The effect of large milk meals on digestive physiology and behaviour in dairy calves

It is commonly believed that young calves should not be fed more than about 2l of milk per meal. If calves are fed beyond this volume, it is said that the capacity of the abomasum may be exceeded and that milk could enter the rumen. This can disturb the microbial flora/fauna of the rumen and increase the risk of indigestion, diarrhoea and reduced growth. The aim of this study was to examine the effect of large milk meals on digestive physiology and behaviour in dairy calves. Six calves (19-23days of age at the beginning of the experiment) were fed 2l of warm whole milk by teat bottle three times per day, which was the recommended Norwegian feeding regime at the time. The calves were given free access to hay, concentrates and water. During three morning feeding sessions, each separated by 48h, all calves were offered larger meals. The offered amounts were calculated according to the within patient 3-level Response Surface Pathway (RSP) design. The milk given on the three test days contained a contrast medium (barium sulphate), and the animals were radiographed before, during and immediately after intake to reveal whether milk entered the rumen. Four out of the six calves drank more than 5l in one meal and the highest voluntary intake was 6.8l in one meal (13.2% of BW). Abdominal radiographs showed that the abomasum has a large ability for distension. Milk in the rumen was not observed in any of the calves, regardless of intake. The behaviour of the calves was observed for 2h after each test session. No behaviour indicating abdominal pain or discomfort was observed regardless of intake. The results indicate that when warm whole milk is administered from a teat bottle, farmers can increase the amount of milk they offer their calves beyond the traditionally recommended portion size without risk of milk entering the rumen. Hence, farmers who want to feed their calves more milk can do so by increasing meal sizes, and not necessarily by introducing an additional meal.