Factors influencing morbidity and mortality in feedlot calves in Ontario.
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Animals↗
Biomedical subjects
S W Martin
Publications and source records attributed to S W Martin.
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↗
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↗
Interrelationships between production and reproductive diseases in Holstein cows. Conditional relationships between production and disease.
By methods of conditional odds ratio with a set of 2960 Holstein lactation records, relationships between occurrences of disease in a lactation were examined. There were strong positive relationships between retained placenta and metritis and between cystic follicle and luteal cyst. Interaction was among dystocia, retained placenta, and metritis and among retained placenta, cystic follicle, and luteal cyst. Metritis was an intervening variable between retained placenta and cystic follicle, retained placenta was a common cause variable for metritis and luteal cyst, and cystic follicle was either an intervening variable or a common cause for metritis and luteal cyst. Discriminant analyses were used to investigate production variables and other diseases as causes of disease, and multiple regression analyses indicated effects of disease on other diseases and current production in a subset of 810 lactation records. Breed class averages for milk and fat, days in milk, and dry period in one lactation had little effect on occurrence of disease in the subsequent lactation. Metritis, cystic follicle, and luteal cyst directly increased calving interval 20 to 27 days. Cystic follicle directly increased breed class averages 5.5 points. None of the five diseases directly increased days in milk.
Animals↗
Interrelationships between production and reproductive diseases in holstein cows. Path analysis.
Path models were constructed to investigate causes and effects of dystocia, retained placenta, metritis, cystic follicle, and luteal cyst. The general model included 12 variables: five diseases, age, previous and current breed class average for milk, previous and current days in milk, days dry, and calving interval. The general model indicated 40 bivariate relationships (34 allegedly causal). Restricted models were derived. These included all variables except dystocia (possibly because the set of 810 lactation records excluded data on primiparous cows) and 26 bivariate associations (20 causal). In these models, breed class average, days in milk, and dry period in the previous lactation had little effect on disease. The most important cause and effect relationship among the diseases was retained placenta causing metritis. Excluding dystocia, all of the diseases caused increases in calving interval (16.79 to 35.82 days), in the breed class average for milk (.50 to 6.51 points), and in days in milk (8.72 to 19.73 days). Most increases in the breed class average were of less than 2 points and were mediated by the increase in calving interval (days open); however, there was a direct effect of cystic follicle on the breed class average for mild of +5.58 points (+297 kg).
Animals↗
The interpretation of antimicrobial susceptibility patterns.
The results of a computer model designed to demonstrate the effect of antimicrobial exposure (therapy) on the likelihood of isolating putative pathogens and on the proportion of successfully isolated organisms resistant to specific antimicrobials are presented. The results indicate that the observed percentage resistant is not a reliable indicator of the actual percentage resistant in the source population. Data from the Bruce County Beef Project in 1979-80 are used to verify some of the assumptions used in the model.
Animals↗
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↗
Use of total and differential somatic cell counts from composite milk samples to detect mastitis in individual cows.
The objective of this study was to ascertain the value of variables measured on composite milk samples as predictors of mastitis in individual cows. The standard of comparison was the results obtained from the bacteriological examination of individual quarter foremilk samples. Cows were classified as negative or positive with regard to mastitis on the basis of one quarter sampling only and cows which were impossible to classify in this manner were omitted from subsequent analyses. The variables that were examined were: the presence or absence of specific bacteria, demographic data, and logarithmically transformed total somatic cell counts and percentages of cell volume in channels 7 through 12 of a Coulter Counter. It was found that the inclusion of all variables resulted in correct classification of 95.9% of cows with regard to their mastitis status. Sequential elimination of individual variables or groups of variables in an attempt to simplify the procedure reduced the correct classification to 86.8% when only the log transformation of the total somatic cell count and the demographic data were included. The ability of a function which included the logarithm of the total somatic cell count, the logarithm of the percentage in channel 8 and demographic data, to classify cows was examined in detail and the sensitivity and specificity of the function also discussed. It is also shown that with increasing age the minimum total somatic cell count required to classify a cow as positive increased and possible explanations of this phenomenon are discussed.
Age Factors↗
Interrelationships between production and reproductive diseases in Holstein cows. Data.
Described are data in a retrospective study of the epidemiology of dystocia, retained placenta, metritis, cystic follicle, and luteal cyst. The 2960 lactation records by 1401 registered Holstein cows in 20 commercial herds were from the Canadian Record of Performance, and the disease data were from the herd health program of the Ontario Veterinary College. Means and standard deviations of production variables were age 4.6 yr, days dry 77.0 +/- 46.9, calving interval 417.6 +/- 71.5 days, breed class average for milk 129.4 +/- 22.5, fat 132.5 +/- 25.5, and days in milk 342.1 +/- 60.6. Rates of disease per lactation were dystocia 5.0%, retained placenta 7.1%, metritis 13.8%, cystic follicle 12.9%, and luteal cyst 3.2%. The distribution of calving ages suggested that the annual herd turnover was 20 to 25%. The distribution of diseases per lactation suggested that diseases occurred together in lactations more often than expected.
Animals↗
Interrelationships between production and reproductive diseases in Holstein cows. Age and seasonal patterns.
Influences of age and season on occurrence of dystocia, retained placenta, metritis, cystic follicle, and luteal cyst were studied retrospectively. The 6 yr of data were from 2960 lactation records of 1401 registered Holstein cows from 20 commercial herds that participated in the dairy herd health program of the Ontario Veterinary College. For each disease, odds ratio analyses compared the risk of disease in each age group to the risk in all other age groups pooled. The following age groups were at increased risks of diseases: dystocia, 2 to less than 4 yr; retained placenta and metritis, 7 to less than 10 yr and 10 or more yr; cystic follicle and luteal cyst, 10 yr or more. For all diseases except dystocia, age 2 to less than 4 yr was at decreased risk. Formal statistical methods were used to test for unimodal seasonal patterns in monthly calvings, in monthly disease incidence (number of diagnoses), and in risk (lactational incidence rate) of disease according to month of calving. There were the following significant peaks: fall calvings in the age group 2 to less than 4 yr, summer-fall risk of metritis, fall-winter incidence of dystocia and metritis, and fall-winter risk of dystocia.
Age Factors↗
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↗
An evaluation of screening programs for the detection of brucellosis in dairy herds.
Data were collected from approximately 1000 dairy herds, initially blood tested for brucellosis in 1977, in each of southeastern and southwestern Ontario. These data were used to evaluate three brucellosis screening programs, the area recertification program, the market cow program and the milk test program. The milk test program was the most efficient program at detecting brucellosis, 29.5% of the herds tested were classified as infected, but lacked the ability to detect a large proportion of "infected" herds (relative sensitivity = 24%). The market cow program was more efficient than the area recertification program at finding infected herds, 3.9% of the herds tested under the market cow program were infected, but had a low relative sensitivity of 12%. The area recertification program was least efficient, 2.3% of herds tested under the area recertification program were infected, but had the highest relative sensitivity (53%). The relative efficiency (predictive value) of the programs was not affected significantly by location of the herds, season of the initial test or herd size. The relative sensitivity of the milk test program was significantly higher in eastern than western Ontario and tended to decrease as herd size increased. The market cow program tended to be more sensitive in the summer months. The relative specificity of the milk test program (0.997) was higher than that of the market cow program (0.960) and the area recertification program (0.884).
Agglutination Tests↗
Canine hip dysplasia: breed effects.
This paper is a refinement of previous studies in that only suitably radiographed dogs were included in the data base. The rate of hip dysplasia varied widely by breed from five percent in siberian huskies to eighty-three percent in english bulldogs. There was a significant difference in the prevalence of dysplasia within at least two breeds; golden retrievers and old english sheepdogs. Physical size per se did not appear to be an important determinant of hip dysplasia.
Animals↗
Epidemiology of equine upper respiratory tract disease on standardbred racetracks.
The outbreaks of upper respiratory tract infections in horses at Standardbred racetracks were investigated over a three year period. The most serious epidemics of respiratory disease occurred in the winter and spring seasons. Both influenza viruses and equine herpesvirus 1 were shown to be present in the horse population. The herpesvirus was associated with respiratory disease particularly in the winter but the equine influenza viruses apparently were responsible for the major epidemics of respiratory disease at these tracks. Younger horses, two or three years of age, were particularly susceptible to upper respiratory disease and showed the greatest rate of seroconversion to influenza viruses. Major outbreaks of respiratory disease occurred when the proportion of young horses which had not previously been exposed to epidemics of respiratory disease reached 30 to 40% of the population at the track. Most horses over four years of age appeared to develop resistance to the infections.
Age Factors↗
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↗
The rates and patterns of survivorship and disease in a university dairy herd.
The rates and patterns of disease occurrence and survivorship were determined over a six year period in a university operated dairy herd. Of the ten diseases selected for study, clinical mastitis occurred most frequently with an incidence rate of 10.1% and displaced abomasum occurred least frequently with an incidence rate of 4.4%. The occurrence of all disease except those of the ovary was associated with the age of the cow. Mastitis, pneumonia and cystic graafian follicles tended to reoccur in the same cow after the initial occurrence. The average culling rate was 25.6% and the median number of years cows survived in the herd was 3.4 years. Methods for calculating the various rates and survivorship are described and their interpretation discussed.
Animals↗
The association between disease, production and culling in a university dairy herd.
The impact of ten diseases of dairy cattle on milk production, calving interval and culling were studied in a university operated dairy herd. Cows with clinical mastitis, ketosis or displaced abomasum had lowered milk production. Cows with metritis, retained placenta, cystic graafian follicles or ovarian hypofunction had longer calving intervals. Cows with clinical mastitis, metritis, pneumonia or retained placenta had increased risks of culling. The relationship between disease and culling was based on the medical history of culled and nonculled cows using a case control approach. Therefore, it is likely that in many cases, the association between disease and culling is due to the impact of that disease on productivity.
Animals↗