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PubMed1975

Estrus detection and estrus detection aids.

There is no substitute for good management. Each animal should be identified carefully. The herds man should know all signs of estrus or impending estrus. In addition, for visual detection of estrus to be highly effective, sufficient time must be taken at least twice a day to catch animals with a short estrus period. Presently there are two visual aids to estrus detection which provide potential 24-h surveillance. One aid is a pressure sensitive device mounted on the back of each cow which can be triggered when the cow stands for mounting. The second one is a marking device worn by sexually aggressive animals which will stripe with colored ink the back of estrous animals as the marker animal mounts and dismounts. Both devices are effective when used properly. Other tests of changes in cervical mucus, vaginal characteristics, temperature, blood flow, and hormone changes in blood and milk are either not suffciently reliable or else simple enough yet to be practical aids for routine detection of estrus in dairy cattle. Milk progesterone can assist in characterizing problem cows.

Animals↗
PubMed1986

Evaluation of androgenized mares as an estrus detection aid.

Ten pony mares that had developed stallion-like sexual behavior as the result of anabolic steroid treatment (boldenone undecylenate, 0.55 mg/kg intramuscularly (i.m.), once weekly for 12 injections) were evaluated for ability to aid in detecting estrus in cycling mares. In across-the-fence estrus detection trials, androgenized mares failed to elicit signs of estrus or diestrus. In 10-min pasture trials, in which each androgenized mare was placed in a group of 10 cycling mares (six of which were estrous), seven of the 10 androgenized mares elicited estrous behavior from one or two mares. Observations of the 10 androgenized mares among a pasture group of 21 cycling mares indicated that approximately one third of the mares in estrus could be identified on the basis of their response to androgenized mares.

Journal Article↗
PubMed1994

The estrus detection problem: new concepts, technologies, and possibilities.

The single most important problem limiting high reproductive efficiency in the national dairy herd is poor detection of estrus. Failure to detect estrus or erroneous diagnosis of estrus results in an estimated annual loss of over $300 million to the dairy industry in the US. New technologies for the solution of this problem must be more effective than visual observation and aids currently used to detect estrus. Ideally, technologies that provide the solution for detection problems should provide the following: continuous (24 h/d) surveillance of the cow, accurate and automatic identification of cows in estrus, operation for the productive lifetime of the cow, minimized labor requirements, and high accuracy in identifying the appropriate physiologic or behavioral events that correlate highly with ovulation. New approaches are aimed at providing automation of detection of estrus using electronic technology. Pedometry, implantable impedance sensors, and surface-applied and implantable pressure sensors are in various stages of development and use.

Animals↗
PubMed2002

Application of electronic estrus detection technologies to reproductive management of cattle.

Artificial insemination and embryo transfer programs are dependent on efficient and accurate detection of estrus. Visual observation is accurate at detecting animals in estrus, but efficiency ranges from approximately 50 to 70%. Electronic technologies have been developed in attempts to improve estrus detection efficiency. Commercially available electronic devices for estrus detection are based on changes in physical activity (pedometers), changes in electrical resistance of reproductive tract secretions (intravaginal resistance probes) or mounting activity (mount detectors). All of the commercially available electronic estrus detection devices can improve the efficiency of estrus detection in cattle. Pedometers are most applicable to lactating dairy cattle and have greater accuracy and efficiency when combined with visual observation. Intravaginal resistance measurement is perhaps the least practical method of estrus detection because of labor and animal handling requirements. Individual resistance measurement may have practical application for confirming other inconclusive signs of estrus. Mount monitors have the broadest application to beef and dairy cattle. HeatWatch, the only real-time radiotelometric system available, requires the least labor and animal handling and provides data on the time and duration of each mount. The less expensive stand-alone mount monitors also provide the necessary information for optimum timing of insemination and embryo transfer, but are more labor intensive.

Animals↗
PubMed2006

Synchronization of estrus in suckled beef cows for detected estrus and artificial insemination and timed artificial insemination using gonadotropin-releasing hormone, prostaglandin F2alpha, and progesterone.

We determined whether a fixed-time AI (TAI) protocol could yield pregnancy rates similar to a protocol requiring detection of estrus, or estrous detection plus TAI, and whether adding a controlled internal device release (CIDR) to GnRH-based protocols would enhance fertility. Estrus was synchronized in 2,598 suckled beef cows at 14 locations, and AI was preceded by 1 of 5 treatments: 1) a CIDR for 7 d with 25 mg of PG F(2alpha) (PGF) at CIDR removal, followed by detection of estrus and AI during the 84 h after PGF; cows not detected in estrus by 84 h received 100 mug of GnRH and TAI at 84 h (control; n = 506); 2) GnRH administration, followed in 7 d with PGF, followed in 60 h by a second injection of GnRH and TAI (CO-Synch; n = 548); 3) CO-Synch plus a CIDR during the 7 d between the first injection of GnRH and PGF (CO-Synch + CIDR; n = 539); 4) GnRH administration, followed in 7 d with PGF, followed by detection of estrus and AI during the 84 h after PGF; cows not detected in estrus by 84 h received GnRH and TAI at 84 h (Select Synch & TAI; n = 507); and 5) Select Synch & TAI plus a CIDR during the 7 d between the first injection of GnRH and PGF (Select Synch + CIDR & TAI; n = 498). Blood samples were collected (d -17 and -7, relative to PGF) to determine estrous cycle status. For the control, Select Synch & TAI, and Select Synch + CIDR & TAI treatments, a minimum of twice daily observations for estrus began on d 0 and continued for at least 72 h. Inseminations were performed using the AM/PM rule. Pregnancy was diagnosed by transrectal ultrasonography. Percentage of cows cycling at the initiation of treatments was 66%. Pregnancy rates (proportion of cows pregnant to AI of all cows synchronized during the synchronization period) among locations across treatments ranged from 37% to 67%. Pregnancy rates were greater (P < 0.05) for the Select Synch + CIDR & TAI (58%), CO-Synch + CIDR (54%), Select Synch & TAI (53%), or control (53%) treatments than the CO-Synch (44%) treatment. Among the 3 protocols in which estrus was detected, conception rates (proportion of cows that became pregnant to AI of those exhibiting estrus during the synchronization period) were greater (P < 0.05) for Select Synch & TAI (70%; 217 of 309) and Select Synch + CIDR & TAI (67%; 230 of 345) cows than for control cows (61%; 197 of 325). We conclude that the CO-Synch + CIDR protocol yielded similar pregnancy rates to estrous detection protocols and is a reliable TAI protocol that eliminates detection of estrus when inseminating beef cows.

Animals↗
PubMed1999

Assessment of estrus detection by visual observation and electronic detection methods and characterization of factors associated with estrus and pregnancy in beef heifers.

One hundred and sixty-four beef heifers representing Angus, Brahman and their crosses were subjected to estrus synchronization treatment following evaluation of weight, body condition score and reproductive tract. Heifers were assigned to 1 of 2 methods of estrus detection, either visual observation for signs of standing estrus or a rump-mounted pressure-sensitive detection device. All heifers were artificially inseminated during a 25d insemination period and then bred by a bull. The effectiveness of estrus detection and timely insemination were evaluated by the type of detection method, breed and breeding event resulting in a pregnancy. Although there was not a significant difference in first service conception for method of detection, at the end of a 25-d insemination period, 60.5% of the visually observed heifers were pregnant, while only 45.8% of the heifers detected by the mount detection device were pregnant (P = 0.05). The reduced 25-d conception rate in the pressure-sensitive detection group suggested that insemination of detected heifers may not have been optimal for pregnancy. The mean time to estrus after implant removal and the time of insemination were evaluated. Heifers pregnant at the first service had a shorter time to estrus (32.11 +/- 1.6 h, P=0.13), a longer mean interval from the start of estrus to insemination (12.10 +/- 1.2 h, P = 0.16) and a positive mean interval between the end of standing estrus and the time of insemination (3.17 +/-1.7 h, P=0.19) than heifers not conceiving at the synchronized estrus (38.5 +/- 2.1, 7.42 +/- 1.9 h and -2.04 +/- 2.1 h, respectively). Breed differences were observed in estrus durations (Angus 8.52 +/- 1.2 h, Brahman 6.65 +/- 1.2 h, crossbred 11.90 +/- 1.2 h; P = 0.03), number of mounts (19 +/- 3.6, 25 +/- 5.4, 37 +/- 5.5, respectively; P=0.02) and gestation length (281 +/- 1.2, 291 +/- 1.8, 286 +/- 1.1 d, respectively; P = 0.001).

Animals↗
PubMedDate not supplied

A field study on estrus detection in lactating beef cattle.

Estrus detection efficacy and heat detection protocol were studied by means of a field study carried out on 878 lactating beef cows in 60 French herds. Average herd size was 48, and 75% of the farmers partly or exclusively used artificial insemination. The cows were calved between October 1992 and March 1993. Estrus was recorded daily by the farmers. Cycling status was determined by progesterone radioimmuno-assay 2 months after calving. The relationship between the estrus detection protocol and the delay period from calving to first observed estrus was analysed using survival curves and the Cox proportional hazard model, adjusting for confounders. Seventy-one percent of the cows were seen in estrus by the farmers; the interval between calving and the first observed estrus ranged from 9 days to more than 5 months and the median was 56 days. Two months after calving, 44% of the cycling cows had not been seen in heat by the farmers and 11% of the non-cycling cows had been reported to have been in estrus. The heat detection protocol varied widely between farmers, depending on the considered estrus signs, schedule and time spent looking for signs. Two factors were significantly related to a shorter interval from calving to first observed heat: the use of artificial insemination (which relates to the farmer's interest in heat detection) and an overall daily time spent for heat detection greater than 1 h. Cows in tie stalls had a delayed interval to the first observed estrus. These results show that many farmers did not adapt their reproduction practice sufficiently to an earlier calving period. There is room for improvement since in many cases the heat detection protocol does not match the required standards for optimal heat detection.

Anestrus↗
PubMed1981

Comparison of estrus detection techniques in dairy heifers.

Detection of estrus was by twice daily heat checks, heat mount detectors, and pedometers. Changes of progesterone concentrations in blood plasma were monitored three times weekly. Method of detection did not affect observed cycle length. Efficiency of estrous cycle detection (as defined by changes of progesterone concentration in plasma) ranged from 67% to 74%. Combinations of two techniques ranged in efficiency from 84% to 93%. Accuracy of estrus detection (based on changes in progesterone concentration) varied widely, from 29% to 95%. Accuracy of twice daily heat checks and pedometer activity detection at two standard deviations greatly exceeded the other techniques. Heat checks and pedometer detection combined gave both high efficiency and high accuracy of detection.

Animals↗
PubMed1993

Use of a vaginal mucus impedance meter to detect estrus in the cow.

Two experiments were conducted to investigate the efficacy of a vaginal mucus impedance meter for the detection of estrus in the dairy cow. In Experiment 1 the positioning of the probe within the vaginal tract was examined in dairy cows (n=6) by measuring mucus impedance at 5-cm intervals during probe withdrawal and comparing these fixed distance measurements with the depth within the vaginal tract at which the lowest impedance measurement was recorded. Measurements at 15 and 20 cm from the vulva were significantly lower than at other fixed depths, but did not show a reduction during estrus. The lowest recording upon withdrawal of the probe, which usually occurred between 15 and 20 cm from the vulva, was significantly lower than at any fixed depth recordings and was reduced proportionate during estrus to 0.14 of its non-estrus value. In Experiment 2 the accuracy of the probe to confirm estrus in cows exhibiting possible estrus signs was examined. Dairy cows (n=191) were inseminated either on the basis of herdsman observation of behavior alone (Treatment A) or on the basis of herdsman observation with cows exhibiting signs of estrous behaviour, but not standing to be mounted, being tested for vaginal mucus impedance (Treatment B). There were no significant treatment differences in the estrus detection rate, conception rate or other reproductive performance parameters. However, in 12% of cows in Treatment B, measurement of vaginal mucus impedance detected an extra estrous event, giving a theoretical increase in the estrus detection rate from 0.67 to 0.74 detected/predicted estrous events. It was concluded that when using a vaginal probe the lowest value in the vaginal tract should be sought, but that using the probe as an adjunct to herdsman's observation would not greatly increase estrus detection rate.

Journal Article↗
PubMed2004

Artificial insemination following observational versus electronic methods of estrus detection in red deer hinds (Cervus elephus).

The objectives were to determine the efficacy of the HeatWatch (HW) electronic estrus detection system for monitoring behavioral estrus (including duration and intensity) in red deer hinds and to evaluate pregnancy rate to AI after detected estrus. Red deer hinds (Cervus elephus; n = 50) were allocated into two treatment groups: AI following synchronization (CIDR/PMSG) and observed estrus (induced estrus group: IE; n = 25) or AI following the detection of natural estrus (NE; n = 25) without hormonal treatment. Hinds were fitted with two HeatWatch (HW) electronic estrus detection transmitters, one above the tail (bottom) and one between the tuber coxae of the pelvic girdle (top), and visual observations for mounting activity began with the aid of young sterile red deer stags (18 months old) fitted with marking harnesses. Hinds in both groups were inseminated (10-12h after observed estrus) with frozen-thawed red deer semen using a transvaginal/cervical AI approach. Following a 26-day period of AI, hinds were placed with a mature fertile stag for an additional 30-day natural breeding period. Pregnancy diagnosis was performed 57 and 86 days after the start of AI. While the hinds were housed with the young stags, 82% were detected in estrus by visual appraisal of stag crayon marks, but only 32% of these were detected by HW. In contrast, in the hinds housed with the mature stag, 93% detected in estrus by crayon marks were also detected by HW. The top HW transmitter consistently recorded more mounts (P < 0.05) than the bottom transmitter. The pregnancy rate was numerically better in IE versus NE hinds (42% versus 29%, P > 0.10). In summary, there were no differences (P > 0.10) in the intensity (number) or duration of mounts (detected by HW) during estrus in IE versus NE hinds, and HW was most effective in detecting estrus in the presence of a heavier, mature stag versus a younger stag. When used in combination with transvaginal AI, an overall first-service pregnancy rate of 36.6% was achieved with AI of frozen-thawed semen in red deer hinds following detected estrus.

Animals↗
PubMed1984

Estrus detection and subsequent reproduction in dairy cows continuously housed indoors.

Records (1554) from 961 cows continuously housed indoors in two types of barns were analyzed for occurrence and detection of estrus and subsequent reproduction. Variables, percentage of cows observed in estrus by 55 days postpartum, days to first recorded estrus and first service, conception rates, service intervals, days open, and services per conception were analyzed by least squares procedures for year of calving, month of calving, genetic line, barn-type-parity subclasses, and interaction of month by line. A higher percentage of multiparous cows in the tie-stall barn (60%) were observed in estrus by 55 days postpartum than those in the loose-housing barn (50%). Days to first recorded estrus and to first service, 54 and 81, were less for tie-stall cows than for loose-housing cows, 66 and 91. Conception rates at first service and overall conception, 54 and 91%, were higher for tie-stall cows than for loose-housing cows, 42 and 80%. A higher percentage of primiparous cows (69%) was in estrus by 55 days than multiparous cows (55%). Days to first estrus and first service were less for primiparous cows, 47 and 70, than multiparous cows, 60 and 80. Days open were less for primiparous cows. Primiparous cows required 1.9 services per conception compared with 1.7 for multiparous cows.

Animals↗
PubMed1994

Conception rates. 1. Derivation and estimates for effects of estrus detection on cow profitability.

Objectives were to derive equations and obtain estimates per cow of days to conception, milk production, semen purchases, calvings, and reproductive failures based on the probability of estrus detection and AI conception. The net benefits of changing rates of estrus detection, including changes in milk production, semen purchases, and replacement inventories (culled cows and calves) were converted to annual values and multiplied by fixed prices to obtain estimates of the annual financial benefit of a change in rates of estrus detection. Improvement in milk production because of a 1-d decrease in DIM at conception was dependent on DIM, peak milk production, and monthly rate of decline in daily milk production. Variation was considerable in expected benefits of improved estrus detection. Under the assumption that replacement was not planned prior to breeding (in which case improved estrus detection would have no value), estimated financial benefits for increasing the probability of estrus detection from 60 to 70% with a 70% AI conception rate were $6/yr; increasing from 20 to 30% the rate of estrus detection with a 50% AI conception rate increased estimated annual benefits to $83. This wide range of values occurred with fixed costs and prices so that fluctuating prices would introduce further variation in financial benefits. Derived equations allow point estimates of expected benefits with input values estimated.

Animals↗
PubMed1997

Evaluation of different protocols for prostaglandin synchronization to improve reproductive performance in dairy herds with low estrus detection efficiency.

The objective of this study was to evaluate different PGF2 alpha protocols against control protocols for herds with estrus detection efficiencies of 35, 55, and 75% using modeling and simulation: 1) PGF2 alpha treatments based on the presence of a corpus luteum diagnosed by rectal palpation, 2) PGF2 alpha treatments based on the presence of a corpus luteum diagnosed by an on-farm milk progesterone enzyme immunoassay, and 3) PGF2 alpha treatments based on a 14-d fixed treatment schedule without prior screening for ovarian status. After the start of each protocol, estrus detection efficiency was 75% for 7 d after treatment and 35 or 0% for the following week. For the third protocol, an additional modification at estrus detection efficiencies of 85 and 55%, respectively, in the 1st and 2nd wk after treatment was evaluated to establish a protocol for best case assumptions. All protocols improved reproductive performance relative to that of controls with estrus detection efficiencies of 35 and 55%. The mean number of days open was reduced from 124.3 d in the control herd to 95.9, 95.0, and 92.7 for the protocols based on rectal palpation, milk progesterone test, and the fixed treatment schedule, respectively. The protocols based on a fixed treatment schedule were superior to protocols based on rectal palpation and on-farm milk progesterone tests and resulted in better reproductive performance and a higher increase in net return per cow per year. Relative to a control herd with an estrus detection efficiency of 55%, it was cost effective to spend up to $10 per dose of PGF2 alpha, $9 per milk progesterone test, and $6 per rectal palpation.

Animals↗
PubMed1989

The efficacy of estrus detection and fertility following synchronization with PGF2a or synchro - mate- B in Zebu cattle.

Two experiments were carried out to assess the efficacy of estrus detection and fertility in Zebu cattle after synchronization with prostaglandin F2a or a progestagen. The first experiment compared estrus detection rates and fertility following insemination in 42 cows previously synchronized with either 25 mg of PGF2a or with a 6 mg of Norgestomet implant plus 5 mg i.m. of estradiol valerate (SMB). Differences were observed in the percentage of cows detected in estrus (54 vs 95%, respectively, P < 0.05), but not in fertility at the first synchronized estrus (26 vs 15%), nor in the detection rate and fertility at the subsequent estrous period (38 v 47%). The second experiment evaluated the efficacy of estrus detection at different time intervals in 30 cows, comparing estrus synchronized with PGF2a with the subsequent estrous period. The observation periods were continuous, day and night, for 100 h both after PGF2a treatment and from Day 18 of the treatment cycle (Period 1). In addition, the animals were administered PGF2a again on Day 10 of the second cycle and observed continuously from 0600 to 1800 h, and from Day 18 of the treatment cycle (Period 2). Finally, the same treatment regimen was used except that the observation was between 0600 to 0700 h and 1800 to 1900 h (Period 3). No differences were obtained in the percentage of cows detected in estrus in the synchronized and nonsynchronized groups (average 75%); however, accuracy in the detection of estrus in Period 3 differed in the nonsynchronized and synchronized estrus groups by 40% (P < 0.05) compared with the other two, more intense observation periods.

Journal Article↗
PubMed1998

Estrus detection using radiotelemetry or visual observation and tail painting for dairy cows on pasture.

The efficiency and accuracy of estrus detection using HeatWatch (DDx Inc., Denver, CO) or visual observation were compared in an autumn-calving Friesian herd (n = 48 per group) and a spring-calving Jersey herd (n = 50 per group) grazing on pasture. Cows in the group monitored by the HeatWatch system were fitted with a pressure-sensitive transmitter that signaled mounting activities associated with estrus. Visual observation was carried out for about 20 min before the morning and afternoon milkings and was aided by a strip of paint applied over the tailhead. Ovarian cyclicity was monitored with progesterone concentrations in milk samples collected twice a week. The efficiency and accuracy of estrus detection were, respectively, 98.4 and 97.6% for visual observation and 91.7 and 100% for HeatWatch detection. Autumn-calving herds differed from spring-calving herds in duration of estrus (9.7 vs. 7.3 h), number of mounts (13.6 vs. 8.5), total duration of mounts (36.8 vs. 19.9 s), and mean duration of a mount (2.6 vs. 2.3 s). There was no significant variation in the distribution of the time of onset of estrus or mounting activities at different hours of the day. Conception rate was similar for AI after estrus detection with HeatWatch (65.8%) or after visual observation (65.0%). The highest conception rate was obtained when AI was carried out between 12 and 18 h after the first mount. Both the HeatWatch system and visual observation plus tail painting can be used for estrus detection of dairy cows on pasture.

Animals↗
PubMed1998

Luteolysis during two stages of the estrous cycle: subsequent endocrine profiles associated with radiotelemetrically detected estrus in heifers.

Our objective was to correlate hormonal changes with the timing and onset of estrus in heifers before and after luteolysis was induced with PGF2 alpha at two stages of the estrous cycle: d 6 to 9 (early; n = 10) or d 14 to 15 (late; n = 10). Blood was collected at intervals of 2 or 12 h to quantify serum concentrations of progesterone, estradiol-17 beta, and LH while heifers were observed visually for estrus and monitored for standing activity by pressure-sensitive, radiotelemetric devices. Although the concentrations of estradiol-17 beta that were associated with the putative appearance of the first dominant follicle declined before luteolysis was induced early in the cycle, some heifers that were given PGF2 alpha were in estrus as early as 35 h. Compared with heifers treated late in the estrous cycle, heifers that were treated early in the cycle produced less progesterone before PGF2 alpha treatment and had greater peak concentrations of estradiol-17 beta at estrus. In addition, heifers that were treated early in the cycle had shorter intervals from PGF2 alpha treatment to estrus, to peak estradiol-17 beta, and to peak LH and to initiation of estrus after the peak in estradiol-17 beta than did heifers treated later in the cycle. The increase in estradiol-17 beta associated with the putative first-wave follicle of the subsequent cycle and the duration of that cycle in early cycle heifers was less than after late cycle luteolysis. Results indicated that greater concentrations of estradiol-17 beta during estrus may be related to the durations of previous cycles and less progesterone exposure before luteolysis. The onset of estrus corresponded closely to, but preceded, the preovulatory LH surge by approximately 3 h.

Animals↗
PubMed1998

Measures of estrus detection and pregnancy in dairy cows after administration of gonadotropin-releasing hormone within an estrus synchronization program based on prostaglandin F2 alpha.

The objective of this study was to assess the use of GnRH in a controlled breeding program (7 d prior to the second of two injections of PGF2 alpha, 14 d apart) as a means to improve the expression and detection of estrus, first service conception rate, and overall pregnancy rate of lactating dairy cows. On 17 farms, 348 cows were assigned randomly to either of two breeding programs prior to first insemination. Cows in both programs received PGF2 alpha approximately 2 wk prior to the end of a herd-specific voluntary waiting period for breeding. One group received GnRH 1 wk later, 7 d prior to the second of two injections of PGF2 alpha. Control cows received saline and a second injection of PGF2 alpha at corresponding times. Cows were observed for 7 d and were bred by artificial insemination following detection of estrus. There were no differences between programs in estrus detection rate, observed signs of estrus, conception rate, days to first service, or interval from calving to conception. The means and standard deviations of the interval from PGF2 alpha to estrus were not different between programs. Administration of GnRH 1 wk prior to PGF2 alpha did not alter the expression of estrus or fertility in lactating dairy cows. In this study population, no advantage was found for the addition of GnRH to a controlled breeding program that was based on two administrations of PGF2 alpha at a 14-d interval.

Animals↗