"Benchmark" - a large observational study of Ontario beef breeding herds: Study design and collection of data

The methods used in a large field study which investigated the health and productivity of Ontario beef breeding herds are described. Beginning in the calving season of 1986, 180 breeding herds on 170 randomly sampled farms were followed for a two year period, using producer records and annual farm visits.

The response (cooperation) rate among the eligible producers initially contacted was 70%. Approximately two-thirds of producers maintained individual animal records, primarily calving season records. Approximately 40% recorded disease occurrences.

The advantages, disadvantages, and interpretation of “on-farm” observational studies are discussed.

     

Torsion of abdominal organs in sows: a report of 36 cases

Necropsy records of 36 sows with torsion of abdominal organs involving individually the stomach, the spleen, a liver lobe or the intestine were reviewed for the years 1970 to 1983, and the age, the clinical signs and the gross lesions were recorded. These acute abdominal accidents were characterized clinically by sudden death. Dry sows from large breeding units were affected. Twenty-six cases were diagnosed between January 1981 and December 1983 while only ten cases had been seen between 1970 and 1980. Gastric torsion was the most common condition (40% of the cases) and the other three conditions were equally represented (20% each). Management practises that could be responsible for the apparent increase in occurrence of this problem are discussed.     

Effects of three methods of restraint an in rhesus and african green monkeys intravenous glucose tolerance testing

The intravenous administration of 0.75 gm glucose per kg and the measurement of serum glucose pretest and at 10, 20, 30, 60, 90 and 120 minutes constitute a satisfactory protocol for intravenous glucose tolerance testing of Rhesus (Macaca mulatto) and African Green (Cercopithecus aethiops) monkeys. No significant differences were noted between animals restrained with ketamine hydrochloride and those restrained with sodium pentobarbital, but the African Green males and females and the male Rhesus monkeys yielded significantly different results while being manually restrained.     

Somatic cell counts: associated factors and relationship to production.

Factors affecting somatic cell counts and the association between somatic cell counts and milk production were evaluated. Data were collected from 748 Ontario Dairy Herd Improvement Corporation supervised herds that were on production and somatic cell count programs between April 1981 and March 1983. Two data files were created; one, the lactation summary file, contained one record per cow on each of 9406 Holsteins and the other, the test day file, included results of all tests during the complete lactation on each of the above cows. The latter file contained 85,236 records. Multiple curvilinear least squares regression was used to create five separate models. The dependent variables used in the models were natural logarithms (Loge) of the geometric mean of the somatic cell count for the lactation, 305 day milk production and breed class average for milk from the lactation summary file, and loge of the 24 hour somatic cell count and 24 hour milk production from the test day file. The somatic cell count at both the lactation and test day level increased with age up to approximately ten years and thereafter slowly decreased. The variable "days in milk" was not significantly associated with the lactation average somatic cell count. A curvilinear relationship was found between days in lactation at the time of test and the somatic cell count of 24 hour milk production. The somatic cell count increased until approximately 250 days in lactation and thereafter slowly decreased. It was found that the highest cell counts occurred in summer and the lowest in winter.(ABSTRACT TRUNCATED AT 250 WORDS)     

A path model of factors influencing morbidity and mortality in Ontario feedlot calves.

The principles of path analysis and causal modelling are discussed. Path analysis was applied to three data sets to assess the relationship between group characteristics (number per group and "mixing" subgroups of cattle, feeding-management of the group and processing factors (vaccination and prophylactic antimicrobials) and subsequent morbidity and mortality in feedlot cattle. The major findings agree with previously reported results but the timing and pathways of the effects are elaborated. In general, morbidity in week 1 was correlated with morbidity in week 2, which was correlated with morbidity in weeks 3-5. The same was generally true for mortality. In general, morbidity was not strongly correlated with mortality. Lots (unmixed groups) did not arrive in better condition, but experienced fewer subsequent health problems than mixed groups. (Silage-fed lots appeared to do poorly, however this was apparently due to the positive association between lots and vaccination, the latter being detrimental to mortality rates.) The more cattle per group, the greater the health problems in weeks 3-5 postarrival. Prophylactic antimicrobials in the water supply on arrival lead to increased health problems in the three to five week postarrival period. Antibiotic containing starter rations had a beneficial effect on health status in this period. This effect appeared to be partly due to delaying making silage the major ration component in silage-fed cattle receiving antimicrobial containing starter rations. Vaccination against respiratory disease in either of the first two weeks postarrival had detrimental direct and indirect effects on subsequent health status. Vaccination during weeks 3-5 postarrival was not significantly related to health status in that period.     

Transitional Cell Carcinoma of the Urinary Bladder in a Beluga Whale (Delphinapterus leucas)

A transitional cell carcinoma of the urinary bladder was found in a beluga whale stranded in the St. Lawrence middle estuary. Various organs of this animal were submitted to high resolution gas chromatography coupled with mass spectrometry analysis. High frequency of urinary bladder cancer in the human population of the same area and the presence of carcinogenic compounds in the marine environment of this animal are discussed.

Concurrent isolation of Edwardsiella tarda from various organs of this whale is also reported.