Effect of dietary factors on rumen metabolism and the microbiome in high yielding dairy cows

Previous work has established that poor diet mixing, diet selection and short-term feed restriction (FR) are common on many UK dairy farms. When cattle sort through a total mixed ration they can alter both their level and pattern of concentrate intake which can increase the risk of subacute rumen acidosis (SARA), although the effects on rumen metabolism and the microbiome are unclear. Periods of short-term FR can occur due to a shortage of the ration, machinery malfunction, or poor management, and when cattle re�feed they can overeat concentrates increasing the risk of SARA, defined as periods of pH depression lasting more than 5 to 6 h/d with rumen pH