Dairies rely greatly on feeding high-quality forages, which in turn produce quality dairy products. Unforeseen circumstances, such as droughts or floods, lower the availability of these forages and tack on expenses. When this occurs, dairies must make the best of the situation and have a backup plan in place. One common strategy is feeding a low-quality forage ration to minimize expenses while maintaining quality milk production.

Low quality considerations

In a recent Hoard’s Dairyman webinar, Kirby Krogstad, assistant professor at The Ohio State University, explained the concerns and results of feeding low-forage rations. Krogstad emphasized that there will always be cases where producers cannot feed the forage they want to, but in these circumstances, they make the best of rough situations.

One of the main considerations when transitioning a dairy herd to a low forage diet is feed intake and digestibility. Farmers need to be prepared to change their benchmarks for their cows as they make this transition. “The amount of feed the animals can digest in the rumen will change, which means that the benchmark should shift,” Krogstad said. Many assume that feeding low-quality forages lower digestibility, but Krogstad reiterated that isn’t always the case. “It depends on the surrounding carbohydrates,” he said. Milkfat concentration and yield are also a consideration. With low forage quality, milkfat concentration normally declines, but Krogstad mentioned despite the drop, it does not necessarily mean that it will remain that way.

Be mindful

The two main concerns with a low-forage diet is rumen acidosis and inflammation. Rumen acidosis occurs when the pH drops in the rumen, leading to inflammation and other health issues. The most common type is sub-acute ruminal acidosis (SARA). SARA occurs when the rumen pH is less than 5.6 for three hours per day or a pH of 5.8 to 6 for five hours a day,” Krogstad said. In one of Krogstad’s studies, cattle were switched from a 22% forage neutral detergent fiber (NDF) to an 18%. The rumen only dropped by roughly one or two tenths. “If you transition properly, you will see a reduced pH, but it will not be a concern,” Krogstad noted. Other issues result from inflammation caused by starch. Krogstad explained that you must find the sweet spot in starch concentrations. “If you have too little, you’ll miss out on milk and protein production,” he said, “and too much causes milkfat depression, SARA, and inflammation,” Krogstad stated that the optimal ration consists of an NDF between 17% to 27% and a 20% starch concentration.

While feeding high-quality forages is optimal, certain circumstances can prevent that from being possible. During those times, transitioning to a low-quality forage ration is the best option. In doing so, milkfat and rumen pH lower; however, properly transitioning cattle can minimize the incidence of rumen acidosis and inflammation. Krogstad plans to research outlying questions such as the impacts of sugars, the various forage sources, and processing in a low-forage diet in upcoming research.