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At least 19 recordsLinked to original sources
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↗
PubMed1979

Prostaglandin in milk, days open, and estrus detection in dairy cows treated with prostaglandin F2 alpha.

Prostaglandin F2 alpha was used to induce estrus in postpartum dairy cows to decrease calving interval and time spent on heat checks. The amount of prostaglandin residue in milk after treatment also was investigated. Twenty-two control cows, checked for heat twice daily, were bred at estrus after 55 days postpartum. Sixty-three cows checked on days 55 to 60 were either bred if in estrus or treated with 30 mg of prostaglandin F2 alpha injected intramuscularly on day 60 and bred at induced estrus or at 75 h posttreatment. Twelve cows were in heat between days 55 and 60 and were bred. Twenty-nine of 51 treated cows were seen in estrus; all of these were bred and 51.7% conceived at this time. Treated cows had fewer days to first service than did controls, but days open were not different, 105.7 versus 101.8. Fertility was similar. Controls required more heat checks than did treated cows (39 to 8.2). Milk from 17 cows at two milkings before and ten milkings after treatment had similar concentrations of prostaglandin (698 +/- 27 pg/ml) except for the first posttreatment milking when prostaglandin concentration almost doubled (1.293 +/- 143 pg/ml).

Animals↗
PubMed1991

[Estrus detection in the bitch with a progesterone rapid test (EIA)--a sensible supplement to vaginal cytology].

Vaginal smears were taken from 42 bitches and the results were compared with serum levels of progesterone, which were measured by a radioimmunoassay as well as by a qualitative enzyme-immunoassay. With the enzyme-immunoassay it was possible to differentiate low progesterone levels (less than 3.9 ng/ml) and high progesterone levels (greater than 4.2 ng/ml). Timing of insemination or mating of the bitches using both methods showed good pregnancy rates.

Animals↗
PubMed1975

Influence of estrus detection on days open in dairy herds.

Data from 10 herds on a herd reproductive status program supported estimates of lost reproductive days per cow per year due to conception failure and missed heat as 23 and 10 days. The corresponding estimates from Ohio Dairy Herd Improvement were 14.7 and 40.3 days. The correlation within the 10 herds between days lost due to failure to conceive and total days open was .38 and between days lost due to missed heats and total days open .92.

Animals↗
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↗
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↗
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↗
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↗
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↗
PubMed1991

Greater participation by veterinarians in the reproductive management of dairy cattle.

A program involving greater veterinary participation in detection of estrus and artificial insemination of cattle was evaluated in a 700-cow dairy herd from January 1987 through August 1988. Previous reproductive performance was below normal. First-service pregnancy rate from artificial insemination was 42%, and mean number of nonpregnant days for the cows was 120. Between postpartum days 55 and 62, all cows with functional corpus luteum assessed by rectal palpation were administered prostaglandin each Monday morning. Return visits were made to the herd each Thursday and Friday to observe cows and to inseminate those in estrus. On the other 5 days of the week, the owner or his employees inseminated all cows in estrus. The first-service pregnancy rate for 842 cows observed in estrus and inseminated by the veterinarian was 59%. The pregnancy rate for cows inseminated by the owner and his employees increased from 42% to 50%. The mean number of nonpregnant days for all 700 cows decreased from 120 to 98 days, resulting in approximately $46,000 of increased income for the dairyman or approximately a 4 to 1 return on investment in veterinary service. Results indicate that veterinarians could improve herd reproductive performance and solve chronic herd breeding problems by more actively participating with their clients in estrus detection and artificial insemination programs in cattle. The program allows practicing veterinarians an opportunity to observe cows for estrous behavior, establish their own pregnancy rate data, demonstrate to owners the importance of observing primary signs of estrus, and teach expert artificial insemination techniques.

Animals↗
PubMed1990

Effects of androgenizing dairy heifers with ear implants containing testosterone and estrogen on detection of estrus.

Lactating dairy cows in four lots were observed for sexual behavior for 6 mo. One freemartin heifer in each lot was implanted with testosterone propionate and estradiol benzoate to aid in detection of estrus. Blood samples were obtained from androgenized heifers every other week for determination of serum testosterone. The addition of an androgenized heifer to each lot increased the number of mounts and attempts to mount cows, both overall and within observation periods. Thus, the likelihood of detecting a cow in estrus was increased with the addition of the androgenized heifers. Greatest benefit was seen when one or two cows were simultaneously in estrus in each lot. Observational data and serum progesterone concentration of mounted cows indicated that androgenized heifers were selectively mounting open cows displaying estrus, whereas the remaining nonandrogenized cows were less selective with their mounting activity. Serum testosterone increased after heifers were implanted, but testosterone was not related to the proportion of sexual activity. Duration of sexual activity by the implanted heifers was approximately 90 d.

Animals↗
PubMed1992

Relative importance of vision and olfaction for detection of estrus by bulls.

The objective of this experiment was to determine the relative importance of olfaction and visual observation of heifer mounting behavior to the detection of estrus by bulls. An observation pen was designed to allow the evaluation of the preference of five sexually experienced bulls under three sets of stimuli. The observation pen was 4 m x 17 m with a smaller enclosure (2 m x 4 m) at each end that housed either a pair of heifers in diestrus (D), a pair of heifers in estrus that were allowed to mount one another (EM), or a pair of heifers in estrus that were separated by an aluminum panel to prevent mounting behavior (E). The preference of bulls was determined between EM heifers compared to D heifers, EM heifers compared to E heifers, and E heifers compared to D heifers. Each bull was individually allowed 5 min inside the observation pen to demonstrate its preference. Preference was defined as the total time that bulls spent within 2.5 m of either pair of heifers. Each bull was subjected to 10 observation periods of each set of stimuli during a 4-mo period. Bulls preferred to be near EM heifers compared with either E or D heifers (P less than .05). However, the bulls demonstrated no preference (P greater than .05) for E heifers compared with D heifers. These data indicate that when physical contact is denied, bulls use visual observation of female homosexual behavior as the primary indicator of estrus and that olfaction alone provides insufficient stimuli for bulls to indicate preference toward heifers in estrus compared with heifers in diestrus.

Animals↗
PubMed1991

[Detection of estrus and determination of the optimal time for insemination in polar foxes (Alopex lagopus)].

Oestrus cycles were investigated in seven polar foxes: the investigation consisted of evaluation of clinical symptoms of heat (vulva enlargement), measurement of vaginal mucus electrical resistance and determination of progesterone concentrations in the blood plasma of foxes; the objective was to determine optimum insemination time. The females were inseminated with fresh semen intravaginally by means of a pseudopenis, a day following the record of maximum electrical resistance of vaginal mucus and at the minimum progesterone concentration in blood plasma of 30 ng.ml-1. The females were reinseminated on the following day. The insemination dose had a volume of 1 ml with sperm concentrations of 150.10(6). Clinical symptoms of heat were observed in six out of the seven test foxes. Heat detection by means of measuring vaginal mucus electrical resistance was successful also in six females. Progesterone test enabled to detect heat in five females. Out of six inseminated females, five foxes became pregnant (83.3%) and a total of 33 cubs were born; this is 5.5 cubs per female.

Animals↗
PubMed1977

Variation in physical activity as an indication of estrus in dairy cows.

Pedometers were used to measure daily physical activity of cows to determine if variation related to estrus was great enough to be useful in estrus detection. Forty cows in free stalls and 28 cows in comfort stalls were studied during the breeding period after calving. Pedometers were enclosed in specially designed cases and attached to a cow's lower rear leg with a plastic ankle strap. Readings were taken twice daily when the cows were milked in a milking parlor. Data from free stalls were available for 5163 intervals between milkings, 87 of which were periods of estrus. Activity definitely increased at the time of estrus; cows were about four times as active during estrus as they were when not in estrus. Data from comfort stalls were available for 2433 intervals between milkings, 39 of which were periods of estrus. Cows in comfort stalls were about 2.75 times as active during estrus as when not in estrus. There was relatively little variation within cow in activity from day to day among cows not in estrus. Activity monitoring appears to have potential as an aid in estrus detection.

Animals↗