Biomedical subjects

J O Goelema

Publications and source records attributed to J O Goelema.

4 recordsLinked to original sources

PubMed1992

Multivariate epidemiological approach to salmonellosis in broiler breeder flocks.

A retrospective, case-control study into risk factors of salmonellosis was undertaken using data from 111 broiler breeder flocks assembled during a 5-yr period. The results of both univariate and multivariate analyses are presented. Many different Salmonella species were detected. Multivariate models were created based on the outcome of univariate analyses. The following variables appeared to be the most relevant: disinfection tubs, hygiene barriers, the interaction of disinfection tubs by hygiene barriers, and feed mills. The final model indicated that flocks housed at farms without a disinfection tub, with poor hygiene barriers, and receiving their feed from a small feed mill had a 46.1 times greater risk of being Salmonella-positive than flocks housed at farms with a disinfection tub, with good hygiene barriers, and receiving their feed from a large feed mill. It is concluded that the application of quantitative epidemiological methods can be valuable not only to identify potential risk factors but also to quantify their contributory effect on the disease outcome. Hence, it may be a useful tool for application in "integrated food chain quality control programs".

Analysis of Variance↗

PubMed1992

Multivariate epidemiological approach to coccidiosis in broilers.

A retrospective, case-control study into risk factors of coccidiosis was undertaken using data from 189 broiler flocks. A case flock was defined as a flock in which at least one bird had intestinal lesions on 1 of 6 wk in a 42-day cycle. Flocks wherein such birds could not be detected were defined as controls. There were 187 variables, measured or derived. These were assigned to subsets of data, each subset being a group of variables representing related information. Uni- and bivariate analyses were performed in each subset. Variables and interactions that were significant in these analyses were entered into a multivariate model across subsets. In the final model, seven variables appeared to be significantly associated with detecting lesions in birds of a flock. Differences among breeds covered a range of about an 80-fold change in risk of being a case. At intermittent lighting, the risk of being a case increased about sevenfold compared with continuous lighting. A higher initial (Week 1) environmental temperature decreased the risk of finding lesions in a flock (about .8-fold per degree Celsius). This risk was also lower at a lower average aerial ammonia content (below versus above 14 ppm) and higher maximum carbon dioxide content (above versus below .4 vol%) changing the risk about .3- and .4-fold, respectively. The risk of being among cases increased with more litter (about twofold per kilogram of litter per square meter). Flocks in houses of 600 to 800 m2 were about 9.8 times more at risk of being scored as lesion-positive than those in smaller houses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Age and weight at first calving and subsequent performance in Dutch dairy cattle from rearing farms.

Calf-cow records from 1081 replacement heifers raised on 42 specialised rearing farms in the province of Noord-Brabant have been analysed. The predominant breed was Meuse-Rhine-Yssel (MRY). The objective was to study the relationship between weight and age at first calving and milk production in subsequent lactations, herd life span, dystocia and first calving interval. Weight appeared to be a better predictor for first lactation Fat and Protein Corrected Milk production (FPCM-1) than age. First lactation FPCM had a significant and positive effect on herd life FPCM. First lactation FPCM was significantly associated with first calving interval.

Age Factors↗

PubMed1990

EPISCOPE: computer programs in veterinary epidemiology.

Veterinary epidemiology is a rapidly developing science. However, many veterinarians are unfamiliar with the relevant techniques because veterinary schools have not introduced biostatistics as a core element of their courses or adopted epidemiology as a specific discipline. EPISCOPE, the computer software presented in this paper, covers many epidemiological principles and calculations. It can assist both the teaching of epidemiology and the analysis of field data.

Animal Diseases↗