Bulk milk quality: can it be improved by dairy farm audits?

Abstract

Udder health is important as it affects milk quality. This is reflected in somatic cell count and total bacterial count (TBC). One way to judge farm management, including udder health management, is the use of milk quality systems based on farm audits with checklists. Audits aim to ascertain and improve product quality. But the effect of audits on product quality is hard to demonstrate empirically as data are not easily available. In this study data on dairy farm audits and data about laboratory results of bulk milk deliveries of individual farms are studied to trace a putative relation between audits and product quality. The objective is to study whether the TBC of dairy bulk milk are reduced in the period around a farm audit and/or afterwards. The data set contained information about 13,006 audits performed on 12,855 farms as well as TBC counts of bi-monthly tested bulk milk of these farms. A record included: logTBC value, variables indicating the timing of the TBC test relative to the audit date, unique audit number, auditor, type of audit, outcome of the audit, audit checklist items, number of attention points and audit date. A random linear regression model was used to quantify the possible relation between LogTBC and the time before, during and after the dairy farm audits and other audit variables. A significant reduction in LogTBC levels were found around the date of the audit and in the period from 1.5 to at least 6 months after the audit. Additionally, LogTBC levels were found to depend on: season, total number of attention points given during an audit, audit type (standard, repeated or first audit), audit outcome (approved, rejected or temporary blocked), year of the audit (2006, 2007 or 2008), checklist items related to the maintenance of the milking equipment and/or utility room and tank and some interactions. Based on this study we can conclude that there is an improved milk quality (i.e. temporary decrease in logTBC) due to the audit.KeywordsDairy FarmSomatic Cell CountTotal Bacterial CountAudit DateMilk QualityThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.