Grass hay can support IOFC in high-producing dairy cows

Tim Lundeen

October 02, 2020

Citing a chronic low milk price scenario that reduced revenues and negatively affected the profitability of U.S. dairy farms, Gonzalo Ferreira and Christy Teets with the Virginia Tech department of dairy science recently completed a study that evaluated production performance and economics of high-producing dairy cows consuming diets containing either alfalfa or grass hay.

The low milk prices caused farmers to maximize income over feed costs (IOFC) by increasing milk production, reducing feeding costs or both, Ferreira and Teets said in an article published in the October issue of Applied Animal Science. For the study, Ferreira and Teets randomly assigned 24 Holstein cows to one of four diets in a replicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments — hay (either alfalfa hay or grass hay) and grain types (corn grain or wheat grain) — and 21-day periods. Regardless of treatment, corn silage was the major forage in all treatments, the researchers pointed out.

Diets were formulated using a least-cost approach. To determine revenues from milk produced, the amount of energy-corrected milk (ECM) was multiplied by 30.3 cents/kg (i.e., class III milk price; U.S. Federal Milk Marketing Order 5). The cost of the ration provided by the formulation software was divided by the predicted dry matter intake (DMI) to obtain the cost of feed, which was then multiplied by DMI to provide the actual daily feed cost, Ferreira and Teets explained.

According to the researchers, cows consuming diets containing alfalfa hay consumed more dry matter than cows consuming diets with grass hay, at 27.1 kg versus 24.4 kg per day. Cows consuming diets containing alfalfa hay also produced more milk than cows consuming diets containing grass hay, at 47.5 kg versus 44.7 kg per day. On the other hand, Ferreira and Teets noted that milk from cows consuming grass hay diets had greater fat concentrations than milk from cows consuming alfalfa diets, at 4.22% versus 3.89%.

Using hay prices of $418 and $154 per ton, respectively, for alfalfa and grass hays, diets containing grass hay resulted in greater IOFC than diets containing alfalfa hay, at $8.39 versus $7.68 per day, respectively, Ferreira and Teets reported.

The researchers concluded that IOFC can be supported when feeding grass hay using a least-cost ration formulation approach.

Ferreira and Teets explained that despite quality differences between the two hays, results from this study showed that IOFC can be supported with less-expensive locally grown hay, such as mixed-grass hay.

They said this is because in dairy farming systems, hays are a component of a diet and not a major ingredient, and cows require nutrients and not ingredients. Therefore, when physically effective fiber is required, grass hay can be a suitable ingredient in properly formulated rations for high-producing dairy cows, Ferreira and Teets noted.