Besides the widely discussed negative environmental effects of dairy production, such as greenhouse gas emissions, the feeding of large amounts of potentially human-edible feedstuffs to dairy cows is another important sustainability concern. The aim of this study was therefore to investigate the effects of a complete substitution of common cereal grains and pulses with a mixture of wheat bran and sugar beet pulp in a high-forage diet on cow performance, production efficiency, feed intake, and ruminating behavior, as well as on net food production potential. Thirteen multiparous and 7 primiparous mid-lactation Holstein dairy cows were randomly assigned to 1 of 2 treatments in a change-over design with 7-wk periods. Cows were fed a high-forage diet (grass silage and hay accounted for 75% of the dry matter intake), supplemented with either a cereal grain-based concentrate mixture (CON), or a mixture of wheat bran and dried sugar beet pulp (WBBP). Human-edible inputs were calculated for 2 different scenarios based on minimum and maximum potential recovery rates of human-edible energy and protein from the respective feedstuffs. Dietary starch and neutral detergent fiber contents were 3.0 and 44.1% for WBBP, compared with 10.8 and 38.2% in CON, respectively. Dietary treatment did not affect milk production, milk composition, feed intake, or total chewing activity. However, chewing index expressed in minutes per kilogram of neutral detergent fiber ingested was 12% lower in WBBP compared with CON. In comparison to CON, the human-edible feed conversion efficiencies for energy and protein, defined as human-edible output per human-edible input, were 6.8 and 5.3 times higher, respectively, in WBBP under the maximum scenario. For the maximum scenario, the daily net food production (human-edible output minus human-edible input) increased from 5.4 MJ and 250 g of crude protein per cow in CON to 61.5 MJ and 630 g of crude protein in the WBBP diet. In conclusion, our data suggest that in forage-based dairy production systems, wheat bran and sugar beet pulp could replace common cereal grains in mid-lactation dairy cows without impairing performance, while strongly increasing human-edible feed conversion efficiency and net food production index.
