Forage and non-forage fiber sources in high-concentrate diets for finishing beef steers: production and behavioral parameters

ABSTRACT: This study analyzed the ingestive behavior, productivity, and carcass characteristics of beef steers fed three different fiber sources during the finishing phase. We used 24 Angus × Nelore crossbred steers, with an initial average weight of 456 ± 50 kg and 24 months old. The experimental design was completely randomized and consisted of 3 treatments and 8 replicates (steers), totaling 68 days. The first 15 days were allocated for adaptation, and the next 53 days for evaluation. The steers were distributed in feedlots and received the following treatments (diets): SH: 20% soybean hulls; CS: 15% corn silage; and OH: 15% oat haylage. The roughage in CS and OH diets were mixed with the concentrate during feeding times (9:00 am and 3:00 pm). The OH presented the highest rumination time, number of daily chewings, and daily chewed boluses. The effective fiber in the OH treatment positively influenced the intakes of dry matter (DMI), crude protein (CPI), and total digestible nutrients (TDNI). The final weight and average daily gain (ADG) were higher for the OH treatment than for SH. Hot carcass yield and subcutaneous fat thickness were higher for the SH and OH, respectively. OH presented high DMI and nutrient intake, reflecting better animal performance. The use of soybean hulls (20% diet) as non-forage fiber source to steers exclusively fed with concentrate, result in shorter rumination time and lower animal performance. Diets with a high proportion of concentrate (85%) must be associated with a minimum of 8% physically effective NDF.