Nutritional value of ensiled grocery food waste for cattle

Assessment of nutrient variability, feed value, ensiling capability, intake, and digestibility of grocery food waste recycled from large retail stores was conducted in 3 experiments. In Exp. 1, 115 proximate nutrient analyses of grocery byproduct feed (GBP) from stores in the southern United States from April 8, 2011, to November 18, 2012, were evaluated for variation in nutrient concentration. Grocery byproduct feed was characterized as being a readily fermentable, high-moisture energy feed with an average DM content of 17.5 ± 3.7% and TDN of 89.8 ± 7.1%. In Exp. 2 and 3, grocery food waste consisting of fruit, vegetables, and bakery items from large retail stores in the Atlanta, GA, area was used for ensiling and feeding studies. The GBP material for Exp. 2 was processed on farm into homogenous slurry and treated to reduce its moisture content and preserved in experimental silos. Drying treatments included 3 levels of citrus pulp substitution (8, 16, and 24% as-fed basis), or passively removing liquid as seepage after stacking for 24 h, or oven drying (24 h at 80°C). All GBP mixtures effectively ensiled after 28 d, as determined by changes in pH, soluble carbohydrates, and fermentation acids. Ensiled GBP was moderately stable during 72-h aerobic exposure. In Exp. 3, a feeding/digestibility trial, 8 yearling Holstein steers were used in a replicated 4 × 4 Latin Square and fed 4 incremental levels of ensiled GBP in total mixed rations (TMR). Steers were fed 0, 18, 36, and 54% ensiled GBP as part of a TMR containing 68% wheat silage and 32% concentrate on a DM basis. The rations averaged 35.9, 30.7, 26.8, and 23.8% DM with incremental levels of GBP. Steers increased DM intake and digestibility when fed increasing GBP (P < 0.5). Digestible energy and TDN were linearly related to the level of GBP fed (P < 0.01). The TDN content of GBP was 82.7% (DM basis) and similar to predicted TDN values from commercial feed analyses of GBP. The feeding and nutritive value of ensiled GBP indicates it can be priced to be used effectively as an energy supplement in TMR for cattle.