Importance of incorporating feeding rate when developing predictions of feed intake

Obtaining individual feed intake data under pastoral grazing studies is important for work relating to feed efficiency and greenhouse gas emissions, but is nearly impossible to obtain. Accelerometer technology has been used to determine the duration of grazing events, but data from feed intake facilities suggests that between-animal variation in feeding rate makes duration alone a poor proxy for feed intake. This study explored in detail the trait of feeding rate (feed eaten/feeding duration) on data collected through a feed intake facility. Feeding rate was demonstrated to be a very consistent trait of an individual animal across their feeding events with a high heritability (0.60 ± 0.14) and considerable between-animal variation. Using feeding rate and feeding duration accurately predicted feed intake. Future accelerometer work to predict feed intake should therefore emphasise whether or not feeding rate can be accurately determined in addition to feeding duration.