Biomedical subjects

D D Hancock

Publications and source records attributed to D D Hancock.

75 records · Page 5Linked to original sources

PubMedDate not supplied

Partitioning the mortality risk associated with inadequate passive transfer of colostral immunoglobulins in dairy calves.

This study developed a method to partition the risk of mortality in dairy calves in the 1st 16 weeks of life. Observed population mortality and the relative risk of mortality in each serum protein concentration stratum were used to determine the population baseline mortality rate and the mortality rate due to inadequate passive transfer of colostral immunoglobulin. A total of 3,479 calves were studied, 8.2% of which died before 16 weeks of age. The population baseline mortality rate was 5.0% and the mortality rate due to inadequate passive transfer was 3.2%. Thirty-nine percent of the observed mortality was attributed to inadequate passive transfer. This partitioning of risk between passive transfer-related and unrelated sources should prove useful in conducting investigations of calf mortality problems in dairy herds.

Animal Husbandry↗

PubMedDate not supplied

Changes in antimicrobial resistance among Salmonella enterica Serovar typhimurium isolates from humans and cattle in the Northwestern United States, 1982-1997.

We compared antimicrobial resistance patterns of Salmonella enterica serovar Typhimurium (ST) of isolates from humans (n = 715) and cattle (n = 378) in the Pacific Northwest from 1982 through 1997. The major changes in antimicrobial resistance can be attributed to the widespread clonal dissemination of multidrug-resistant definitive phage type 104 ST.

Animals↗

PubMedDate not supplied

Effect of passive transfer status and vaccination with Escherichia coli (J5) on mortality in comingled dairy calves.

The effect of vaccination with a commercially available R-mutant coliform mastitis vaccine on the survival of comingled dairy calves on a farm with endemic salmonellosis was examined. A total of 864 calves were randomly assigned to either vaccine (n = 435) or control (n = 429) groups. Passive transfer status of each calf was determined using refractometer determination of serum total protein concentration. Logistic models were developed to determine the effects of vaccine group and passive transfer status on calf survival to 100 days of age. In a model in which serum protein concentration was treated as a categorical variable, increasing serum total protein concentrations were associated with decreased mortality until these concentrations exceeded 6.0 g/dL. Calves with serum protein concentrations > 6.0 g/dL had increased risk for mortality compared with calves with serum protein concentrations > 5.5 g/dL but < or = 6.0 g/dL. This increased risk for mortality was supported by the results of a logistic model in which serum protein concentration was treated as a continuous variable. The increased risks associated with high serum protein concentration probably reflect the effect of dehydration in calves with occult disease. Neither model demonstrated any significant association between vaccination status and survival to 100 days of age. Based on these results, the routine immunization of calves cannot be recommended as a strategy to prevent mortality on farms with endemic salmonellosis.

Animal Husbandry↗