A novel method of estimating milking interval-adjusted 24-h milk yields in dairy cattle milked in automated milking systems

Irregular milking intervals in automated milking systems contribute to additional variation in daily milk yield records in comparison to those derived from systems using regular milking intervals. Various methods have been developed to estimate 24-h adjusted milk yields, though they are not well suited for the evaluation of serial milk yield data, particularly when milking intervals span calendar days. The objective of this study was to develop a methodology to estimate serial 24-h milk yields by adjusting for irregular milking intervals. Using data collected from an automated milking system (AMS), the total yield at a given milking event and the elapsed time from the previous entry into the AMS were used to calculate the milking interval and the average rate of milk secretion over that interval. Milking intervals and associated milk secretion rates were then realigned to calendar days to allow the proportional distribution of milk yield when milking intervals spanned more than one day. Using this method, variation in daily milk yield was decreased and adjusted estimates of 24-h milk yield were visually more similar to those typically observed in milking systems with regular milking intervals. Estimates of interval-adjusted milk yields were strongly correlated to those calculated using moving averages, suggesting that this method can yield comparable results to established methods for estimation of test-day milk yield.