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Results for “Estrus Detection”

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PubMed1988

Use of an androgenized mare as an aid in detection of estrus in mares.

A study was conducted over a 2-mo period to compare estrus detection results obtained using an androgenized teaser mare with those obtained with a stallion, using the same group of 10 normally cyclic mares. The teaser mare was androgenized by administration of boldenone undecylenate (500 mg i.m. every 1 to 2 wk), and allowed to run loose with the mare group. Estrus was determined by observation of the group for a 30-min period daily. In the second month of the experiment, a marking harness was used on the androgenized mare to help detect mares mounted when in estrus. Estrous periods detected by each teasing method were 1) first month: stallion, 18; androgenized mare, 5; 2) second month: stallion, 16; androgenized mare, 9. There were no estrous periods detected by the androgenized mare that were not also detected by the stallion. Under these conditions, the androgenized mare was not an adequate estrus detection aid. Also discussed are the successful results of an independent trial on a breeding farm using an androgenized mare as an estrus detection aid.

Journal Article↗

PubMed1990

Financial comparison of three testing strategies for detection of estrus in dairy cattle.

Three commercial tests that measure progesterone content in milk were evaluated for accuracy of estrus detection. The tests were evaluated on 96 milk samples collected from Holstein cows at a commercial dairy farm in central Florida. The test results were compared with the results of radioimmunoassay on the same sample. Comparisons were made by calculating the sensitivities, specificities, and predictive values. The significance of the statistical association between the tests and the radioimmunoassay was evaluated by use of the McNemar chi 2 test. Decision-tree analysis was used to determine the most useful testing strategy, considering both cost and accuracy. The cowside progesterone assay on estrus-mount detector-positive cows was more profitable than use of estrus-mount patches alone. The return on investment was higher with the cowside test, making it preferred as a field test for detecting estrus.

Animals↗

PubMed1996

Detection of estrus by visual observation and radiotelemetry in peripubertal, estrus-synchronized beef heifers.

The effectiveness of two estrus-detection methods (visual observation and radiotelemetric, pressure-sensitive, rump-mounted devices) was compared in peripubertal, crossbred yearling beef heifers. Heifers (n = 50) were fitted with a pressure-sensitive device affixed to their rumps to which a battery-operated radio transmitter was connected. Activation of the sensor sent a radiotelemetric signal to a microcomputer via a fixed radio antenna. Heifer identification, date, time, and duration of standing events were recorded. Estrus was synchronized by feeding melengestrol acetate (MGA) for 14 d and then injecting PGF2 alpha 17 d after the last daily dose of MGA. Following the injection of PGF2 alpha, heifers were observed visually for signs of estrus at 0730 and 1630 (45 min each). Estrus was detected in 41 of 49 heifers (one lost the device) by visual observation and(or) the radiotelemetric device. Number of standing events during estrus, determined by the radiotelemetric device, averaged 50.1 +/- 6.4 per heifer, with the duration of estrus ranging from 2.6 to 26.2 h (average = 14 +/- .8 h). Visual observation failed to detect 11 of 41 heifers (37%) that were detected by the radiotelemetric device. Heifers with fewer standing events (19.3 vs 60.5; P < .001) and estrus of shorter duration (8.4 vs 15.6 h; P < .001) were those not identified by visual observation. Based on intervals between the first detected standing event of estrus and time of insemination, a wide window of fertility seems to exist in some heifers. Radiotelemetric devices were useful in identifying a greater (P < .05) proportion (100%) of heifers in estrus (increased efficiency) compared with visual observation (73%). However, accuracy of both methods was similar.

Animals↗

PubMed2003

Economic value of timely determination of unexpected decreases in detection of estrus using control charts.

Total economic effects of decreased estrus detection efficiency (EDE) are a function of the economic loss per day and the length of the decrease. A stochastic dynamic dairy herd simulation model was used to determine whether estimates from permanently different EDE rates in herds of 100 and 1000 cows could approximate net returns due to temporary decreases in EDE. The default EDE was 65% and was either permanently or temporarily decreased to 55, 45, or 35%. Temporary decreases in EDE were assumed to continue until identified using cumulative sum or Shewhart control charts. Marginal changes in net return were greater at lower permanent rates of EDE, with losses ranging from 0.73 to 1.24 dollars per extra day open. Temporary decreases in EDE typically yielded smaller effects on net return than permanent decreases, but estimates were not consistently significantly different. However, temporary (30 to 960 d) decreases in EDE affected projected herd economic performance for several years after EDE was reset to 65%. Total losses in net return due to temporary decreases in EDE ranged from 4.44 dollars (accepting more false alarms) to 12.53 dollars (fewer false alarms) per cow for the 100-cow herd. For the 1000-cow herd, total losses in net return ranged from 0.95 to 10.43 dollars per cow. Total losses were not dependent on magnitude of decreased EDE because lower EDE could be detected earlier, thereby compensating for higher daily losses; for example, 35% EDE resulted in lower total losses than 55% EDE. Decreases to 55% EDE were detected sooner by cumulative sum charts, whereas decreases to 35% EDE were detected earlier by Shewhart charts. Both control charts used together can identify unexpected decreases in EDE more efficiently, thereby minimizing potential economic losses.

Animal Husbandry↗

PubMed1991

Activity monitoring and an enzyme immunoassay for milk progesterone to aid in the detection of estrus.

The accuracy and efficiency of estrus detection using an electronic activity monitor tag in conjunction with an enzyme immunoassay for milk progesterone were studied during 55 observed estrous periods in 37 cows. At approximately 30 d postpartum, cows were equipped with an activity tag and visually observed for estrus, an activity tag with a flashing light-emitting diode, or both twice daily. Milk progesterone concentrations were determined from cows observed in estrus or with an activated tag. Mean daily activity was greater on the day of estrus than during any of the 3 d preceding or 3 d following estrus. Functioning activity tags correctly identified 55% of all visually observed estrous periods that coincided with low milk progesterone levels. The overall accuracy of a flag by the tag for identifying true estrus was 21%. The enzyme immunoassay for milk progesterone was in agreement with 98% of all visually observed estrous periods and false flags committed by the tags. Although the activity tags detected some cows in estrus, a more durable and reliable tag must be developed before it is of practical value to dairy producers.

Algorithms↗

PubMed1985

Insemination management for a one-injection prostaglandin F(2)alpha synchronization system. II. One versus two inseminations following detection of estrus.

Following detection of estrus in an estrus synchronization system, 216 dairy heifers were inseminated (A.I.) randomly either soon after detected estrus (1X) or soon after detected estrus and again 10 to 12 h later (2X). Average h from detection of estrus to A.I. was 1.8+/-0 for 1X and 1.1+/-0 and 11.1+/-0.4 for 2X. During the regimen, heifers were checked visually for estrus daily for five consecutive days with 16.0 and 17.3% showing estrus and receiving A.I. in the 1X and 2X groups, respectively. Those not seen in estrus were injected with 25 mg PGF(2)alpha with observations for estrus and A.I. continuing for five more days. Response rates as indicated by estrus following prostaglandin F(2)alpha (PGF(2)alpha) were 74.7 and 75.8% for 1X and 2X, respectively. Percentages of heifers in estrus <24, 25 to 48, 49 to 72, 73 to 96 and >96 h after PGF(2)alpha were 3.7, 22.8, 47.1, 15.4 and 11.0, respectively. Based on rectal palpation for pregnancy between 45 and 60 days after A.I., conception rates of 70.2% for 1X and 68.6% for 2X did not differ significantly (P>0.05). Progesterone concentrations at injection for heifers not responding to PGF(2)alpha were lower than was seen in responding heifers (2.7 vs 5.8 ng/ml) (P<0.01). Data from the present experiment supports the conclusion of an earlier experiment that satisfactory conception can be achieved with a single, established daily insemination period.

Journal Article↗

PubMed1986

The use of heat detection aids in estrus synchronization programs.

The use of tailhead paste and chin-ball markers for estrus detection in beef cows following estrus synchronization was evaluated. The estrous cycles of 85 cows were synchronized with a prostaglandin analogue in a two-injection program. At the time of the second injection, each cow's tailhead was painted with an estrus detection paste and the cows were placed in pastures with four intact bulls with chin-ball markers. Blood samples for plasma progesterone assays were obtained at the time of each injection and daily for five days following the second injection. Based on progesterone values, tailhead paste was incorrect 27% of the time in indicating estrus and chin-ball markers were incorrect 24% of the time. Detecting particular cows in estrus in groups of synchronized cows is difficult even with estrus detection aids.

Journal Article↗

PubMed2000

Effects of boar contact and housing conditions on estrus expression in weaned sows.

Our objective was to study the effects of housing conditions and the amount of boar contact in a protocol for estrus detection on estrus detection rate, timing of onset of estrus, duration of estrus, and timing of ovulation. After weaning, 130 multiparous sows were assigned to three treatments: HI, in which 52 sows were housed individually in crates and received a high amount of boar contact during estrus detection; HG, in which 52 sows were housed in groups and received a high amount of boar contact; and NI, in which 26 sows were housed individually in crates and received a normal amount of boar contact. Estrus detection was performed every 8 h. For each treatment, the standing response to three levels of stimuli was recorded: a back pressure test (BPT) by a man (man-estrus), presence of a teaser boar (spontaneous-estrus), and BPT in the presence of a teaser boar (boar-estrus). In addition, for HI and HG, the standing response to a fourth level of stimuli was recorded: BPT in a detection-mating area, surrounded by four boar pens (DMA-estrus). To detect ovulation, ultrasonography was performed every 4 h during estrus. Of 117 sows that ovulated, 46% showed man-estrus, 56% spontaneous-estrus, 90% boar-estrus, and 97% DMA-estrus. Mean onset of man-estrus was 107 h (SD 26) after weaning, of spontaneous-estrus was 106 h (SD 22) after weaning, of boar-estrus was 99 h (SD 21) after weaning, and of DMA-estrus was 93 h (SD 22) after weaning. Duration of man-estrus was 22 h (SD 14), of spontaneous-estrus was 29 h (SD 16), of boar-estrus was 42 h (SD 20), and of DMA-estrus was 55 h (SD 18). The high amount of boar contact reduced the number of sows showing man-estrus (P < .05; 41% for HG and HI vs 68% for NI) and reduced duration of boar-estrus (P < .05; 43 h for HG and HI vs 52 h for NI). Duration of DMA-estrus for HG and HI was similar to duration of boar-estrus for NI. Onset of estrus and timing of ovulation were not affected by amount of boar contact. Group housing did not affect detection rate and duration of estrus, but it did postpone average onset of estrus by 10 h, paralleled by a postponement of ovulation. In conclusion, estrus expression is similar at the highest level of stimuli in different protocols for estrus detection. Including higher levels of stimuli in a protocol reduces estrus expression at lower levels of stimuli. This reduction indicates adaptation of sows to a given protocol for estrus detection. Group housing can delay ovulation and related behavioral estrus.

Animals↗

PubMed1977

Detection of estrus by three methods.

Estrus was detected by three methods in 88 postpartum Holstein cows housed in tie-stalls and allowed free activity 1 to 2 h daily in separate exercise lots. Cows in each of three groups were observed visually for standing estrus by herdsmen. Cows (31) in Group I were observed only visually and served as controls, cows (33) in Group II were fitted with MateMaster rump-mounted detectors, and cows (24) in Group III were exposed to a testosterone-treated marking heifer. Cows with less than 1 ng/mg progesterone in serum on the day of detection and greater than 1 ng/ml 10 days later were designated as accurately detected in estrus. Accuracies of detections for cows in Groups I, II, and III were 68, 66, and 79%. Efficiencies of detections were the total observed estrous periods divided by the total expected estrous periods and were 51, 51, and 52%. In addition, overall accuracy, a mathematical product of individual accuracy and efficiency, represented the best measure of a detection method. Overall accuracies in Groups I, II, and III were 35, 34, and 41%.

Animals↗

PubMed1994

Measuring efficiency and accuracy of detection of estrus.

The ability of management to detect estrus efficiently and accurately in cows and heifers profoundly influences reproductive performance and profitability of dairy herds. Routine estimates of efficiency and accuracy are important to monitor reproduction in a herd and to evaluate management in problem breeding herds. Detection efficiency is usually expressed as the percentage of possible estruses that were observed over a given time period. Eight methods are presented that approximate efficiency using estrus and insemination dates. Efficiency can be estimated from herd summary information using the equation recommended by the Dairy Reproduction Core Parameter Committee or using equations that calculate the breeding interval. Milk progesterone concentrations measured by on-farm tests can be used to approximate efficiency. Seven of the nine Dairy Record Processing Centers calculate an efficiency estimate. Accuracy of detection of estrus is the percentage of estruses observed that are true estruses. Inaccurate detection of estrus results in breeding of cows not in estrus, thus lowering conception rates. Detection accuracy should be evaluated for herds experiencing low conception rates. Comparison of interestrual intervals, results of uterine and ovarian palpation, and progesterone concentrations of cows perceived to be in estrus can be used to estimate the accuracy of detection of estrus.

Animals↗

PubMed1993

Detection of estrus by radiotelemetric monitoring of vaginal and ear skin temperature and pedometer measurements of activity.

Methods to improve detection of estrus in dairy cows have been studied extensively without wide acceptance of any one method. In the present study, the use of body temperatures and pedometer-monitored activity were evaluated as methods of estrus detection. Twice daily activity levels of 13 lactating cows were monitored using pedometers, and vaginal and ear skin temperature measurements were made continuously using radiotelemetry. Activity increased 2.8-fold at estrus for the 8-h daytime period (0630 to 1430 h), during which cows were given a 5-h turnout period, but not for the 16-h overnight period (1430 to 0630 h), during which cows were confined to tie stalls. When increased activity was used to detect estrus on an individual cow basis, 20 of 25 estruses were detected with 4 false positives. Vaginal temperature increased by .6 +/- .3 degree C at estrus and remained elevated by at least .3 degree C for 6.8 +/- 4.6 h. When increased vaginal temperature was used on an individual basis, 17 of 21 estruses were detected with 3 false positives. Rate of detection of estrus by visual observation was 66%.

Animals↗

PubMed2001

Detection and characterization of estrus in dairy cattle with an electronic heatmount detector and an electronic activity tag.

The length and onset of estrus was studied in 71 lactating dairy cows using an electronic heatmount sensor (HeatWatch; DDx Inc., Boulder, CO, DeForest, WI) and an electronic activity tag (Heat Seeker, Boumatic, Madison, WI). Three methods were used to determine estrus: 1) the electronic heatmount system, 2) an increased activity ratio algorithm determined by the Heat Seeker, and 3) an increased activity count algorithm calculated for each estrous period. Mounting and physical activity variables were characterized, and the effects of synchrony, parity, and weather on these variables were determined with data from two different trials. Cows in trial 1 were not synchronized, while cows in trial 2 were synchronized. The results of the study were consistent as follows: mean numbers of mounts were 6.70 +/- 0.7 and 5.42 +/- 0.80 for trials 1 and 2, respectively; each mount lasted 3.20 +/- 0.19 s (trial 1) and 3.36 +/- 0.42 s (trial 2). Total mounting activity averaged 5.83 +/- 0.78 h per estrous period in trial 1 and 5.57 +/- 1.02 h in trial 2. Estrus identified by the increased activity count algorithm corresponded more closely to standing mount activity (determined by the HeatWatch System) than did the increased activity ratio algorithm. Synchrony, parity, and weather did not have a direct effect on physical activity. Hot weather decreased the duration of standing mount activity significantly, but did not affect the number or duration of individual mounts. All three methods of estrus detection employed improved the efficiency of detection over visual observation.

Activity Cycles↗

PubMed1990

Effectiveness of rump-mounted devices and androgenized females for detection of estrus in dairy cattle.

Detection of estrus was evaluated in 1124 estrous cycles for the effectiveness of rump-mounted devices and androgenized females equipped with chin-ball markers. Estrous number, location, type of detection method (compared with visual observation of estrus), and milk progesterone influenced standing behavior. Rates of disagreement with visual observation of estrus were 13.2, 17.0, and 18.5% for Kamar, Hot Flash, and the two devices used simultaneously. Frequency of observed standing behavior was greater with fourth and subsequent estrous periods. Percentage of high milk progesterone during suspected estrus for cows inseminated was 3.8% for controls, 11.0% for Kamar cattle, 18.5% for Hot Flash cattle, and 12.6% when both devices were used. Androgenized cattle equipped with chin-ball markers marked 47% of the cattle observed in estrus but no cows with high milk progesterone. Combination of rump-mounted devices and androgenized females increased the percentage of estrous detection by 1.3 to 6.2% compared with device or androgenized female used alone. Loss rates of rump-mounted devices exceeded 40%. High milk progesterone at estrus was associated with lower fertility.

Androgens↗

PubMed1991

The effects of administration of gonadotrophins and estrogens on prenatal survival in gilts.

In gilts ovulation occurs over a 4 to 8-hour period, with 70% of the ova being shed over a relatively short span of time. These oocytes supposedly give rise to more developed embryos at Days 10 to 12 which advance the uterine environment and reduce survival rates of less developed embryos because of an asynchronous environment. The aim of this experiment was to reduce embryo mortality by influencing the duration and pattern of ovulation. Crossbred gilts (n=98) were bred at their first observed estrus after being exposed to boars at 200 days of age. Estrus detection was carried out daily at 0000, 0800 and 1600 hours. All gilts were artificially inseminated with fresh semen, with a minimum of 2.7 billion spermatozoa, at both 16 and 32 hours after detection of estrus. Gilts were randomly assigned to one of the following treatments at detection of estrus: 1) 500 IU (2 ml) chorionic gonadotrophin (hCG) injected intravenously at the onset of estrus (n=22); 2) 16 microg (4 ml) gonadotrophin releasing hormone (GnRH) injected intravenously at the onset of estrus (n=25); 3) 11.5 microg estrogen added to the semen at the time of AI (n=25); 4) control, untreated gilts (n=26). All gilts were slaughtered at Day 30 of gestation (Day 0=day of detected estrus). The mean (+/-SEM) number of ovulations in pregnant gilts per treatment was 13.0+/-0.52, 12.6+/-0.51, 13.6+/-0.54 and 13.3+/-0.52, while the mean (+/-SEM) number of normal embryos per treatment was 10.3+/-0.67, 10.5+/-0.66, 10.3+/-0.69 and 10.5+/-0.67 for hCG, GnRH, estrogen and control groups, respectively, for an embryonic survival rate of 80+/-4.2%, 83+/-4.1%, 74+/-4.3% and 79+/-4.2% in pregnant gilts. If nonpregnant gilts are included, the embryonic survival rate for treatments 1 to 4 was 76+/-7.0%, 73+/-6.5%, 60+/-6.5%, and 64+/-6.4%, respectively. There was no significant difference between treatments for any of these variables. There was no evidence that administration of hCG, or GnRH at the onset of estrus, or the addition of estrogen to semen improved embryonic survival in gilts by Day 30 in this experiment.

Journal Article↗

PubMed1977

Testosterone treatment of cows for use in detection of estrus.

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Animals↗

PubMed1976

Detection of estrus in dairy cows by electrical measurements of vaginal mucus and by milk progesterone.

Electrical resistance (ohms) of mucus were analyzed in 20 postpartum Holstein cows by use of a probe inserted into the anterior vagina every other day for 30 days. Composite milk samples were taken on the same day, and progesterone was determined by radioimmunoassay. Cows were observed twice daily for standing estrus and reproductive organs palpated weekly per rectum (rectal palpation). Fifteen cows which were cycling showed increasing progesterone 6 to 7 days after the onset of estrus with values of 8.1 to 10.0 ng progesterone/ml milk on days 10 to 17. Concentrations had declined rapidly 2 days before onset of the next estrus. Progesterone in milk was affected by cow and by day of the cycle. Electrical resistance followed a similar cyclical pattern, but variability was large and only cows differed. The correlation between milk progesterone and mucus resistance was .22. Progesterone concentrations for four cows with follicular cysts fluctuated randomly with a mean of 2.6 ng/ml. Mean resistance of vaginal mucus was 44 omega for both cycling and cystic cows, indicating that a single measurement of electrical resistance every 2nd day was unreliable in distinguishing physiological states. One cow had high progesterone in milk on days 19 to 25 and was diagnosed pregnant by rectal palpation 3 wk later. Cows were not seen in estrus 28% of the time when milk progesterone and rectal palpation indicated they were in the follicular phase of the estrous cycle and were cycling.

Animals↗

PubMed1989

Electrical conductivity of reproductive tissue for detection of estrus in dairy cows.

The pattern of temporal measurements of electrical conductivity obtained from electrodes that had been surgically implanted in the mucosa of the vagina or in the submucosa of the vulva in each of five dairy cows was evaluated for changes associated with the occurrence of estrus. Tissue conductivity was monitored at 6-h intervals during and around estrus by hard-ware devices operating at either 16 or 100 kHz. Blood samples were taken at time of conductivity measurement for progesterone determination and at 2-h intervals during estrus for LH determination. Vaginal and vulvar biopsies were performed during diestrus and estrus to measure tissue hydration. Conductivity increased significantly at estrus relative to a nonestrus base period in both vaginal and vulvar tissue. Both electrical frequencies were found to be satisfactory for characterizing changes in tissue conductivity associated with estrus. Peak concentrations of luteinizing hormone, increases in tissue hydration, and patterns of blood progesterone were consistent with the occurrence of estrus during the time of elevated tissue conductivity.

Animals↗

PubMed1992

Comparison of a prostaglandin-F2alpha-based reproductive program with an estrus detection-based reproductive program on a large commercial dairy herd.

The purpose of this study was to describe biological outcomes of two reproductive management strategies in commercial dairy cows: estrus detection with and without the use of prostaglandin-F2alpha. At regular preinsemination examinations, cows were allocated randomly to two cohorts: 1) prostaglandin cohort -- cows with palpable corpora lutea were injected with 25 mg dinoprost tromethamine and were bred by appointment 72 and 96 hours later, followed one week later by standard estrus detection practices (twice daily observation and tail chalking, with breeding approximately 12 to 24 hours later); and 2) estrus detection cohort -- cows identified as exhibiting estrus (observed estrus) were bred through the above standard procedures, without exposure to prostaglandin therapy. Age, milk production, weight, milk progesterone levels and reproductive data were collected for all cows. Although certain between-cohort effects were statistically significant, no differences could be found between the cohorts regarding standard measures of reproductive performance (average days in milk at conception (P=0.79), services per conception (P=0.48), proportion of animals failing to conceive to artificial insemination (P=0.53), and survival analysis on time to conception (P=0.30). With evidence for biological equivalence between the two reproductive strategies, nonbiological standards such as economics or ease of execution would be appropriate in choosing between the two strategies.

Journal Article↗