Parathyroid hormone-related protein (PTHrP) produced by dog lymphoma cells

Parathyroid hormone-related protein (PTHrP) was investigated in a canine lymphoma case with hypercalcemia by means of immunoradiomentric assay (IRMA) and molecular analysis. The plasma calcium level of the patient dog was 13.7 mg/dl. The PTHrP concentration examined by IRMA was 6.1 pmol/L in the plasma sample from the dog, but it was undetectable (< 1.1 pmol/L) in plasma samples from 4 lymphoma cases without hypercalcemia or 5 normal dogs. The PTHrP concentration examined in the culture supernatant of the lymphoma cells from this case was 1.3 pmol/L, whereas those of the lymphoma cells from a lymphoma case without hypercalcemia was undetectable. PTHrP mRNA was clearly detected not only in the lymphoma cells from this dog with hypercalcemia but also in lymphoma cells from 4 lymphoma cases without hypercalcemia and 2 canine lymphoma cell lines.     

Expression of parathyroid hormone-related protein (PTHrP) mRNA in mammary gland of periparturient cows

The expression of parathyroid hormone-related protein (PTHrP) mRNA was examined in mammary gland with or without lactation, and during periparturient period in a Holstein cow and a Jersey cow. In the lactating mammary gland, PTHrP was detected in alveolar epithelial cells and the lumen by immunohistochemical analysis. The relative expression levels of PTHrP mRNA in mammary gland from lactating cows were significantly higher than those from non-lactating cows (P<0.05). During periparturient period, relative PTHrP mRNA level was remarkably low before the parturition in a Jersey and a Holstein cow, however, both levels were gradually increased and reached a peak level at 5-6 weeks after the parturition. In addition, the peak level in a Jersey cow was approximately 3-fold higher than that in a Holstein cow. From these results, PTHrP was synthesized and secreted in alveolar epithelial cells in mammary gland and increased subsequently with the lactation, suggesting a possible mechanism for the regulation of local calcium homeostasis.     

Parathyroid hormone-related protein and calcium concentrations in milk and blood of ewes

Parathyroid hormone-related protein (PTHrP) and calcium (Ca) concentrations were measured 2 to 3 months postpartum in milk and plasma or serum of 22 ewes by the use of commercial radioimmunoassay kits for PTHrP concentration, colorimetry for serum total Ca concentration (Ca_tot), and atomic absorption spectrophotometry for milk total Ca concentration. Scatter plots did not reveal dependency between milk Ca and Ca_tot, Ca_tot and plasma PTHrP, milk Ca and milk PTHrP, and milk PTHrP and plasma PTHrP. Thus, the systemic and mammary effects of PTHrP are not major determinants of the endocrine, paracrine, and autocrine regulation of Ca homeostasis during lactation in ewes.     

In vitro model of parathyroid hormone-related protein secretion from mammary cells isolated from lactating cows

Parathyroid hormone-related protein (PTHrP) is produced by the lactating mammary gland and is present in milk in a biologically active form. The goal of this investigation was to determine if cells cultured from the lactating mammary glands of cows would secrete PTHrP in vitro. Mammary acini were isolated from lactating cows at 1–6 wk after calving, and fresh or cryopreserved mammary acini were cultured for 14 d on Type I collagen. Cultures on thick layers of collagen (2.5 mm) were detached and allowed to contract on Day 6. PTHrP production was measured by N-terminal radioimmunoassay and bioassay (increased cAMP levels in ROS 17/2.8 osteoblast-like cells). The mammary cells reached confluence at Day 6. PTHrP production was low at Day 2 (<0.5 ng/ml) but increased to peak production (2–4 ng/ml) at approximately Day 6 and remained constant until Day 14. Immunoreactive and bioactive PTHrP levels in the culture medium correlated well. The cultures produced lactoferrin (2,000–2,300 ng/ml) and α_s1-casein (14–19 ng/ml). Prolactin stimulated PTHrP production approximately 50% on Days 6–14. PTHrP production was increased approximately 100% by treatment with epidermal growth factor (10 ng/ml) for 2 d. Morphologic evaluation of cultures on thick, contracted collagen at Day 14 revealed an inner layer of mammary epithelial cells overlying myoepithelial cells and an outer layer of collagen containing stromal cells. Immunohistochemistry demonstrated positive staining for PTHrP and cytokeratin in both mammary epithelial and myoepithelial cells and a-smooth muscle actin in myoepithelial cells. These data demonstrated that cryopreserved mammary tissue from lactating cows could be cultured in vitro and secreted PTHrP in a regulated manner. This in vitro model will be useful to investigate the function and regulation of PTHrP in the lactating mammary gland.     

Starch levels on performance,milk composition and energy balance of lactating dairy cows

The objective of this experiment was to evaluate the effects of starch levels in diets with the replacement of citrus pulp for corn on milk yield, milk composition, and energy balance of lactating dairy cows. Twenty-eight multiparous Holstein cows were used in seven 4?×?4 Latin squares conducted concurrently, and each experimental period consisted of 20 days (16 days for adaptation and 4 days for sampling). The experimental treatments comprised four starch levels: 15, 20, 25, and 30 % in the diet. The dry matter intake increased linearly with increasing starch levels. The milk yield and 3.5 % fat-corrected milk yield showed quadratic response to increasing starch levels. The milk protein content and milk total solids content responded linearly to increasing starch levels. The feed efficiency, milk lactose content, milk urea nitrogen, plasma urea nitrogen, and plasma glucose concentration were not affected by starch levels. The estimated net energy for lactation (NE_L) intake increased linearly as the starch level was raised. Although the milk NE_L output per kilogram of milk was not affected by starch, the milk NE_L output daily responded quadratically to starch levels. In addition, the NE_L in body weight gain also responded quadratically to increasing starch levels. The efficiency of energy use for milk yield and the NE_L efficiency for production also responded quadratically to increasing starch levels. Diets for mid-lactating dairy cows producing around 30 kg/day of milk should be formulated to provide around 25 % starch to optimize performance.

     

The effect of free amino acid levels in the blood and milk of cows on protein levels in milk

In the cows of the whole group under study, a significant negative relation (r = = -0.4797) was found between the histidine level in arterial blood and protein content in milk; further, there was a significant positive relation (r = 0.4624) between alanine level in milk and protein content in milk, and a significant negative relation (r = -0.5028) for the level of threonine. The group of cows with a higher milk output showed a significant negative relation between methionine level in milk and protein content in milk (r = -0.7482) and a highly significant negative relation between threonine level and protein content in milk (r = -0.8410). The negative relations of some amino acids to the content of protein in milk suggest that there is a poor supply of these amino acids for the production of protein in milk.     

Immunohistochemistry for parathyroid hormone-related protein (PTHrP) in benign and malignant mammary mixed tumors of dogs with and without hypercalcemia

We evaluated the expression of parathyroid hormone-related protein (PTHrP) by immunohistochemistry in eight benign and malignant mammary mixed tumors of dogs with (n = 4) and without (n = 4) hypercalcemia. Positive immunoreactive staining for PTHrP was observed in all four tumors from hypercalcemic dogs. The mammary tumors from 2 of the 4 normocalcemic dogs stained positively for PTHrP, but the numbers of immunoreactive cells and intensity of the immunoreaction were less than in the hypercalcemic dogs. In the other 2 tumors without hypercalcemia, the tissue samples were negative for PTHrP.     

Pharmacokinetics of phenylbutazone in plasma and milk of lactating dairy cows

Phenylbutazone was administered intravenously (i.v.) to a group of four lactating cows at a dosage of 6 mg/kg body weight. Whole plasma, protein-free plasma and milk were analysed for phenylbutazone residues. Pharmacokinetic parameters of total and free phenylbutazone in plasma were calculated using a non compartmental method. In regards to whole plasma data, the mean volume of distribution at steady state ( V _ss), was 147 mL/kg body weight, with a mean (± SEM) terminal elimination half-life ( t _1/2) of 40 ± 6 h. The mean clearance ( Cl ) was 3 mL/h/kg body weight. The V _ss as determined from the protein-free plasma fraction was 50 021 mL/kg body weight. This larger V _ss of free phenylbutazone compared to total plasma phenylbutazone was attributed to a high degree of plasma protein binding, as well as the greater penetration of free phenylbutazone into tissues. The mean t _1/2 of free phenylbutazone was 39 ± 5 h. This similarity to the t _1/2 estimated from total plasma phenylbutazone data is attributed to an equilibrium between free and plasma phenylbutazone during the terminal elimination phase. Mean t _1/2 as determined from milk, applying a urinary excretion rate model, was 47 ± 4 h. Milk clearance of phenylbutazone was 0.009 mL/h/kg body weight, or about 0.34% of total body clearance. Furthermore, evidence suggests that phenylbutazone either binds to milk proteins, or is actively transported into milk, as its concentration in milk was greater than that predicted due to a simple partitioning from plasma into milk.     

影响奶牛乳蛋白质含量的因素及营养调控技术研究

乳蛋白是牛奶中最重要的成分之一,受多种因素的影响,如品种、奶牛泌乳阶段、胎次、疾病和饲料组成与营养等。文中阐述了乳蛋白的合成机理及有关影响乳蛋白的营养和非营养因素;同时对国内外乳蛋白营养调控的技术进展作了全面的阐述,旨在为提高乳蛋白含量和产量提供参考。     

Serum and milk concentrations of apramycin in lactating cows, ewes and goats

A 20% solution of apramycin was administered intravenously (j.v.) and intramuscularly (i.m.) to lactating cows with clinically normal and acutely inflamed udders, to lactating ewes with normal or subclinically infected, inflamed udders and i.v. to lactating goats with normal udders. The i.v. disposition kinetics of apramycin was very similar in cows, ewes and goats. The elimination half-life was approximately 2 h and the steady-state volume of distribution was 1.26–1.45 L/kg. The absorption rate of the drug from the i.m. injection site was rapid, the i.m. bioavailability was 60–70% and the mean elimination half-life was 265 min in cows and 145.5 min in ewes. The binding percentage of apramycin to serum protein was low (< 22.5%). Concentrations of apramycin in milk produced by clinically normal mammary glands of cows, ewes and goats were consistently lower than in serum; the kinetic value AUC _milk/ AUC _serum was < 0.32. Drug penetration into the milk from the acutely inflamed quarters of cows was extensive; mastitis milk C _max values were more than tenfold greater than the C _max in normal milk. On the other hand, the drug had limited access to the milk produced by subclinically infected inflamed half-udders of ewes.     

On-farm feeding interventions to increase milk production in lactating dairy cows

Tropical Animal Health and Production - The objective of this study was to investigate the effect of tropical legume (Phaseolus calcaratus) mixed with ruzi grass feeding on the performance of...     

Relation between milk urea content and nitrogen excretion from lactating cows

Abstract

Thirty-two Chinese Holstein lactating cows were used to investigate the relationship of milk urea nitrogen (MUN) and nitrogen excretion loading to the environment. Cows were fed a similar amount of forage, and concentrates according to milk production. Total collection of urine and faeces were conducted continuously for three days. The milk urea nitrogen was significantly correlated to total nitrogen excretion (R ²=0.70), urinary nitrogen excretion (R ²=0.85), and nitrogen excretion from faeces (R ²=0.22). The following equation was proposed to predict total nitrogen excretion (TNE) (g/d) based on milk urea nitrogen (MUN) (mg/dl): TNE?=?15.46(±1.83)×MUN?+?193.40(±28.79). The results obtained in this study suggested that MUN might be used to predict TNE from lactating cows.     

Effect of brewer's grain on rumen fermentation, milk production and milk composition in lactating dairy cows

Six lactating Holstein cows were divided into two groups (n = 3) and used in a double reversal trial with three periods of 14 days each to evaluate the rumen fermentation, milk production and milk composition of cows fed brewer's grain (BG). The control diets contained 14% chopped Sudangrass hay, 24% corn silage, 18% alfalfa hay cube, 34% concentrate mixture‐1 and 10% concentrate mixture‐2 (wheat bran, soybean meal and cottonseed). In the experimental diet, wet BG replaced the concentrate mixture‐2. The protozoal population, concentration of ammonia‐N and volatile fatty acids in the ruminal fluid did not differ between the control and BG diets. The molar percentage of acetic acid was significantly higher (P < 0.05) with the BG diet at 5 h after feeding. The milk yield, the percentage of protein, lactose, solids not‐fat and somatic cell counts of milk did not differ between the two diets. The percentage of milk fat tended to increase with the BG diet. The BG diet significantly increased the proportions of C18:0 and C18:1 in milk fat (P < 0.01, P < 0.05, respectively) and tended to increase that of conjugated linoleic acid.     

The usefulness of determining urea levels and the acidity of milk for evaluating protein nutrition in cows

Samples of blood, urine and milk were examined in 94 clinically healthy cows of 10 herds. The average milk samples and the feed ration used in these herds were also examined. The determination of urea concentration and milk acidity was evaluated as to its suitability for the assessment of the protein-glycide ratio and acid-base activity of feed ration. The determination of urea content in an average milk sample was found to be an expeditious procedure. The results of this examination can be used for the evaluation of the protein supply to cows with the same reliability as the determination of serum urea. The passage of urea from serum to milk was proportional. The correlation coefficient for the relation of both parameters was statistically highly significant (r = 0.940). According to the calculated equation of regression line (f2 = 0.734 + 0.669 X f1), the values from 2.94 to 4.10 mmol/l are approximately adequate to the reference range of serum urea from 3.30 to 5.00 mmol/l in milk used in Czechoslovakia. The acidity of milk was found to have a low sensitivity for being used with success for the determination of the acid-base activity of feed ration. The examination of the net acid-base urinary output cannot be replaced by the determination of milk acidity.     

Forage intake by lactating beef cows differing in potential for milk production

Two feeding trials (early and late lactation) were conducted to measure ad libitum forage intake by beef cows from three breed groups of similar mature weight, but with different milk production potential. Twenty-four cow-calf units, eight from each milk production level (low, medium and high) were grouped (two/pen) based on similarity of cow weight and previous weigh-suckle-weigh and calf weaning weight data. Each pair of cow-calf units was confined to separate pens and allowed ad libitum access to chopped native Sandhills meadow hay. Dry matter intake, cow and calf BW and calf milk consumption were determined. Daily DMI (kg/hd) and milk consumption showed a positive linear response (P less than .05) among low, medium and high milk-producing cows. When cow DMI was expressed as g/unit mean cow BW during the trial, both a positive linear (P less than .05) and a quadratic response (P less than .01) expressed the relationship among production levels during early and late lactation. Calf forage intake, birth weight and adjusted 181- and 205-d weaning weight had no linear or quadratic relationship (P greater than .10) to milk production levels. However, June 1 calf weight, actual calf weaning weight and calf rate of gain (birth to weaning) had a positive linear (P less than .07) relationship. Best fit regression models with DMI as the dependent variable were developed for each trial based on R2 and CV values of the potential models. The best fit model (R2 = .94, SE = .33) for early lactation included production level as a class variable with cow BW.75 and calf birth weight as independent variables. The best fit model (R2 = .92, SE = .53) for late lactation included actual weaning weight in addition to the variables used during early lactation.     

Plasma cholesterol levels and short-term adaptations of metabolism and milk production during feed restriction in early lactating dairy cows on pasture

Low plasma total cholesterol (TC) concentrations are characteristic during the negative energy balance in early lactating dairy cows. The objective was to investigate short-term effects of different TC concentrations during an aggravated energy deficiency through a 1-week concentrate withdrawal on adaptations of metabolism and milk production. Multiparous Holstein cows (n = 15) were investigated during 3 week beginning at 24 ± 7 DIM (mean ± SD). Cows were kept on pasture and received additional concentrate in experimental week 1 and 3, while in week 2, concentrate was withdrawn. Blood was sampled once and milk twice daily. Based on their average TC concentration during week 1 (prior to concentrate withdrawal), cows were retrospectively assigned into a high (H-Chol; n = 8, TC ≥ 3.36 mmol/L) and a low TC groups (L-Chol; n = 7, TC < 3.36 mmol/L). Concentrations of phospholipids and lipoproteins were higher in H-Chol compared to L-Chol throughout the study (p < 0.05). During concentrate withdrawal, milk yield, glucose and insulin concentrations decreased similarly in both groups, while milk fat, milk acetone and plasma BHB were higher in H-Chol compared to L-Chol (p < 0.05). Compared to initial values, plasma NEFA, TAG and VLDL increased in both groups within 2 days after concentrate withdrawal (p < 0.05). Concentrations of NEFA during week 2 were greater in L-Chol compared to H-Chol (p < 0.05). Despite reintroduction of concentrate, milk yield in H-Chol remained lower for two more days compared to week 1 (p < .05), whereas milk yield recovered immediately in L-Chol. Activity of aspartate aminotransferase was higher in H-Chol compared to L-Chol in week 2 (p < 0.05). Greater plasma TC concentrations were associated with a reduced increase of NEFA. Further research is warranted if TC concentrations are related to adipose tissue mobilization and fatty acid turnover.     

Performance of lactating simmental cows fed two diets differing in the content of digestible intestinal protein (PDI)

In each of two trials, two diets differing in intestinal digestible protein (PDI) content (LP: low protein, 70 g kg⁻¹ dry matter; HP: high protein, 120 g kg⁻¹ dry matter) were given to multiparous Simmental cows in early lactation. Effective rumen degradabilities of nitrogen and non-protein dry matter of feed ingredients, estimated by the nylon-bag technique, were used to calculate PDI contents of diets. In trial 1, two groups of six cows were fed, in two successive periods of 7 weeks each, the diets LP and HP allocated according to energy requirements (LPR and HPR). In trial 2, the diets LP and HP were fed in two periods of 6 weeks each to 24 cows (six cows/group) according to energy requirements (LPR and HPR) or ad libitum (LPL and HPL).In trial 1, total and energy-corrected milk (ECM) yields were significantly higher (P < 0.01) for cows receiving diet HPR (20.7 and 19.2 vs. 18.9 and 17.4 kg day⁻¹), while milk fat and protein contents were similar. Live weight changes were different between groups (−126 and +39 g day⁻¹ respectively, for LPR and HPR diets) but this difference was not significant.In trial 2, cows fed HPL diets had significantly higher milk yields compared with the LPL and LPR diets (20.0 vs. 17.7 and 17.4 kg day⁻¹, respectively, P < 0.05), but not with the HPR diet (19.0 kg day⁻¹). ECM yield was higher (P < 0.05) for cows receiving more protein both between restricted groups (18.4 vs. 16.4 kg day⁻¹, respectively for HPR and LPR groups) and between ad-libitum groups (18.8 vs. 17.0 kg day⁻¹, respectively for HPL and LPL groups). Milk composition was not affected by dietary treatments. Diets fed according to requirements caused negative, but differing, live weight changes (−783 and −44 day⁻¹ respectively for LPR and HPR diets, P < 0.05). For ad-libitum treatments, LPL cows lost live weight while HPL cows gained live weight (−221 vs. 433 day⁻¹, respectively, P < 0.05). In the present experiments, increasing the supply of dietary PDI improved milk production even if the recycled nitrogen and live weight change could have contributed to protein requirements.     

Determination of milk/plasma ratio and milk and plasma pharmacokinetics of amoxicillin after intramuscular administration in lactating cows

This study was conducted to determine the passage ratio of amoxicillin into milk and its pharmacokinetics in milk and plasma after intramuscular administration. Five healthy dairy cows (Holstein, weighing 450–500 kg, aged 2–4 years) were used in this study. They received single intramuscular amoxicillin at a dose of 14 mg/kg body weight. Blood and milk samples were collected prior to drug administration (0); after 15, 30, 45, 60, and 90 min; and 2, 3, 4, 6, 8, 10, and 12 hr after administration. The plasma and milk concentrations of amoxicillin were determined using high‐performance liquid chromatography with ultraviolet detection. The passage ratio of amoxicillin into milk and plasma was determined using both AUC‐based calculation and milk and plasma concentrations at sampling times; it was calculated 0.46 and 0.52, respectively. The terminal half‐life and mean residence time of amoxicillin were 6.05 and 8.60 hr in plasma and 2.62 and 5.35 hr in milk, respectively. The C_max2 levels of amoxicillin in plasma and milk were measured as 1,096 and 457 ng/ml, respectively. It was observed that amoxicillin exhibited a secondary peak in plasma and milk. This study was the first to report on the passage ratio of amoxicillin into milk in lactating cows.     

盐藻粉对奶牛产奶性能与血清免疫球蛋白的影响

为了探讨盐藻粉对奶牛产奶性能免疫机能的影响,试验选择处于泌乳中期的健康荷斯坦奶牛18头分为对照组、1.5倍维生素A(165 IU/kg)组和盐藻粉组进行饲喂试验.结果表明:日粮中添加盐藻粉或1.5倍维生素A对奶牛的产奶性能有一定促进效果,盐藻粉组优于1.5倍维生素A组;添加盐藻粉可显著降低乳中体细胞数,血清IgG抗体和IgM抗体浓度也有明显增加的趋势;添加1.5倍维生素A也可显著降低乳中体细胞数,血清IgG抗体浓度有明显升高的趋势.     

Influence of estradiol administration to lactating cows on bacterial growth in milk whey

Bacterial growth (E. coli) in whey was studied by turbidometric technique during estradiol benzoate administration (0.02 mg/kg of body weight/day for 12-19 days) to 13 ovariectomized cows at three stages (early, mid and late) of the 1st- and 3rd-lactations. Whey samples from cows at early stage (60-90 days) of 1st-lactation promote the growth of E. coli during the estradiol treatment. This included a significant increase in the maximum turbidity and a decrease in the generation time. Bacterial growth was inhibited in whey from cows at other stages of lactation during the hormone treatment. The degree of inhibition varied at different stages of lactation. No significant alterations in the ability of whey to support bacterial growth were observed in 3 ovariectomized cows treated with the drug vehicle (arachis oil) alone. Majority of the quarters included in the present study were bacteriologically negative throughout the study.