Evaluation of reticuloruminal pH measurements from individual cattle: sampling strategies for the assessment of herd status

Publication date: Available online 14 November 2018Source: The Veterinary JournalAuthor(s): Nicholas N. Jonsson, Joachim L. Kleen, R. John Wallace, Ivan Andonovic, Craig Michie, Marianne Farish, Malcolm Mitchell, Carol-Anne Duthie, Dan B. Jensen, Matthew J. DenwoodAbstractThe application of pH observations to clinical practice in dairy cattle is based on criteria derived primarily from single time-point observations more than 20 years ago. The aims of this study were to evaluate these criteria using data collected using continuous recording methods; to make recommendations that might improve their interpretation; and to determine the relationship between the number of devices deployed in a herd and the accuracy of the resulting estimate of the herd-mean reticuloruminal pH. The study made use of 815,475 observations of reticuloruminal pH values obtained from 75 cattle in three herds (one beef and two twice-daily milking herds) to assess sampling strategies for the diagnosis of sub-acute rumen acidosis (SARA), and to evaluate the ability of different numbers of bolus devices to accurately estimate the true herd-mean reticuloruminal pH value at any time.The traditional criteria for SARA provide low diagnostic utility, the probability of detection of animals with pH values below specified thresholds being affected by a strong effect of time of day and herd. The analysis suggests that regardless of time of feeding, sampling should be carried out in the late afternoon or evening to...
Source: The Veterinary Journal - Category: Veterinary Research Source Type: research