Evaluation of horn bud wound healing following cautery disbudding of preweaned dairy calves treated with aluminum-based aerosol bandage

Pain management during and following disbudding procedures has been studied extensively, though few studies have evaluated wound healing following cautery disbudding in dairy calves. The purpose of this study was to observe wound healing following cautery disbudding with or without treatment using a topical aluminum-based aerosol bandage (ALU) in preweaned dairy calves. Dairy calves were disbudded within the first 3 wk of life using a standard cautery disbudding protocol. The ALU treatment was randomly allocated to the right or left horn bud within each animal. The outcomes measured were lesion score (LS) and wound diameter (WD). The LS was evaluated on a scale of 1 to 3, with LS = 1 representing normal healing without a scab or exudate, LS = 2 having the presence of a scab, and LS = 3 showing the presence of wound exudate. Lesion score and WD were evaluated on a weekly basis following dehorning for 3 wk. A total of 209 animals completed the study. No difference was observed in LS between groups during the first 2 wk postdisbudding, but the proportion of LS = 3 on wk 3 postdisbudding was greater for the control group when compared with ALU (17 vs. 8%, respectively). During wk 1 and 2 postdisbudding, the odds of having delayed healing, or a LS ≥2, were similar for both groups. However, the odds tended to be different at wk 3 postdisbudding with control disbudding sites being 1.42 times more likely to have delayed healing than ALU. In wk 3, WD was 1 mm smaller in the treatment group compared with the control, and treatment decreased diameter over time compared with controls. Overall, once abnormal wound healing was observed, the likelihood of having abnormal wound healing the following week was increased. However, treatment with ALU diminished this effect on delayed healing during the follow-up period. Based on these results, the use of ALU improved wound healing following cautery disbudding of preweaned dairy calves.

Herd Management Practices and Their Association with Bulk Tank Somatic Cell Count on United States Dairy Operations

The objective of this study was to evaluate associations between bulk tank somatic cell count (BTSCC) and herd management practices using data collected in the National Animal Health Monitoring System Dairy 2002 study. Twenty-six percent and 17.8% of 1,013 operations reported a BTSCC < 200,000 cells/mL and > 400,000 cells/mL, respectively. Univariate analysis identified associations between management variables and BTSCC. The use of mattresses, sand, and newspaper as bedding were all associated with a lower BTSCC. Primary lactating cow housing facility, outside maternity housing area, flooring type cows walk or stand on, and use of automatic take-offs were also associated with BTSCC. Multivariate associations between management variables and BTSCC were determined by backward elimination ordinal logistic regression. The odds of an operation from the West, Midwest, and Northeast having a high BTSCC were lower than those from the Southeast. The odds of a higher BTSCC were 2 times greater for operations with a rolling herd average milk production < 9,090 kg/cow per year compared with those with > or = 9,090 kg/cow per year. Operations using composted manure were 2.9 times more likely to have a higher BTSCC than those not using composted manure. Finally, operations that reported not using a coliform mastitis vaccine were 1.7 times more likely to have a higher BTSCC than those using one. Future studies of the association between management practices and BTSCC should include an evaluation of the quality of management practice application and herd prevalence of contagious mastitis pathogens. Significant variables identified in this study dealt with housing, use of composted manure for bedding, and coliform mastitis vaccine use, suggesting the effect of environmental mastitis pathogens may be more influential on BTSCC than previously thought.

Short communication: Efficacy of parenteral ceftiofur for treatment of systemically mild clinical mastitis in dairy cattle

The objective of this study was to evaluate the effect of intramuscular (i.m.) ceftiofur (2.2 mg/kg) on important outcomes of systemically mild clinical mastitis episodes in lactating dairy cattle. Cows with clinical mastitis were randomly assigned to a treatment group: pirlimycin intramammary (i.m.m.) (n = 35), pirlimycin i.m.m. and ceftiofur i.m.m. (n = 36), cephapirin i.m.m. (n = 40), cephapirin i.m. and ceftiofur i.m. (n = 33). Sixty-nine, 22, and 9% of initial cultures were gram-negative, gram-positive, and mixed, respectively. Logistic regression analysis showed no significant associations between treatment groups and loss of quarter, recurrence, or culling. Mixed infections, positive milk culture at 7 d after leaving hospital pen, decreased rumen motility, and absence of udder firmness were associated with increased odds of mastitis recurrence. The results suggest that i.m. ceftiofur treatment has no beneficial effects on the outcome of systemically mild clinical mastitis.

Bacteremia associated with naturally occuring acute coliform mastitis in dairy cows

OBJECTIVE

To determine the incidence of bacteremia in dairy cows with naturally occurring acute coliform mastitis (ACM) with a wide range of disease severity.

DESIGN

Cohort study.

ANIMALS

144 dairy cows with ACM from 6 herds.

PROCEDURE

Cows were examined at time of identification of ACM (time 0) and classified as having mild, moderate, or severe mastitis on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. Cows were reexamined at 24 or 48 hours. Bacteriologic culturing of milk and blood (30 ml), CBC, and serum biochemical analysis were performed at each time point. Appropriate samples were obtained at a single point from herdmates without mastitis (controls) that were closely matched for lactation number and days since parturition. Blood culture results were compared among severity groups and controls by use of chi2 tests, as was outcome of an ACM episode for cows grouped by blood bacterial isolates.

RESULTS

Bacteria were isolated from 52 blood samples from 46 of 144 (32%) cows with ACM, which was significantly more than control cows (11/156; 7.1%). Group-1 isolates (Escherichia coli, Pasteurella multocida, Mannheimia haemolytica, Klebsiella pneumoniae, Enterobacter agglomerans, and Salmonella enterica serotype Typhimurium) were identified in 20 of 144 (14%) cows with ACM and 0 of 156 control cows. Group-1 isolates were identified in 4.3, 9.1, and 42% of cows classified as having mild, moderate, and severe ACM, respectively. Escherichia coli and K pneumoniae milk and blood isolates obtained from the same cow were of the same genotype. Bacillus spp were identified in 21 of 144 (15%) cows with ACM, which was significantly more than control cows (3/156; 1.9%). Thirty-five percent of cows with a group-1 isolate died during the mastitis episode.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that bacteremia develops in a substantial proportion of cows with ACM. Classification of severity of disease is important for establishment of effective treatment protocols; parenteral antimicrobial treatment may be indicated in cows with ACM.

Environmental gram-positive mastitis treatment: in vitro sensitivity and bacteriologic cure

A clinical trial was conducted in a large dairy herd to determine the efficacy of intramammary pirlimycin hydrochloride administration during lactation for bacteriologic clearance of gram-positive environmental clinical and subclinical mastitis infections. Quarters infected with environmental streptococci that received pirlimycin therapy (13/28) were 1.8 times more likely to resolve infection than untreated quarters (5/14). The small numbers of quarters infected with coagulase-negative staphylococci resulted in inadequate power to assess treatment differences in cure rate. Although the association was not statistically significant, quarters from cows with sensitive environmental streptococci isolates from composite samples (8/13) resolved infection with treatment at approximately twice the rate of treated quarters with resistant isolates (3/10).

Use of systemic disease signs to assess disease severity in dairy cows with acute coliform mastitis

OBJECTIVE

To evaluate the use of systemic disease signs for classifying severity of acute coliform mastitis in dairy cows.

DESIGN

Prospective cohort study.

ANIMALS

144 dairy cows.

PROCEDURE

Cows were examined at the time of initial identification of disease (time 0) and classified as having mild, moderate, or severe disease on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. A CBC and serum biochemical analyses were performed, and milk samples were submitted for bacterial culture at time 0 and 48 hours later.

RESULTS

69 cows were classified as having mild disease, 44 as having moderate disease, and 31 as having severe disease. Median WBC and neutrophil counts were significantly lower in cows with moderate or severe disease at time 0 than in cows with mild disease. Band neutrophil count was significantly higher at 48 hours and serum calcium concentration was significantly lower at time 0 and at 48 hours in cows with severe or moderate disease, compared with cows with mild disease. Twenty-eight, 51, and 77% of cows with mild, moderate, and severe disease, respectively, had > 100,000 colony-forming units/ml of milk at time 0. The odds that a cow with severe disease would die or be culled were 3.6 times the odds for a cow with moderate disease and 11.2 times the odds for a cow with mild disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that a classification scheme based on readily observable systemic disease signs can be used to classify disease severity in cows with acute coliform mastitis.

Malignant catarrhal fever: polymerase chain reaction survey for ovine herpesvirus 2 and other persistent herpesvirus and retrovirus infections of dairy cattle and bison

Using a polymerase chain reaction (PCR) test for sequences of ovine herpesvirus 2 (OHV2), this virus was shown to be significantly associated with sheep-associated malignant catarrhal fever (SA-MCF) in terminal cases of disease in 34 cattle and 53 bison. Ovine herpesvirus 2 was not detected in cattle (38) and bison (10) that succumbed to other diseases. Other persistent herpesviruses, retroviruses, and pestivirus, some of which have been previously isolated from cases of SA-MCF, were not associated with the disease. These included bovine herpesvirus 4 (BHV4), bovine lymphotrophic herpesvirus (BLHV), bovine syncytial virus (BSV, also known as bovine spumavirus), bovine immunodeficiency virus (BIV), and bovine viral diarrhea virus (BVDV). A PCR survey for OHV2 in DNA from individual cow's peripheral blood lymphocytes in 4 dairies showed that the 1 dairy that was in close contact to sheep had a prevalence of OHV2 of 21.3%, whereas the 3 other dairies had no OHV2. Prevalence of the other herpesviruses and retroviruses in the dairy cows was variable, ranging from 2% to 51% for BHV4, 52% to 78.7% for BLHV, and 10% to 34% for BSV. Bovine lymphotrophic herpesvirus and BSV were also found in a few (1-4 of 21 tested) cases of terminal SA-MCF, but BIV and BVDV were not found in either the dairy cows sampled, or in the cases of SA-MCE No significant correlation was found between the presence of any 2 viruses (OHV2, BHV4, BLHV, BSV) in the dairy cows or terminal cases of SA-MCE

Detection and identification of Mycoplasma from bovine mastitis infections using a nested polymerase chain reaction

A polymerase chain reaction (PCR) test was compared with culture for the detection and diagnosis of bovine Mycoplasma intramammary infection. The PCR test was applied to 24-hour Mycoplasma enrichment cultures of milk from cows with suspected mastitis and from bulk tank milk. In comparison to culture, the sensitivity and specificity of the PCR method were 96.2% and 99.1% for individual cow milk and 100% and 99.8% for the bulk tank milk, respectively. However, in discrepant cases where PCR was positive and culture was negative, the PCR test was correct; subsequent PCR tests and culturing of the individual cow's milk yielded positive results. The PCR test simultaneously detected and differentiated among 11 bovine Mycoplasma species.

Treatment of dairy cows at parturition with prostaglandin F2 alpha or oxytocin for prevention of retained fetal membranes

OBJECTIVE

To evaluate the effects of treatment at parturition with dinoprost tromethamine, fenprostalene, or oxytocin on postpartum disease and reproductive performance during the subsequent breeding season in dairy cows.

DESIGN

Prospective study.

ANIMALS

1,400 Holstein cows from 5 commercial dairies.

PROCEDURE

Cows were assigned within 2 hours after calving to serve as untreated control cows or to be treated with 1 mg of fenprostalene, SC; 25 mg of dinoprost tromethamine, IM; or 20 IU of oxytocin, IM. Cows were confined to treatment pens and monitored daily until fetal membranes were expelled. Cows with retained fetal membranes (RFM) were treated according to existing treatment protocols for the dairy, with the provision that intrauterine infusions were not allowed. All other disease conditions were recorded, and appropriate treatment was administered. Postpartum reproductive examinations were performed 28 to 56 days after parturition Breeding records were maintained for all cows until pregnancy was confirmed or the cow was removed from the herd.

RESULTS

Fetal membranes were retained in 12.1% of all cows, and this outcome was unaffected by treatment. Compared with cows without RFM, cows with RFM had longer intervals to first insemination (76.4 vs 82.0 days), reduced first insemination conception rates (46.8 vs 28.0%), and increased number of days not pregnant (103.2 vs 127.4 days). Farm, as a variable, significantly affected development of RFM and postpartum disease conditions as well as reproductive performance during the subsequent breeding season. Fetal membranes were retained in 12.4, 15.2, 8.7, 6.3, and 16.9% of cows on farms 1, 2, 3, 4, and 5, respectively. Mean days to first insemination varied from 64.5 days (farm 3) to 91.5 days (farm 1). Mean number of days not pregnant varied from 94.8 days (farm 3) to 15.9 days (farm 4).

CLINICAL IMPLICATIONS

Administration of prostaglandins or oxytocin at the time of calving does not reduce the incidence of RFM or improve reproductive performance. Farm management practices have the greatest impact on dairy cow performance.

Oxytetracycline residues in milk after intrauterine treatment of cows with retained fetal membranes

OBJECTIVE

To establish the maximum concentration and duration of oxytetracycline residues in milk from cows with retained fetal membranes given the antimicrobial via intrauterine infusion, and to investigate whether the number of infusions or the presence of fever (> 39.7 C) affected the duration of residues.

DESIGN

Prospective study.

ANIMALS

54 Holstein cows with retained fetal membranes on a single 1,400-cow commercial dairy.

PROCEDURE

Cows were treated once a day with 5 g of oxytetracycline (50 ml of 100 mg/ml solution in a povidone base) by intrauterine infusion for at least 2 days, or until the membranes were expelled. Cows that became febrile (rectal temperature > or = 39.7 C) were also given 20,000 IU of procaine penicillin G/kg of body weight, i.m., for 2 to 4 days. Milk samples were collected at 24-hour intervals during treatment. and at 12-hour intervals after the last treatment. All samples were frozen and submitted every 2 weeks for high performance liquid chromatography analysis for oxytetracycline.

RESULTS

Oxytetracycline was detected in milk of all cows during treatment, at a maximum concentration ranging from 47.2 to 1,804.6 micrograms/kg (mean, 316.9 micrograms/kg). Duration of oxytetracycline residues after the last infusion ranged from 0 to 144 hours (mean, 52.3 hours). Neither the number of infusions received, nor development of rectal temperature > 39.7 C, affected the maximum concentration or the duration of oxytetracycline residues in milk.

CLINICAL IMPLICATIONS

Milk obtained from cows that had been treated for retained fetal membranes by intrauterine infusion of oxytetracycline should be discarded to avoid illegal residues.

Naturally occurring acute coliform mastitis in Holstein cattle

Physical examination and clinicopathologic findings from 44 adult Holstein cows with naturally occurring coliform mastitis were studied. The cattle were grouped for comparison by stage of lactation and survival. Cattle within the first 4 weeks of lactation maintained higher median mature neutrophil counts (1,200 versus 300/microL) in peripheral blood than cattle later in lactation. Nonsurviving cows had higher median creatinine concentration (2.5 versus 1.6 mg/dL) and anion gap (25 versus 20 mEq/L), and lower serum protein (7.1 versus 7.6 gm/dL) and total CO2 (19.8 versus 25 mEq/L) concentrations than surviving cows (P < .05). These findings indicate that cattle with uremia and metabolic acidosis are less likely to survive the infection. Bacteriologic blood cultures were performed on 34 of the 44 cows studied. Escherichia coli was isolated from the blood in 11 (32%) cows. Clinical presentation and clinicopathologic data were compared in bacteremic versus nonbacteremic cows to evaluate these data as predictors of bacteremia. Bacteremic cows were sick longer prior to admission (2 versus 1 days), maintained higher median counts of total nucleated cells (6.6 versus 2.4 x 10(3) cells/microL), myelocytes (0.2 versus 0 x 10(3) cells/microL), metamyelocytes (0.5 versus 0.02 x 10(3) cells/microL), band neutrophils (0.7 versus 0.1 x 10(3) cells/microL), and lymphocytes (2.1 versus 1.4 x 10(3) cells/microL) than nonbacteremic cows, and had higher plasma fibrinogen concentration (600 versus 500 mg/dL) (P < .05). There were no differences between the physical or serum biochemical measurements. Four of 11 bacteremic cows and 5 of 23 nonbacteremic cows died or were euthanized (P > .05). The high prevalence of bacteremia seen in cows with coliform mastitis has not been reported previously, and may have been due to the duration of disease, severity of signs, or culture technique. These findings suggest that systemic antibiotic therapy may be beneficial in some severe cases of coliform mastitis.

Evaluation of the use of intrauterine infusions of oxytetracycline, subcutaneous injections of fenprostalene, or a combination of both, for the treatment of retained fetal membranes in dairy cows

Dairy cows (n = 207) that had retained fetal membranes for more than 8 hours after parturition were randomly assigned to 1 of 4 treatment groups (group 1, daily intrauterine infusion of oxytetracycline; group 2, daily intrauterine infusion of oxytetracycline and a single SC injection of fenprostalene; group 3, a single SC injection of fenprostalene; and group 4, untreated controls). Cows were monitored daily. Subsequent disease conditions were recorded, and appropriate treatments were initiated. Interval from parturition to expulsion of fetal membranes was unaffected by treatment regimen. The frequency of cows with high rectal temperatures (> or = 39.5 C) was significantly (P < 0.05) less in cows treated with oxytetracycline infusions; however, the frequency of displaced abomasum, ketosis, and mastitis was unaffected by treatment method. Treatment method appeared to influence the development of postpartum uterine pathologic conditions. Treatment with oxytetracycline and fenprostalene (group 2) increased (P < 0.05) the frequency of pyometra. Treatment with fenprostalene (groups 2 and 3) decreased the number of cows with a palpable uterine lumen detectable during per rectal palpation at 28 to 42 days after parturition. Reproductive efficiency, as determined on the basis of the interval from parturition to conception, was unaffected by treatment protocol.

Efficacy of a Propionibacterium acnes immunostimulant for treatment of chronic Staphylococcus aureus mastitis

This study determined the efficacy of treatment of chronic Staphylococcus aureus IMI of lactating dairy cows with a biological response modifier consisting of a killed preparation of Propionibacterium acnes. Fifty-one lactating dairy cows with chronic S. aureus IMI on two commercial dairies were enrolled in a controlled, randomized field trial. Twenty-four cows received 1 ml of the immunostimulant twice weekly for 4 wk, and the remainder of the cows served as untreated controls. Quarter milk samples were collected for SCC from all cows at 3 and 6 wk after initiation of treatment and for culture at 6 wk after initiation of treatment. If samples were negative for S. aureus at 6 wk, cows were sampled again for culture 1 wk later for 2 successive d before being considered cured. For the cows treated with immunostimulant, 16.7% (36.7% of infected quarters) were cured of S. aureus IMI; for the untreated group, 11.1% of cows (32.2% of quarters) were cured. The difference was not statistically significant. Immunostimulant treatment had no effect on quarter SCC in infected quarters overall, but, in those quarters that were cured of S. aureus infection, quarter SCC of treated cows tended to be lower than SCC of control cows.

Efficacy of dry cow therapy and a Propionibacterium acnes product in herds with low somatic cell count

Dry cow therapy and a Propionibaterium acnes product were evaluated in four commercial herds with low SCC. Cows were randomly assigned within herds to treatment groups of approximately 90 cows receiving dry cow therapy, P. acnes, dry cow therapy plus P. acnes, or no treatment in a factorial arrangement. Each lactating quarter of cows that received dry cow therapy was infused via the teat duct with 300 mg of cephaprin at drying off. Cows that received P. acnes were infused intravenously with .4 mg of killed P. acnes at drying off, 7 to 10 d prepartum, and within 7 d after calving. A second prepartum injection of P. acnes immunostimulator was administered to cows that did not calve within 10 d after the first prepartum injection. Dry cow therapy enhanced bacteriological cures of IMI by Staphylococcus aureus and Corynebacterium bovis at drying off. Dry cow therapy reduced incidence of new IMI by environmental streptococci and C. bovis that originated during the dry period. Cows treated with P. acnes alone had a greater incidence of new IMI by Gram-negative bacilli originating during the dry period than did cows in the other treatment groups. Incidence of clinical mastitis at calving was greater for cows receiving no treatment than for cows receiving dry cow therapy, P. acnes, or dry cow therapy plus P. acnes.

Use of augmented cultural techniques in the diagnosis of the bacterial cause of clinical bovine mastitis

Preculture incubation, preculture freezing, and increased plate inoculation volumes were tested in an attempt to increase the recovery rate of pathogens in milk from cases of clinical bovine mastitis. Culture of milk from 291 cases of clinical bovine mastitis was performed using standard milk culture techniques (.01 ml of fresh milk streaked on trypticase soy agar plates with 5% sheep blood and .1% esculin). The sensitivity of this method was compared with that of cultures performed using augmented techniques: 4 and 18 h of preculture incubation; preculture freezing of samples overnight at -20 degrees C; and increasing the plate inoculation volume to .05 and .1 ml for fresh, incubated, and frozen samples. Preculture incubation and larger plate inoculation volumes significantly increased the recovery rate of bacterial pathogens over the standard culture method. The greatest improvement in sensitivity without a concomitant increase in contamination was achieved when samples were incubated for 4 h and plates were inoculated with .1 ml of the sample. Recovery was enhanced significantly by this method for several organisms, including environmental streptococci and coliform bacteria. Freezing milk before culture yielded a significantly higher positive culture rate overall, but freezing did not affect the positive culture rate of any individual bacterial species.

Evaluation of methods for the diagnosis of Streptococcus agalactiae intramammary infections in dairy cattle

The sensitivity, specificity, and positive and negative predictive values were compared for six methods of collecting or culturing milk samples for the diagnosis of chronic Streptococcus agalactiae intramammary infection. Cows in four dairy herds were cultured three times in 2 wk to determine infection status. At the second sample period, individual quarter and composite milk samples were taken before and immediately after milking, and two volumes of milk from the composite samples were streaked on culture plates. The sensitivity, specificity, and predictive values for these cultures ranged between 95 and 100% for all diagnostic methods, and no significant differences were found between methods. The results indicate that when either quarter or composite samples are collected before or immediately after milking, 95 to 100% of S. agalactiae culture-positive cows will be infected with S. agalactiae in herds with a prevalence of S. agalactiae between 35 and 55%. A similar proportion of culture-negative cows will be uninfected.

Performance studies of an enzyme-linked immunosorbent assay for detecting Staphylococcus aureus antibody in bovine milk

An enzyme-linked immunosorbent assay (ELISA) for detecting Staphylococcus aureus antibody in bovine milk samples was examined for repeatability. A set of 51 bovine milk samples from 4 universities with confirmed culture results was assembled, and a panel of 30 milk samples was randomly selected. When the selected panel was tested at the collection laboratory, there was 97% agreement between the ELISA and the culture test. The panel was tested with the ELISA by the 4 university laboratories. Results were scored by both visual and optical density reader methods. When compared to reference ELISA results, the university laboratory ELISA results showed an agreement of 99.8% for negative samples, 98% for positive samples, and 99% for all samples. Additional studies on 19 milk samples that cultured positive for bacteria other than S. aureus showed 100% specificity. Overall comparison of ELISA and culture results showed high agreement between the 2 techniques. Disagreement appeared to result from explainable differences in antibody and bacterial levels and not from errors in either of the 2 techniques.

Effect of milk sample delivery methods and arrival conditions on bacterial contamination rates

A cross sectional study was performed of factors believed to contribute to the contamination of bovine milk sample cultures submitted to the Ithaca Regional Laboratory of the Quality Milk Promotion Services/New York State Mastitis Control. Of 871 samples entered in the study, 137 (15.7%) were contaminated. There were interactions between the sample source (veterinarian vs dairyman), delivery method, and time between sample collection and arrival at the laboratory. If only those samples collected and hand delivered by the dairyman within 1 day of collection were compared to a like subset of samples collected and hand delivered by veterinarians, no statistically significant differences in milk sample contamination rate (MSCR) were found. Samples were delivered to the laboratory by hand, US Postal Service, United Parcel Service, via the New York State College of Veterinary Medicine Diagnostic Laboratory, or Northeast Dairy Herd Improvement Association Courier. The MSCR was only 7.6% for hand delivered samples, while 26% of Postal Service samples were contaminated. These rates differed significantly from other delivery methods (P less than 0.0001). The USPS samples arrived a longer time after sampling than did samples sent by other routes, and time had a significant effect on MSCR (0 to 1 day, 8.9%; greater than 1 day, 25.9%; P less than 0.01). Samples packaged with ice packs sent by routes other than the Postal Service had a lower MSCR than those not packaged with ice packs, but ice packs did not reduce the MSCR for samples sent by the Postal Service.(ABSTRACT TRUNCATED AT 250 WORDS)

An evaluation of simultaneous GnRH and cloprostenol treatment of dairy cattle with cystic ovaries

In a randomized double-blind clinical trial, 75 cows with ovarian cysts were treated with the synthetic gonadotropin releasing hormone, gonadorelin acetate (GnRH). Forty-two of these cows were simultaneously treated with cloprostenol (CP), and the remaining 33 cows received sterile saline. Milk progesterone (P(4)) was measured at treatment and two days later. Clinical response 30 days after treatment was determined by palpation per rectum, and estrus and breeding dates were recorded up to 90 days after treatment. Cows were examined for pregnancy by palpation per rectum 40 days or more after breeding. Milk progesterone levels two days after treatment were significantly lower and the 30-day clinical response rate was significantly higher in the GnRH + CP group than in the GnRH group. Intervals to first estrus and to conception, proportion in heat by day 21 after treatment, and pregnancy rate by 90 days did not differ significantly between the groups. The same relationships held in a subset of cows with P(4)>/=1 ng/mL at treatment. Fewer cows in the GnRH + CP group became pregnant by day 90 after treatment, but this difference was not significant. These results suggest that simultaneous GnRH and cloprostenol treatment of all cows with cystic ovaries cannot be recommended at this time.

Effect of gonadotropin-releasing hormone on clinical response and fertility in cows with cystic ovaries, as related to milk progesterone concentration and days after parturition

We gave gonadotropin-releasing hormone (GnRH) or an analog of GnRH to 264 lactating cows with cystic ovaries. The effects of milk progesterone concentration (MPC) and days after parturition (DAP) at diagnosis on clinical response 30 days after treatment and on subsequent fertility were examined. Palpation per rectum revealed ovarian cysts in 264 cows; 118 had true follicular cysts (MPC less than 1 ng/ml). Clinicians with more than 3 years of experience reported significantly more true cysts than did less experienced clinicians. Clinical response 30 days after treatment did not differ in 3 groups of cows (divided on the basis of MPC at treatment), but fewer cows with MPC less than 1 ng/ml were bred or conceived than were cows with MPC greater than or equal to 33 ng/ml. Days after parturition at diagnosis did not affect 30-day clinical response rate, but cows treated less than 35 DAP had significantly more days to first estrus and to conception than did cows treated greater than 90 DAP. Significantly more cows treated less than 35 DAP had MPC less than 1 ng/ml at treatment.

Bar suture (toggle pin) vs open surgical abomasopexy for treatment of left displaced abomasum in dairy cattle

Fifty-nine dairy cows with left displacement of the abomasum were randomly assigned to receive 1 of 2 treatments. Twenty-eight were treated by right paramedian abomasopexy via laparotomy, and 31 were treated by percutaneous fixation of the abomasum, using the bar suture or toggle pin technique. Comparisons of the 2 groups, at 4 follow-up examinations, yielded no significant differences in return to normal milk production, return to normal feed intake, mortality, culling rate, tissue reaction at the surgical site, or redisplacement up to 60 days into the subsequent lactation.

A randomized clinical trial of the effect of the time of administration of cloprostenol on detention of estrus in dairy cattle

We performed a clinical trial to study whether cows with palpable corpora lutea treated with cloprostenol by the farmer on the morning following examination (median time 0630 hours) were seen in heat and conceived more frequently than cows treated by the veterinarian immediately following the reproductive examination (median time 1210 hours).There were no significant differences between the two groups in the proportions of cows seen in estrus or fertility at the induced estrus.The proportions of animals that had the time of onset of estrus recorded and were seen in estrus during working hours (0800-1600 hours) were also not significantly different between the veterinary-treated and farmer-treated groups.Under the conditions of this study, there was no reason to prefer prescribing early morning administration of cloprostenol by farmers over immediate administration of the drug by the clinician.

The relationships among palpator experience, milk progesterone concentration and estrus and fertility in cows with palpable corpora lutea treated with cloprostenol

Two hundred and fifty-one cows fresh at least 37 days with normal reproductive tracts and palpable ovarian structures which clinicians believed to be corpora lutea and which were presumed to be producing progesterone were treated with 500 micrograms of cloprostenol. The cows were stratified into three groups based on milk progesterone concentrations in whole milk samples taken at the time of examination. The low group had milk progesterone concentrations less than or equal to 1 ng/ml, the intermediate group had milk progesterone concentrations between 1 and 3 ng/ml, and the high group had milk progesterone concentrations greater than or equal to 3 ng/ml. The proportion of cows in each group inseminated within 5 days of treatment and the fertility at that breeding were compared. There were no significant differences among the groups with respect to the proportion of cows that came into estrus within 5 days. However, the conception rate of the high group (54%) was significantly greater than that of the intermediate group (26%). To study the relationship between practitioner experience and diagnostic accuracy the proportion of cows with low, intermediate and high concentrations of progesterone selected by clinicians with more than 3 years experience was compared to that for clinicians with 3 years of experience or less. Less experienced clinicians were significantly more likely to make a false positive diagnosis of functional luteal tissue in cows with palpable ovarian structures than were more experienced clinicians.

Immune-mediated hemolytic anemia induced by penicillin in horses

Three horses developed severe, immune-mediated hemolytic anemia after treatment with penicillin. The horses had positive direct antiglobulin (Coombs) tests and high titers of IgG antibody that agglutinated penicillin-coated equine red cells. Two of the horses were tested for antibodies to autologous red cell antigens; autoantibodies were not present. Titers of antipenicillin antibody decreased after penicillin was discontinued but IgG antibody was detectable months after recovery. One of the horses was challenged with penicillin; antibody titer increased slightly, but anemia did not develop. Antipenicillin antibody of the IgM class was present in low titer in 23 (77%) of 30 non-anemic horses tested. Apparently, the horse is similar to man in that penicillin-induced anemia is rare but the percentage of individuals with antipenicillin antibody is high.

A randomized double blind clinical trial of two GnRH analogs for the treatment of cystic ovaries in dairy cows

A randomized double blind clinical trial was conducted to compare the efficacy of the gonadotrophin-releasing hormone, buserelin, to that of the hormone gonadorelin for the treatment of bovine ovarian cysts. Two hundred and sixty five cows with a clinical diagnosis of follicular cysts were included in the study. At 30 days post treatment 85% of the gonadorelin and 89% of the buserelin treatment groups no longer had a palpable ovarian cyst. No significant differences were found between treatment groups in the number of cows bred by 90 days post treatment, conception rate by 90 days post treatment, services per conception, milk progesterone at 30 days post treatment, days post treatment to first heat, and days post treatment to conception.

Physical Aspects of GR-S and Alfin Polymer Modifications

It seems that the possibilities of this development, both as a lead to improved rubbers and as a spur to the explanation of rubber behavior, are exceptionally stimulating. Far from being a completed work, this is more likely to be the first and exciting chapter of a series yet to be unfolded. It is a distinct possibility that useful improvements to natural rubber, as well as to synthetic, may result from further investigation of the field. It is perhaps unnecessary to caution that the quantitative relationships developed are not sacrosanct and may be altered by more extensive data. The importance of the results, however, is not entirely dependent on their numerical values.

Properties of Some Synthetic Rubbers

X-RAY STRUCTURE OF SYNTHETIC RUBBER In presenting a series of x-ray diagrams of various types of synthetic rubber in comparison with natural rubber, in both the stretched and the unstretched condition, it is our purpose to bring out the fact that the molecular structure of synthetic rubbers is entirely different from that of natural rubber. It is proposed also to review briefly the theories which have been advanced, based on the x-ray analysis of rubber, to account for the elasticity of natural rubber, and to advance the possible reason for the difference shown by the x-ray diagrams of synthetic rubber. At the present time, from the most general point of view, the molecular structure of a rubberlike material is envisaged as a sort of brush-heap structure of entangled long chain molecules. x-Ray diffraction patterns show that, for some rubberlike materials, notable regularities of structure sometimes occur in the tangle of long-chain molecules. It is now realized that these regularities are not essential for rubberlike behavior. Nevertheless their observation and study is important because they afford a unique opportunity for studying the molecular structure of the chains and the molecular rearrangements which occur with the application of stress.

An X-Ray Study of Rubber Hydrochloride

The x-ray diagram of rubber hydrochloride is a worthy addition to those of other natural high polymers and derivatives, and its study is a fruitful field for investigating the internal structure of such materials. Various peculiarities have been pointed out which have raised a question as to whether the properties of rubber hydrochloride can be explained on the basis of a chemical structure consisting of long, chlorinated, paraffin chains. These disturbing facts are (1) the effect on the x-ray diagram of the first addition of hydrogen chloride; (2) the failure to secure the theoretical chlorine content; (3) the possibility of vulcanization; (4) the amorphous diagram of balata hydrochloride, and (5) the shortening of the chains compared to normal paraffin chains. A partial departure from the strict formula may, in turn, lead to a colloidal structure which may be essential for such properties as the elasticity shown at higher temperatures and the ability to rack. The interpretation of the x-ray diagram seems to be possible on the basis of such long chains if some deformation from the zig-zag form is permitted to shorten them about 10%.

Laboratory Rubber Testing. Its Relation to Service

The rubber technologist of today is situated in one of the most competitive and rapidly changing industries. He is faced with the necessity of producing an important structural material of varied forms and compositions which must constantly be modified to meet new requirements of economy and service. He must be prepared to furnish, upon demand, rubber in new forms and colors, which will serve successfully in increasingly exacting conditions of temperature, flexing, abrasion, and more often than not in conjunction with a totally dissimilar material. To anticipate these demands he must engage in a ceaseless search for new and more effective materials, both in his own research laboratory and amid the countless new natural and synthetic materials which appear on the market. The time has passed when long periods of preparation can be utilized for the development of new compounds and products. The pressure of modern industrial development constantly brings about new conditions which must be met when they arise. The success with which the technologist fulfils these obligations depends in large measure upon his ability to predict the behavior of his materials under the conditions of service. When, as is often the case, his knowledge of both materials and service conditions is limited, results frequently fall far short of expectations.

Stearic and Oleic Acids as Rubber-Compounding Ingredients

IT IS proposed in this brief discussion to touch upon the relative effects of stearic and oleic acids in a few typical rubber stocks; then to discuss certain anomalies as to the effect of stearic acid on chemical and physical cure; and, lastly, to consider some of the differences found by use of different accelerators. Inasmuch as oleic acid is the chief impurity in commercial stearic—running from 10 to 15 per cent—it seems desirable to know the behavior of oleic acid alone. Comparison of Stearic and Oleic Acids The following data show the comparative effects of double-pressed stearic and commercial oleic acids in typical rubber

Some Practical Aspects of Rubber Evaluation

In various papers, published in the past three years, E. C. Zimmerman and the writer have made references to the variability of crude rubber as determined by the properties of vulcanized compounds of various types. We were, I believe, the first to point out the chief stumbling block in the way of establishing a standard test formula for evaluating crude rubber, namely the variation in both quality and rate of cure produced by curing the same rubber with different curing agents. At the outset we were confronted with difficulties which resulted from a deplorable lack of standardization of rubber testing methods, and more specifically from a lack of agreement as to the proper way to select comparable cures. Indeed, it is obvious that these drawbacks have been among the major causes for lack of correlation of available data on the subject. We have stressed the importance of considering those properties of the vulcanizate which are reflected in the performance of the finished product, and have stated our objections to many of the popular criteria, such as “slope,” tensile product, tensile, and coefficient of vulcanization. We had concluded that aging should be the chief criterion of best technical cure. Accelerated age tests cannot be relied upon for comparison of different mixes, but experience has shown that for lightly loaded mixes hand tear is a reliable method of fixing the best aging cure. With this as a means of selecting the time of cure, the quality was studied by comparing the stiffness of the stress-strain curve at best cure. Later, in a paper on acceleration classification, if was shown that these conclusions might properly be modified when dealing with loaded mixes. Here the cures, as selected by hand tear and by maximum, tensile product, were in substantial agreement, except in the case of non-accelerated stocks.

A Scheme for Accelerator Classification

MUCH has been written about the constitution and chemical behavior of vulcanization accelerators. Theories have been advanced regarding the mechanism of vulcanization effected with their aid. Yet even the authors of such papers—presumably best qualified to interpret their contents—would hesitate to predict, from chemical structure, many of those features which are of practical interest to the rubber manufacturer. Nevertheless, an increasing number and variety of organic accelerators are being offered on the market, and it is not strange that the mind of the average rubber man is confused by the excess at his command and the conflicting claims of the distributors. In these circumstances it is natural to hesitate to undertake the somewhat formidable task of sorting and classifying. Fortunately, however, it is not necessary to do all the work of classification on a factory scale. Certain laboratory helps are available and can be used to reduce considerably the arduousness of the task. It is believed that an outline of such methods, a discussion of their significance, and a table of results, may be helpful to many in the industry, and it is for this purpose that this paper has been written.