Abstract
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.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bross D. S., Sharpiro S. Direct and indirect associations of five factors with infant mortality. Am J Epidemiol. 1982 Jan;115(1):78–9. doi: 10.1093/oxfordjournals.aje.a113282. [DOI] [PubMed] [Google Scholar]
- Burridge M. J., Schwabe C. W., Pullum T. W. Path analysis: application in an epidemiological study of echinococcosis in New Zealand. J Hyg (Lond) 1977 Apr;78(2):135–149. doi: 10.1017/s0022172400056047. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Erb H. N., Martin S. W., Ison N., Swaminathan S. Interrelationships between production and reproductive diseases in holstein cows. Path analysis. J Dairy Sci. 1981 Feb;64(2):282–289. doi: 10.3168/jds.S0022-0302(81)82565-9. [DOI] [PubMed] [Google Scholar]
- Etherington W. G., Martin S. W., Dohoo I. R., Bosu W. T. Interrelationships between ambient temperature, age at calving, postpartum reproductive events and reproductive performance in dairy cows: a path analysis. Can J Comp Med. 1985 Jul;49(3):254–260. [PMC free article] [PubMed] [Google Scholar]
- Etherington W. G., Martin S. W., Dohoo I. R., Bosu W. T. Interrelationships between postpartum events, hormonal therapy, reproductive abnormalities and reproductive performance in dairy cows: a path analysis. Can J Comp Med. 1985 Jul;49(3):261–267. [PMC free article] [PubMed] [Google Scholar]
- Goldsmith J. R., Griffith H. L., Detels R., Beeser S., Neumann L. Emergency room admissions, meteorologic variables, and air pollutants: a path analysis. Am J Epidemiol. 1983 Nov;118(5):759–778. doi: 10.1093/oxfordjournals.aje.a113687. [DOI] [PubMed] [Google Scholar]
- Martin S. W. A mail survey of the efficacy of prophylactic medication in feed and/or water of feedlot calves. Can J Comp Med. 1985 Jan;49(1):15–20. [PMC free article] [PubMed] [Google Scholar]
- Martin S. W., Meek A. H., Davis D. G., Johnson J. A., Curtis R. A. Factors associated with mortality and treatment costs in feedlot calves: the Bruce County Beef Project, years 1978, 1979, 1980. Can J Comp Med. 1982 Oct;46(4):341–349. [PMC free article] [PubMed] [Google Scholar]