Everything in calf nutrition is debated these days. How much milk or milk replacer should be fed? Is pasteurized milk better than milk replacer? When is the best time to wean calves? Should starters be textured or pelleted? What approved drug should be included, if any? Should hay be fed?
Here we will address several issues related to dry feeds for calves less than 4 months old, based on published, expert-reviewed research.
Intake drives growth
Calf growth is positively related to intake. Energy intake drives growth in the weaned calf. Manage calves in ways to promote intake. Keep feed offered to calves fresh. Do not restrict intake by underfeeding. Always have free, clean water available.
Limit fines
There are a number of papers dating back 40 years that report that intake of starters is lowered because of fine particles. This appears to be a function of taste or preference of the calves. Large particles of grains or good-quality pellets appear to maximize feed intake in calves.
High starch
Numerous papers report more bodyweight gain of calves up to 4 months old fed high-starch versus low-starch feeds â in fact, it appears that gain increases as starch increases. Fibrous ingredients like soyhulls, wheat midds and cottonseed hulls are less digestible than cereal grains and limit digestible energy intake in calves.
Limited hay post-weaning
Feeding hay pre-weaning is debated, but there are more papers showing no benefit to negative effects than positive benefits. At birth the rumen is small (maybe as small as a baseball or smaller) and undeveloped.
Hay and fiber does not ferment to produce the volatile fatty acids that promote development of the rumen lining as well as starch does. Therefore, hay intake should be limited in the early weaned calf to 5 or 10 percent of intake.
High-quality alfalfa hays may be fed at higher rates but less than 20 percent of intake, whereas lower-quality grass hays may be more appropriate to feed at approximately 5 percent of intake. By 3½ to 4 months old, forage intake can increase since the rumen has generally grown large enough to accommodate it.
18 percent protein starters
On an as-fed basis (feed tag basis), 18 percent crude protein is adequate for calves less than 2 months old. Protein sources should be predominantly or all soybean meal.
Sources of undegraded protein have not been found to be needed, likely because rumen degradation is low in these calves. Altering the metabolizable lysine and methionine concentration of the diet from a diet based on soybean meal has not improved growth.
15 to 16 percent protein growers
On an as-fed basis, 15 to 16 percent crude protein is adequate for calves between 2 and 4 months old. Again, soybean meal appears the preferred source of protein.
Low fat
Adding fat has not improved calf growth. Some fat sources, especially those high in linoleic acid (i.e., corn and soy oils), have reduced growth. Fat has reduced intake. Watch the use of ingredients that are high in fat like distillers dried grains and roasted soybeans.
Specific fatty acids
Specific short-chain fatty acids, medium-chain fatty acids and linolenic acid are naturally low in ingredients commonly used in dry feeds.
Supplementing these fatty acids have improved bodyweight gain, frame growth and feed efficiency in calves up to at least 4 months old. Supplementing these fatty acids provides very little total fat to the diet and will not reduce intake or calf performance.
Low molasses
Studies where different amounts of cane molasses were added to feeds have resulted in the best bodyweight gains with the lowest concentration of molasses.
Young calves do not secrete the sugar-digesting enzyme sucrose, but sugar in molasses is fermented in the rumen and large intestine.
Coccidiostat
Coccidiosis is a significant problem in young calves. Include an approved coccidiostat in dry feeds for calves.
Debate
Rumen development is driven by starchy feeds that are fermented in the rumen, but some people believe digestible fiber sources are also important. Others believe hay or structural fiber is important.
Certainly some hay, or structural fiber, is needed post-weaning. The issue with feeding too much hay is that it creates a large gut and also reduces intake of starter or grower feeds that are much more digestible.
There are recent published trials that show how the rumen is developed with feeding starter, especially starch, and that the intestinal mass increases with fiber intake from hay due to fiberâs low digestibility.
When hay or structural fiber intake is high in the post-weaned calf, gut fill can increase and artificially increase bodyweight gain while not increasing muscle or frame (carcass) growth.
However, hay buffers the rumen compared to digestible fiber or additives like bicarbonate. In the weaned calf, as intake is increasing weekly, limited amounts of hay (5 to 20 percent of diet depending upon hay quality) appear to be an important dietary ingredient to stabilize the rumen.
Much more information is needed in this area, especially as relates to how to best use fibrous ingredients.
The starch in pelleted starters with finely ground grains can be fermented rapidly in the rumen. The starch in coarsely processed or whole grains should be fermented in the rumen slower than finely processed grains.
In trials comparing calf performance within the first two months of life, there appears to be little difference in calf performance between completely pelleted high-starch diets and textured high-starch diets with coarse or whole grains, provided the diets have the same ingredient and nutrient composition and there are no fines in the diets.
However, in calves between 2 and 4 months old, textured diets with coarse or whole grains supported more intake and subsequently weight gain than pelleted diets when each diet was fed with 5 percent chopped grass hay.
These differences in intake and weight gain may be caused by some rumen acidosis in calves fed the pelleted diets.
Again, we need more research in this area of calf nutrition and management.
In summary, there is good research on many factors involved in formulating dry feeds for calves (see sidebar).
However, we need more expert-reviewed research to settle some debates and to create some new debates. PD
Jim Quigley is a technical and research manager of calves and heifers for Provimi North America. Gale Bateman is a ruminant nutritionist with Akey.
Mark Hill
Ruminant Nutrition and Research
Provimi North America
