Feeding straw can help solve behavioral problems in dairy heifers consuming limit-fed rations, say researchers at the University of Guelph, Ontario.

They point out that limit-feeding replacement heifers controls growth while reducing feed costs and increasing efficiency. But it also poses behavioral concerns.

Twenty-four Holstein heifers were divided into groups of four and exposed to three replicated, 28-day treatments: total mixed ration (TMR), TMR with straw offered as a choice, and TMR with straw mixed in. The TMR contained 19% haylage, 21% corn silage, 45% high-moisture corn and 15% protein supplement.

Feeding behavior was recorded for the last 14 days of each period, standing time was recorded for the last seven days, and rumination behavior was recorded twice each of the last two weeks. Dry matter intake for each group was measured daily and body weights were recorded weekly.

Dry matter intake was lowest for heifers fed the TMR and no straw, but feed efficiency was better than for the other two treatments. Average daily gain tended to be lowest for the TMR with straw mixed in. Daily feeding time averaged 76.1 minutes for TMR-only heifers, compared with 207 minutes for those offered straw as a choice and 279 minutes for animals eating the TMR that included straw. TMR-only heifers tended to do less ruminating than the others.

“The results suggest that provision of straw as a choice, alongside a limit-fed ration, will allow heifer growth rates to be targeted, as well as provide a suitable foraging source that heifers can use to satisfy their natural feeding behavior patterns,” say the researchers.