Search PubMed⌕ Search

Biomedical subjects

R A Curtis

Publications and source records attributed to R A Curtis.

At least 37 records · Page 2Linked to original sources
PubMed1984

Effects of gonadotrophin releasing hormone on reproductive performance of dairy cows with retained placenta.

The effects of gonadotrophin releasing hormone (GnRH) on the reproductive performance of dairy cows with retained placenta were studied. Three hundred and seventy-eight cows diagnosed as having retained placenta received intramuscular injections of either 2 mL sterile water or 200 micrograms of GnRH in 2 mL sterile water between day 8 and day 14 postpartum. Rectal palpation was performed at the time of treatment and ten to 20 days after treatment in order to determine the rate of uterine involution. Thereafter, monthly rectal examinations were carried out until insemination. Pregnancy diagnosis was made by rectal palpation at 40 days or more after breeding. Using the entire experimental population, there were no significant differences between GnRH-treated and control cows for the rate of uterine involution, the occurrence of reproductive problems, the interval from parturition to first observed estrus, the interval from parturition to first insemination, the interval from parturition to conception, the number of services per conception, the total number of services per cow regardless of conception and the incidence of culling for infertility. When the data for herds in which breeding began earlier in the postpartum period (herds having a mean less than or equal to 80 days from parturition to first service for retained placenta cows) were considered, the GnRH treatment resulted in a significantly shorter (p less than or equal to 0.01) calving to conception interval as compared to control cows. Also, there was a significant reduction (p less than or equal to 0.05) in the total number of services per cow regardless of conception and a significant reduction in the interval from parturition to first service.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Antimicrobial use in feedlot calves: its association with culture rates and antimicrobial susceptibility.

Data were collected on anti-microbial usage and health problems, in beef feedlot calves. Although the association between them was not significant, many feedlot owners did not use recommended dosages or duration of treatment and this may have led to a reduced recovery rate.Injectable tetracyclines were the most frequent antimicrobial for primary treatment of sick calves; whereas chloramphenicol was selected most frequently when the primary treatment appeared to be ineffective. Treatment with anti-microbials reduced the likelihood of isolating both Pasteurella multocida and Haemophilus somnus. Chloramphenicol therapy reduced the likelihood of isolating Pasteurella haemolytica. Therapy with a particular antimicrobial, in the week prior to death, increased the level of resistance in P. haemolytica to that antimicrobial. Treatment with other antimicrobials also increased the level of resistance to that antimicrobial; although to a lesser degree. The lowest levels of resistance were observed in Pasteurella isolated from nontreated cattle. After adjustment for antimicrobial exposure, resistance to penicillin, tetracyclines and chloramphenicol occurred together more frequently than expected by chance alone.

Animal Husbandry↗
PubMed1982

Factors associated with mortality and treatment costs in feedlot calves: the Bruce County Beef Project, years 1978, 1979, 1980.

Three years of data on factors associated with death losses and health costs in Ontario feedlot calves were analyzed. The results support the previously reported findings; however, significant differences in the third year (1980-81) of the study were noted. Calf groups that were "mixed" after arrival in the feedlot or had a larger than average number of calves (means = 142) had increased death losses and health costs. Calf groups whose ration was changed from dry hay to hay silage or corn silage as the major component of the ration during the first month after arrival had higher death losses and health costs. Feeding grain (barley/oats/corn) prior to, or concurrent with, the change to silage appeared to decrease the harmful effects. Cattle groups vaccinated against respiratory disease within two weeks of arrival experienced increased death losses and health costs. These effects were ameliorated by delaying vaccination in groups switched to silage; however, no benefits from delaying vaccination were noted in dry hay fed groups. Prophylactic antimicrobials in the water supply during the first week after arrival appeared particularly deleterious to the health of calf groups. The effects of prophylactic antimicrobials in the starter ration were unclear. During 1980-81, there was a marked decrease in the relative importance of fibrinous pneumonia as a cause of death and the feeding of silage was not significantly associated with mortality. Both these events may have arisen from the drastic decrease in the percentage of groups fed silage by two weeks postarrival (from 32% in previous years to 7% in 1980-81).

Animals↗
PubMed1981

Factors associated with morbidity and mortality in feedlot calves: the Bruce County beef project, year two.

The results of the second year of the project confirmed most of the major findings from the initial year. Feeding cornsilage, particularly as the major roughage in the first month after arrival was associated with excess mortality. Mixing of cattle from different sources and vaccinating against respiratory disease appeared to be the most important additional factors that increased mortality rates. Delaying vaccination at least two days postarrival may have prevented the negative effects of vaccination but only in calves fed cornsilage. Morbidity rates were highly variable among farms but were positively correlated with mortality rates and treatment costs. The occurrence of infectious thromboembolic meningoencephalitis appeared to share some of the same risk factors as mortality; whereas, urolithiasis did not. Water deprivation may be a risk factor in the occurrence of urolithiasis. Fibrinous pneumonia was again the most frequent cause of death. Relative to year one, infectious thromboembolic meningoencephalitis increased in frequency and only one death was attributed to bovine virus diarrhea.

Animal Feed↗
PubMed1980

All silage forage programs for dairy cattle. III. Health, survival, and reproduction.

Holstein-Friesian heifer calves were fed roughage consisting of corn silage only, corn silage and haycrop silage (60:40, dry matter), or corn silage and dry hay (60:40 dry matter) from birth through completion of three lactations. Forages were fed ad libitum throughout and supplemented as required. Objectives were to determine effects of forage on survival, health, and reproduction. Of the 15 calves allotted per treatment 6, 10, and 7 completed three lactations fed corn silage, corn silage plus haycrop silage, or corn silage plus hay. At any time fewer animals survived on corn silage treatment resulting in 22 completed lactations compared to 36 and 29 lactations for those receiving haycrop silage or hay. Primary reasons for removal from experiment were enzootic pneumonia, 7; reproductive failure, 8; and mastitis, 6; and not forage treatment. Fewer animals on corn silage treatment were primarily from calfhood pneumonia. Reproduction measured by age at first calving (24.6 mo), calving interval (398 days), and services per conception (2.1) was similar across treatments. Incidence of health problems was in normal ranges and similar across treatments. Forage treatment had no effect on incidence of ketosis, left displaced abomasum, or simple indigestion.

Animal Feed↗
PubMed1980

Factors associated with mortality in feedlot cattle: the Bruce County Beef Cattle Project.

The design of and the analysis of data from the Bruch County Beef Cattle Project, particularity the field study, are presented and discussed. A major value of the study may lie in its ability to relate laboratory findings to events in the field. The factor most strongly related to mortality was ration, with cattle on hay based rations having a much lower mortality on average than cattle on corn based rations. In general, management activities associated with growing cattle (as opposed to fattening) over the first winter were sparing for mortality. Groups of cattle given prophylactic vaccines or drugs within two days of arrival tended to experience higher mortality (not statistically higher) than those cattle not receiving those measures, or cattle groups recieving the same prophylactics more than 48 hours after arrival. However, these results require validation in the remaining years of the study. Fibrinous pneumonia was the most frequent diagnosis in the calves on postmortem examination.

Animal Feed↗
PubMed1979

The effect of retained placenta and metritis complex on reproductive performance in dairy cattle -- a case control study.

A study of the computer stored records of 293 dairy cows and 652 calvings reveals the effects of retained placenta and metritis complex on reproductive performance. The overall incidence rate of retained placenta was 11.2%. Retained placenta was 4.6 times more likely to occur following twin births than following single births. Most cases of retained placenta occurred during the fall. Forty-five percent of that seasonal increase was explained by an increased number of calvings. Metritis complex was diagnosed following 54.8% of retained placenta cases. Retained placenta alone did not significantly impair reproductive performance. Metritis complex, in the presence or absence of retained placenta, caused a significant (P</=0.05) increase in days open, services per conception, calving to first heat intervals and days from calving to first service. There is an indication (interaction P</=0.1) that cows with both retained placenta and metritis complex are more severely affected than cows with either retained placenta or metritis complex alone. The influence of retained placenta on fertility appears to depend on the proportion of cows with retained placenta that have metritis complex.

Animals↗
PubMed1979

Atypical interstitial pneumonia in cattle.

Atypical interstitial pneumonia is described as two clinical syndromes in young cattle. One syndrome occurs in animals which have clinical evidence of pneumonic pasteurellosis, responds initially to treatment for one to two days and then develops acute signs of atypical interstitial pneumonia. The second syndrome involves acute respiratory distress in young calves due to atypical interstitial pneumonia with antecedents of enzootic pneumonia. The postmortem lesions are described along with discussion of the possible pathogenesis of the condition and treatment.

Animals↗
PubMed1978

A study of the role of genetic factors in the etiology of left abomasal displacement.

The ancestry of 69 cows having left displaced abomasum was compared with that of 69 cows (matched for age, farm and lactation) not having experienced left displaced abomasum. A variety of tests were used to ascertain if certain bulls or families of bulls produced daughters with an increased risk of developing left displaced abomasum. However, there were no significant differences between the pedigrees of the affected and nonaffected cows.

Abomasum↗
PubMed1975

Technological feasibility of the 2 fibers/cc asbestos standard in asbestos textile facilities.

The technical feasibility of developing dust control practice which would bring the asbestos industry into compliance with the OSHA I fibers/cc standard, scheduled to become effective July 1, 1976, has been questioned since its promulgation. This paper presents the results of industrial hygiene surveys, including the results of 243 asbestos air samples, conducted at two asbestos textile production facilities which have achieved the 2 fibers/cc standard. Both facilities use nonconventional production techniques. Conclusions drawn from the investigations express the need for: (1) a study of new products; (2) a tool to motivate consumers to switch to the new products when appropriate; and (3) legislation which will protect all domestic producers of asbestos textiles from certain producers who do not have to absorb the added expense of meeting the OSHA standard.

Air Pollution↗