Management strategy defines the success of calf programs. Calves are challenged from birth with an immature immune system and at the same time they are programmed to grow quickly. A large part of managing young calves is their feeding program. It is an important first step to ensure that the milk replacer has been formulated with good quality milk ingredients for optimal digestion and growth.

However, other ingredients in the form of additives can also be used as part of the milk replacer program to strengthen calf health and growth. Animal agriculture has traditionally relied on medication in the feed to help maintain animal health. As regulations change and consumer pressures increase, a reduction in usage of medication becomes the landscape of the future. However, the fact remains that young animals will be exposed to pathogens and producers need another tool in the toolbox to fight on farm disease pressure.

Acidification of milk replacer is a concept that has been studied and used for many years. Acidification refers to lowering the pH of the milk with the addition of organic acids. Often two different types of programs are discussed simultaneously.

Program 1: Formic acid is added to the milk replacer when it is being mixed on farm, best added when the milk is cool (with careful attention that you aren’t adding more liquid and reducing the % of solids fed) since it can cause clotting if skim milk powder is a part of the formulation.

This type of acidification program supports ad-libitum milk programs – lowering the pH to 4.2 – 4.5 can retard bacterial growth allowing milk to be left available for calves at all times.

Program 2: Organic acids are added to the milk replacer at time of manufacture which lowers the pH (5.5) of the solution once mixed. This program has been associated with less scouring, increased intakes, and lower pH in the abomasum (true stomach) (Jaster et al, 1990; Woodford et al, 1987). The reduction of pH in the abomasum is expected to improve digestion of milk ingredients by facilitating the clot formation (Peris and Calafat, 2001).

To evaluate acidification of milk replacer as an alternative to medication, a commercial heifer raising facility was used as the test spot where 268 heifer calves were admitted into the study over a period of 6 months. Calves were allocated to one of 4 milk replacer groups: (a) acidified – medicated; (b) acidified – not medicated; (c) regular milk replacer – medicated; (d) regular milk replacer – not medicated. The milk replacer fed was a 26% all milk protein, 18% fat (Grober® Excel).

Calves were fed by automatic feeding machine in groups. Medication was added at the farm through the medicator (attached to the machine); it was dispensed to calves over a period of 1 week. Calves were monitored for health events (1 health event = a course of treatment), body weight gain (calves were weighed upon entry, at 4 weeks and 9 weeks of age) and total milk replacer intake. All milk replacer was fed at 17% dry matter for a period of 8 weeks (56 days). Data was collected for the 8 weeks on milk and then 1 week post-weaning.

Milk replacer intake was different between groups (Table 1). Calves fed the acidified – medicated milk replacer drank the most; calves drinking regular milk replacer – not medicated drank the least.

The feed:gain ratio was not very different between the groups indicating the rate of gain did not change based on the milk replacer; if calves drank less they also grew less. Table 1 reflects an estimated cost per pound of gain based on the average feed:gain ratio for each group.

Calves fed acidified milk replacer – not medicated and calves fed regular milk replacer – medicated were the least expensive at turning milk powder into gain.

The two groups receiving acidified milk replacer (medicated and not medicated) had the largest average daily gain over the 9 week period.

¹ ² ³ Columns with different superscripts are significantly different at p<0.05.
*cost of gain based on prices from September 2012

The group receiving regular milk replacer – medicated and the group receiving acidified milk replacer – not medicated had the lowest number of health events; the number of scour cases were reduced when calves received acidified milk replacer and further reduced in calves receiving acidified milk replacer – medicated (Table 1).

Based on these results, acidifying milk replacer had a beneficial effect on milk intake consistent with previously published literature. There was a reduction in health events when calves received acidified milk replacer but were not medicated. This is different from the reduction in scours which was seen in acidified milk replacer whether animals were medicated or not.

In conclusion, the acidification process used for this trial enabled similar results to be achieved when compared to regular milk replacer and medication. With the many benefits of reducing on farm usage of medication and the significantly lower cost of organic acids as compared to medication this feeding strategy for calves can be an effective management tool.