Effects of forage level in broiler litter-based diets on feed intake, digestibility and particulate passage rate in Holstein steers at different live weights

Sixteen Holstein steers were used in a split-plot experiment to determine influences of dietary inclusion of broiler litter and level of forage in litter-based diets on feed intake, digestibility and particulate passage rate at different body weights. Body weight (BW) at the end of four 3 week periods, separated by periods of 3 weeks or more, was 151 ± 2.3, 190 ± 3.1, 252 ± 3.7 and 298 ± 3.8 kg in Period 1, 2, 3 and 4, respectively. All steers consumed approximately 1% BW (dry matter) of ground corn; bermudagrass (Cynodon dactylon) hay (76% neutral detergent fiber) was consumed ad libitum (Control) or at 0.3 (L), 0.6 (M) or 0.9% BW (H; dry matter); and L, M and H steers consumed ad libitum deep-stacked broiler litter (29% crude protein, 19% ash and 43% neutral detergent fiber). Intake of organic matter (OM) was increased (P < 0.05) by dietary inclusion of litter in each period (Period 1: 4.20, 4.93, 4.75 and 4.92; Period 2: 5.63, 5.97, 6.43 and 6.64; Period 3: 6.92, 8.05, 8.15 and 8.58; Period 4: 7.89, 9.60, 9.58 and 9.55 kg day−1 for Control, L, M and H, respectively). Digestible OM intake did not differ between Control and litter diets but increased linearly (P < 0.05) as level of hay in litter diets increased (3.91, 3.81, 4.05 and 4.06 kg day−1 for Control, L, M and H, respectively; SE 0.067). Particulate passage rate for Yb-labeled hay was greater (P < 0.05) for diets with than without litter, and changed quadratically (P = 0.05) as hay level in litter diets increased (3.45, 5.42, 4.31 and 4.85% h−1 for Control, L, M and H, respectively). In conclusion, optimal forage level in broiler litter-based diets for high digestible OM intake by growing Holstein steers appeared to be at least 0.6% BW (i.e. 15% of dry matter intake).