Effect of Dermatophiluscongolensis infection on reproductive performance of dairy cattle

The effect of $\text{Dermatophilus}$$\text{congolensis}$ on reproductive performance and milk production of dairy cattle was investigated using a prospective cohort study design. The following results were obtained: the calving to conception interval was 122 vs 104 days (P<0.05) for cows with lesions (cases) and those without lesions (non-cases), respectively; the 180-day pregnancy rate was 70.3% vs 84.3% (P<0.02) for cases and non-cases, respectively; the interval to first service was 69 days for cases and 64 days for non-cases (P<0.05) and the interval from first to second service was 32.7 days for cases and 49.4 days (P<0.01) for non-cases. The prevalence of cows with lesions was 33% ($\text{66}\text{200}$). Lesions were most commonly found on the skin covering the coccygeal and sacral vertebrae and the gluteal muscles. White skin had a greater prevalence of lesions than did black skin (P<0.05).     

Effect of monensin and suckling on the GnRH induced luteinizing hormone surge and the effect of monensin on the postpartum interval in Brangus cows

Twenty-seven fall calving Brangus cows were randomly allotted to one of four treatment groups: nonsuckled monensin (NSM), suckled monensin (SM), nonsuckled control (NSC), and suckled control (SC). Cows were group fed 1.82 kg/hd/day concentrate and Coastal bermuda grass hay $\text{ad}$$\text{libitum}$. Monensin cows received 200 mg monensin/hd/day in the concentrate. At 0800 hr on day 21 postcalving, the calves were separated from the cows. Suckled monensin and SC cows were allowed to suckle their calves for 30 min at 6-hr intervals. Nonsuckled monensin and NSC cows were not suckled. Calves were given free access to the cows after 1400 hr on day 22 postpartum. At 0800 hr on day 22 postpartum, a blood sample was collected. A 100 μg GnRH challenge was administered IM at 0801 hr. Blood samples were collected at 15-min intervals for 6 hr postinjection. Changes in body weight and body condition from day 21 postpartum to the day of first estrus were not different (P>0.10) by dietary treatment. Monensin cows consumed 10.7% less hay than did the control cows. Serum luteinizing hormone (LH) following GnRH was greater (P<0.005) in suckled than nonsuckled cows. Control cows released more (P<0.005) LH in response to GnRH than did the monensin cows. The postpartum interval (to first estrus) for the monensin cows (92.4±14.7 days) was shorter (P<0.025) than the controls (138.5±9.5 days). A greater proportion (P<0.005) of the monensin cows (8 of 14) exhibited estrus by 90 days postpartum compared to the control cows (0 of 13). Monensin and suckling appear to exert independent and agonistic influences on pituitary function in the postpartum beef cow.     

Diagnosis of trichomoniasis in pregnant cows by culture of cervical-vaginal mucus

The objective of this study was to evaluate the effectiveness of Cervical-Vaginal Mucus (CVM) cultures for isolating $\text{Trichomonas fetus}$ from pregnant cows. Cervical-vaginal mucus was cultured from sixty-eight cows averaging 98 days of gestation. $\text{Trichomonas fetus}$ was isolated from 7 of 36 cows in groups exposed to bulls found to be infected at the end of the breeding season. The remaining 32 cows which were bred to bulls found not to be infected at the end of the breeding season were negative. Seven of the cows serviced by infected bulls aborted. Three of these had been positive and 4 negative on culture. The incidence of abortion was determined by examination 81 days after the previous examination and CVM culture. During the same interval there were no abortions in the 32 cows served by non-infected bulls. Culture of CVM identified infected groups of cows which had a high risk for abortion.     

Effect of monensin on postpartum interval to first estrus and serum LH response to 0, 1, 2 or 4 mg estradiol-17β at 21 days postpartum

A 2×4 factorial design was used to evaluate the effects of monensin (0 vs 200 mg) and estradiol-17β (E2) dose (0, 1, 2 vs 4 mg) on postpartum interval (PPI) to first estrus and on serum LH release at 21 days postpartum. Forty-eight spring calving Brangus cows were randomly stratified by calving date and sex of calf into two feeding groups within 24 hr of calving. Each group received 2.7 kg/head/day of a milo:cottonseed meal (4:1) mixture containing either 0 or 200 mg monensin. Coastal bermuda grass hay and water were available $\text{ad}$$\text{libitum}$. During the period of E2 treatment and bi-hourly blood sampling, suckling was controlled at 6-hr intervals.Mean cow weight and body condition score within cell changed less than 23 kg and 0.5 points, respectively, from day 1 to day 21 postpartum and were unaffected by treatment (P>0.10). PPI was reduced (P<0.01) and proportion of cows exhibiting estrual behavior by 85 days postpartum was increased (P<0.05) by treatment with 200 mg monensin and unaffected by E2 dose. Monensin fed cows had a longer (P<0.05) interval to LH response (ILH) and to peak LH (ILHP) at the 4 mg E2 dose. Monensin had no effect (P>0.10) on LH variables at 0, 1 or 2 mg E2.     

Reproductive studies of Brahman cattle I. Behavioral effect of various dose levels of Estradiol-17β upon ovariectomized Brahman,Brahman × Hereford and Hereford cows

Six ovariectomized mature cows each of Brahman (B), Brahman × Hereford (BH) or Hereford (H) breeding were injected intramuscularly with Estradiol-17β (E). Dose levels of 1, 2, 4 and 8 mg E were given in 2 ml corn oil. Cows were allowed a 2 week recovery period between treatments. After injection the cows were placed with 18 epididymectomized bulls and observed constantly for 36 hours. B failed to accept the bulls at any E dose level. Proportions of BH accepting the bull were $\text{2}\text{6}$, $\text{6}\text{6}$, $\text{6}\text{6}$ and $\text{6}\text{6}$ and proportions of H accepting the bull were $\text{5}\text{6}$, $\text{6}\text{6}$, $\text{5}\text{6}$ and $\text{6}\text{6}$ at 1, 2, 4 and 8 mg E, respectively. BH were less responsive at 1 mg E than H (P<.10) and B were less responsive at any level (P<.005). The number of stances increased significantly with dose level (P<.005) and a breed × dose level interaction (P<.10) was found. The duration of standing estrus behavior was longer in H cows at 1 and 2 mg E than in BH (P<.05) but was identical at 4 and 8 mg E. Duration of estrus was shorter in B except at the 2 mg dose level. Breed (P<.005) and breed × dose level interactions (P<.05) were found. Response time (injection of E to stance event) did not differ between dosages of E within breed groups. However, response time was significantly longer in B (19.3 hrs, P<.05) versus the response time of either H (10.1 hrs) or BH (12.8 hrs). If homosexual stance behavior is accepted as estrus, B were less responsive at 1, 2, 4 and 8 mg E than were BH or H (P<.10).     

The present status of the role of the Parainfluenza-3 (PI-3) virus in fetal disease of cattle and sheep

The Bovine Parainfluenza-3 (PI-3) virus was isolated and identified from an aborted bovine fetus. The fetal isolate was characterized and found to be similar to the respiratory isolate. $\text{In}$$\text{utero}$ inoculations of bovine fetuses with the PI-3 fetal isolate established fetal pathogenicity, and fetal immune competency. Inoculation of pregnant immune heifers and ewes failed to demonstrate transplacental transmission of virus. Sera from 1500 cows were examined for the presence of PI-3 serum neutralizing (SN) antibody. All serum samples contained PI-3 SN antibody at the 1:2 dilution and greater. Since PI-3 seropositive animals resist transplacental transmission of virus, and since seronegative animals are rarely available, the Bovine Parainfluenza-3 virus is probably not a common cause of fetal disease and abortion in Wyoming.     

Effects of intrauterine infusion of gentamicin sulfate on bovine fertility

Gentamicin sulfate was administered by intrauterine infusion 10 minutes following first-service insemination at the rate of 200 mgs to dairy cows allotted at random to treatment and control groups to evaluate the effect on fertility. Pregnancy was determined by palpation of fetal membranes $\text{per rectum}$ 45–75 days after breeding.The first-service pregnancy rate was 43.8% in 233 treated cows and 51.7% in 232 control cows (P>0.1). The second-service pregnancy rate was 54.7% in 106 treated cows and 47.4% in 95 control cows (P>0.1). The pregnancy rate for both first and second services was 68.7% for 233 treated cows and 71.1% for 232 controls (P>0.1). Fertility was not enhanced by this treatment.     

Early postabortion recovery of Neospora-infected lactating dairy cows

This study was designed to assess the reproductive performance of Neospora caninum–infected dairy cows (Bos taurus) after abortion. The population examined was composed of 92 aborting cows subsequently subjected to at least one artificial insemination (AI) attempt. Of these animals, 68 were N. caninum seropositive and 24 were seronegative. Only animals producing at least 25 kg milk at the estrus after abortion were inseminated. Normal uterine involution was verified at first AI after abortion in cows showing estrous signs within 30 d of abortion. Of the 92 aborting cows, 73 (79.3%) became pregnant after abortion: 57 (83.8%) and 16 (66.7%) of the N. caninum seropositive and seronegative cows, respectively. The factors days of gestation and lactation number at abortion failed to differ between the two Neospora serostatus groups, based on Student's t-test or Kruskal-Wallis tests, respectively. The interval from abortion to first AI, the number of AIs necessary for an animal to become pregnant, and the interval from abortion to next pregnancy in cows becoming pregnant were lower for the N. caninum–seropositive than for the N. caninum–seronegative cows (P < 0.0001). Logistic regression analysis indicated no significant effects of herd, lactation number, days of gestation at abortion, and the interval from abortion to AI on the likelihood of pregnancy at first AI after abortion. Based on the odds ratio, Neospora-seropositive cows were 6.22 times more likely to become pregnant at first AI after abortion compared with their seronegative partners. Fifty-three of the Neospora-seropositive cows (78%) were inseminated within 30 d after abortion and 26 (49%) became pregnant, whereas only one seronegative cow (4.2%) was ready for insemination within this 30-d period and remained open after first AI. These results indicate that Neospora-infected cows suffering abortion can be inseminated with a likelihood of high fertility within the first month of abortion. We recommend checking that uterine involution is normal early after abortion in N. caninum–seropositive cows.     

Synchronization of estrus in cyclic beef heifers with the prostaglandin analog alfaprostol

Seventy-eight Hereford-Angus crossbred heifers were injected intramuscularly twice with 6 mg of alfaprostol^b in 6 ml of propylene glycol. On each representative day of a 20-day estrous cycle (estrus = Day 0), either three or four heifers received their first injection. The second injection was given 12 days after the first, regardless of the response to the first injection. Thirty-nine heifers were not treated. The first alfaprostol injection reduced serum progesterone to less than 1 ng/ml in all heifers injected after Day 4. A total of 79.5% ($\text{62}\text{78}$) of the heifers exhibited estrus by five days after the first injection. Average interval from injection to estrus was 63 hours. The second injection occurred on Days 6 through 16 for all but one heifer, with 75.6% ($\text{59}\text{78}$) falling on Days 8 through 11 of the estrous cycle. Estrus was detected in 93.6% ($\text{73}\text{78}$) of the heifers within five days after the second injection, with an average interval to estrus of 66 hours.Day of cycle at second injection did not affect the interval to estrus. Conception occurred in 79.4% ($\text{58}\text{73}$) of the heifers inseminated in the five days after the second injection. Occurrence of estrus and conception was no different in treated heifers after five days of the insemination period than in nontreated heifers after 21 days of the insemination period, where 94.9% ($\text{37}\text{39}$) were observed in estrus and 83.8% ($\text{31}\text{37}$) conceived. Overall percent conception for a 55-day insemination period was 89.7 ($\text{70}\text{78}$) for treated and 87.2 ($\text{34}\text{39}$) for nontreated heifers. Day of cycle at first or second injection did not affect conception after the second injection. Some signs of estrus were observed in 11 of the 16 heifers injected before Day 5.A second trial to determine if alfaprostol induced luteolysis early in the cycle was conducted. Twenty purebred Angus, Hereford, or Simmental heifers received either one or two injections of alfaprostol on either Day 1, 2, 3, or 4. Only five heifers showed any signs of estrus, and the three that were inseminated did not conceive. Subsequent cycle length indicated that luteolysis occurred in only one heifer.Data suggest that alfaprostol is an effective luteolytic agent in cyclic beef heifers after Day 4 and that two injections 12 days apart will effectively synchronize estrus in heifers when distributed throughout the cycle at the first injection without affecting conception rate.     

Uterine infections in the postpartum cow: II. Possible synergistic effect of Fusobacteriumnecrophorum and Corynebacteriumpyogenes

Clinical conditions, which were observed in primiparous Angus and Hereford heifers with postpartum uterine infections are reported. Forty-three of sixty-four cows (67%) had uterine infections. $\text{Corynebacterium}$$\text{pyogenes}$ and $\text{Fusobacterium}$$\text{necrophorum}$ were the most frequently isolated aerobe and anaerobe, respectively. Twelve of the sixty-four cows (18.8%) had infections that involved these species. Three of these twelve cows were infected only with $\text{C.}$$\text{pyogenes}$, two were infected only with $\text{F.}$$\text{necrophorum}$, and seven were infected with both organisms. All five of the cows which were infected with either $\text{C.}$$\text{pyogenes}$ or $\text{F.}$$\text{necrophorum}$ showed signs of estrus and four of the five cows conceived by 110 days postpartum. The single cow that did not conceive was infected with $\text{C.}$$\text{pyogenes}$. Three of the seven cows which were infected with both organisms showed signs of estrus and none of the seven cows conceived by 110 days postpartum. In addition, when only $\text{C.}$$\text{pyogenes}$ or $\text{F.}$$\text{necrophorum}$ was isolated from the uterus, cows had either mild or no clinical signs of infection. In contrast, the seven cows which were infected with both organisms had severe clinical signs of infection that included excessive vulvar discharge, uterine abscesses and pelvic adhesions. These observations suggested that a pathogenic synergism between $\text{C.}$$\text{pyogenes}$ and $\text{F.}$$\text{necrophorum}$ might have caused the increased severity of postpartum uterine infections, and the subsequent detrimental effect on return to estrus and conception.     

Induced abortion in cattle

Several procedures were used to abort cattle during the second and third trimesters of gestation. The treatment to abortion interval was better (P<0.05) when dexamethasone trimethyiacetate (DTMA) injections repeated at either 6 or 4 day intervals than when a single injection of DTMA was followed 6 days later by the administration of stilboestrol. The treatment to abortion interval was not significantly shorter when DTMA was repeated after 4 days rather than 5 days (0.10<P>0.05). Prostaglandin F_2α produced abortion 1 to 4 days following direct administration into the foetai fluids.Peripheral plasma progesterone concentration had a tendency to rise immediately following the second injection of DTMA given at a 6 day interval. This was followed by a decline. Two injections of DTMA given at 4 day intervals resuited in a decline in progesterone concentration. Abortion occurred when plasma progesterone concentrations were about 1 ng/ml in cows treated with DTMA. In cows treated with prostagiandin F_2α the plasma progesterone concentration fell rapidly within one day of administration to approximately 2 ng/ml, at which concentration abortion took place.     

The effect of PGF-2 alpha on reproductive performance of naturally bred dairy cows with or without pyometra

Five hundred thirty-four naturally bred Holstein dairy cows from two Colorado dairies were examined $\text{per}$$\text{rectum}$ between 21 and 36 days after calving. Alternate cows in each herd received either 25 mg PGF-2 alpha or no treatment at the time of initial examination. No differences were found in days open or pregnancy rates between groups (P>0.25).Days open in 23 cows with pyometra were 98.7 ± 9.4, and 77.0 ± 2.2 in 493 herdmates without pyometra. The large inequalities in numbers precluded valid statistical comparisons between these groups. No overall difference (P>0.25) in reproductive performance was found in cows with pyometra treated at the initial examination compared to those not treated until two to four weeks after the initial examination. Contributing to the lack of significance were a number of cows with pyometra that had spontaneous cures before treatment was considered. Untreated cows that recovered spontaneously had better (P<0.05) reproductive performance than herdmates that required later treatments to initiate uterine evacuation. No overall advantage in reproductive performance was obtained by the routine treatment of postpartum dairy cows with PGF-2 alpha but treatment of cows with pyometra should not be delayed.     

Studies on closure of the ductus arteriosus. XII. In utero effect of indomethacin and sodium salicylate in rats and rabbits

Administration of prostaglandin synthetase inhibitors to pregnant does and dams in late gestation was followed by $\text{in utero}$ contraction of the fetal ductus arteriosus when studied by the whole-body freezing method. In the rat this contraction was well established within 6 h and persisted up to 36 h following 15 mg/kg indomethacin p.o. No effect was observed in the 18 d rat fetus but fetuses at 20 d and 22 d of gestation responded significantly to indomethacin. Doses of indomethacin approaching clinical usage (2.5 mg/kg) also caused a positive response $\text{in utero}$. The rat was found to be sensitive also to sodium salicylate and in the rabbit both indomethacin and sodium salicylate were effective. Exposure $\text{in utero}$ to prostaglandin synthetase inhibitors with resulting contraction of the ductus may seriously disturb cardiac function in the fetus.     

Synchronized breeding in cattle using PGF2α and LHRH/FSHRH stimulatory analogs

Two studies were conducted to synchronize breeding in cattle using PGF₂α and LHRH/FSHRH analogs. In the first study, 60 mature lactating Angus cows were assigned at random to 4 treatment groups: saline and saline (SS); 30 mg PGF₂α tham salt + saline (PS); saline + 2 mg D-ala⁶-des-GlyNH₂¹⁰ LHRH/FSHRH ethylamide (D-ala⁶) (SA); 30 mg PGF₂α tham salt + 2 mg D-ala⁶ (PA). The first letter of the two-letter code for each group always indicates a dual injection at an 11-day interval. PGF₂α or saline was administered intramuscular (im) twice at an 11 day interval. D-ala⁶ or saline was administered 48 hr after PGF₂α treatment. In the SA group, the D-ala⁶ was administered at first signs of estrus, and cows were then artificially inseminated (AI) 24 hr later. All cows in the PS group were inseminated 72 hr after the second PGF₂α injection. In the SS group, cows were inseminated 24 hr after first signs of estrus. An additional 6 mature lactating Angus cows were added equally to the PS and PA groups to evaluate changes in serum LH. The percent calf crops was: SS = 40% (frsol|6/15); PS = 47% ($\text{7}\text{15}$); SA = 47% ($\text{7}\text{15}$); PA = 53% ($\text{8}\text{15}$). In the second study, 51 mature lactating Angus cows and 39 Holstein heifers were assigned at random to 3 treatment groups: saline + saline (SS); 33.4 mg PGF₂α tham salt + saline (PS); 33.4 mg PGF₂α tham salt + 1 mg D-leu⁶-des GlyNH₂¹⁰ LHRH/FSHRH ethylamide (D-leu⁶) (PL). PGF₂α tham salt or saline was administered im twice at an 11 day interval. D-leu⁶ or saline was administered 68 hr following the second PGF₂α treatment. Cows pretreated with PGF₂α were inseminated 80 hr after the second PGF₂α injection. In the SS group, cows were administered saline at the time of natural estrus and were artificially inseminated 12 hr later. Calving percent to the first AI was SS = 70% ($\text{21}\text{30}$); PS = 53% ($\text{16}\text{30}$) and PL = 40% ($\text{12}\text{30}$). An additional 10 mature lactating Angus cows were used to evaluate changes in serum LH. Five of the cows were assigned to the PS treatment and five to the PL treatment. Sequential blood samples were collected to monitor serum LH levels. Using the Chi-square test, there were no significant differences between calving percentages of the control and PGF₂α treated cows in either study. These results indicate that the PGF₂α treatments were successful in timed artificial insemination of cows without detection of estrus. The LHRH/FSHRH analogs did not improve the conception even though they appear to induce a pituitary release of LH simultaneously in all cows within 1 hr of treatment.     

The influence of ovulation number and ovarian dimensions on embryo production in superovulated cattle

Twenty-one cycling Angus heifers and five Holstein cows received a subcutaneous (SC) injection of 50 mg of progesterone (P) in oil for 14 consecutive days. On day 6 of (P) treatment, animals were injected intramuscularly (IM) with 6 mg of estradiol valerate, and on day 13, received an IM injection of 2,000 IU of Pregnant Mare Serum Gonadotropin. Three additional Angus heifers were used as non-hormone treated controls. Seventeen of 21 heifers and 4 of 5 cows (81%) exhibited estrus within 48 to 132 hr following P treatment. Two of the five animals in which estrus was not observed were palpated as pregnant and discarded from the study. Treatment animals showing estrus were randomly assigned either to Group I, animals bred by natural service, or Group II, animals artificially inseminated with two straws of frozen semen at 12-hr intervals for a total of four breedings. Twenty-one animals were slaughtered 2 to 6 days after the onset of estrus, and those animals in which estrus was not detected were slaughtered 10 days after the last P injection. Two of the 24 treated animals had no ovulations. A total of 397 ovulation points ($\text{397}\text{22}$) were counted for a mean ovulation rate of 18 ovulations per animal. One hundred and fifty-six ova were recovered ($\text{156}\text{397}$) for a collection rate of 39%. Group I animals had 44 of 66 (67%) of their ova fertilized while 23 of 71 (32%) of the ova in Group II were fertilized. Nineteen unfertilized eggs were collected from the three animals not observed in estrus. No differences in fertilization rates between the Group I and Group II animals were found. Mean ovarian width, length and weight in the treated animals was measured and found to be 3.5 ± 1.1 cm, 4.8 ± 1.4 cm, and 21.7 ± 21.2 gm, respectively. Ovarian width, length and weight were all positively correlated with the number of ovulations per ovary r=.74, r=.74, and r=.55, respectively. No significant correlation existed between ovarian width (r=.16), lenght (r=.21), or weight (r=.13) when compared to ova recovery rate. This result suggests that ovarian size or weight may not be the limiting factor involved in embryo recovery.     

An attempt to isolate Brucellaabortus from uterine flushings of brucellosis-reactor donor cattle

Two experiments were conducted to test for the recovery of brucella organisms from uterine flushings and harvested embryos of sero-positive embryo donor females. In Experiment I, 16 sero-positive cows were superovulated with FSH treatments and artificially inseminated at 12, 24 and 36 hours following the onset of estrus with brucella-free semen. At 48 hours after the onset of estrus, one half the potential donor females were administered an intrauterine inoculation of 3.3 to 4.6 × 10⁴$\text{Brucella}$$\text{abortus}$ (strain 2308) organisms while the remainder received a control inoculation. In Experiment II, the same 16 cows were similarly administered superovulatory treatments and inseminated following estrus. The uterine inoculation was increased to 1.5 to 2.5 × 10⁸ organisms administered 48 hours following estrus. Samples of recovered flushing medium and homogenized embryo residues were placed into a validated $\text{in}$$\text{vitro}$ culture system to detect the presence of brucella bacteria. Uterine flushings and embryos recovered from 31 females exhibiting estrus following FSH treatments were free from either field strain or the inoculated $\text{B.}$$\text{abortus}$ (strain 2308) contamination. The flushings obtained from a single female, which did not respond with estrus following FSH treatment but was inoculated at appointment, did contain $\text{B.}$$\text{abortus}$ which was identified as the inoculated strain 2308 and not field strain organisms. These results indicate that brucella contamination of flushing media and harvested embryos will not likely be incurred when collecting embryos from sero-positive donor females. These findings offer further encouragement for the use of embryo transplantation as a method to produce brucella-free offspring from infected cows.