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1.
Since visual observation is the most commonly used way of detecting oestrus and is supposed to be as effective as detection with technical devices, we evaluated a recently developed oestrus detection scoring system in daily dairy practice. In this scoring system nine signs of oestrus are scored with points, ranging 3 to 100. Twenty-one dairy farmers used the scoring system during a period of 3 weeks. All cows that were more than 30 days post partum and not confirmed pregnant were monitored, using the scoring system, by the herd owners. Oestrus was confirmed by measuring progesterone concentrations in milk. With the scoring system a detection rate of 47% was achieved. This was lower than expected, because in an earlier control period, the detection rate was 64%. We concluded that this new method might be too complicated to introduce to normal herd management, because in daily practice it is too demanding to watch cows twice a day for 30 minutes, especially if the cows show only vague and infrequent symptoms of oestrus. It also appeared to be too complicated to watch the herd at the most appropriate time. However, if the scoring system is included in the daily routine, meaning that farmers are trained to watch for other symptoms than standing heat only and are able to recognize their different values, it can be a valuable aid to oestrus detection.  相似文献   

2.
The efficiency of treatments for unobserved oestrus and their effect on the reproductive performance of a dairy cattle herd with low oestrous detection rate till 60 days post‐partum (dpp), attributed to the declivous and slippery concrete floor were investigated. The herdsman requested advice in order to improve the mean days open of the herd, but no investments were allowed because a new unit was about to be built. Due to the low oestrus detection rate of the herd, the breeding policy was to inseminate at the first detected post‐partum oestrus. Cows were examined at 20–30 dpp to assess uterine involution, ovarian activity and prevalence of reproductive disorders and, at 60 dpp if no previous oestrus was detected. Each examination included palpation per rectum, ultrasound scanning and collection of a blood sample for plasma progesterone (P4) measurement. Cows with unobserved oestrus till 60 dpp were allocated either to a treatment group (n=139) or to a control group (n=139). Three treatments were used: (a) injection of PGF2α (PG) upon detection of a corpus luteum (CL; n = 30), cows not observed in oestrus being re‐injected 11–12 days later. AI was at oestrus; (b) PRID (n=35) or Crestar (n=74) devices kept in situ for 12 and 9 days, respectively, were associated to an injection of PG and of equine chorionic gonadotrophin (eCG) at device removal. Cows were double‐fixed time‐inseminated at 48 and 72 h after device removal. All treated cows were examined at 48–72 h after treatment to confirm oestrus. The percentage of cows detected in oestrus up to 60 dpp remained unchanged through the trial (35 and 47% for years before intervention: 1994–95; 51 and 48% for years of intervention: 1996–97). In contrast, the oestrous detection rate was high both in treated (93%) and control (100%) cows. This possibly resulted from an improvement in the oestrous detection efficiency of the herd's personnel and from examination of cows at 48–72 h after treatment. Treated and control cows had identical conception rate (CR; 36 and 37%, respectively) and reproductive performance. However, the mean days open of the herd in 1996 was significantly improved in comparison with previous years (mean ± SEM: 134 ± 6, 126 ± 5, 110 ± 4 and 114 ± 5 days, for years 1994, 1995, 1996 and 1997, respectively, p < 0.05, ANOVA ). Conception rate to AI up to 40 dpp was significantly reduced, compared with the period between 60 and 100 dpp but, mean days open were significantly improved in cows inseminated up to 60 dpp, compared with thereafter (p < 0.05).  相似文献   

3.
The corpus luteum (CL) may be looked upon as a compact or cavitary structure. A number of papers have addressed the relationship between CL type and parameters such as fertility or progesterone levels. The present study assessed the morphological and functional sequence observed in cows with different CL types, comparing pre-ovulatory follicle size, progesterone levels, luteal tissue formation and some blood biochemical parameters (calcium, albumin, inorganic phosphorus, glucose, magnesium, copper and zinc), oestrus cycle length and oestrus expression, as a function of CL type. Twenty-eight lactating dairy cows from two commercial dairy farms in southern Spain were studied. Oestrus detection was performed by monitoring daily oestrus behaviour, and artificial insemination (AI) was perfomed using the AM/PM rule. Ovaries and uterus were sonographically examined and blood samples were collected to measure progesterone and various biochemical parameters. There was a slight tendency towards the appearance of luteal cavities when pre-ovulatory follicles were larger (1.9 ± 0.2 vs 1.7 ± 03; p = 0.074). Fertility was not affected by cavity presence (cavity = 42.9% and compact = 57.1%; n.s.). Luteal tissue and function were not modified as a function of CL type. Cows with luteal cavities displayed significantly higher levels of albumin, suggesting a possible metabolic influence on the formation of these structures, although specific research is required to confirm this observation.  相似文献   

4.
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   

5.
Ovarian ultrasonography and plasma progesterone levels were monitored in 37 lactating Holstein cows with a history of repeat breeding; the data obtained were analysed in conjunction with clinical and behavioural signs, to identify the aetiology of the syndrome. Differences were detected between RBCs displaying apparently normal cycles and others with irregular cycles. There were also differences in heat expression; a large number of repeat breeder cows (RBCs, 50%) displayed delayed or silent oestrus. Ovarian disorders were common in RBCs, and included ovarian cysts, mistimed AI, subluteal progesterone levels, luteal dysfunction or ovulation defects. Both ultrasonography and plasma progesterone assays are useful tools for ascertaining the aetiology of the repeat breeder syndrome.  相似文献   

6.
Oestrus detection in dairy cows by milk temperature measurement   总被引：1，自引：0，他引：1  
The milk and body temperatures of 15 cows were monitored twice daily at milking times, over a total of 30 oestrous periods. The best determination of oestrus was based on a temperature rise of at least 0.2 degree C over the corresponding mean temperature of the three preceding days. This resulted in 72 +/- 16 per cent of oestruses, predicted by serial progesterone assays, being successfully detected by serial progesterone assays, being successfully detected and 11 +/- 3 per cent of false positives. The variable extent of the temperature rise at oestrus and the large daily fluctuations in temperature for individual cows, resulted in a moderate oestrus detection rate accompanied by an unacceptable level of false positives.  相似文献   

7.
A short calving to conception interval is of main importance to achieve high economic efficiency in dairy cow industry. In order to reduce this interval, several hormonal treatments have been put on the market, in which cloprostenol, a synthetic analogue of prostaglandin F2alpha (PGF2alpha). The aim of this study was to compare fertility of cloprostenol-induced oestrus to that of spontaneous oestrus in dairy cows. In a group of 525 cows, 280 (treated group) were administered 0.5 mg cloprostenol i.m. after transrectal corpus luteum (CL) detection, and inseminated at detected oestrus during the following week. The other 245 cows (control group) were inseminated during spontaneous oestrus. Whey progesterone concentrations were checked at treatment and at insemination in order to remove from the study cows whose P4 levels indicate a non-functional CL, or a lack of luteolysis respectively. Moreover, cows that were not inseminated due to genital problems were also excluded from this study. Conception (59% vs 54.5%) and calving rates (93.7% vs 93%) were not significantly different between the two groups.  相似文献   

8.
The aim of this study was to investigate the effect of applying a progesterone‐based oestrous synchronization protocol at 51–57 days postpartum in high‐producing dairy cows. The data analysed were derived from 1345 lactating cows. Cows between 51 and 57 days postpartum were assigned to the groups: control, PRID (receiving a progesterone‐releasing intravaginal device for 9 days, and prostaglandin F2α 24 h before PRID removal) or GnRH–PRID (the same as the PRID group plus GnRH at PRID insertion). Oestrus was detected by using pedometers and confirmed by examination of the genital tract at AI. Oestrous and conception rates before days 71–77 postpartum, pregnancy loss in early pregnant cows or the cumulative conception rate registered on day 120 postpartum were considered as the dependent variables in four consecutive logistic regression analyses. Based on the odds ratios, the oestrous rate increased by a factor of 1.73 in cows showing oestrus before treatment for each unit increase in the number of previous oestruses; decreased by a factor of 0.44 in the control group with respect to the treatment groups; and by a factor of 0.61 in cows without luteal structures at treatment with respect to cows with corpora lutea. The conception rates of cows inseminated before days 71–77 postpartum remained similar across the groups, whereas the likelihood of pregnancy loss for cows becoming pregnant during this period was 0.11 times lower in the PRID group than in the control. Based on the odds ratio, the likelihood of a higher cumulative conception rate on day 120 postpartum: increased in cows showing oestrus before treatment by a factor of 1.41 for each unit increase in the number of previous oestruses, was reduced 0.56‐fold in control cows compared with treated cows, and was also reduced by a factor of 0.98 for each kilogram of milk production increase recorded at treatment. In conclusion, although oestrous synchronization programmes performed in this study did not improve fertility, cows treated with progesterone could be inseminated earlier than untreated cows, such that the treatments increased the cumulative pregnancy rates determined on day 120 postpartum. In addition, fewer pregnancy losses were observed in early pregnant cows in the PRID group than the GnRH–PRID group.  相似文献   

9.
The objective of this study was to monitor the reproductive performance of dairy cows in smallholder farms under the Tanga Dairy Development Project (TDDP). The findings can be used to improve reproductive efficiency. Dates of oestrus, artificial insemination (AI) or service by bull and calving were recorded, and pregnancy was diagnosed by rectal palpation. Daily milk yields, monthly body condition score (BCS) measured on the scale of 1-9, feed availability, calf rearing, and diseases were also recorded. Milk progesterone (P4) concentration was measured by radioimmunoassay (RIA) in 1327 sequential samples collected between day 15 and 120 in 46 post-partum Zebu x Friesian crossbred dairy cows. The mean interval from calving to first P4 rise above 2 nmol/L (cyclicity) was 66.1 +/- 6.8 days. Resumption of ovarian activity postpartum was early (< 60 days) in 45%, and late (> 60 days) in 55% of the cows. In about 45% of the cows the first post-partum ovarian cycles were short (< 14 days) and had low P4 concentrations. Oestrus was missed once or several times in 34.7% of the cows, most likely indicating poor oestrus detection, silent oestrus, or farmers deliberately not taking or reporting their cows for insemination. The mean interval to conception was within 130 days postpartum. Average daily milk production was 5.7 +/- 2.2 L and the mean BCS Was 3.1 +/- 1.3. Both milk production and BCS had no clear influence on the measured reproduction parameters. Clinical uterine involution was complete within 29 +/- 2.6 days of calving in the majority of cows. Progesterone profiles and rectal palpation revealed various causes of infertility, which included anoestrus, silent oestrus, irregular oestrous cycles, and infection of the uterus. The major causes of animal culling, death, slaughter or sales include tick-borne diseases and trypanosomiasis, which have high prevalences in the area, infertility, low productivity and old age. Greater attention should be focused on reproduction and its interaction with nutrition and disease control.  相似文献   

10.
The purpose of this survey was to evaluate the reproductive performance of dairy cows on problem farms in southern Iceland. In all 229 cows on 6 farms were studied. The animals were examined clinically by rectal palpation, once a month. Blood samples were taken 2–5 and 7–10 weeks after calving. The blood samples were analysed for the contents of glucose, urea, inorganic phosphate, calcium and magnesium. Milk samples for progesterone profiles were taken, by the farmer, every 4th day from day 10 postpartum until first oestrus. Because of this sampling method, 128 cows had no rise in progesterone levels, when milk sampling was stopped. These 128 animals were excluded from the study. The results are based on 101 animals.There was a large variation between cows in postpartum reproductive performance. In the total material 1st ovulation occurred later than reported in many other countries. Fifty percent of the cows had ovulated 35 days after calving and 90 percent 70 days after calving.The first luteal phase was short in about 60 % of the cows. The progesterone values assayed from those short cycles were lower than the values assayed from the following cycle. First artificial insemination (ai) was on the average 77 days postpartum (pp). The conception rate to first service was 49 %. Of 100 milk samples taken at the time of ai, 20 had high progesterone value. This indicates a high frequency of luteal phase inseminations.Clinical ketosis was diagnosed in 35 cows. Of these, 31 had a low glucose value. Cows with clinical ketosis ovulated, on the average, later than other animals and 24 ovulated later than 40 days pp. The results indicated that the fertility problems of these cows studied were late ovulations, low conception rate, probably in part, due to luteal phase inseminations, and a high frequency of ketosis which could be caused by low quality feedstuff.  相似文献   

11.
Shortened and weakened oestrous signs in dairy cows may cause a failure of oestrus detection and artificial insemination timing error leading to poor reproductive performance. The aims of this study were to investigate the duration of standing oestrus in high-producing dairy cows under a free stall system, to determine the duration of expression of secondary oestrous signs before and after standing oestrus (Expt 1) and to compare the duration and intensity of oestrus between cows and heifers (Expt 2). Cattle were checked for primary and secondary oestrous signs at an interval of 4 h. Heat detection aids were also used. In Expt 1, of 56 cows which were detected in oestrus, 36 cows (64.3%) showed standing oestrus and other 20 cows (36.6%) showed secondary oestrous signs only. Duration of the standing oestrus was 6.6 +/- 6.3 h on average (+/-SD), ranging between 2 and 32 h. The cows in standing oestrus showed secondary oestrous signs during a period from 9.6 +/- 8.1 h before onset of standing to 18.4 +/- 18.8 h after the end of standing oestrus. In the cows that did not show standing oestrus, expression of secondary oestrous signs were observed for 25.7 +/- 20.5 h, which was 7.5 h shorter than the average duration of oestrus in cows showing standing oestrus. In Expt 2, nine (82%) of the 11 lactating cows in oestrus showed standing, while all the 10 heifers exhibited standing oestrus. Average duration of standing oestrus was 6.4 +/- 4.3 h in cows and 6.2 +/- 3.9 h in heifers, respectively. It may be concluded that the duration of standing oestrus is substantially shortened in lactating dairy cows, and more than one-third of cows did not show standing oestrus. In cows showing standing oestrus, duration of expression of secondary oestrous signs before and after standing is not shortened. Duration of standing oestrus in heifers was as short as that in cows.  相似文献   

12.
This report reviews the most recent developments in prostaglandin‐based oestrous synchronization programmes for postpartum dairy cows and addresses the efficiency of controlled breeding protocols based on such developments for cows with abnormal ovarian conditions. A double prostaglandin protocol applied 11–14 days apart seems to be capable of bringing most cows to oestrus. Because of varying oestrus onset times, improved conception rates are obtained following artificial insemination (AI) at detected oestrus rather than fixed‐time AI in prostaglandin‐treated cows. The administration of oestradiol or human chorionic gonadotrophin, or both these hormones, after prostaglandin treatment, improves the synchrony of oestrus yet does not enhance the conception rate. Progesterone‐based treatments for oestrous synchronization are considered the most appropriate for non‐cyclic or anoestrous postpartum dairy cows; prostaglandin alone being ineffective because of the absence of a mature corpus luteum in these cows. Improved oestrus synchrony and fertility rate have been reported using short‐term progesterone treatment regimes (7–9 days) with or without oestradiol benzoate combined with the use of a luteolytic agent given 1 day before, or at the time of, progesterone withdrawal. The ovulation synchronization (Ovsynch) protocol, based on the use of gonadotrophin releasing hormone and prostaglandin, was developed to coordinate follicular recruitment, CL regression and the time of ovulation. This protocol allows fixed time insemination and has proved effective in improving reproductive management in postpartum dairy cows. However, timed AI following Ovsynch seems to have no beneficial effects in heifers, because of an inconsistent follicle wave pattern, and in anoestrous cows, given their lack of prostaglandin responsive CL. To date, there are several prostaglandin based, fixed‐time insemination oestrous synchronization protocols for use in early postpartum dairy cows with ovarian disorders such as ovarian cysts and acyclicity.  相似文献   

13.
Oestrus during pregnancy in the cow   总被引：1，自引：0，他引：1  
Forty-three oestruses were observed in 35 pregnant cows in one beef suckler herd and 17 dairy herds; at each oestrus the pregnant cow stood willingly to be mounted by another cow or bull. Such oestruses were observed at all stages of pregnancy, although more often between 121 and 240 days, occurred more than once per pregnancy and were also seen in successive pregnancies. On one farm where the dairy cows were observed for four 30 minute periods daily, oestrus was recorded in 5.7 per cent of pregnant cows. The behavioural signs associated with oestrus during pregnancy were indistinguishable from those of true oestrus in non-pregnant animals and although its duration was shorter (mean 5.6 hours), its intensity was comparable to that of the true oestrus. Pregnant cows showing oestrus were usually seen interacting with other oestrous cows in the sexually active group. Pregnant cows showing oestrus had a higher mean condition score (3.9 +/- 0.64) than control pregnant cows (3.0 +/- 0.36). Physiological changes in the genital tract normally associated with true oestrus were not observed in pregnant cows showing oestrus. There was no ovulation or metoestrous bleeding. The characteristics of cervical mucus, including ferning patterns, were similar to those of pregnant cows at the same stage of pregnancy. Hormonal changes associated with oestrus in non-pregnant cows were not observed in the pregnant cows exhibiting oestrus. Seven of nine pregnant cows at oestrus stood willingly to be mounted by a bull. On seven occasions, bulls exposed only to cervical mucus from pregnant cows showing oestrus did not display flehmen.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

14.
Oestrus prediction in dairy cows using an ELISA progesterone test   总被引：1，自引：0，他引：1  
The commercially available test kit for assaying milk progesterone was used in the practice laboratory on samples taken daily from cows 17 to 24 days after service. Improved oestrus detection rates and accuracy were achieved by predicting the onset of oestrus. Similar results were obtained by sampling on days 18, 20, 22 and 24 or on days 19, 21 and 23 after service. Calving to conception intervals improved from 115 to 84 days in one herd and from 85 to 74 days in another and the potential economic benefits in these two herds outweighed the costs by 7.4:1 and 3.4:1, respectively.  相似文献   

15.
The following reproductive parameters were studied in 40 Icelandic dairy cows on 2 farms with free stall and tie stall housing: The time of onset of post-partum luteal activity; the time of first post-partum artificial insemination (AI); the time of conception; conception rate to first post-partum AI; the number of AI's per conception; length of gestation; and the number of days between 2 consecutive calvings. Milk for progesterone analysis was sampled 3 times a week from calving until first AI on farm 1, but every day for 90-100 days from calving on farm 2. In this study the average onset of luteal function was 21 days post-partum, the cows were inseminated 62 days and conceived 74 days post-partum. Conception rate to first AI was 71% and number of AI's per conception was 1.6. Significant differences were not found between the 2 farms. The reproductive performance of the cows in this study was greater than found in earlier studies of the Icelandic dairy cows and indicate that this animal has reproductive capabilities comparable to high producing foreign dairy cows.  相似文献   

16.
This study focused on the use of radioimmunoassay of progesterone in milk for the diagnosis of post-partum ovarian cyclicity and accurate detection of oestrus and non-pregnancy in cows in the artificial insemination (AI) programme in Bangladesh. In Investigation 1, milk samples were collected on day 0 (day of AI), day 9–13 and day 21–24 from 444 milking cows of various breeds presented for the first post-partum insemination by 413 farmers living at 182 villages/regions in Mymensingh District from 6 AI centres and sub-centres. Each cow was then examined three times after each AI until it stopped returning to oestrus. Sixty to 90 days after the last AI, the cows were examined per rectum to confirm the pregnancy. Milk progesterone data on day 21–24 contributed to a clear diagnosis with respect to non-pregnancy in 100% cows, indicating a possible use of this progesterone assay for identifying non-pregnant cows in AI programmes. In Investigation 2, milk progesterone was monitored two times in a month with a 10-day interval in 88 cows. The samples were taken between 10 days after calving and the first detected oestrus, followed by two more samples 10 days apart. The proportion of cows accurately detected in oestrus was 30%. Another 30% were stated to be in oestrus when they were not (false positive) and 40% were not detected when they were in oestrus (false negative). The mean intervals between calving and oestrus and between calving luteal activity were 40 to 362 days (median = 120, n = 82) and 34 to 398 (median = 111, n = 64) days, respectively. The body condition scores at calving and at the initiation of luteal activity influenced the interval between calving and luteal activity (p < 0.05). Cows suckled twice daily initiated luteal activity earlier than their counterparts suckled several times daily (p < 0.05). Determination of progesterone in milk on day 21–24 is a good means for detecting non-pregnant cows.  相似文献   

17.
Reproductive management programmes based on strategic use of prostaglandin F2 alpha (PGF2 alpha) to induce and synchronize oestrus in post-partum dairy cows are widespread. Repeated shortening of the oestrous cycle during early lactation in high-yielding dairy cows, however, could impair corpus luteum function and thus decrease fertility. The objective of this study was to analyse the effect of repeated treatments with the prostaglandin F2 alpha analogue D (+) cloprostenol sodium on progesterone concentrations indicative of a functional corpus luteum in post-partum dairy cows. Furthermore, the influence of milk production, parity and endometritis on progesterone concentrations under these circumstances were studied. Eighty-four cows of a commercial dairy operation were treated three to four times with D (+) cloprostenol sodium (Preloban; Hoechst Roussel Vet, Wiesbaden, Germany) at 14-day intervals, starting 22-28 days post-partum. Blood samples were collected prior to treatment 1 (sample 1) and 14 days after treatments 1, 2 and 3 (samples 2-4) and serum progesterone (P4) levels were determined. The percentage of cows with P4 levels < 1 ng/ml decreased from 51% in sample 1 to 23% in samples 3 and 4. More primiparous cows had low P4 levels 14 days after the second treatment than older cows (P < 0.05). Cows with low progesterone levels in sample 3 or 4 had lower protein contents in milk on the second milk test day post-partum and in their cumulative milk yield of the first 100 days of lactation. Clinical endometritis at post-partum examination did not influence progesterone levels after treatment with PGF2 alpha. Repeated application of PGF2 alpha (more than twice) in the post-partum period does not influence serum progesterone levels 14 days after treatment. Failure to develop luteal tissue after treatment contributed to the conception failures after first service.  相似文献   

18.
AIMS: To assess if raising concentrations of crude protein (CP) in pasture in spring by the frequent application of urea fertiliser would affect ovarian follicular dynamics, luteal function, onset of oestrus and reproductive performance of dairy cows under farming conditions in New Zealand. METHODS: Spring-calved dairy cows were grazed for 101 days in paddocks that were either not fertilised (Control; n=20) during the course of the study, or were fertilised with 40-50 kg nitrogen (N)/ha every 4-6 weeks (High-N; n=20). Similar generous pasture allowances were offered to both groups. Concentrations of CP in pasture, urea in serum and progesterone in milk were measured. Ovarian follicular and luteal dynamics were determined using ultrasonography. Oestrous behaviour and the number, time and outcome of inseminations were also recorded. RESULTS: Mean concentrations of CP in pasture and urea in serum was higher in the High-N than the Control group (25.2 vs 21.6 and 8.3 vs 5.4 mmol/L for CP and urea, respectively; p<0.001). Intervals between calving and first oestrus, first insemination and conception, the time of first emergence of a dominant follicle, milk progesterone concentration, and the diameter of the corpus luteum (CL) in the first luteal phase did not differ significantly between groups. The interval from calving to first ovulation tended (p=0.10) to be lower and the diameter of the dominant follicle of the oestrous cycle at which cows conceived was greater (p=0.02) in Control than High-N cows. CONCLUSIONS: The use of large amounts of urea fertiliser during spring and the consequent increases in concentrations of CP in pasture and urea in serum did not negatively affect any of the parameters of reproductive performance of pasture-fed dairy cows that were assessed in this study.  相似文献   

19.
AIM: To compare the sensitivity, specificity, predictive values and accuracy of detection of oestrus using a novel oestrus detection strip (ODS) and a camera-software device (CSD) with typical farm management practices of visual observation and use of tail paint in dairy cattle at pasture. METHODS: Dairy cows (n = 480) in a seasonal-calving herd managed at pasture under typical commercial conditions in New Zealand were stratified by age, body condition score and days in milk, then randomly allocated to one of two groups prior to the planned start of mating (PSM). Tail paint was applied to all cows and oestrus detected by visual observation of oestrous behaviour and removal of paint, by farm staff. One group (n = 240) was fitted with ODS and also monitored for signs of oestrus using a CSD, while the Control group (n = 240) was monitored using tail paint and visual observations only. Cows detected in oestrus were artificially inseminated (AI), and pregnancy status determined using rectal palpation and ultrasonography, 51-52 days after the end of a 55-day A period. Results of pregnancy diagnosis were used to confirm the occurrence of oestrus, and the sensitivity, specificity, predictive value and accuracy of detection of oestrus compared between oestrus detection methods. RESULTS: The sensitivity and accuracy of oestrus detection in the Control group, using visual observation and tail paint, were low. Compared with the Control group, detection of oestrus using the ODS and CSD resulted in greater sensitivity (85% vs 78%; p = 0.006), specificity (99.6% vs 98.0%; p < 0.001), positive predictive value (PPV; 88% vs 51%; p < 0.001) and overall accuracy (99.0% vs 98.0%; p < 0.001). Negative predictive value (NPV) did not differ significantly between groups (99.4% vs 99.3%; p = 0.28). Pregnancy rate to first service was higher in the CSD group than in the Control group (72% vs 39%; p < 0.05). Use of the CSD significantly increased the cumulative proportion of cows pregnant to AI over the breeding period (p = 0.044). CONCLUSION AND CLINICAL RELEVANCE: The ODS and CSD was satisfactory for detection of oestrus in seasonal calving dairy herds grazing on pasture and could improve the sensitivity and accuracy of detection of oestrus in herds where these are low.  相似文献   

20.
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   

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