Effect of recovered grocery food substituted for corn grain and molasses on milk production and total-tract digestibility in lactating dairy cows

A large proportion of human food is lost during storage, processing, and distribution and has a large impact on the efficiency and environmental footprint of the food system. Grocery stores and other distributors provide a convenient point for the industrial collection and recovery of unsalable food items such as fruits, vegetables, bakery items, and other products that can be diverted into animal feed, reducing disposal costs and methane production associated with landfilling and composting while upcycling nutrients. Twenty primiparous and 28 multiparous Holstein cows were blocked by parity and milk production and randomly assigned to either control or a TMR containing recovered grocery food at 7.5% or 15% of diet DM for 40 d in an incomplete randomized block design. Recovered grocery food was collected from several grocery stores and was delivered to the farm approximately every 4 d and was stored on a concrete pad. The average pH of the product before feeding was 3.5 and was never above 4.5. Recovered grocery food averaged 33.2% NDF, 14.3% starch, 10.9% water-soluble sugars, 15.5% CP, and 17.9% total fatty acids. There was a treatment by parity interaction for DMI. The recovered grocery food decreased DMI on d 7 in both parity groups, but intake then progressively increased. Multiparous cows were not different from the controls after d 21 and the grocery food increased intake in primiparous cows after 21 d. There was no main effect of treatment or interactions of treatment and time or treatment and parity on milk yield or milk fat percentage or yield, but there was a quadratic effect of treatment on milk yield on d 21. There was a treatment by time interaction on milk protein concentration with a linear decrease from d 21 to 40 (3.15% vs. 3.01%). However, there was no effect of treatment on milk protein yield. Milk urea nitrogen was linearly increased with increasing grocery product inclusion. There was no effect on total-tract DM digestibility, but NDF and fatty acid digestibility were linearly increased by the recovered grocery food. The grocery product maintained a very low pH and a relatively stable nutrient composition during the experiment. Feeding up to 15% of the ration as recovered unsaleable grocery fruit, vegetables, and bakery products in place of molasses and ground corn maintained milk and milk component production and increased fiber digestibility, providing evidence that this byproduct can be effectively used in rations of lactating dairy cattle.