Limit-feeding of heifers offers the potential to reduce cost and improve feed efficiency. But limit-fed heifers spend less time feeding, and the animals may engage in certain behaviors that show their frustration with the feed restrictions and lack of satiety in some cases.
Providing supplementary straw alongside a limit-fed TMR has been found to help alleviate some of these behavioral concerns, point out researchers at the University of Guelph in Canada in an article in the June edition of the Journal of Dairy Science.
“Heifers offered straw in addition to their TMR spent more time feeding and had higher (dry matter intake), while still gaining benefit from feed efficiency, when compared with animals that are fed ad libitum a high-forage diet,” they write. So, the question becomes: If you are going to offer straw, is it better to offer larger amounts of long straw in comparison to short straw?
The researchers set up an experiment involving 10 Holstein heifers with access to a limit-fed ration, along with long-particle oat straw (85 percent of particles greater than 8 millimeters) and short-particle oat straw (45 percent of particles greater than 8 millimeters). The heifers chose to consume similar amounts of long straw and short straw. But the long straw appeared to have some advantages. Although the heifers consumed similar amounts of long straw and short straw, they spent more time consuming the long straw at a slower rate across the day.
“When given the choice, heifers prefer to consume long straw, perhaps in an effort to maximize their foraging needs or to increase satiety through sufficient rumen fill,” the researchers wrote. Therefore, “it is recommended to offer a supplementary low-nutritive feedstuff alongside of a TMR to allow limit-fed heifers to engage in feeding patterns more conductive to natural behavior and to alleviate frustration and hunger due to insufficient foraging or rumen fill.”