Preweaned heifer management on US dairy operations: Part III. Factors associated with Cryptosporidium and Giardia in preweaned dairy heifer calves

Authors: URIE, NATALIE - Animal And Plant Health Inspection Service (APHIS); LOMBARD, JASON - Animal And Plant Health Inspection Service (APHIS); SHIVLEY, CHELSEY - Animal And Plant Health Inspection Service (APHIS); ASHLEY, ADAMS - Animal And Plant Health Inspection Service (APHIS); KOPRAL, CHRISTINE - Animal And Plant Health Inspection Service (APHIS); Santin-Duran, Monica

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2018
Publication Date: 5/30/2018
Citation: Urie, N., Lombard, J., Shivley, C., Ashley, A., Kopral, C., Santin, M. 2018. Preweaned heifer management on US dairy operations: Part III. Factors associated with Cryptosporidium and Giardia in preweaned dairy heifer calves. Journal of Dairy Science. 101(10):9199-9213. https://doi.org/10.3168/jds.2017-14060.
DOI: https://doi.org/10.3168/jds.2017-14060

Interpretive Summary: A study was conducted to identify factors associated with management practices and environmental conditions that have an impact on prevalence of Cryptosporidium and Giardia in preweaned dairy heifer calves on U.S. dairy operations. Fecal samples were collected from 2,249 calves at 104 dairy operations in 13 states. Factors that were found to be associated with Cryptosporidium infection included herd size, days of age at fecal collection, and average temperature and humidity index for the month of fecal collection. Factors associated with Giardia infection included herd size, days of age at fecal collection, average temperature and humidity index for the month of fecal collection, failure of passive transfer status, and average daily gain (kg/d) during the preweaning period. These findings will be useful to other research scientists, veterinarians, and dairy farmers by providing insight into factors associated with the presence of Cryptosporidium and Giardia in preweaned dairy calves.

Technical Abstract: The objective of this study was to evaluate management practices and environmental factors associated with cryptosporidiosis and giardiasis in preweaned heifer calves on U.S. dairy operations. This study was conducted as part of the calf component of the National Animal Health Monitoring System’s Dairy 2014 study. The calf component included 104 dairy operations in 13 states and was an 18-mo longitudinal study focused on dairy heifer calves from birth to weaning. Fecal samples were collected from 2,249 calves: 839 calves in the West region (CA, CO, WA) and 1,410 calves in the East region (IA, MI, MN, MO, NY, OH, PA, VT, VA, WI). Fecal samples were collected only once from calves during the preweaning period. Samples were collected from calves 3 to 66 d of age, with a mean of 22 d. Overall, Cryptosporidium and Giardia were detected in 43.1% and 30.5% of fecal samples, respectively. Backward elimination logistic model selection was used after univariate screening to determine which management practices and environmental factors significantly impacted the presence of Cryptosporidium or Giardia. The final Cryptosporidium model included herd size, days of age at fecal collection, and average temperature and humidity index (THI) for the month of fecal collection. Cryptosporidium was found on a higher percentage of large operations (500 or more cows) than small operations (30 to 99 cows). Younger calves were more likely to have a fecal sample positive for Cryptosporidium than samples from older calves. Fecal samples from calves during the warmer parts of the year (THI >70) were more likely to be positive for Cryptosporidium than samples collected in colder months. The final Giardia model included herd size, days of age at fecal collection, average THI for the month of fecal collection, failure of passive transfer status, and average daily gain (kg/d) during the preweaning period. In contrast to Cryptosporidium, Giardia was isolated more frequently from calves on small operations than on large operations and calves that were older compared with younger calves. Similar to results for Cryptosporidium, Giardia was more frequently isolated in warmer months. Samples from calves with failure of passive transfer were more likely to have Giardia isolated than samples from calves with adequate passive transfer (>10 g/L IgG). Average daily gain during the preweaning period was lower in calves where Giardia was isolated from fecal samples. These results highlight the factors associated with the presence of Cryptosporidium and Giardia in preweaned dairy heifer calves.