Calf starter programs can significantly impact how well a calf transitions from milk replacer or milk to a grower ration. The transition to solid feed is very important in the development of a functioning rumen. Establishment of rumen microflora and proper development of rumen papillae increase the digestive capability of the growing calf. Rumen development is dependent on microbial fermentation (mainly the presence of volatile fatty acids butyrate and propionate) and, to a lesser extent, physical stimulation. Because butyrate and propionate are produced primarily from the fermentation of grains, the calf starter feed plays an important role in the development of the rumen.

Most starter feeds are a combination of protein and grain sources with appropriate minerals and vitamins, and are available in different physical forms. Physical forms of typical starters include either whole corn or processed corn, or starter in the form of a pellet. Although research comparing calf starters of different physical forms is limited, the available research indicates no differences in growth rates or starter intakes of calves consuming different starter forms. In an abstract recently presented (June 1999) at the American Dairy Science Association meetings, starter formulations utilizing corn processed several different ways were compared. No differences in weight gain of the calves through 38 days of age were observed when the complete formulation was pelleted or when corn was steam flaked, rolled, roasted, or fed whole. Consumption of the starter was similar among the different processing methods.

Several trials have been conducted by ADM Alliance Nutrition comparing pelleted starters to texturized starters containing whole corn and oats. Most of these studies have shown similar performance (growth and intake) of the calves. University trials compared finely ground starters to unprocessed or coarsely ground starters. Weight gains at ten weeks of age were similar among calves regardless of starter form.

The limited data available also suggest physical form of the starter feed has little effect on the ruminal development of the calf. Finely ground formulations were similar to unprocessed starters in total rumen bacterial numbers and rumen weight. In a separate study, finely ground starters were also found to be similar to intermediate or coarse-textured starters in rumen weight gain. In both of these studies, rumen papillae length was increased somewhat by finely ground starters. A previous study indicated finely ground starters can lead to keratinization of the rumen wall which decreases the absorptive capability of the rumen. The keratinization was not observed in a subsequent experiment.

Conclusion
The starter feed is an important component of a heifer development program. It is important economically and nutritionally to get the calf consuming solid feed as rapidly as possible. Intake and acceptance of the starter is important. A review of the existing research indicates the physical form of the starter does not influence the intake or performance of the weaned calf.