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PubMed2004

Effect of bST and reproductive management on reproductive performance of Holstein dairy cows.

The objective was to determine the effects of bovine somatotropin (bST) and two artificial insemination (AI) protocols on reproductive performance of Holstein cows. Lactating cows (n = 840) were assigned at 37 d in milk (DIM) to one of four treatments in a 2 x 2 factorial arrangement. Treatments consisted of either bST (500 mg/14 d) starting at 63 +/- 3 DIM or no bST (control), with cows either submitted for timed AI following a synchronized ovulation (Ovsynch) protocol or assigned to receive AI based on estrus detection (ED). Two injections of PGF2, at 37 +/- 3 and 51 +/- 3 DIM were used to presynchronize estrous cycles. Cows then received an injection of GnRH at 63 +/- 3 DIM, followed 7.5 d later by PGF2. Cows assigned to ED treatments were inseminated after observed estrus during a 7-d period. Cows in Ovsynch treatments received a second GnRH injection 48 h after the last PGF2alpha and received timed AI 16 to 18 h later. Pregnancy was diagnosed by ultrasound at 31 d after AI and confirmed 14 d later. Frequency of anovulation (18.5%) at 63 DIM was similar across treatments, but proportions of anovulatory cows decreased quadratically as body condition at 70 DIM increased from 2.25 to 3.75. Estrus detection rate after PGF2alpha tended to be lower in multiparous cows receiving bST, and bST reduced returns to estrus in nonpregnant cows. Conception rates were higher in cows receiving AI after ED and bST improved conception rates to first AI in cyclic cows by reducing embryonic mortality. Pregnancy loss was similar for cows inseminated following ED or the Ovsynch protocol. There was a positive impact of bST on fertility of cyclic cows inseminated at fixed time or at detected estrus, but effective resynchronization protocols are needed to optimize reinsemination of non-pregnant bST-treated cows.

Abortion, Spontaneous↗

PubMed1998

Evaluation of timed insemination during summer heat stress in lactating dairy cattle.

We wished to compare the effect of summer heat stress on pregnancy rate in cows that were inseminated at a set interval associated with a synchronized ovulation vs those inseminated upon routine estrus detection. The study was carried out on a commercial dairy farm in Florida from May to September 1995. Lactating dairy cows were given PGF2 alpha (25 mg i.m.) at 30 + 3 d postpartum and randomly assigned to be inseminated at a set time (Timed group) or when estrus was detected (Control group). Cows in the Timed group were synchronized by sequential administration of Buserelin (8 micrograms i.m.) on Day 0 at 1600 h, PGF2 alpha (25 mg i.m.) on Day 7 at 1600 h and Buserelin (8 micrograms i.m.) on Day 9 at 1600 h. They were inseminated on Day 10 between 0800 and 0900 h (Day 9 + 16 h). Cows in the Control group were given PGF2 alpha at 57 + 3 d postpartum and inseminated when detected in estrus. Estrus detection or insemination rate for control insemination cows was 18.1 +/- 2.5% versus 100% for time inseminated cows (P < 0.01). Mean interval from PGF2 alpha to insemination was shorter for time inseminated cows (3 +/- 2.1 d < 35.5 +/- 1.9 d; P < 0.01). Pregnancy rate was greater for time inseminated cows (13.9 +/- 2.6 > 4.8 +/- 2.5%; P < 0.01) as was overall pregnancy rate by 120 d postpartum (27.0 +/- 3.6 > 16.5 +/- 3.5%; P < 0.05). Number of days open for cows conceiving by 120 d postpartum was less for time inseminated cows (77.6 +/- 3.8 < 90.0 +/- 4.2 d; P < 0.05), as was interval to first service (58.7 +/- 2.1 < 91.0 +/- 1.9 d; P < 0.01). Services per conception were greater for time inseminated cows (1.63 +/- 0.10 > 1.27 +/- 0.11; P < 0.05). The timed insemination program did improve group reproductive performance. However, the timed insemination program will not protect the embryo from temperature-induced embryonic mortality, but management limitations induced by heat stress on estrus detection are eliminated. An economical evaluation of the timed insemination program indicates an increase in net revenue per cow with implementation of timed insemination for first service during the summer months.

Animals↗

PubMed2000

Reproductive outcomes for dairy heifers treated with combinations of prostaglandin F2alpha, norgestomet, and gonadotropin-releasing hormone.

We conducted three experiments to test various protocols for synchronizing estrus, ovulation, or both before insemination of heifers. In experiment 1, 23 controls received two PGF2alpha injections; 23 heifers were treated like the controls plus a norgestomet implant for 8 d, with the second PGF2alpha injection 24 h before implant removal; and 23 heifers were treated like the previous group plus 100 microg of GnRH 54 h after the second PGF2alpha injection. Although norgestomet and GnRH altered some estrual characteristics, conception rates in experiment 1 (n = 69) and experiment 2 (278 heifers receiving the same treatments as those in experiment 1) generally were not different among treatments. Reproductive outcomes were not improved by adding norgestomet and GnRH to a standard PGF2alpha protocol. In experiment 3, control heifers received PGF2alpha and were inseminated after detected estrus or at 72 to 80 h after a second injection of PGF2alpha given 14 d after the first injection. Select Synch heifers, treated with GnRH either 6 or 7 d before PGF2alpha were inseminated after detected estrus, whereas Ovsynch heifers were treated like Select Synch heifers but also received a second GnRH injection approximately 36 h after PGF2alpha and were inseminated 18 h later. Estrus detection and pregnancy rates after Ovsynch were less than those of controls, whereas conception and pregnancy rates did not differ between control and Select Synch heifers. Therefore, the Select Synch protocol was equivalent to a standard PGF2alpha protocol, whereas Ovsynch was inferior to both of those protocols.

Age Factors↗

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↗

PubMed1998

Incidences and effects of diseases on the performance of Swedish dairy herds stratified by production.

Incidences of diseases and their effects on reproductive performance and risk of culling in herds stratified by production and estrus detection efficiency were studied. Data were from the Swedish milk and disease recording systems and consisted of records for 33,748 first parity Swedish Friesian cows. A standardized mixed threshold model was used for statistical analyses of categorical outcome variables, and an ordinary linear mixed model was used for continuous outcome variables. An increase in production was associated with increased frequencies of treatments of most diseases, shorter intervals from calving to first artificial insemination, fewer days open, and lower culling rates. Cows treated for metritis, silent estrus, and cystic ovaries had an increased number of days to first artificial insemination and more days open. However, the negative consequences of these diseases on reproductive performance decreased as herd production increased. The risk of culling was higher for cows treated for dystocia, cystic ovaries, and mastitis, but the increase in the risk of culling was lower for higher producing herds. Similar trends were observed when herds were stratified by estrus detection efficiency. The results support the hypothesis that herd management, as characterized by milk production or estrus detection efficiency, is important in the incidences and consequences of diseases. Herd management, measured directly or indirectly, should be considered when the health status or cost of disease for a given herd is evaluated.

Animals↗

PubMed2005

Technical and economic effects of an inline progesterone indicator in a dairy herd estimated by stochastic simulation.

For several years progesterone in milk or blood has been recognized as an indicator of different cow states related to reproduction. For this study, an existing simulation model was modified in order to analyze the technical and economic effects of including information on progesterone status in an automatic inline monitoring system. Implementation of an inline progesterone indicator was assumed to directly affect the estrus detection rate, the period until treatment for post-partum anestrus and the number of mistimed AIs. Different implementations of an inline progesterone indicator were simulated in a typical Danish dairy herd with 120 cows and in other herd situations represented by: a herd with poor reproduction efficiency, a herd with a high estrus detection rate and a herd using a 9 week postponed AI period for primiparous cows. It was concluded that implementation of an inline progesterone indicator in a dairy herd previously using visual estrus detection has a break-even price of 3-81 euros per cow-year depending on differences in implementation type and herd reproduction management. The highest break-even price was found using the assumptions that simulated a herd with initially poor reproductive efficiency. With the assumptions that simulated a typical Danish herd the break-even price was 46 euros per cow-year. Attributable effects of using the indicator, including effects of labor time, are discussed.

Animals↗

PubMed1987

Economic impact of the use of prostaglandin to induce estrus in dairy cows.

An economic model concerning the value of using prostaglandin (PG) in dairy cows with nondetected estrus was developed. Considering numerous and varied assumptions, it was more profitable to treat cows with PG and to breed the cows at a detected estrus than it was not to treat the cows and to wait to breed the cows at a detected estrus. Generally, using timed artificial insemination, it was also more profitable to breed PG-treated cows than it was not to use PG. However, timed insemination was less profitable than was breeding PG-treated cows by artificial insemination at a detected estrus.

Animal Husbandry↗

PubMed1979

Control of estrus in dairy cows with a synthetic analogue of prostaglandin F2 alpha.

Trials were carried out on 1184 dairy cows calved at least six weeks before treatment and 255 heifers to determine effectiveness of the prostaglandin analogue, cloprostenol to control estrus. In trial 1, following two injections of cloprostenol given 12 days apart, there was no difference in calving rate following AI either at 72 and 96 hr after treatment (71 163 ) or at a detected estrus (53 118 ) compared to control cows bred at estrus (54 110 ). In trial 2, treated cows were injected once after 5 to 7 days of estrous detection and AI. The calving rate following AI either at 72 and 96 hr after cloprostenol (46 100 ) or at a detected estrus (39 71 ) was similar to that in control cows bred at estrus (45 86 ). In trial 3, cows were bred at a detected estrus after the first cloprostenol injection. Twelve days after this injection, cows not bred were given a second injection and bred 72 and 96 hr later. The calving rate in treated cows bred at estrus after the first injection (66 138 ) was similar to calving rate in controls (55 95 ). However, calving rate in cows given a second injection and bred 72 and 96 hr later was significantly (P angle 0.05) lower (30 98 ). Similar results were obtained in heifers, except calving rate in trial 3 after the second cloprostenol injection was not reduced.

Journal Article↗

PubMed1994

Conception rates. 2. Economic value of unit differences in percentages of sire conception rates.

The objectives of this research were to estimate 1) the annual increase in profitability and 2) the value of a unit of semen because of an increase of 1 in percentage of AI conception rate. Factors contributing to increased annual profit per cow included more milk production, less semen purchased, more calvings, and fewer reproductive cullings. With a 7% average monthly rate of decline in milk production between peak and end of lactation, $ .24/kg of milk net income over feed cost, $ 20/unit of semen, $ 150 per calving, and $ 400 per reproductive culling, values for increased annual profitability per cow ranged from $ .88 to $ 7.36, and increased value per unit of semen ranged from $ .60 to $ 5.01, when estrus detection and AI conception were each constrained to minima of 30% and maxima of 70%. Additional probability of concept was worth less at high rates of estrus detection and of AI conception. Within-herd variation can be attributed to differences between cows in milk production, asset value of the cow based on future expectations of milk production, and seasonal differences in milk price and rates of estrus detection. Further differences between herds can be expected as producers vary in discounting values for uncertainty of information. Therefore, generalizations from a single set of assumptions may be limited, and application of methods to specific cows and producers may be desirable.

Animals↗

PubMed1985

An investigation of skin temperature differentials in relation to estrus in dairy cattle using a thermal infrared scanning technique.

To evaluate the effectiveness of thermal infrared scanning as a technique to detect estrus, 27 Holstein-Friesian cows were observed for a 90-d period beginning in the second week postpartum. The area enclosed by the 37-C isotherm on the gluteal region of a cow's body tended to increase in association with the occurrence of estrus. This increase became statistically significant at the third postpartum estrus. During the first 50-postpartum d, infrared scanning enhanced detection of estrus when compared with standard dairyman-detection accuracy. However, detection of estrus using infrared scanning was hampered by false positives (33% around the third postpartum estrus) and inability to detect estrus for some cows (7%). It appears at present that the usefulness of infrared scanning for routine detection of estrus in dairy cows is limited, but the technique may have potential as a research tool for the study of skin temperature patterns.

Animals↗

PubMed2002

The control of follicular wave development for self-appointed embryo transfer programs in cattle.

Our expanding knowledge of the control of follicular wave dynamics during the bovine estrous cycle has resulted in renewed enthusiasm for the prospects of precisely controlling the follicular and luteal dynamics and finely controlling the time of ovulation. Follicular wave development can be controlled mechanically by ultrasound-guided follicle ablation or hormonally by treatments with GnRH or estradiol and progestogen/progesterone in combination. Treatment of cattle with GnRH in combination with prostaglandin F2 alpha (PGF) 7 d later and a second GnRH 48 h after PGF (known as Ovsynch) has resulted in acceptable pregnancy rates after fixed-time AI in lactating dairy cows and in recipients in which embryos were transferred without estrus detection. Alternatively, treatments with estradiol and progestogen/progesterone-releasing devices resulted in synchronous emergence of a new follicular wave and, when a second estradiol treatment was given 24 h after device removal, synchronous ovulation and high pregnancy rates to fixed-time AI. Self-appointed embryo transfer (without estrus detection) using estradiol and progesterone treatments have resulted in pregnancy rates comparable with those obtained with recipients transferred 7 d after estrus. Furthermore, estradiol and progesterone treatments combined with PGF and eCG (given 1 d after the expected time of wave emergence) have resulted in high rates of recipients selected for transfer (84.6%) and an overall pregnancy rate of 48.7% (recipients pregnant/recipients treated). Estradiol and progestogen/progesterone treatments have also been widely used for self-appointed superstimulation protocols with equivalent embryo production to that of donor cows superstimulated using the traditional approach beginning 8 to 12 d after estrus. In summary, exogenous control of luteal and follicular development facilitates the application of assisted reproductive technologies in cattle by offering the possibility of planning the superstimulation of donors and synchronization of recipients at a self-appointed time, without the necessity of estrus detection and without sacrificing results.

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↗

PubMed2006

Economic comparison of timed artificial insemination and exogenous progesterone as treatments for ovarian cysts.

The objective of this study was to compare the economic benefits of timed artificial insemination (AI) and a progesterone insert as therapeutic treatments for cows diagnosed with cystic ovarian disease (COD). A secondary objective was to illustrate the use of a stochastic dynamic simulation model to fully account for all changes in revenues and costs affected by differences in treatments. First, 4 herds of 1,000 cows each were simulated until steady state. These cows were free from COD and inseminated based on estrus only. Herds differed by probability of estrus detection (46 or 70%) and days in milk (DIM) when nonpregnant cows were culled (330 or 400 d). Second, 3 herds were created with 1,000 nonpregnant cows at 90, 170, or 250 DIM. These cows were considered diagnosed with COD at the start of the simulation (d 0); no new cases of COD developed after d 0. Cows spontaneously recovered or were treated. Treatments were either timed AI or intravaginal device containing progesterone followed by PGF(2alpha) and then AI if estrus was detected. Effects of treatments were evaluated in 48 scenarios based on compliance of timed AI (82 or 100%), probability of estrus detection (46 or 70%), and DIM when nonpregnant cows were culled (330 or 400 d). As cows became pregnant or were replaced, the herd evolved into the associated steady-state herd. Seven scenarios resulted in less than 50% of cows conceiving before they were culled. The percentage of cows diagnosed with COD that calved again ranged from 14.0 to 74.4% and was significantly reduced when COD was diagnosed later in lactation. Treatments in all cases were more valuable than waiting for spontaneous recovery. The average values of timed AI (82 or 100% compliance) and the progesterone insert were 83.29 dollars, 86.83 dollars, and 71.89 dollars, respectively, compared with waiting for spontaneous recovery. Treatments were least beneficial at 90 DIM. The benefits of timed AI (82 or 100% compliance) compared with the progesterone insert, adjusted for DIM and days to culling, were 14.98 dollars and 21.53 dollars when the probability of estrus detection was 46%. At 70% probability of estrus detection, the benefits were 7.81 dollars and 8.34 dollars, respectively. Overall benefit of treatment by timed AI was 11.39 dollars greater than by progesterone insert.

Administration, Intravaginal↗

PubMed1981

Postpartum ovarian function of dairy cows in a tropical environment.

Intervals from parturition to first estrus and to the first three ovulations were studied in 25 Holstein and 31 Jamaica Hope cows in Jamaica. Casual observations for signs of estrus were supplemented by twice nightly observation periods. Samples of blood plasma were obtained twice weekly from all cows and assayed for progesterone. The progesterone profile for each cow was used to determine when ovulations occurred. Intervals and standard deviations from parturition to first, second, and third ovulations were 19.8 +/- 8.8, 39.4 +/- 9.0, and 58.6 +/- 9.2 days for Holsteins, which were shorter than the same intervals for Jamaica Hope cows (28.7 +/- 15.6, 46.9 +/- 13.6, and 66.3 +/- 12.6 days). Intervals from parturition to first detected estrus were 46.0 +/- 21.4 days for Holsteins and 45.5 +/- 18.7 days for Jamaica Hopes. There were no significant differences between seasons of calving in intervals to ovulations or in intervals to first detected estrus. Percentages of cows detected in estrus at the first, second, and third ovulations were 19, 61.9, and 57.8% for Holsteins and 43.3, 55.2, and 73.1% for Jamaica Hopes. Holstein cows kept in a tropical environment are capable of returning to a cycling, rebreedable state and of showing detectable signs of estrus as soon after calving as can be expected reasonably.

Animals↗

PubMed2000

Importance of inseminating only cows in estrus.

Reproductive efficiency is a key component in successful dairy farm management. A study was initiated to evaluate the incidence and consequences of inseminating dairy cows in the middle of the estrous cycle or while pregnant. In a research herd of 242 Holsteins, managed for reproduction under typical farm conditions, milk progesterone (P4) was assayed 3 times per wk for at least 120 d postpartum. The P4 cycle was compared with the estrus detection and breeding records and pregnancy diagnosis 6 wk after insemination. About 19% of the inseminations were performed when P4 was high in the estrous cycle and in pregnant cows. Insemination of pregnant cows led to an estimated 17% induced embryonic death or abortion. In Israel, inseminators are extensively trained to detect cows not in estrus. They reject about 16% of the cows submitted for reinsemination, with a 95% accuracy of rejection of 44% of the cows that were pregnant. The pattern of submission of cows for reinsemination in areas around New York State was similar to Israel and to the experimental herd. These results indicate that more careful submission and rejection can reduce the unnecessary use of semen, reduce abortions and minimize long calving intervals, all contributing to the success of a dairy herd operation.

Abortion, Veterinary↗

PubMed2003

Effect of time of ovulation and sperm concentration on fertilization rate in gilts.

In normal production practices, sows and gilts are inseminated at least twice during estrus because the timing of ovulation is variable relative to the onset of estrus. The objective of this study was to determine if a normal fertilization rate could be achieved with a single insemination of low sperm number given at a precise interval relative to ovulation. Gilts (n=59) were randomly assigned to one of three treatment groups: low dose (LD; one insemination, 0.5 x 10(9) spermatozoa), high dose (HD; one insemination, 3 x 10(9) spermatozoa) or multiple dose (MD; two inseminations, 3 x 10(9) spermatozoa per insemination). Twice daily estrus detection (06:00 and 18:00 h) was performed using fenceline boar contact and backpressure testing. Transrectal ultrasonography was performed every 6 h beginning at the detection of the onset of standing estrus and continuing until ovulation. Gilts in the LD and HD groups were inseminated 22 h after detection of estrus; MD gilts received inseminations at 10 and 22 h after detection of estrus. Inseminations were administered by using an insemination catheter and semen was deposited into the cervix. The uterus was flushed on Day 5 after the onset of estrus and the number of corpora lutea, oocytes, and embryos were counted. Time of insemination relative to ovulation was designated as 40 to >24 h, 24 to >12 h, and 12 to 0 h before ovulation and >0 h after ovulation. The LD gilts had fewer embryos (P<0.04), more unfertilized oocytes (P<0.05) and a lower fertilization rate (P<0.07) compared to MD gilts. The effects of time of insemination relative to ovulation and the treatment by time interaction were not significant. We conclude that a cervical insemination with low spermatozoa concentration may not result in acceptable fertility even when precisely timed relative to ovulation.

Animals↗

PubMed2005

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

In this paper, the authors review the effects of boar contact and different components of boar presence on onset and expression of estrus in weaned sows. Evidence is presented that boar contact may influence LH release, onset of follicle development and timing of ovulation after weaning. Once the sow is in estrus it is important that she shows estrous behavior, because her expression of estrus determines whether she will be inseminated. Boar contact or components thereof affect expression of estrus in sows. There are distinct differences between different components of boar contact in their effectiveness in the induction of estrous behavior (standing response) in sows. Habituation to boars (due to frequency of boar contact or housing of boars near sows) also affects estrus expression in sows. It is important to inseminate sows at the correct moment relative to ovulation. The use of different estrus detection protocols (e.g., by giving sows different levels of boar stimuli during estrus detection) may result in the definition of distinct periods of estrus that may help to predict the moment of ovulation. However, results to date are not very encouraging. Besides boar stimuli, the housing conditions of sows may affect onset of estrus and estrus expression. This paper focuses on social sow-to-sow interactions. The effects of group housing (as compared to individual housing) on onset of estrus and expression of estrus are equivocal. These effects likely depend on factors like aggression between pen mates, reproductive status of pen mates and social rank of sows within the group.

Animals↗

PubMed1998

Evaluation of systematic breeding programs for lactating dairy cows: a review.

Observing cows in estrus and inseminating them at the optimum time are necessary steps for effective reproductive management of a dairy herd. However, larger herd sizes can lead to reproductive inefficiency and decreased profits on dairy farms. Synchronization of estrus behavior through pharmacological control has been used to improve reproductive efficiency. Methods of synchronizing estrus were originally devised to decrease the time spent detecting estrus; however, systematic breeding programs are now being used for convenience and efficiency in reproductive management. Systematic breeding programs provide an organized approach for administering artificial insemination (AI) at first service. Moreover, reproductive management is based on a methodical approach for the entire herd rather than for the individual cow. Targeted Breeding (Pharmacia-Upjohn, Kalamazoo, MI) consists of a series of three PGF2 alpha injections at 14-d intervals. For convenience, injections are usually given one day a week to all cows that surpass the specified target date. The PGF2 alpha injections may be continued until detection of estrus and AI or fixed-time AI. Ovsynch consists of a GnRH injection at a random stage of the estrous cycle, followed by PGF2 alpha 7 d later, a second GnRH injection 36 to 48 h after PGF2 alpha, and timed AI. Research has shown that both Ovsynch and Targeted Breeding can improve reproductive performance over that of traditional programs.

Animals↗