How much grass or silage a sheep eats each day is important for both farm profitability and climate impact, but measuring individual feed intake is expensive and time-consuming. In this study, we tested whether we can “read” an ewe’s daily feed intake from a short-term measurement of the gases she breathes out. We worked with two Norwegian sheep breeds and measured their methane and carbon dioxide emissions in portable accumulation chambers, along with their body weight and time spent eating. At the same time, we recorded exactly how much each ewe ate each day using electronic feed bins. We then used machine learning methods to predict daily feed intake from these gas and on-farm measurements. The best model, based on a random forest algorithm, predicted daily intake with good accuracy, typically within about 300 g per day. Models using only gas measurements performed almost as well as those that also used body weight and eating time. Our results show that gas measurements can be used as a more rapid, practical way to estimate how much feed gestating ewes eat when housed indoors. This approach could help farmers and breeders monitor feed use and identify animals that use feed more efficiently.

Read the full article in the Journal of Animal Science.