PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Estrus”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

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↗
PubMed1977

[Attempts at biotechnical induction of puberty in young female pigs. 2. Effects of various time intervals between one puberty induction with PMS and HCG to the following estrus synchronization on estrus and ovulation in animals about 190 days old].

A biological engineering approach to induce puberty in 125 young female fattening pigs aged 190 days was undertaken on the basis of a mixture of 500 IU PMS (Prolosanserum, Dessau) with 250 IU HCG (Gonabion, Dresden). The injections were made subcutaneously. Pronounced oestrus symptoms were recorded from the external genital organs of 80% of the probands up to ten days after injection, associated with toleration in 52.8% of them. Toleration usually started on the fourth to sixth days after injection. Cycles began to develop in 57.1% up to the next oestrus period. Animals with -/x weight increase per die of 400 g exhibited lower responses. Results in terms of heat and ovulation were lower along with shorter intervals, when oestric synchronisation was undertaken 53, 32, and 17 days after the induction of puberty (20 days Suisynchron, Bernburg; 750 IU PMS).

Animals↗
PubMed1991

[Estrus and ovulation synchronization in Merino meat sheep. 1. Effect of Gonavet "Berlin Chemie" after estrus synchronization with prostaglandin F2 alpha in Merino meat sheep].

Oestrus synchronisation by means of PGF2 alpha analogues was followed by injection of Gonavet "Berlin-Chemie" which triggered off an LH peak, 2 to 3 hours from injection. Injection of Gonavet "Berlin-Chemie", 44 hours after PGF2 alpha application, caused synchronisation of all LH peaks. The interval between injection of Gonavet "Berlin-Chemie" and onset of ovulation amounted to 22 hours. The length of ovulation was not accurately determinable. Ovulation was successfully induced to all sheep by application of Gonavet "Berlin-Chemie", 44 or 48 hours after PGF2 alpha injection. Ovulation rates were 1.75 or 1.54. Luteolytic action on sheep of Cloprostenol "Jenapharm", a PGF2 alpha analogue, proved to be just as good as that of Oestrophan (SPOFA).

Animals↗
PubMed1991

[Estrus and ovulation synchronization in Merino meat sheep. 2. Fertility outcome after estrus and ovulation synchronization with Cloprostenol "Jenapharm" and Gonovet "Berlin-Chemie" and term-oriented artificial insemination].

49 of 102 sheep of one production herd, which had returned to oestrus once or twice within the 1985 breeding season, were treated twice in a nine-day interval with the PGF2 alpha analogue Cloprostenol "Jenapharm". 53 animals received an additional dose of 10 micrograms of Gonavet "Berlin-Chemie". A lambing rate of merely 15% was achieved by subsequent term-oriented artificial insemination. 31 sheep still in oestrus one day after term-oriented artificial insemination were served, bringing the lambing rate from synchronisation of oestrus and ovulation to 26% and the lambing result to 154%. Serving of the remaining sheep in 2 subsequent oestric cycles, on balance, yielded lambing rates and results of the remaining sheep in 2 subsequent oestric cycles, on balance, yielded lambing rates and results which were higher with significance than those recorded from untreated sheep in the same herd.

Animals↗
PubMed1975

[Estrus synchronization in cattle by means of chlormadinone acetate ("Bovisynchron" Jenapharm) in the tropics. II. First results of the estrus synchronization of cattle with "Bovisynchron" at the Republic of Mali].

The first experiments are reported on oestrus synchronization in cattle in the Republic of Mali. The animals recieved Bovisynchron twice a day orally over a period of 15 days. The synchronization effect was marked; insemination was performed on the 5th and 6th day p.s. The intensity of the oestrus and especially the results of pregnancy are in close relationship to the breeding conditions and the general status of the animals. The oestrus synchronization is considered a favourable biotechnical method for regulating the reproduction provided that the animals are kept stationary or temporarily stationary.

Animals↗
PubMed1992

Steroids and plasminogen activator concentrations in follicular fluid of gilts at first and third estrus.

An experiment was conducted to determine whether morphological and functional characteristics of follicles differed at a similar stage of pubertal (first) and third estrus in the same gilts. Nine prepubertal gilts were checked three times daily for estrus and laparotomized 6 h after detected first and third estrus. Samples of vena cava and ovarian venous blood were collected, follicle numbers and diameters were recorded, and follicular fluid (FF) was aspirated from all follicles 8 to 12 mm in diameter. Sera and(or) FF were analyzed for progesterone (P4), estradiol-17 beta (E2), testosterone (T), androstenedione (A4), 5 alpha-dihydrotestosterone (DHT), plasminogen activator (PA), and plasmin (PLM). Overall mean number of follicles > or = 8 mm in diameter did not differ between gilts at first and third estrus (P > .05) but gilts at first estrus had more follicles 4 to 8 (P < .05) and 8.1 to 10 mm in diameter (P < .01) and fewer 10.1 to 12 mm in diameter (P < .07) than at third estrus. Mean FF concentrations of E2, T, and A4 at third estrus were significantly greater than at first estrus, whereas FF concentrations of P4, DHT, PA, and PLM were similar at first and third estrus (P > .05). Mean concentrations of E2 in systemic and ovarian venous sera were also greater in gilts at third than at first estrus (both P < .05). Systemic concentrations of P4 in gilts at first and third estrus did not differ (P > .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Androstenedione↗
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↗
PubMed1990

Modes of estrus induction as a factor in studies of the reproductive behavior of rodents.

The choice of a mode of estrus for use in studies related to reproductive processes often is made arbitrarily. Females may be in hormone-induced estrus (HIE), cycling estrus (CE), male-induced estrus (MIE), or postpartum estrus (PPE). Although mode of estrus affects various aspects of copulatory behavior in different species in different ways, males mating with PPE females generally require more intromissions to reach ejaculation than with females in HIE or CE; males mating with females in CE generally attain more ejaculations than with PPE females. The duration of receptivity generally is shorter in PPE than in CE. Females in CE and PPE have different stimulus thresholds for pregnancy initiation, with the direction of the difference varying with the species. Among the other phenomena affected by mode of estrus are sperm competition, mate choice, and the Bruce effect. Because mode of estrus can be an important determinant of results, selection of a mode of estrus for any experiment should not be simply a matter of convenience. Further study of effects of mode of estrus is warranted.

Animals↗
PubMed1990

Influence of gonadotropin-releasing hormone and timing of insemination relative to estrus on pregnancy rates of dairy cattle at first service.

The objective was to determine the influence of gonadotropin-releasing hormone on pregnancy rates of dairy cattle at first services, when both the timing of hormone injection and insemination were altered relative to the onset of estrus. Cows (n = 325) were assigned randomly to six groups making up a 2 X 2 X 2 incomplete factorial experiment; dose of GnRH (100 micrograms versus saline), timing [1 h (early) or 12 to 16 h (late) after first detected estrus] of AI, and timing of hormone injection (early versus late) were the three main effects. Cows were observed for estrus 4 times daily. Treatments and resulting pregnancy rates were: 1) hormone injection early plus AI early (35%), 2) hormone injection late plus AI early (34%), 3) saline injection early plus AI early (30%), 4) hormone injection late plus AI late (30%), 5) hormone injection early plus AI late (46%), and 6) saline injection late plus AI late (43%). Pregnancy rate in the first four groups (32%) was less than that in the latter two groups (44%). Concentrations of LH in serum were greater for cows given hormone or saline injections in early estrus than for cows injected with either hormone of saline during late estrus. Concentrations of LH in serum 2 h after GnRH were elevated above those of controls, whether GnRH was injected during early or late estrus. Neither concentrations of LH during estrus nor concentrations of progesterone 8 to 14 d after estrus explained the possible antifertility effect of GnRH given during late estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Influence of an agonist of gonadotropin-releasing hormone (buserelin) on estrus synchronization and fertility in beef cows.

The objective of this experiment was to determine the effect of sequential treatment with buserelin (a GnRH agonist) and cloprostenol (a prostaglandin F2 alpha analog) on estrous response and fertility in beef cattle with different ovarian conditions. On d 0 (1st d of treatment), the control group (n = 52, 10 heifers and 42 cows) and the GnRH group (n = 48, 10 heifers and 38 cows) received 2 mL of saline or 2 mL of Receptal (8 micrograms of buserelin), respectively. On d 6, all cows that had not exhibited spontaneous estrus were given i.m. 500 micrograms of cloprostenol (PGF). Ultrasonography on d 0 and assays of progesterone in blood on d -11, 0, and 6 were used to identify follicular and luteal status of animals. Cattle were observed for estrus from d 0 to 10. Cows showing estrus were bred artificially 12 h after onset of estrus. Over the 10-d period, the number of cows detected in estrus and pregnancy and conception rates were identical for the two groups. However, between d 0 and 6, the proportion of cows exhibiting estrus was lower (P less than .01) in the GnRH group than in the control group. Between d 6 and 10, the synchronization rate and precision of estrus were greater (P less than .01) in the buserelin-treated group than in the control group. Conception rate and interval from PGF injection to onset of estrus were not different between the two treatment groups. Presence of a large (greater than 10 mm) follicle on d 0 enhanced synchronization rate and precision of estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2026

Saliva-based RT-LAMP assays support heat shock protein 70 as a promising transcript marker for estrus identification in buffaloes.

Buffaloes do not exhibit overt estrus signs particularly during summer, leading to a significant economic loss to farmers. Previous studies have identified several candidate transcripts (HSP70, TIMP1, TLR4 and HSD17B1), abundant in buffalo saliva during estrus stage. However, there is no widely applicable technology for estrus detection targeting these transcripts. Therefore, the present study aimed to develop reverse transcription loop mediated isothermal amplification (RT-LAMP) assays for these candidate transcripts using buffalo saliva. Saliva samples were collected from 10 cyclic buffaloes and RT-LAMP assays were optimized for salivary RNA as well as direct saliva. Among the four candidate transcripts, HSP70 showed a statistically significant colour change (p-value&#x2009;=&#x2009;0.0191) at the estrus stage compared to the diestrus stage. This abundance of HSP70 was also supported in large simulated population datasets (10,000 animals) generated using R. Further, the RT-LAMP assays were tested using direct saliva without RNA isolation, and the colour change in the samples during estrus suggested the feasibility of estrus identification using direct saliva, overcoming the tedious step of RNA isolation. The detection of HSP70 using either direct saliva or salivary RNA indicated its potential as a marker for estrus identification. Similarly, TLR4 appeared to be another potential biomarker for RT-LAMP reaction using direct saliva, but it needs further validation in both RNA and direct saliva samples. Overall, the proof-of-concept on RT-LAMP assays optimized for salivary transcripts in the present study would be useful for estrus identification in tropical production systems following further validation on a larger sample size.

Animals↗
PubMed1990

Effects of 21-day treatment with melengestrol acetate (MGA) with or without subsequent prostaglandin F2 alpha on synchronization of estrus and fertility in beef cattle.

Beef cattle were treated to synchronize estrus using one of three procedures, and effects on subsequent endocrine responses and fertility were studied. Procedures were 1) feeding .5 mg.head-1.d-1 of melengestrol acetate (MGA) for 21 d (M), 2) feeding .5 mg.head-1.d-1 of melengestrol acetate for 21 d followed 14 d later by a single injection of prostaglandin F2 alpha (M + P) and 3) two injections of prostaglandin (PGF) 14 d apart (P). In Exp. 1, 94 beef cows were assigned to be artificially inseminated 12 h after detection of estrus. Procedures for synchronizing estrus did not affect the proportion of cows observed in estrus within 7 d (mean = 70.2%). However, conception rate of cows treated with MGA alone was lower (P less than .01) than that of cows treated with PGF alone (31.8 vs 78.3%). The conception rate of cows in the M + P group was intermediate (57.1%) but greater than that of cows treated with MGA alone (P less than .10). In Exp. 2, 18 heifers were observed for estrus four times daily and bled daily from 1 wk before predicted estrus until second estrus or 35 d post-treatment. Heifers treated with MGA alone maintained lower concentrations of progesterone and higher concentrations of estradiol-17 beta before first estrus than heifers treated with MGA and PGF or PGF alone (P less than .01). Conception rate following insemination was lower after long-term feeding of MGA than after two injections of PGF. Delaying insemination until after a PGF-shortened cycle 14 d after MGA resulted in an intermediate conception rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Synchronization of estrus in dairy goats given norgestomet and estradiol valerate at various stages of the estrous cycle.

Dairy goats were given subcutaneous implants with 3 mg of norgestomet (NOR) and IM injections of 0.625 mg of estradiol valerate and 0.375 mg of norgestomet on day 0 of the estrous cycle (estrus; NOR 0, n = 18), on postestrus day 4 (NOR 4, n = 18), or on postestrus day 11 (NOR 11, n = 15). Ear implants were removed after 9 days. Mean (+/- SE) hours from removal of ear implants to onset of estrus and proportion of goats responding were 36 +/- 3.8 and 83%, 33 +/- 4.0 and 61%, and 36 +/- 2.7 and 93% for groups NOR 0, NOR 4, and NOR 11, respectively. There were no significant differences between treatment groups in time to onset of estrus. The percentage of goats in group NOR 11 that had signs of estrus was significantly greater than the percentage of goats in group NOR 4. Of the goats in groups NOR 0, NOR 4, and NOR 11 that had signs of estrus, 53, 55, and 86%, respectively, had onset of behavioral estrus between 24 and 48 hours after implant removal. All goats that had signs of estrus had onset of behavioral estrus between 12 and 72 hours after implant removal. Mean (+/- SE) hours from removal of ear implants to time of peak concentrations of luteinizing hormone (LH) were 49 +/- 4.1, 49 +/- 3.8, and 49 +/- 4.0 for groups NOR 0, NOR 4, NOR 11, respectively (not different). The percentage of goats in group NOR 11 that had LH peaks was significantly greater than the percentage of goats in group NOR 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Body weight and food intake at early estrus of rats on a high-fat diet.

Body weight, food intake, and age at vaginal opening and estrus were studied for two groups of weanling rats (age 21 days), fed on high-fat (24.6% by weight) and low-fat (5.0%) diets. Fat was substituted isocalorically for carbohydrate in the high-fat diet. The high-fat rats had estrus at 33.3 +/- 0.8 days, significantly earlier (P less than 0.001) than the age at estrus, 37.4 +/- 0.7 days, of the low-fat rats. Estrus was simultaneous with vaginal opening in 81% of the high-fat rats, in comparison to 48% of the low-fat rats. The caloric intake per 100 g of body weight of the high-fat and low-fat rats did not differ at vaginal opening or at estrus, whereas the two groups differed significantly at both events in age, body weight, absolute food intake (g/day), and relative food intake (g/100 g of body weight per day) and absolute caloric intake (calories/day). Caloric intake/100 g of body weight as a function of chronological age first increased and then decreased steadily before estrus for both high-fat and low-fat rats. The findings support Kennedy's hypothesis that a food intake signal, now further defined as caloric intake/100 g of body weight, is a signal for puberty, and are in accord with the hypothesis that a critical body composition of fatness is essential for estrus in the rat, as in the human female.

Age Factors↗
PubMed1977

Carcass components at first estrus of rats on high-fat and low-fat diets: body water, protein, and fat.

Carcass analysis data show that weanling rats fed high-fat (HF) and low-fat (LF) diets until the day of first estrus had similar body compositions at estrus, although the HF rats had estrus significantly earlier and at a lighter body weight (P less than 0.01) than the LF-diet rats. Total water as percent of wet weight, protein as percent of wet weight, and the water/protein ratios of the HF- and LF-diet rats did not differ significantly, whereas the absolute amounts of body water and protein of the two diet groups differed significantly (P less than 0.01), in accord with means (+/- SEM) of total body water as percent of wet weight were 66.2 +/- 0.3% for the HF rats and 66.4 +/- 0.3% for the LF-diet rats, whereas the mean absolute total body water for the two diet groups was 69.7 +/- 2.2 g and 81.1 +/- 2.4 g, respectively (P less than 0.01). Carcass fat of the HF rats, 15.6 +/- 1.0 g, was identical with that of the LF-diet rats, 15.6 +/- 0.9 g. The HF rats were therefore relatively fatter, 14.6 +/- 0.6 wet weight %, than the LF-diet rats, 12.6 +/- 0.4 wet weight % (0.05 greater than P greater than 0.01). The percentage of water in the fat-free wet weight of the HF rats, 77.5 +/- 0.3%, was significantly (P less than 0.01) greater than that of the LF-diet rats, 76.1 +/- 0.3%. These data and the high percentages of total water of body weight show that at first estrus the HF- and LF-diet rats had not as yet attained an adult body composition, similar to the human female at menarche. Within each diet group, the percentages of total water/body weight, protein/wet weight and fat/wet weight, or fat/dry weight, did not change significantly with increasing age of estrus, whereas each absolute carcass component--body water, protein, and fat--increased significantly with increasing age of estrus. The carcass data support G.C. Kennedy's hypothesis that a metabolic signal, related to fat stores, is a signal for puberty in the rat and are in accord with the hypothesis that a critical body composition of fatness is necessary for estrus in the rat, as in the human female. The greater relative fatness of the HF-diet rats may be associated with higher levels of estrogen in the HF rats than in the LF-diet rats.

Age Factors↗
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↗
PubMed1991

Effect of a prostaglandin F2 alpha injection 96 hours after introduction of intact bulls on estrus and calving distribution of beef cows.

Most estrus synchronization schemes facilitate the use of artificial insemination; however, combining estrus synchronization with natural service also offers several benefits to beef producers. This experiment was designed to study the effectiveness of one injection of prostaglandin F2 alpha (PGF2 alpha) 96 h after introduction of intact bulls on estrus synchronization and calving distribution of beef cows and heifers. Three hundred sixty beef cows and 45 beef heifers in seven trials were allotted by age, breed, and prior calving date to one of two treatments. Within each subclass, one group was injected with an appropriate dose of PGF2 alpha and the second group at each location received 5 ml of saline (SAL). Cows were classified as estrual or anestrual at the start of breeding based on serum progesterone levels and were observed for behavioral estrus regularly during the first 25 d of the breeding season in two of the trials (d 0 = day before bull turn-in). Pregnancy data and calving dates were recorded in each of the studies. All cows were palpated per rectum for pregnancy approximately 70 d after the introduction of bulls. During d 5 to 9 after treatment, the percentage of cows exhibiting behavioral estrus (P = .02) and the pregnancy rate (P = .02) obtained was greater for PGF2 alpha-treated cows than for SAL-treated cows. There were 6.5% more (P = .05) calves born during the overall calving period from animals treated with PGF2 alpha compared with those in the SAL group. In summary, treatment of cows and heifers with PGF2 alpha 96 h after bull turn-in was effective in synchronizing behavioral estrus of beef cows and heifers and increasing the calving rate during the subsequent calving season.

Animals↗