Possible causes and treatment strategies for the estrus and ovulation disorders in dairy cows

The reproductive performance of dairy cows has declined, along with an increase in their milk yield. First-service conception rates in lactating dairy cows are often lower than 50%. The precise detection of estrus is an important factor in the reproductive management of dairy cows for successful fertilization and pregnancy. However, estrus expression has been decreasing in modern dairy cows, affecting the detection rate of estrus. In addition to estrus, a high incidence of ovulation disorders affects the fertility of dairy cows. To address these problems, it is necessary to understand the changes in the endocrine functions that underlie estrus and ovulation disorders, and to develop effective treatment strategies. Recent studies have revealed that neurokinin B and neurokinin 3 receptor signaling play important roles in the regulation of the secretion of gonadotropin-releasing and luteinizing hormones, suggesting a potential clinical avenue for the stimulation of gonadal function. In this review, I have discussed the problems in estrus and ovulation disorders in modern dairy cows as well as the possible applications of neurokinin 3 receptor agonists in the treatment of these disorders.     

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.     

Synchronizing estrus and(or) ovulation in beef cows after combinations of GnRH, norgestomet, and prostaglandin F2alpha with or without timed insemination

Three experiments were conducted to induce estrus and(or) ovulation in 1,590 suckled beef cows at the beginning of a spring breeding season. In Exp. 1, 890 cows at three locations were allotted to three treatments: 1) GnRH on d -7 + prostaglandin F2alpha (PGF2alpha) on d 0 (Select Synch); 2) GnRH on d -7 + PGF2alpha on d 0 (first day of the breeding season) plus a norgestomet implant (NORG) between d -7 and 0 (Select Synch + NORG); or 3) two injections of PGF2alpha given 14 d apart (2xPGF2alpha). More (P < 0.05) cycling cows were detected to have been in estrus after both treatments that included GnRH, whereas, among noncycling cows, the addition of norgestomet further increased (P < 0.05) the proportion in estrus. Pregnancy rates were greater (P < 0.01) among noncycling cows after treatments that included GnRH. For cows that calved >60 d before the onset of the breeding season, conception rates were greater (P < 0.01) than those that calved < or =60 d regardless of treatment, whereas days postpartum had no effect on rates of detected estrus. When body condition scores were < or =4 compared with >4, rates of detected estrus (P < 0.05) and conception (P = 0.07) were increased. In Exp. 2, 164 cows were treated with the Select Synch + NORG treatment and were inseminated either after estrus or at 16 h after a second GnRH injection (given 48 h after PGF2alpha). Conception and pregnancy rates tended (P = 0.08) to be or were less (P < 0.05), respectively, for noncycling cows inseminated by appointment, but pregnancy rates exceeded 53% in both protocols. In Exp. 3, 536 cows at three locations were treated with the Select Synch protocol as in Exp. 1 and inseminated either: 1) after detected estrus (Select Synch); 2) at 54 h after PGF2alpha when a second GnRH injection also was administered (Cosynch); or 3) after detected estrus until 54 h, or in the absence of estrus, at 54 h plus a second GnRH injection (Select Synch + Cosynch). Conception rates were reduced (P < 0.01) in cows that were inseminated by appointment. An interaction of AI protocol and cycling status occurred (P = 0.05) for pregnancy rates with differing results for cycling and noncycling cows. Across experiments, variable proportions of cows at various locations (21 to 78%) were cycling before the breeding season. With the GnRH or GnRH + NORG treatments, ovulation was induced in some noncycling cows. Conception rates were normal and pregnancy rates were greater than those after a PGF2alpha program, particularly when inseminations occurred after detected estrus.     

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.     

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.     

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.     

The strategic use of estradiol to enhance fertility and submission rates of progestin-based estrus synchronization programs in dairy herds

Two experiments were performed to evaluate the efficacy of a progestin-based estrus synchronization program that incorporated the use of estradiol at the initiation of progestin treatment and at 48 h after progestin withdrawal (Exp. 2). In Exp. 1, cyclic, lactating dairy cows (n = 112) were assigned to receive either 1 (1mg) or 2 (2mg) mg of estradiol benzoate via an i.m. injection on d -9 (d 0 = initiation of the breeding season). All cows received an intravaginal progesterone-releasing insert (IPI; CIDR-B) on d -9. On d -2, the IPI was withdrawn and all cows were administered 500 microg of cloprostenol sodium. Beginning on d 0, cows were bred by AI upon detection of estrus. Estrus was observed in similar proportions of cows in each treatment during the first 6 d of AI (90% across treatments), but the interval to estrus was shorter (P < .05) in 1mg (1.26 +/- .18 d) than in 2mg (1.77 +/- .18 d). Conception and pregnancy rates did not vary among treatments; however, cows in estrus on d 0 tended to be less fertile (P = .11) than those in estrus on d 1. In Exp. 2, 408 cyclic cows from three herds were assigned to receive either no synchrony treatment (Control, n = 214) or the treatments described in Exp. 1 (1mg, n = 100; 2mg, n = 94). Anestrous cows from all herds received an IPI from d -9 to -2 (n = 143; Anestrus). All cows in the 1mg, 2mg, and Anestrus groups, with the exception of those detected in estrus between d -1 and 0, also received 1 mg of estradiol benzoate on d 0. Greater than 90% of cows that received an IPI were in estrus between d -1 and 3, and 92.1% of cows in the Control group were in estrus by d 21. Conception rate to first service in 2mg (61.7%) was similar to Control (57.0%), tended to be higher (P = .06) than 1mg (49.0%), and was greater (P < .05) than Anestrus (39.9%). The mean day of conception was earlier (P < .05) in the 2mg (d 13.1 +/- 2.0) than the Control (d 23.2 +/- 1.6) and Anestrus (d 22.4 +/- 1.9) groups. Conception occurred earlier in 1mg (d 17.4 +/- 2.1) than in Control. The proportion of cows that were pregnant at the end of the breeding season tended (P = .09) to be greater in the 2mg and Anestrus groups. This regimen of estrus synchronization improved reproductive competence in cyclic cows and resulted in similar reproductive performance in anestrous cows and untreated cyclic cows inseminated at a spontaneous estrus.     

Use of prostaglandin F2 alpha in the treatment of unobserved estrus in lactating dairy cattle

A field trial was conducted to evaluate the use of prostaglandin F2 alpha (PGF2 alpha) (lutalyse)a in lactating dairy cattle with unobserved estrus in the presence of a functional corpus luteum (CL) and clinically normal reproductive tract. Seventy-three Holstein and 9 Jersey cows, weighing between 340.0 and 772.7 kg, were allotted to treatment and control groups. All treated cows were inseminated within 80 hours after treatment as assigned by this trial. Control cows were inseminated at the first observed estrus. Of the treated cows, 50% showed estrus within 80 hours after treatment. In this trial, 96% of the treated cows and 92% of the control cows were determined to have at least 1 functional CL on the day of treatment. For the treatment group and the control group, mean serum progesterone concentrations were 4.1 ng and 3.5 ng (P less than 0.2, by Student's t test), respectively, on day of treatment and were 0.4 ng and 5.0 ng (P less than 0.005, by Student' t test) on day 5 after treatment. Pregnancy rates were 57% for treated and 47% for control cows (P = 0.5, by X2). Days from treatment to first-observed estrus, treatment to first service, and treatment to conception were significantly reduced in the treatment group compared with these criteria for the control group (P less than 0.05, 0.005, and 0.01 respectively). It was concluded that induction of luteolysis with PGF2 alpha in lactating dairy cattle with unobserved estrus and a palpable functional CL will be an effective addition to reproductive health programs.     

同期发情技术在规模化奶牛场中的应用

目的 为探讨同期发情技术在规模化奶牛场中的应用方案。方法 分别采用3 种不同处理方法对产后80 天奶牛进行同期发情处理,试验结束后比较不同处理方法对奶牛发情率和受胎率的影响。结果 试验A组、B组和C组的发情率分别为72.50%、80.00%和87.50%;受胎率分别为62.07%、65.63%和68.57%,其中试验C组的发情率显著高于另外两组（P<0.05）。结论 同情发情技术的推广可以大大提升奶牛养殖业的经济效益,且在本试验条件下,试验C组的同期发情效果最优。     

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.     

Optimizing breeding decisions for Finnish dairy herds

The purpose of this study was to determine the effect of reproductive performance on profitability and optimal breeding decisions for Finnish dairy herds. We used a dynamic programming model to optimize dairy cow insemination and replacement decisions. This optimization model maximizes the expected net revenues from a given cow and her replacements over a decision horizon. Input values and prices reflecting the situation in 1998 in Finland were used in the study. Reproductive performance was reflected in the model by overall pregnancy rate, which was a function of heat detection and conception rate. Seasonality was included in conception rate. The base run had a pregnancy rate of 0.49 (both heat detection and conception rate of 0.7). Different scenarios were modeled by changing levels of conception rate, heat detection, and seasonality in fertility. Reproductive performance had a considerable impact on profitability of a herd; good heat detection and conception rates provided an opportunity for management control. When heat detection rate decreased from 0.7 to 0.5, and everything else was held constant, net revenues decreased approximately 2.6%. If the conception rate also decreased to 0.5 (resulting in a pregnancy rate of 0.25), net revenues were approximately 5% lower than with a pregnancy rate of 0.49. With lower fertility, replacement percentage was higher and the financial losses were mainly from higher replacement costs. Under Finnish conditions, it is not optimal to start breeding cows calving in spring and early summer immediately after the voluntary waiting period. Instead, it is preferable to allow the calving interval to lengthen for these cows so that their next calving is in the fall. However, cows calving in the fall should be bred immediately after the voluntary waiting period. Across all scenarios, optimal solutions predicted most calvings should occur in fall and the most profitable time to bring a replacement heifer into a herd was in the fall. It was economically justifiable to keep breeding high producing cows longer than low producing cows.     

A field study on the usefulness of milk progesterone determination to confirm estrus and pregnancy of dairy cows in the Fraser Valley area of British Columbia

A field study was conducted to determine the usefulness of milk progesterone determination at the time of breeding to confirm estrus and at 21 days postbreeding to detect open cows. Twenty-seven dairy farmers collaborated in this study by providing milk samples on the day of breeding and 21 days later, together with pregnancy diagnosis data and information on herd reproductive management. Herd size ranged from 15 to 175 cows, the average being 65 milking cows. Six hundred and sixty-seven breeding-day samples and 472, 21-day samples were provided by the farmers. Analysis of milk samples for progesterone by a solid phase radioimmunoassay showed that only 32 (4.8%) of the services were performed when the cow was not in estrus (progesterone > 1 ng/mL). Of the 472, 21-day samples, 337 (71%) showed progesterone levels of > 1 ng/mL, while 135 (29%) showed progesterone levels of < 1 ng/mL. Subsequently, 243 (72%) of the cows with progesterone > 1 ng/mL and eight (6%) of the cows with progesterone < 1 ng/mL were diagnosed pregnant by transrectal palpation, giving a pregnancy rate of 53%. Progesterone concentration on the day of breeding was not associated with season or herd size. However, progesterone concentration at 21 days and pregnancy rate were associated with herd size. These results indicate that fertillzation failure and/or early embryonic mortality, rather than inaccurate detection of estrus, are the major reproductive problems encountered by the dairy farmers in British Columbia. Furthermore, progesterone values at 21 days were closely related to reproductive status and indicate the usefulness of milk progesterone assay for the early detection of open cows.     

Synchronization of estrus in postpartum beef cows with melengestrol acetate and prostaglandin F2 alpha

At the beginning of the breeding season, most beef herds consist of a population of cyclic and anestrous postpartum cows. To be most effective and economical, an estrous synchronization method for postpartum beef cows must be capable of synchronizing estrus in cyclic cows and inducing estrus in anestrous cows. In the first of two experiments, the combination of melengestrol acetate (MGA) fed for 9 d and prostaglandin F2 alpha (PGF2 alpha) administered on the last day of MGA feeding synchronized estrus in cyclic cows (94%) and induced estrus in anestrous cows (66%) as effectively as combining PGF2 alpha with a progestin implant (97 and 75%, respectively). In the second experiment, MGA treatment was necessary for 7 d prior to administering PGF2 alpha to maximize the expression of estrus in cyclic and anestrous cows. In both experiments the proportion of cows exhibiting a synchronized estrus and the pregnancy rates tended to be higher for cows that were cyclic prior to treatment. However, the MGA-PGF2 alpha treatments consistently induced estrus in more than 50% of the anestrous cows and approximately one-third of the cows that were anestrous prior to treatment conceived during the synchronized breeding period. The MGA-PGF2 alpha treatment was 33 to 46% less expensive than a comparable estrous synchronization method that is approved by the U.S. Food and Drug Administration. If feeding MGA and administering PGF2 alpha is approved, it may be the treatment of choice for synchronizing estrus in cyclic cows and inducing estrus in anestrous cows when supplemental feeding is feasible.     

Variation in conception rates following synchronization of estrus with melengestrol acetate and prostaglandin F2 alpha

Beef cows and heifers (n = 263) at three locations that were exhibiting estrous cycle either were fed .5 mg/d melengestrol acetate (MGA) for 7 d and administered prostaglandin F2 alpha (25 mg, i.m.) on the last day of MGA feeding or were untreated. State of the estrous cycle at the beginning of the experiment was determined based on estrous detection and (or) progesterone concentrations in pretreatment blood samples. Estrous was checked twice daily for 30 d posttreatment. Animals were artificially inseminated approximately 12 h after detection of estrus. A synchronized estrus (less than 7 d posttreatment) was detected in 72% of the treated animals. More animals in the treated group became pregnant during the first 7 d of breeding, but their conception rate was lower than that of animals in the control group (P less than .05). Conception rate (36%) was reduced among treated animals when MGA feeding began late (d 14 to 20) in the estrous cycle. Conversely, the conception rate (66%) of treated animals fed MGA beginning earlier in the cycle was not different from that of control animals (73%; treatment x stage of cycle; P less than .05).     

Duration of estrus induced after GnRH‐PGF2α protocol in dairy heifer

Estrous expressions in dairy cows have been shortened and weakened. Dairy heifers, on the other hand, may not have had such changes in estrous signs as observed in cows, since they have less stresses than cows. The aim of this study was to describe the duration of estrus in a herd of dairy heifers. A total of 56 Holstein Friesian heifers estrus was synchronized using two different hormonal protocols. They were checked for primary and secondary estrous signs with the help of heat detection devices for 48 h at an interval of 4 h starting at 16.00 hour, one day after PGF_2α treatment. Onset and end of standing estrus during 48 h observation period was recorded in 35 of the 44 heifers coming into estrus within 5 days after PGF_2α treatment during the observation period. The duration of standing estrus on the average (±SD) was 9.7 ± 5.3 h. Percentage of heifers with standing estrus longer than 12 h was 40%, and 53% showed standing estrus only for 4–8 h. It is indicated that duration of estrus in dairy heifers has been shortened recently.     

定时输精对奶牛第一情期受胎率的效果分析

[目的]探讨不同月份和精液类型对利用定时输精程序处理奶牛后第一情期受胎率的影响.[方法]选择93头产后60 d以上不发情和产后配1～3次仍未受胎的奶牛,不检查卵巢直接利用激素生源2+1进行同期发情处理.1～3月份处理41头奶牛,6～8月份处理52头;其中,利用性控精液配种58头,常规精液配种35头.[结果]表明:经定时...     

Conception rates to artificial insemination in primiparous, suckled cows exposed to the biostimulatory effect of bulls before and during a gonadotropin-releasing hormone-based estrus synchronization protocol

The objective of these studies was to evaluate whether exposing primiparous, suckled beef cows to the biostimulatory effect of bulls alters breeding performance associated with an estrus synchronization protocol that included GnRH followed 7 d later by PGF(2alpha) and fixed-time AI (TAI). This was a composite analysis of 3 experiments that evaluated (1) the effects of bull exposure at different days after calving (yr 1); (2) the biostimulatory effects of bull excretory products (yr 2); and (3) the biostimulatory effects of familiar and unfamiliar bulls (yr 3) on the resumption of ovarian cycling activity. In all studies, cows were exposed (biostimulated; n = 94) or not exposed (nonbiostimulated; n = 67) to bulls or excretory products of bulls for at least 60 d before the beginning of the estrus synchronization protocol. Average calving day did not differ among years and was 52 +/- 5 d. Year did not affect the proportions of biostimulated and nonbiostimulated cows that were cycling at the beginning of the estrus synchronization protocol; however, a greater (P < 0.001) proportion of biostimulated than nonbiostimulated cows were cycling at this time. In each year, cows were given GnRH followed by PGF(2alpha) 7 d later. Cows were observed for estrus twice daily (am and pm) after PGF(2alpha). Cows that exhibited estrus before 54, 60, and 64 h after PGF(2alpha) were inseminated by AI 12 h later in yr 1, 2, and 3, respectively. Cows that failed to show estrus were given GnRH and TAI at 62, 72, and 72 h after PGF(2alpha) in yr 1, 2, and 3, respectively. Conception rates were determined by transrectal ultrasonography 35 d after TAI in each year. The percentages of cows that exhibited estrus after PGF(2alpha) and before TAI, the interval from PGF(2alpha) to estrus, and the percentages of cows inseminated 12 h after estrus or at TAI did not differ between biostimulated and nonbiostimulated cows and were 51%, 54.7 +/- 7.3 h, 35%, and 65%, respectively. Conception rates for cows bred by AI 12 h after estrus did not differ between biostimulated and nonbiostimulated cows; however, the TAI conception rate was greater (P < 0.05) for biostimulated cows (57.6%) than for nonbiostimulated cows (35.6%). We conclude that TAI conception rates in an estrus synchronization protocol that includes GnRH followed 7 d later by PGF(2alpha) may be improved by the biostimulatory effect of bulls in postpartum, primiparous cows.     

Effectiveness of GnRH plus prostaglandin F2alpha for estrus synchronization in cattle of Bos indicus breeding

Postpartum and lactating crossbred cows containing a percentage of Bos indicus breeding at three locations were studied to determine the efficacy of GnRH + PGF2alpha combinations for synchronization of estrus and(or) ovulation. Cows were equally distributed to each of three treatments by body condition score at the start of the experiment (d 0). All cows received 100 microg of GnRH on d 0 and 25 mg of PGF2alpha 7 d later. The three insemination protocols included 1) AI 12 h after exhibiting estrus during d 7 to 12 of the experiment (Select-Synch; n = 197); 2) timed-AI + 100 microg of GnRH on d 9 of the experiment (CO-Synch; n = 193); 3) AI 12 h after exhibiting estrus during d 7 to 10 of the experiment. Cows not exhibiting estrus by d 10 were timed-AI and injected with 100 microg of GnRH on d 10 of the experiment (Hybrid-Synch; n = 200). The percentage of cows exhibiting estrus during d 7 to 12 of the experiment was lower (P < 0.05) for CO-Synch (17.6%) cows than for Select-Synch or Hybrid-Synch (45.2 and 33.0%, respectively) cows, which did not differ (P > 0.05). For the Select-Synch and Hybrid-Synch cows that exhibited estrus during d 7 to 10 of the experiment and were artificially inseminated, conception rates were similar across treatments (50.5%). Pregnancy rates were greater (P < 0.01) for CO-Synch and Hybrid-Synch (31.0 and 35.5%, respectively) cows than for Select-Synch (20.8%) cows. A greater (P < 0.01) percentage of cycling cows became pregnant (34.5%) than noncycling cows (25.9%) across all treatments. The CO-Synch and Hybrid-Synch synchronization protocols resulted in greater pregnancy rates compared with the Select-Synch protocol in postpartum and lactating crossbred cows containing a percentage of Bos indicus breeding.     

Epidemiologic and economic analyses of an unusually long epizootic of trichomoniasis in a large California dairy herd

An epizootic of trichomoniasis in a large California dairy herd caused an estimated economic loss of $66,538 ($665/infected cow). Greatest losses were caused by infertility (about 50% of losses caused by excess days open). The disease continued in the herd, despite culling older bulls and replacing them with young uninfected bulls and despite institution of an artificial insemination (AI) breeding program for 2 high-production strings. The AI breeder's practice of checking for estrus by vaginal examination was implicated in the spread of the disease. Of 5 cows that became infected before or at conception, 1 had the infection throughout the gestation period and into the next lactation. The prevalence of trichomoniasis in the herd (estimated on the basis of culture results) was 10.67%. The culture method had a calculated sensitivity of only 58.7%. Of 940 cows in the herd, 132 aborted during the epizootic (8 aborted twice); 45 abortions would have been expected in a dairy herd of this size in the absence of trichomoniasis. In high-density mass-bred herds, conditions and/or management practices may be conducive for trichomoniasis transmission, and generally recommended control programs should be adjusted on such dairies. In particular, dairy operators should not assume that culling older bulls and replacing them with young uninfected bulls and that institution of an AI program will be effective in limiting the spread of the disease. Moreover, a diagnostic test with improved sensitivity would greatly assist in the identification of infected cows.     

Review: Cost of Reproductive Diseases and Conditions in Cattle

Based on information from USDA National Animal Health Reporting System early State pilot studies and more recent national studies, the cost of reproductive diseases and conditions was estimated for beef and dairy cattle. We estimate the total yearly cost of female infertility, abortions/stillbirths, dystocia, retained placentas, and metritis/pyometra to be $441 to $502 million for beef producers and $473 to $484 million for dairy producers with an aggregate national total of approximately $1 billion annually. This loss is over six times more costly than that resulting from respiratory diseases. Three-fourths of the cost for reproductive diseases and conditions can be attributed to female infertility and dystocia and the failure to produce a healthy calf that will survive the first 24 h of life. Aggregate national costs are roughly evenly divided between beef and dairy; per cow costs are more than three times greater for dairy cows ($52.60) than for beef cows ($14.00). Approximately equal national costs are attained because there are more than three times more beef cows than dairy cows. One factor contributing to the greater cost for dairy cows is lost milk production associated with dystocia and retained placentas. Lost milk production accounts for one-third of the costs associated with reproductive diseases and conditions in dairy cattle. We conclude from this review and our resulting estimates that focusing on developing strategies to increase the probability of conception, minimize dystocia, and produce a healthy calf that survives beyond the first 24 h of birth must continue to receive high priority in both dairy and beef cattle management and research.