I visit literarily hundreds of dairy farms across Canada each year. On most, pre-weaned dairy calves are raised away from the main lactation barn or older replacement heifer facilities. Whether these baby calves are housed in hutches, group pens or brand-new calf barns, when I find a group of calves that are sick and not growing, a lot of their poor performance can be traced back to poor nutrition causing indigestion.
I see a lot of commonality in these unfortunate situations. They often fall into four main categories of gut aches, namely: nutritional scours, abomasum bloat, rumen acidosis and hay belly. In order to take corrective action, I recommend a return to a simple calf feed and management program.
A large part of this problem stem from feeding pre-weaned calves as if they were mature dairy cows.
A newborn baby dairy calf starts off with a small, undeveloped rumen without an established microbe population (it gets this from its surrounding environment later on). It must rely upon a few selected enzymes released by its own abomasum and small intestine in order to break down simple-type essential nutrients, which are only found in milk such as casein and other milk proteins, lactose sugar, and saturated fats.
By four weeks of age, the calf’s abomasum and small intestine become a little more developed. Now, the calf’s rumen has a variety of new digestive enzymes as well as a limited type of microorganisms, which together can convert simple starches/sugars from grain-based calf starters into volatile fatty acids (VFA) which are absorbed across the rumen wall.
It is these absorbed VFAs, particularly butyric and propionic acids, which stimulate the absorptive tissue lining of the young calf’s rumen to become very active — rumen papillae elongate and the rumen walls thicken. The whole rumen grows, and the small calf is on its way to become a true ruminant.
The results of unsound programs
Rather than promote steady ruminal development in six- to eight-week-old dairy calves; many askew and unsound pre-weaned calf-feeding programs do just the opposite and cause the following digestive upsets:
1. Milk and milk replacer scours: It is frequently seen as bright yellow, cream-coloured or nearly white liquid; all signs that a recently consumed milk or milk replacer meal was poorly digested. Not only does poor milk digestion lead to poor absorption of essential nutrients that the calf requires to live and grow, but unabsorbed nutrients left in the calves’ gut tend to draw retained water from the calf’s tissues, which amplifies scouring and life-threatening dehydration.
For example, I often see milk replacer scours in calves when producers mix milk replacers at a rich 150 grams of powder per litre of solution, rather than 130 grams per litre of solution, which is the natural dry matter content of whole cow’s milk.
2. Baby calf rumen acidosis: It has been proven that pre-weaned dairy calves can get acidosis eating too much grain-based calf starter, much like a milking cow that eats too much grain. For example, the University of Tennessee (1998) fed a conventional calf starter pellet formulated with corn and other common feed ingredients to a group of milk-fed calves from one week to 12 weeks of age. As a result, these researchers found that SARA (sub-clinical rumen acidosis; depicted when pH in a cow’s rumen falls below 5.8) was reported in experimental calves at two weeks of age.
Similarly, some producers have told me that when they feed more than 3 lbs. of texturized calf starter or on a free-choice basis found that many calves seem to go off feed after a couple of days of vigorous eating of calf starter — a possible sign of acidosis.
3. Abomasum bloat: This is caused by the rapid proliferation of clostridium perfringens that produces a severe buildup of excess gas in the abomasum of pre-weaned calves. From the outside, there is severe distension on the right side of the calf, while similar ruminal bloat is distension on its left side.
Unfortunately, abomasum bloat seems to occur suddenly, and the calf often perishes before any treatment can be administered. Some research suggests that feeding higher concentrations of milk replacer than 130 grams per litre of mixed solution that supply a high level of lactose sugar to the bacterium, which may lead to a high incidence of abomasum bloat.
4. Hay belly: Many good studies prove that feeding straw or other low-quality forage for its “scratch factor” is a myth. Virginia Tech (2010) showed that two- to four-month-old calves fed a textured grower diet had similar growth to calves that were fed texturized feed plus added wheat straw. The wheat straw group did weigh 21 lbs. heavier at the end of the test, but it was attributed to 21 lbs. of gut fill and water. Similarly, I find that many calves fed in this manner suffer from semi-impaction and/or bloat — literarily walking balloons on sticks for legs.
To avoid each of these four gut ache or indigestion problems, I strongly recommend following a simply nutritious calf-feeding program.
Make sure colostrum is fed to newborn calves and afterwards provide whole milk or a milk replacer at 2.5-4.0 litres per calf per feeding (twice a day) at approximately the same times (a.m./p.m.) each day. Subsequently, start to feed a high-quality grain-based calf starter to calves at two to three weeks of age. Avoid feeding any forage until after weaning. Finally, assure that clean water is provided in addition to all whole milk or milk replacer feedings.