urine production in cows was accurately estimated from the regression equation of urine K excretion on urine volume. Urine volume was not affected by urinary Na excretion. These results suggest that the increase of urine volume in cows affected by the increasing urinary excretion of K and N may be due to the maintenance of urine or plasma osmolality.     

奶牛蹄叶炎与血浆中矿物元素含量的相关性分析

采集15头健康奶牛和36头蹄叶炎患病奶牛血浆样品,检测其Fe、Zn、Cu微量元素和Mg、Ca、P常量元素的含量及钙磷比,结果表明：2组间Fe、Cu、Mg、Ca和P矿物元素含量及钙磷比无显著性差异（P〉0.05）,患病牛Zn含量却显著低于健康牛（P〈0.05）。因此,奶牛血浆中Zn含量与蹄叶炎发病显著相关,Zn含量可能会作为蹄叶炎发病的监测指标,也可用于奶牛蹄叶炎的早期诊断和防治。     

Preanalytical factors affecting blood inorganic phosphate concentration in dairy cows

BACKGROUND: Hypophosphatemia is a condition that affects feed intake and milk production in dairy cows, and, to assess it, a precise biological parameter is needed. Plasma inorganic phosphate (Pi) can be used as a potential indicator of bioavailability of feed phosphorus in dairy cows. OBJECTIVE: The purpose of this study was to evaluate the effects of sample type (serum vs. plasma), blood sampling site (jugular vs. coccygeal), and morning feeding on blood Pi concentration in dairy cows. METHODS: Blood samples from 28 clinically healthy multiparous Holstein cows were analyzed for Pi concentration. The animals were sampled twice by coccygeal vessel into Vacutainer tubes both with and without sodium heparin, 3 hours after the morning feeding. In 4 additional cows, the concentration of Pi was measured in blood samples obtained simultaneously by jugular and coccygeal venipuncture into heparinized tubes before the morning feeding and 2, 4, and 6 hours after the feeding. The results were analyzed using parametric statistical tests. RESULTS: Serum and plasma concentrations of Pi were correlated (r(2) = 0.999, P < .0001), but serum Pi concentration was higher than plasma Pi (P < .02). Plasma Pi concentration 2 hours after feeding tended to be higher than that before feeding in jugular samples, but the difference was not significant. There was no significant variation in plasma Pi during the morning postfeeding times, although jugular concentrations were 19% lower than coccygeal (P = .04). CONCLUSION: To increase the precision of plasma Pi measurements as an indicator of bioavailability of feed phosphorus, sample type, sampling time, and site must be taken into account, to correctly interpret plasma Pi concentrations.     

The orotic acid concentration in the blood, milk, and urine of dairy cows fed with urea supplemented diet

The experiment was performed on 4 cows Black and White, 550-650 kg of body weight, before and during 100 days after parturition. Two cows were fed with control and the next two with urea supplemented diet (urea-N constituting about 20% of total N in ration, 13% c.p. in DM). In cows fed with urea supplemented diet the considerable but unequal increase of urinary orotic acid excretion (particularly evident in first 30 days of lactation) was observed. There was however no influence of urea ration on the level of orotic acid in milk. The average orotic acid level in blood plasma (1.14 +/- 0.71 mumol X l-1 and 0.94 +/- 0.22 mumol X l-1 for control and urea fed cow respectively) established 0.01 and 0.001 of the average orotic acid concentration in urine and milk, respectively. Feeding with urea ration did not affect the level of orotic and UMP but increased the uridine concentration in blood plasma. During the parturition the lowest level of orotic acid in blood plasma, milk and urine was observed.     

The effects of hypocalcaemia due to a 4-hour infusion of Na2EDTA solution on various blood and urine analytes in dairy cows and a comparison of these effects between cows with high and low erythrocyte potassium concentrations.

Six HK (high erythrocyte potassium) and 7 LK (low erythrocyte potassium) dairy cows were subjected to a 4-h intravenous infusion of 4.7% Na2EDTA solution to induce and maintain hypocalcaemia. Blood samples taken immediately before infusion, hourly for 7 h, and at 24 h after commencement of infusion were subjected to determination of concentration (or count) of 16 analytes. The mean changes in concentrations (or counts) of the various blood analytes were calculated for the periods 0-4, 4-7, 7-24, and 0-24 h after commencement of the infusion for all cows combined, and then separately for the HK and LK groups of cows. Plasma Ca(PCa), plasma inorganic phosphorus (PiP) and plasma potassium (PK) showed significant decreases during the 4-h infusion period and were still below pretreatment levels 24 h later. AST, CPK, PCVs and white cell-counts (WCCs) showed significant early increases which were still significantly elevated 24 h later. Plasma magnesium (PMg) and erythrocyte Na(ENa) and K(EK) all showed delayed changes which still persisted 24 h later. Significant between-group differences were present for PCVs which increased significantly more in the LK than the HK group during the infusion period, for PCa which showed a greater increase in the HK cows than the LK cows during the 4-7 h early clinical recovery period, and for plasma bilirubin (PBil) which showed a greater increase from 0 to 24 h in the HK group than in the LK group. Urine samples, collected before infusion, 4-7 h and 24 h after commencement of the infusion, were subjected to analysis for glucose, protein, pH, 'blood' and ketones. Most cows showed increases in urinary glucose, protein and 'blood'.     

Relationship between milk urea concentration and the fertility of dairy cows

The relationship between milk urea concentration and the fertility of dairy cows was examined in two studies. The first examined the relationship between bulk milk urea concentration and overall herd fertility, using data collected from 250 herds in the UK. There was no relationship either between bulk milk urea concentration and fertility, or between changes in bulk milk urea concentration and fertility. The second study compared the relationship between the milk urea concentration five days after service, and the fertility of individual cows on 11 UK dairy farms. There was no significant difference between the milk urea concentration of the cows that became pregnant and those that did not.     

异丁酸钠对奶牛泌乳性能和血液指标的影响

文章旨在研究异丁酸钠对奶牛泌乳性能和血液指标的影响。选用20头体重为(567±11.8)kg、已产奶(148±4.5)d且日均产奶量为(22.3±0.81)kg的的健康中国黑白花奶牛进行一项重复4×4拉丁方饲养试验。处理为:对照(不做添加)和低[LIB,20g(/头·d)]、中[MIB,40g(/头·d)]、高[HIB,60g(/头·d)]添加量。试验每个阶段为期30d(预饲15d,正饲15d)。本试验条件下,异丁酸钠的添加对干物质采食量(DMI)没有影响,MIB添加组的产奶量最高,但处理组之间差异不显著;除乳脂中各处理之间差异不显著外,乳蛋白、乳糖、乳非脂固形物和乳灰分的HIB添加组的均低于其他3个处理的,且差异显著(P0.05);其中,均以LIB添加组的最高。血中葡萄糖和生长激素的浓度呈线性增加(P0.05),而游离脂肪酸的浓度呈线性下降;LIB、MIB和HIB三个添加水平的血清总胆固醇浓度均低于对照,以MIB组的最高;MIB组的血浆总蛋白(P0.01)、白蛋白含量最低;LIB组的血清尿素氮水平低于对照,但随着添加量的增加提高了;但对血浆甘油三酯没有影响。结果表明,该日粮中添加异丁酸钠时,MIB组的泌乳母牛产奶量最高,且不会影响到下一胎次的繁殖性能。因此建议异丁酸钠的最适添加量为40g(/头·d)。     

Relation between biochemical parameters in the blood of cows and milk production

No differences in blood samples were found out when the biochemical parameters in arterial and venous blood of dairy cows were compared before and after milking. Negative correlation coefficient (r = -0.3460) approaching the significance level was determined by comparing the values for milk yield on the day of sampling (in ascending phase of lactation) and protein content in venous blood after milking, and significant negative correlation coefficient (r = -0.3813) for daily milk yield and gamma-globulin concentration in venous blood before milking. The relationship between butterfat content on the day of milking and the values of alkaline phosphatase can be characterized by significant up to highly significant negative correlation coefficients in all three blood samples (r = -0.3232 to -0.3908).     

钠盐对乳房水肿奶牛钠钾氯血清水平的影响

本试验在以往对石河子地区奶牛乳房水肿的调查情况的基础上,对围产期奶牛停止摄入钠盐,统计奶牛乳房水肿发病率、以及检测围产期健康奶牛和乳房水肿奶牛的血清中钠(Na+)、钾(K+)、氯(Cl-)水平。试验结果显示,围产期奶牛限制摄入钠盐前后乳房水肿的发生率分别为29.77%、22.08%,同时检测奶牛血清显示,患乳房水肿奶牛血清钠(Na+)水平为150.03 mmol/L,且极显著高于健康奶牛(P<0.01);乳房水肿奶牛血清钾(K+)水平为5.12 mmol/L,与健康奶牛没有差异;患乳房水肿奶牛血清氯(Cl-)水平为112.13 mmol/L,且显著高于健康奶牛(P<0.05)。试验表明,尽管不添加钠盐会使围产期奶牛乳房水肿发病率有所降低;但围产期奶牛发生乳房水肿的重要原因是特殊生理时期机体钠、氯离子代谢障碍。本次试验不但验证了钠、氯离子代谢障碍引起围产期奶牛发生乳房水肿,而且在临床实践中为本地规模化牛场养殖建议围产期奶牛不补给钠盐提供数据支持。     

An association between the level of oxidative stress and the concentrations of NEFA and BHBA in the plasma of ketotic dairy cows

The aim of this study was to evaluate the oxidative status in ketotic cows. We observed changes in the oxidative status and correlations between the oxidative and metabolic status in non‐ketotic (n = 10), subclinical ketotic (n = 10) and ketotic cows (n = 10). Plasma samples were analysed by standard biochemical techniques and ELISA to determine traditional metabolic parameters: triglyceride (TG), phosphonium (P), calcium (Ca), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total protein (TP), albumin (ALB), immune globulin (Ig), total cholesterol (TC), high‐density lipoprotein (HDL), very low‐density lipoprotein (VLDL) and lactate dehydrogenase (LDH); energy metabolism indices: glucose, β‐hydroxybutyrate (BHBA) and non‐esterified fatty acids (NEFA); and indices of oxidative status: malondialdehyde (MDA), hydrogen peroxide (H₂O₂), vitamin C, vitamin E, superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), catalase (CAT), xanthine oxidase (XOD) and total antioxidant capacity (TAOC). The results of this study showed that plasma glucose levels were lower in ketotic and subclinical ketotic cows than in non‐ketotic cows; however, the plasma NEFA and BHBA concentrations were higher. In addition, significant decreases in TC, HDL and VLDL and significant increases in AST, ALT and LDH were observed in the plasma of the ketotic cows. The ketotic cows showed decreased plasma SOD, CAT, vitamin C and vitamin E, inhibited hydroxyl radical capacity and increased plasma H₂O₂ and MDA. There were positive correlations between the plasma NEFA and ALT, AST, LDH and MDA and negative correlations between the plasma NEFA and TC, HDL, VLDL, SOD, vitamin C, vitamin E, 1542280 uric acid and inhibited hydroxyl radical capacity. In addition, there were positive correlations between BHBA concentrations and ALT, AST and LDH and negative correlations between plasma BHBA concentrations and TC, HDL, VLDL, vitamin E and inhibited hydroxyl radical capacity. Overall, ketotic dairy cows experience oxidative stress, which is presumably associated with hyperketonemia and higher NEFA.     

低磷奶牛血红蛋白尿症红细胞膜脂质过氧化损伤的观察

研究观察了土壤、牧草低磷条件下,诱发奶牛红细胞膜脂质过氧化损伤。发现血清磷、红细胞膜总脂和过氧化物歧化酶（ＳＯＤ）明显下降：血清磷由（４３．１０±８．１０３）ｍｇ／ｇ下降至（２１．３３±２．２３１）ｍｇ／ｇ;膜总脂由（０．００２６７±０．０００１２９）ｇ／ｍＬ下降至（０．００２２４±０．０００１２９）ｇ／ｍＬ;ＳＯＤ由（２１７．６５±３．０４１）Ｕ／ｍＬ下降至（４０．６２±５．４４）Ｕ／ｍＬ,差异显著（Ｐ＜０．０１）。但微粘度（η）和红细胞丙二醛（ＭＤＡ）上升：η值由０．８４３３±０．０２１５上升至１．７２８５±０．１４５１,表明膜流动性下降;ＭＤＡ由（０．５３６±０．０７８）ｎｍｏｌ／ｍＬ上升至（１．０９３±０．１８０）ｎｍｏｌ／ｍＬ,差异显著（Ｐ＜０．０１）。结果显示,低磷不仅引起奶牛血红蛋白尿症而且诱导红细胞膜脂质过氧化损伤。     

A comparison of plasma glucose and oxidative status in lactating dairy cows in summer and autumn

The objective of this study was to investigate the effects of the hot summer season on plasma glucose and oxidative stress markers. For two 14‐day experimental periods, namely periods 1 (July‐August) and 2 (October‐November), 12 and 14 lactating dairy cows, respectively, that were milked using an automatic milking system, were fed diets containing similar ingredients, and their milk production, plasma metabolites and oxidative status markers were investigated. Dry matter intake and milk yield were not affected by the experimental period. Rectal temperature at 18.00 hours and milk protein concentration in period 1 were higher and lower, respectively, than in period 2 (P < 0.05), suggesting that the hot summer season had an effect on the experimental dairy cows. Plasma glucose and the ascorbic acid + dehydroascorbic acid (AA) concentrations in period 1 were lower than in period 2 (P < 0.01). The plasma malondialdehyde (MDA) concentration did not differ between the experimental periods. The increase in the cellular AA uptake in peripheral tissues in period 1 might be a possible compensatory mechanism to balance the occurrence of reactive oxygen species and the antioxidant capacity in the cells, resulting in the absence of an effect of the hot summer season on plasma MDA concentration. © 2016 Japanese Society of Animal Science     

Factors affecting acetone concentration in blood of dairy cows at the first stage of lactation

The aim of this paper was to determine effects of selected genetic and environmental factors on the concentration of acetone in blood of cows in the first trimester of lactation. The study included 124 Polish Holstein-Friesian primiparous cows born, reared and managed on the same farm. The samples of blood were collected on day 2, 5, 30, 60 and 90 after calving. The highest serum acetone concentration in the animals examined was observed on day 5 after calving. The level of this compound was inversely related to the contribution of the original Holstein-Friesian breed in gene pool. Significantly higher serum acetone level was observed in cows calved in January-March period when compared to other months of the year. Besides, the level of acetone determined on day 5 after calving was associated positively with body weight determined at the same day and negatively with body weight changes between days 5 and 60 after calving.     

Interdependence of the level of total proteins, magnesium and beta-carotene in the plasma of dairy cows

The degree of dependence of the concentration of total protein, magnesium and beta-carotene in the blood plasma of over 3,400 dairy cows in the first and second phases of lactation and in months 8 and 9-9.5 of pregnancy was attested statistically. It was shown that in late pregnancy the concentration of all three indices drops both with winter and summer feed rations and that the connection between all three pairs of indices is positive. The highest values of the linear correlation coefficient were ascertained between the total protein and magnesium of blood plasma (+0.87 in the winter period, +0.63 in the summer period and +0.75 in both periods), the correlation was somewhat lower between magnesium and beta-carotene (+0.56, +0.75 and +0.36) and it was lowest between total protein and beta-carotene (+0.45, +0.41 and +0.42). The discussion deals with the causes of the stochastic correlation of these components of blood plasma.     

Variation in selected blood plasma constituents during the post-partum and breeding periods in dairy cows

Concentrations of insulin-like growth factor-I, albumin, beta hydroxybutyrate, glucose and urea were measured in 12 plasma samples collected over 9 weeks from mid-August from each of 40 cows in four seasonal herds which calved from mid-July. These herds comprised Jersey or Holstein-Friesian animals, with each breed grazed at two stocking rates. Daily dry matter intakes (kg dry matter/cow/day), which were estimated from pasture assessments before and after grazing, ranged from 4% (low stocked Jersey herd) to 38% (high stocked Friesian herd) below recommended intakes for each breed of cow in peak lactation. Stocking rate was associated with a 4% reduction in liveweight for cows in the high stocked herds and a 20% reduction in daily milk production (as a proportion of the low stocked herds' liveweight and milk production). Eight cows produced at least one blood sample with a beta hydroxybutyrate concentration of more than 1.0 mmol/l. There were 42% of samples with glucose concentrations greater than 4.1 mmol/l. These two concentrations were the maximum values classified as normal for these two metabolites by the Ruakura Animal Health Laboratory. No concentrations of the other metabolites were outside their respective normal ranges. Breed, age and individual animals usually had greater effects on the average metabolite concentrations than did stocking rate. The greatest effect was associated with sample day, especially for insulin-like growth factor-I and urea. A significant breed x stocking rate x sample day interaction in urea concentrations indicated that changes in the feeding value of the grazed pastures available to each herd were sufficient to produce separate fluctuating patterns in the daily average concentrations. These results showed that frequent sampling on a herd basis would be necessary to identify the significance of factors which may be contributing to sample day variation in the concentration of metabolites in the plasma of pasture-fed cows.