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1.
The skim milk progesterone profile was assessed by radioimmunoassay, without extraction, from the day of insemination (day 0) until the cows were dried off on day 225 of gestation. A total of 418 samples were collected from 154 pregnant Holstein cows. The daily variation in skim milk progesterone was recorded from day 1 until day 45 of pregnancy to detect the commencement of progesterone secretion from the corpus luteum after insemination. Subsequent determinations were made every 2 weeks from day 46 until lactation ceased. On the day of artificial insemination and for the first 2 days after insemination, all the cows had a basal progesterone concentration <0.1 ng/ml. A rise in progesterone (0.2±0.1 ng/ml) was first detected on the third day after insemination. The progesterone values then increased significantly (p<0.001) until day 15.The values then remained nearly constant (2.5–3.5 ng/ml) until day 106 of pregnancy, when they began to decline. Between days 120 and 180 of gestation, progesterone was significantly decreased (2.2–2.9 ng/ml) before it rose again to the previous plateau (3.5–3.9 ng/ml) around day 180. The progesterone concentration then remained at the higher level until the animals were dried off.Abbreviations AI artificial insemination - RIA radioimmunoassay  相似文献   

2.
In 160 cows with ovarian cysts as determined by rectal palpation, differentiation was made of follicular cyst, luteal cyst, and cystic corpus luteum on the basis of milk progesterone concentrations estimated by an enzyme immunoassay before and at 10 days after cows were treated with gonadotropin-releasing hormone. Cows having a progesterone concentration in skim milk less than 1.0 ng/ml were considered to have follicular cysts and those with concentrations of 1.0 ng/ml or higher were regarded as the cases of luteal cyst or cystic corpus luteum. Luteal cyst was characterized by progesterone values remaining high in the cows for 10 days after treatment, and cystic corpus luteum was characterized by a decrease in progesterone concentration after cows were treated. By the rectal palpation procedure it was impossible to differentiate luteal cyst and cystic corpus luteum from follicular cyst. The frequencies of follicular cyst, luteal cyst, and cystic corpus luteum were 65%, 19%, and 16%, respectively. Of 104 cows with follicular cysts as defined by milk progesterone assay result, 73 (70%) responded to the treatment with gonadotropin-releasing hormone, the milk progesterone concentration increasing from 0.7 +/- 0.2 ng/ml (mean +/- SD) to 1.8 +/- 1.1 ng/ml. The accuracy of rectal palpation 10 days after treatment for judgment of luteinization of follicular cyst confirmed by milk progesterone analysis was only 30% (48 cows of 160).  相似文献   

3.
Oestrone sulphate concentrations were measured by radioimmunoassay in milk samples obtained weekly during pregnancy from Jersey and Friesian cows, with each breed grazed at two different stocking rates. Mean milk yields differed significantly (P<0.05) between the four herds, while mean percentage milk fat and protein values differed significantly (P<0.05) between the two breeds. In all four herds, oestrone sulphate concentrations in milk rose progressively during pregnancy from a mean value of approximately 80-100 pg/ml at 60-80 days of pregnancy to a plateau value of approximately 1 ng/ml at 181-200 days. In non-pregnant cows, oestrone sulphate concentrations in milk ranged from non-detectable to 110 pg/ml, with a mean +/- s.e.m. value of 59 +/- 4 pg/ml. There was considerable variation in milk oestrone sulphate concentrations between cows in each herd, and oestrone sulphate concentrations could also fluctuate markedly within cows from week to week. Despite this variation, the concentration of oestrone sulphate in 98% of milk samples obtained after 120 days of pregnancy was greater than the highest concentration found in milk from non-pregnant cows. Measurement of oestrone sulphate concentrations in milk samples taken at least 120 days after mating or insemination may provide an alternative, non-invasive means of determining or confirming pregnancy in New Zealand dairy cows.  相似文献   

4.
The aim of the study was to evaluate the concentrations of amyloid A in serum (SAA) and in milk (MAA) of cows with mastitis caused by Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis and healthy cows. The blood and milk samples were obtained from Holstein-Friesian cows with clinical signs of mastitis from two tie-stall housing systems herds in the Lublin region in Poland. A total of 80 milk and serum samples from 30 cows with mastitis and 10 healthy cows were selected for study. In the quarter milk samples from cows with mastitis Streptococcus strains were isolated: Strep. agalactiae (7 cows), Strep. dysgalactiae (9 cows) and Strep. uberis (14 cows). The present study indicates that amyloid A concentration was significantly higher in milk of cows with mastitis compared to control cows (1134.25 ng/mL and 324.50 ng/mL, P < 0.001). The highest concentration of amyloid A was found in milk of cows with mastitis caused by Strep. agalactiae and Strep. uberis whereas lowest in the milk of cows with mastitis caused by Strep. dysgalactiae (3882.50 ng/mL, 2587.75 ng/mL and 812.00 ng/mL, respectively). No statistically significant difference in amyloid A concentration in serum was revealed between all unhealthy cows and control group (2140.00 ng/mL and 2510.00 ng/mL, P > 0.05). There was also no statistically significant difference between the level of amyloid A in serum and in milk of cows with mastitis caused by Strep. agalactiae and Strep. uberis. Whereas, in the case of Strep. dysgalactiae, like in the group of healthy cows, the level of amyloid A was significantly higher in serum compared to this in milk (2100 ng/mL and 812.00 ng/mL, P < 0.001; 2510.00 ng/mL and 324.50 ng/mL, P < 0.001; respectively).  相似文献   

5.
Twenty-four healthy Holstein cows, 2.72 ± 0.64 (mean ± SD) years old, weighing 603.96 ± 73.22 kg (mean ± SD), and representing various levels of milk production, were used to determine the depletion of gentamicin (GT) in milk. The cows had not received antibiotics or other drugs that could interfere with study for at least 60 days before the beginning of the investigation. The cows were divided into six groups (n = 4) and treated with single (treatments A, B and C) or repeated (treatments D, E and F) doses of GT. Cows were acclimated for 7 days before administration of GT and milked twice a day at 12-h intervals (06.00 hours, 18.00 hours) throughout the duration of the study. Control milk samples were obtained after the arrival of the cows and assayed to establish their GT free status. On day 1 of each treatment, a baseline milk sample was collected from the milk produced (06.00 hours) by each cow. A single dose of GT was administered intramammarlly (A, i.m.m. left front quarter, 500 mg), intravenously (B, i.v., 5 mg/kg body weight) or intramuscularly (C, i.m., 5 mg/kg body weight). Cows in treatments D (i.m.m., 500 mg), E (i.v., 5 mg/kg body weight) and F (simultaneous i.m.m. 500 mg plus i.v. 5 mg/kg body weight) were treated twice a day for 5 consecutive days just after the morning and evening milkings. Milk samples from individual cows were collected every day after each milking during and after dosing until GT concentration in the milk was below the safe level of ± 30 ng/mL. The concentration of GT in milk was determined by a high-performance liquid chromatographic procedure. Depletion of GT to a concentration ± 30 ng/mL occurred at the seventh (84 h), third (36 h), third (36 h), eleventh (132 h), third (36 h) and nineteenth (228 h) post-dosing milking, for cows in treatments A, B, C., D, E and F respectively. The highest mean ± SEM) concentrations of GT were 14 710 ± 1213.89, 167.87 ± 46.94 and 91.62 ± 14.55 ng/mL measured in the first milking post dosing (12 h) for cows in treatment A, B and C respectively; for cows in treatments D, E and F, during the dosing period, they were 14067.50 ± 2989.09, 446.07 ± 100.92, and 22900 ± 2843.66 ng/mL and occurred at the seventh, third and eighth milking respectively. Because GT is not approved for use in dairy cattle and because of the long depletion time associated with some possible treatments, illegal and extra-label use is likely to cause residues in milk.  相似文献   

6.
The objective of this study was to determine the effect of evaporative cooling and dietary supplemental Zn source on blood metabolites, insulin and mineral concentrations, and milk mineral concentrations following intramammary lipopolysaccharide (LPS) infusion. Seventy-two multiparous Holstein cows were assigned to one of four treatments with a 2 × 2 factorial arrangement. Treatments included two environments: with or without evaporative cooling using fans and misters over the freestall and feedbunk, and two dietary sources of supplemental Zn: 75 mg/kg of dry matter (DM) supplied by Zn hydroxychloride (inorganic Zn; IOZ) or Zn hydroxychloride (35 mg of Zn/kg of DM) + Zn–Met complex (ZMC; 40 mg of Zn/kg of DM). A subset of cows (n = 16; 263 ± 63 d in milk) was infused with 10 μg of LPS or a saline control in the left or right rear quarters on day 34 of the environmental treatment. Individual milk samples collected from LPS-infused quarters at −4, 0, 6, 12, 24, 48, 72, 96, and 144 h relative to infusion were analyzed for minerals. Blood samples were collected at the same time with an additional sample collected at 3 h post-infusion to analyze glucose, nonesterified fatty acids (NEFA), insulin, and minerals. Cooling by time interactions (P ≤ 0.07) were observed for plasma glucose, NEFA, and serum insulin. Compared with cooled cows, non-cooled cows had lower concentrations of plasma glucose except at 3 h following intramammary LPS infusion, greater serum insulin at 3 and 12 h, and lower plasma NEFA at 24 and 48 h after infusion. Relative to cooled cows, non-cooled cows tended (P = 0.07) to have lower serum K concentration and had lower (P < 0.01) serum Zn 6 h following infusion (cooling by time interaction: P < 0.01). Relative to ZMC cows, IOZ cows had greater (P ≤ 0.09) concentrations of plasma Se, skim milk Na and Se, and skim milk Na to K ratio. Regardless of treatment, intramammary LPS infusion reduced (P < 0.01) serum or plasma concentrations of Ca, Mg, Zn, Fe, and Se, but increased (P < 0.01) their concentration in skim milk. In conclusion, deprivation of cooling resulted in more rapid and prolonged insulin release and influenced the systemic and mammary mineral metabolism during mammary inflammation induced by LPS of lactating dairy cows. Dietary supplementation of Zn–Met complex reduced blood and milk Se concentrations compared with cows fed Zn from an inorganic source.  相似文献   

7.
A field study was conducted to determine the usefulness of milk progesterone determination at the time of breeding to confirm estrus and at 21 days postbreeding to detect open cows. Twenty-seven dairy farmers collaborated in this study by providing milk samples on the day of breeding and 21 days later, together with pregnancy diagnosis data and information on herd reproductive management. Herd size ranged from 15 to 175 cows, the average being 65 milking cows. Six hundred and sixty-seven breeding-day samples and 472, 21-day samples were provided by the farmers. Analysis of milk samples for progesterone by a solid phase radioimmunoassay showed that only 32 (4.8%) of the services were performed when the cow was not in estrus (progesterone > 1 ng/mL). Of the 472, 21-day samples, 337 (71%) showed progesterone levels of > 1 ng/mL, while 135 (29%) showed progesterone levels of < 1 ng/mL. Subsequently, 243 (72%) of the cows with progesterone > 1 ng/mL and eight (6%) of the cows with progesterone < 1 ng/mL were diagnosed pregnant by transrectal palpation, giving a pregnancy rate of 53%. Progesterone concentration on the day of breeding was not associated with season or herd size. However, progesterone concentration at 21 days and pregnancy rate were associated with herd size. These results indicate that fertillzation failure and/or early embryonic mortality, rather than inaccurate detection of estrus, are the major reproductive problems encountered by the dairy farmers in British Columbia. Furthermore, progesterone values at 21 days were closely related to reproductive status and indicate the usefulness of milk progesterone assay for the early detection of open cows.  相似文献   

8.
The aim of this study was to investigate whether the skim milk progesterone concentrations at artificial insemination (AI) and day of rise of post-ovulatory progesterone concentration thereafter affect the conception and embryonic death rates in repeat-breeding cows. Milk samples were obtained from 96 repeat-breeding cows that failed to conceive to three or more AIs. The samples were taken from the cows at the day of AI and three times/week until day 45 post-AI. Skim milk was obtained after centrifugation and used for progesterone assay. The cows with a progesterone concentration more than 0.5 ng/ml at AI showed a significantly higher incidence of late embryonic death than those having a progesterone concentration<0.5 ng/ml at AI (p<0.01). As the progesterone level at insemination rose, conception rate declined. A negative correlation was shown between conception rate and skim milk progesterone level at AI. Of 56 cows showing a rise of progesterone to 1 ng/ml or more within 6 days after AI, 28 cows (50%) conceived. On the contrary, only eight of 39 cows (20.5%) conceived when the progesterone rose up to 1 ng/ml after day 6 post-AI. We concluded that increased progesterone concentration at the time of AI and delayed rise of progesterone post-AI might lead to decrease in fertility in repeat-breeding cows.  相似文献   

9.
OBJECTIVE: To determine if failure to detect oestrus in cows treated to resynchronise oestrus leads to fewer cows being inseminated than are truly in oestrus. PROCEDURE: Cows in three herds were enrolled in a controlled breeding program that involved synchronisation of oestrus for a first round of artificial insemination (AI) followed by resynchronisation for a second round of AI. Just before oestrus was expected at the second round of AI, aids for the detection of oestrus were fitted, which included pedometers, radiotelemetric transmitters (HeatWatch), tail-paint and heatmount detectors. Milk samples were collected at the second round of AI (day 33, herds A and B; day 35, herd C of the treatment program) and were used in combination with pregnancy testing to determine the number of cows that were in oestrus (milk progesterone < 2.0 ng/mL) and cows that were not in oestrus (milk progesterone > 2.0 ng/mL or pregnant at second round of AI) at the time samples were collected. RESULTS: The mean sensitivity of detection of oestrus at the resynchronised oestrus was 92.5% and did not differ significantly between herds (P = 0.19). A total of 75% (60/80) of cows that were retrospectively determined to be not pregnant at the time of the second round of AI were classified as having high (> or = 2.0 ng/mL) concentrations of progesterone in milk at that time. Pregnancy testing of cows about 35 days after AI suggested that early pregnancy loss also contributed to a reduction in submission rates at the resynchronised oestrus. CONCLUSION: Failure to submit cows for insemination at a resynchronised oestrus was mainly due to cows not being in oestrus rather than due to a failure to detect oestrus.  相似文献   

10.
奶牛早孕诊断乳汁孕酮临界值的确定   总被引：3，自引：0，他引：3  
随机选择健康荷斯坦母牛６３头，其中发情周期牛５头，配后１８－２４天牛３０头和通过直接确定的怀孕牛２８头，按程序采集末乳乳样。用放射免疫测定法（ＲＬＡ）测定乳汁孕酮（ＭＰ４）浓度。以发情第３天ＭＰ４浓度加上２倍标准差为未孕临界值的土限，以配后１８－２４天怀孕牛ＭＰ４浓度的平均值减去１倍标准差为怀孕临界值的下限。结果表明，奶牛ＭＰ４早孕诊断临界值为：≥７．１９ｎｇ／ｍｌ为怀孕，〈４．７２ｎｇ／ｍｌ为未  相似文献   

11.
Progesterone concentrations have been measured in defatted milk of British Friesian cows of four herds during the oestrus cycles (other than short cycles) immediately before artificial insemination (AI) at oestrus and immediately after AI (in non-pregnant cows), and during early pregnancy. Differences in mean progesterone concentrations between herds were significant (P less than 0.05) on all days within the day 10-18 period after AI, both in pregnant and in non-pregnant, inseminated cows but were not significant between pregnant and non-pregnant cows within herds until day 17 or 18. It is concluded that up to this time (that of luteolysis in non-pregnant cows) undefined factors, variable among herds, can have a much greater influence on the rate of progesterone secretion by corpora lutea and consequent progesterone concentration in plasma and milk than does the presence of conceptuses. Maximum mean progesterone concentration reached during early pregnancy in two herds did not differ significantly; it was reached in the 11-15-day period in one herd but not until 46-50 days in the second. Mean progesterone concentration declined after day 90.  相似文献   

12.
The relationships between insulin-like growth factor-I (IGF-I) and the fertility and milk yield of Holstein-Friesian dairy cows were investigated. The concentration of IGF-I in blood was measured weekly from one week before to 12 weeks after calving in 177 multiparous cows and at four times during this period in 142 primiparous cows; the concentration of IGF-I in milk was measured in 50 of the multiparous cows. The plasma concentrations of IGF-I were higher in the primiparous than in the multiparous animals. In the primiparous cows, high concentrations of IGF-I before calving were associated with longer calving to conception intervals. Conversely, in the multiparous cows low concentrations of IGF-I before and after calving were associated with a failure to conceive, despite repeated services. Multiparous cows with IGF-I concentrations of greater than 25 ng/ml in the week after calving were 11 times more likely to conceive to first service than those with lower concentrations. Concentrations of IGF-I greater than 50 ng/ml at first service increased the likelihood of conception five-fold. Cows with higher peak milk yields had lower plasma concentrations of IGF-I and took longer to return to ovarian cyclicity. The negative relationship between milk yield and return to cyclicity was stronger in the multiparous cows (P < 0.002) than in the primiparous cows (P < 0.04). The concentrations of IGF-I in milk followed a different pattern and were not associated with the changes in plasma IGF-I or fertility.  相似文献   

13.
This investigation studied the effects of intravaginal administration of a mixture of lactic acid bacteria (LAB) on the incidence of purulent vaginal discharges (PVD), plasma haptoglobin concentrations, and milk production in dairy cows. A total of 82 pregnant primiparous and multiparous Holstein dairy cows were used in this study. Half of the cows received intravaginally 1 mL of LAB at 1010–1012 cfu/mL and the other half 1 mL of reconstituted skim milk (i.e., carrier) (controls). Administration of LAB was conducted once per wk during 2 and 1 wk before the expected day of calving and at 1, 2, 3, and 4 wk postpartum. Data demonstrated that intravaginal administration of LAB decreased the occurrence of PVD at 3 wk postpartum (P < 0.05). Concentrations of plasma haptoglobin, an acute phase protein often associated with uterine infections, was lower in cows treated with the LAB mixture at 2 wk (P < 0.001) and 3 wk (P < 0.05) postpartum. Treatment with LAB did not improve overall pregnancy rate, but the treated multiparous cows produced more milk than their control counterparts (P < 0.05), whereas no difference was observed in primiparous cows regarding milk yield (P > 0.05). Overall, this is the first study demonstrating that intravaginal LAB administration lowers the incidence of PVD and enhances milk production in dairy cows. Further research is warranted to evaluate the effects of LAB on reproductive performance in a larger cohort of cows.  相似文献   

14.
The concentrations of lactoferrin (Lf) in quarter milk from normal lactating cows and subclinical mastitic cows were measured to determine whether the Lf concentration in milk is influenced by the age of the cow, the stage of lactation, number of milk somatic cells and the presence of pathogens. Lf concentrations in 111 quarter milk samples from 28 normal lactating cows and 270 quarter milk samples from 198 subclinical mastitic cows were measured by means of a single radial immunodiffusion test. Lf concentrations (means +/- standard deviations; logarithmic form) in normal cows and subclinical mastitic cows were 2.23 +/- 0.39 and 2.70 +/- 0.39, respectively. The mean milk Lf concentration (log) in subclinical mastitic cows was significantly (p<0.01) higher than that in normal cows. The mean milk Lf concentration (log) in normal lactating cows aged 5 years was lower than those in normal lactating cows aged 2 years (p<0.01) and 3 years (p<0.05). The results showed that the milk Lf concentration (log) is associated with age of the dairy cow (one-way analysis of variance test, p<0.01). The mean milk Lf concentration (log) in the latter lactational period tended to be higher than those in the peak and middle periods. Milk Lf concentrations (log) tended to be proportional to the level of the somatic cell count (SCC) score. Mean milk Lf concentrations (log) in subclinical mastitic cows infected with Staphylococcus aureus and with other streptococci species were significantly (p<0.01) higher than those in cows infected with coagulase-negative staphylococci and with Corynebacterium bovis.  相似文献   

15.
An ovine-specific RIA, shown to be reliable for bovine leptin determination, was used to study the effects of breed, body fatness, feeding level, and meal intake on plasma leptin level in adult cattle. Eighteen fat Charolais, fat Holstein, and lean Holstein adult cows were either well-fed (130% of maintenance energy requirements [MER]) or underfed (60% of MER) for 3 wk. The breed tended to have a small effect on plasma leptin level, which was decreased by 70% (P < 0.05) in lean compared to fat Holstein cows. A strong curvilinear relationship was found between mean adipocyte volume and plasma leptin concentrations in well-fed (r = +0.95) and underfed (r = +0.91) cows. Underfeeding caused a significant decrease in plasma leptin levels from 8.0+/-3.1 to 6.1+/-2.3 ng/mL (P < 0.01). Nine adult Holstein cows initially fed at 130% of MER (control) were underfed to 21% of MER for 7 d, and five of them were refed to 237% of MER for 21 d. Plasma leptin measured 1 h before meal distribution was decreased from 5.9+/-0.4 to 3.8+/-0.2 ng/mL (P < 0.01) by underfeeding and increased to reach 8.8+/-1.0 ng/mL (P < 0.01) after refeeding. It was positively related to plasma glucose (r = +0.52, P < 0.01) and negatively related to plasma NEFA (r = -0.67, P < 0.001). Plasma leptin measured 4 h after meal distribution was positively related to feeding level and to plasma 3-OH-butyrate (r = +0.61, P < 0.005) and negatively related to plasma NEFA (r = -0.56, P < 0.01). Differences between pre- and postprandial leptin concentrations showed a decrease after meal intake in control and well-fed cows (-7 and -19%, P < 0.01, respectively) and an increase in underfed cows (+12%, P < 0.01). Leptin response to meal intake was positively related to glucose response (r = +0.66, P < 0.001) and negatively related to 3-OH-butyrate response (r = -0.78, P < 0.001). By using the "multispecies" commercial RIA, leptin concentrations were lower and we observed similar physiological responses, although less related to other hormones or metabolites. These data provide evidence, first, that a specific RIA for ruminant leptin determination is necessary to better understand leptin regulation, and second, that plasma leptin is strongly related to adipose cell size and positively related to feeding level in adult cattle, and that an effect of meal intake could be mediated by glucose and(or) ketone bodies.  相似文献   

16.
The accuracy of rectal palpation and of a rapid milk progesterone enzymeimmunoassay (EIA) for determining the presence of a functional corpus luteum (CL) in subestrous dairy cows was investigated, using the results of a radioimmunoassay (RIA) for progesterone in skimmed milk as the “gold standard”. The ovaries and uterus of each of 359 subestrous cows from 32 dairy herds were palpated per rectum, the presence or absence of a functional CL was predicted, and a milk sample was collected for analysis by both the rapid EIA and the RIA.

The nine clinicians participating in the study had a combined sensitivity of 82.6% and specificity of 52.6%, compared to the EIA which had a sensitivity of 90.3% and a specificity of 84.2% for predicting the presence of functional luteal tissue.

It was concluded that the technique of rectal palpation was inaccurate at assessing the functional (progesterone-secreting) status of ovarian structures. In addition, a qualitative EIA was as sensitive and more specific than rectal palpation in predicting the presence of a functional CL in the subestrous cow.

  相似文献   

17.
By inoculating Klebsiella pneumoniae into the teat canals of mammary glands, coliform mastitis was induced experimentally in 6 lactating cows. Release of eicosanoids, histamine, and serotonin in plasma and milk was studied in response to 2 doses of K pneumoniae. A low dose (mean, 5,000 organisms/ml) was inoculated into cows 1 through 4, and a high dose (mean, 200,000 organisms/ml) was inoculated into cows 5 and 6. Milk and blood samples were collected before inoculation (0 hours), and hourly, from 3 to 24 hours after inoculation. Concentrations of prostaglandin F2 alpha (PGF2 alpha), prostaglandin E (PGE), thromboxane B2 (TxB2), histamine, and serotonin were measured in plasma and milk obtained from control (NaCl solution-inoculated) and infected quarters. Fluorometric analysis of milk from infected quarters revealed significantly increased histamine and serotonin concentrations regardless of the dose of K pneumoniae. The mean (+/- SEM) peak concentrations of histamine were significantly (P less than 0.01) increased from the preinoculation value of 44 (+/- 12) ng/ml to 312 (+/- 104) ng/ml in milk from infected quarters and 72 (+/- 24) ng/ml in milk from control quarters. The mean peak concentration of serotonin increased significantly from the preinoculation concentration of 436 (+/- 37) ng/ml to 1,754 (+/- 662) ng/ml and 4,867 (+/- 1,248) ng/ml in milk from control (P less than 0.02) and infected (P less than 0.001) quarters, respectively. However, serotonin concentration in milk from infected quarters was approximately 2.8 times greater than that in milk from control quarters. Concentrations of PGF2 alpha, PGE, and TxB2 in milk and plasma were evaluated by radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
Very little is known about the effects of hormonal synchronization of follicle waves and superovulation on the estrogen content of a cow’s milk. The objective of this study was to determine the effect in dairy cows of synchronization with estradiol-17β (E2) and progesterone (P4) on milk E2 concentrations and to compare these levels with those achieved during superstimulation for 4 d with porcine follicle-stimulating hormone (FSH). The milk E2 concentrations were raised significantly above pretreatment levels (P < 0.05) for 2 d after synchronization, the mean peak being 40.2 ± 18.5 (standard error) pg/mL and the pretreatment mean 1.5 ± 0.5 pg/mL. The mean peak E2 concentration during ovarian stimulation was 4.4 ± 0.7 pg/mL. The mean E2 concentration was significantly higher (P < 0.05) after synchronization than during superstimulation for the 1st milking after synchronization but not subsequent milkings. The milk estrone concentrations were above pretreatment levels for 1 d after synchronization and were not different from those observed during superstimulation.  相似文献   

19.
Our objectives were to investigate the effects of genotype, yield and composition of milk, and changes in BW and body condition on the initiation of cyclic ovarian activity in nonsuckled beef and dairy cows milked twice daily. Nulliparous heifers were selected from three breeds, 12 Angus, 13 Simmentals, and 26 Holsteins, based on their EBV for milk yield. Cows were machine-milked twice daily, and daily milk yield was recorded; composite samples of milk were collected twice weekly for analyses of milk components. Blood was collected from all cows thrice weekly for 75 d postpartum, and concentrations of progesterone in serum measured by RIA were used to estimate day of first postpartum ovulation. Holstein cows produced more (P less than .05) milk (unadjusted or 3.5% fat-corrected) than Angus or Simmental cows during the first 30 d of lactation. Holstein cows had higher (P less than .01) peak yield of milk than Simmental and Angus cows. Days to peak milk yield were similar for Simmental and Holstein cows, and both were more (P less than .05) than those for Angus cows. Percentages of fat, protein, and total solids in milk were highest (P less than .05) for Simmental cows, whereas milk of Holstein cows had the highest (P less than .05) percentage of lactose and lowest (P less than .05) concentration of somatic cells. Average BW at ovulation differed (P less than .05) among breeds. Estimated daily changes in BW from calving to first ovulation were different (P less than .05) for Holstein and Simmental cows but were similar to those of Angus cows.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
New tools are needed to detect chronic sub-clinical mastitis, especially in automatic milking systems. Haptoglobin and serum amyloid A (SAA) are the two most sensitive bovine acute phase proteins, and their concentrations increase in milk from cows with clinical mastitis and in milk from cows with experimentally induced chronic sub-clinical Staphylococcus aureus mastitis. The aim of this study was to further evaluate the potential for haptoglobin and SAA in milk as indicators of chronic sub-clinical mastitis. Quarter milk samples were collected from 41 cows with a mean composite milk somatic cell count (CSCC) above 300,000 cells/mL during at least two months prior to sampling. Quarter milk samples were also taken from eleven cows with a mean CSCC below 80,000 cells/mL during at least two previous months. These samples were analysed for haptoglobin, SAA, adenosine triphosphate (ATP) activity and bacterial growth. The samples were grouped according to their ATP, haptoglobin and SAA status. ATP+ samples had ATP > 2 x 10(-10) mol/mL, Hp+ and SAA+ samples had detectable levels of haptoglobin (> or = 0.3 mg/L) and SAA (> or = 0.9 mg/L), respectively. In udder quarter samples from healthy cows, 42 out of 44 samples belonged to the ATP-Hp-SAA- group. Among cows with chronic sub-clinical mastitis, the ATP+Hp+SAA+ group contained 66 out of 164 samples while 44 samples belonged to the ATP+Hp-SAA- group. Detectable levels of haptoglobin and SAA were found in 92 and 80 samples, respectively. Growth of udder pathogens was detected in 28 samples and Staphylococcus aureus was the most common bacteria. In conclusion, haptoglobin and SAA concentrations below the detection limit were considered as good indicators of healthy udder quarters. A substantial variation in haptoglobin and SAA concentrations in milk was observed in udder quarters with chronic sub-clinical mastitis.  相似文献   

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