What Is in My Calf Starter?

Feeding dry feed to calves is a priority for stimulating rumen development. In conjunction with an appropriate milk feeding program, feeding starter and grower feeds can maximize growth performance and help maintain calf health. As part of a research project conducted by Penn State Extension, both calf starters and weaned calf rations were analyzed to determine the nutritional content of the rations being fed on commercial dairies. The research was done on 20 Conventional and 20 Organic Dairy Farms in Central and South-Central Pennsylvania. The research revealed that farmers may not always know exactly what their calves are consuming.

As rations are formulated for any age group on farms, it is critical that the ingredients within that ration meet the nutritional requirements for that animal to not only maintain its life, but to support its health, growth, and future performance. If nutritional requirements are not met or if intakes are inadequate, farms can experience increased morbidity and mortality.

The following table shows the results of a nutritional analysis of both calf starters and weaned calf rations from farms in the research project.  

The range of protein levels found in this study raises concerns across many areas related to supporting adequate calf growth.  Severely deficient protein levels will impact skeletal growth and height. Excessive protein intake is expensive, and the surplus will be excreted in the urine, which is a nutrient management concern. Also, excreting excess protein requires energy, which can be detrimental to growth. Typical commercially available calf starters range from 18% to 24% crude protein. The correct amount of protein to be fed in a starter largely depends on the milk feeding program. Whole milk versus milk replacer will affect this decision, as well as the amount of milk being fed. High milk volumes may require less protein supplementation from starter feeds. It is also important to note that calves have separate protein requirements for maintenance and growth, and protein supplementation should be balanced to match the growth potential supported by energy intake rather than exceed it (National Academies of Sciences, 2021).

Starch also plays an important role in starter feeds. Rations deficient in starch will affect the animal’s energy status and ruminal development, leading to very thin heifers. Calves should be offered fermentable carbohydrate sources found in starter grains by two weeks of age. This is crucial for rumen development in young animals, as it supports microbial fermentation and rumen development through butyrate production (National Academies of Sciences 2021). Starch sources in commercially available calf starters most typically come from cereal grains, and starter feeds usually range between 20-40 percent starch (National Academies of Sciences 2021). Research has found that ground ingredients in pelleted feeds containing starch are digested to a greater extent than grains that are steam-rolled or flaked (Ghaffari et al., 2021). Although rapidly digestible starch sources benefit butyrate production, they can also lower ruminal pH, which increases VFA absorption but reduces saliva production (National Academies of Sciences 2021). Slowing down the digestion of starch while adding more rapidly digestible fiber sources may be the key to a balanced environment to support the development of rumen microbes in calves.

The physical form of starters also varied widely across farms, which might also be associated with differences in texture, moisture, palatability, nutritional content, and smell. Calf starter grains are not all created equal. There are many factors to consider when choosing a starter feed.  A great deal of variability is evident in the starter grains shown above.

In addition, the cost varies from starter to starter. Some farmers choose to mix and grind their own starters, often resulting in one with unknown nutritional content. While this may be a cheaper route, it may not yield the most favorable calf starter and may be detrimental to performance. These starters tend to be finely ground, as shown in the photo. Calves usually avoid dry, dusty feeds.  Dry feed ingredients can also break down into excessive fines, leading to sorting. Calves that eat pelleted starters typically exhibit less sorting if pellet integrity is strong and fines are minimal. Despite potential differences in feeding behavior, sorting may not be detrimental to calf performance and

A study by Castro, et al. (2025) examined the physical form of calf starters and measured their impact on performance and health in 24 female Holstein calves. In that study, researchers compared a textured starter with a pelleted starter. They found no difference in intake or growth performance; however, calves fed the textured starter showed better overall health outcomes, including fewer incidences of scours and better respiratory and health scores. Although further research is needed, this suggests that textured starter feeds may improve calf welfare and gastrointestinal health. These are important factors when deciding on what calf feed is right for your calf-rearing program.

Molasses is also a popular ingredient in many starter feeds. It improves palatability and reduces dust and ingredient separation in both textured and pelleted feeds. Its high sugar content entices young calves to consume more starter grains sooner. Also, the highly fermentable sugars break down into VFA’s, specifically butyrate, which encourages papillae growth in the rumen. Some starters visibly contain more molasses than others. Although there are benefits to feeding molasses, inclusion levels should be limited. Lesmeister and Heinrichs (2005) reported that starters may contain 5-12 percent liquid molasses.  The study recommends avoiding the upper limit of that value, as exceeding it will lead to negative effects. Too much molasses can decrease palatability, especially in cold weather, reduce intake, and even increase the prevalence of scours.

Youngstock are the future of the dairy herd, and heifer rearing is a crucial component in the cycle of dairy production. With so many starters on the market, choosing one can be a hard decision. Setting specific goals for the calf rearing program, in conjunction with liquid feeding protocols, is the first step in deciding which calf starter is right for your calves. While producing feed on farm may be more economical, there are many commercially available options that take the guesswork out of filling nutritional gaps.  The calf's biological needs for growth and maintenance should be considered when deciding on calf-rearing programs.

Sources:

Castro, Í.R.R., G.B.C. Leite, I.F. Carrari, L.N.C. Silva, J.C.C. Chagas, D.D. More, and M.I. Marcondes. "Effects of the Physical Form of Starter Feed on the Intake, Performance, and Health of Female Holstein Calves." Science Direct., vol. 19, no.2, 2025. Accessed June 26, 2026.

Lesmeister, K. E., & Heinrichs, A. J. (2005). Effects of Adding Extra Molasses to a Texturized Calf Starter on Rumen Development, Growth Characteristics, and Blood Parameters in Neonatal Dairy Calves. Journal of Dairy Science, 88(1), 411–418. doi.org/10.3168/jds.s0022-0302(05)72702-8

National Academies of Sciences, Engineering, and Medicine; Division on Earth and Life Studies; Board on Agriculture and Natural Resources; Committee on Nutrient Requirements of Dairy Cattle. Nutrient Requirements of Dairy Cattle: Eighth Revised Edition. Washington (DC): National Academies Press (US); 2021 Aug 30. 10, Nutrient Requirements of the Young Calf. Accessed June 30, 2026.