Adsa Logo White Adsa Title White

Assessing the utility of leukocyte differential cell counts for predicting morbidity, mortality and growth in a grain-fed veal facility: A prospective single cohort study.

T. E. von Konigslow

Abstract:

189
Assessing the utility of leukocyte differential cell counts for predicting morbidity, mortality and growth in a grain-fed veal facility: A prospective single cohort study.
T. E. von Konigslow*, D. L. Renaud, T. F. Duffield, C. B. Winder, D. F. Kelton. University of Guelph Guelph, ON, Canada.

On farm machine leukocyte differential cell counts (DCC) that can be acquired quickly may be useful to augment calf risk identification protocols at the time of arrival at a veal or dairy beef operation. The objective of this study was to assess the utility of DCC taken at the time of arrival at a grain-fed veal facility and 72 h post arrival for determining morbidity risk, mortality risk and growth during the production cycle. Data were collected between June and October 2018, from 240 calves upon arrival and a subset of 160 calves 72 h post arrival at a veal research facility in Ontario, Canada. DCC were evaluated using the QScout BLD test for leukocyte differential cell counts (Advanced Animal Diagnostic, Morrisville, NC). All calves were screened using a standardized protocol and a blood sample was collected to evaluate serum total protein (TP) and DCC. Cox proportional hazards models were constructed for both morbidity and mortality outcomes. Mixed linear regression models were constructed for the outcome of average daily gain. Models were constructed in Stata 15 (StataCorp LP, College Station, TX). Results from data collected at the time of arrival suggest that TP values >5.1 g/dL reduce the hazard of mortality (HR = 0.29, P < 0.001) and a rectal temperature >39.6�C was associated with an increased hazard of morbidity (HR = 1.48, P = 0.04). Calves that were dehydrated gained less (−0.09 kg/d, P = 0.03), however, an increased lymphocyte count was associated with calves having a higher level of growth (+0.05 kg/d, P = 0.02). Results from DCC collected 72 h post arrival suggest that lymphocyte counts between 4.8 and 5.8 � 109 cells/L decrease the hazard of mortality (HR = 0.22, P = 0.03) and >7.0 � 109 cells/L decrease the hazard of morbidity (HR = 0.56, P = 0.02), whereas, neutrophil counts >6.0 � 109 cells/L increased the hazard of mortality (HR = 5.2, P = 0.02). This study demonstrates that machine DCC at the time of arrival and 72 h post-arrival has potential for use in calf risk identification protocols in veal and dairy beef facilities.

Keywords: male dairy calf, biomarker, risk factors.