Well weaning, or the transition from a liquid to a solid diet-- in nature, this happens very gradually, and in commercial dairy farming it's quite a short-term activity.
When we increase our feeding planes towards LifeStart-like feeding plans, then weaning becomes much more important because we have already a very high energy intake in the beginning of the life. And therefore, also solid feed intake and rumen development will be slowed down. Therefore, the transition is particularly important.
We did some research within Nutreco about weaning strategies, and one of the things we studied was weaning age. So, we looked at whether it matters if you wean at six weeks of age or at eight weeks of age. And it appeared to be much more beneficial to wean calves at eight weeks of age.
Another comparison that we made is that we looked at abrupt weaning; so weaning in one day, compared to a gradual weaning for six or 14 days of time. And it appeared that the gradual weaning is much more beneficial, to slowly increase solid feed intake and to prevent a growth dip that you normally see around weaning.
Weaning and rumen development are very closely related. So, when we start weaning, solid feed intake increases, and at the same time rumen development increases. Now with a higher plane of nutrition for the milk replacer scheme, rumen development slows down, because solid feed intake also slows down. So, it's more important to have a gradual weaning process and to have a very efficient rumen development. So that's why I emphasize also, rumen development and optimization of that.
We advise to provide solid feed from two weeks of age, including both starter feed or concentrate feed, and roughage. For the roughage, our preferred type of roughage is chopped straw because straw has a very constant quality. But, of course, if there are alternative high quality roughage sources that would be fine as well, as long as it's fresh. Considering chop size, we advise a chop size of at least three centimetres or more, because it's really important to also benefit from the physical structure of the solid feed. So, when you include roughage in the diet of a calf, we see that rumen pH increases and that it may prevent acidification.