When to feed water after feeding milk
A client question was about how long to wait after feeding whole pasteurized milk to feed water. The data were pretty thin but the calf care person observed that "some calves were drinking 4 to 5 quarts of water as soon as the water was fed." Neither the age of the calves was specified nor what proportion of the calves were the big drinkers.
- Milk goes into the abomasum.
- Milk in the abomasum mixes with enzymes and acids. Within a few minutes casein protein reacts with rennet to form curds. Whey can move on to the small intestine.
- Water goes into the rumen and then progresses through the digestive system.
- At birth the rumen volume is likely to be less than 1 liter.
- By 3 weeks rumen volume has been measured at roughly 3 liters.
- Given another week or two we may estimate rumen volume approaching 4 liters.
In my experience caring for calves the "big" drinkers generally did not include the youngest calves - less than three weeks old. Further, only a small percentage of calves were "big" drinkers - somewhere between 10 and 20 percent of calves between three and six weeks of age.Thus the practical significance of the question is somewhat limited - not very many calves are involved.
If most of these "big" drinkers are 4 to 5 weeks old the rumen volume is great enough to hold most of the water they are drinking. If the water is in the rumen it cannot have any effect on milk digestion.
From a practical point of view I like to see us feed water while the calves are still standing up from the milk feeding. If the farm routine makes it convenient to feed water 10 to 15 minutes after feeding milk I recommend staying with the present routine.
The goal is to get calves to drink water since water consumption drives calf starter grain intake. Given our goal of efficient fermentation of grain we recall that for every pound of grain eaten the calves will need four pounds (2 quarts) of water.
For the scientists readers, I cannot recall a single research report that examined the consequences of feeding water at different intervals post-milk feeding at varying water temperatures under given environmental conditions.