Effects of processing and fat content of coarse canola screenings on voluntary intake and total tract nutrient digestibility of beef steers

Abstract

The effects of feeding canola screenings on voluntary intake (VI) and nutrient digestibility by growing steers were determined in two experiments. Twelve steers were involved in the first experiment to study the effects of processing (grinding and pelleting) of canola screenings on VI and apparent total tract dry matter digestibility (DMD), crude protein digestibility (CPD), fatty acid digestibility (FAD), neutral detergent fiber digestibility (NDFD), and acid detergent fiber digestibility (ADFD). In the second experiment, the effects of fat level from canola screenings on VI and total tract nutrient digestibilities were determined using 12 steers. The fat levels tested were 67, 100, 128, and 162 g kg−1 ether extract (EE). Feeding processed canola screenings (176 g kg−1 EE) reduced (P < 0.05) VI by 31% and improved (P < 0.05) DMD, CPD, and FAD by 18, 19, and 28%, respectively. Processing of canola screenings reduced (P < 0.05) ADFD by 15% with no effect on NDFD. Increasing dietary fat level from 67 to 162 g kg−1 reduced VI in a quadratic manner (P < 0.05) and improved NDFD in a linear (P < 0.05) fashion. However, DMD, CPD, and ADFD were not affected by fat level in the diet. Total tract digestibility of fatty acids decreased linearly (P < 0.05) from 822 to 640 g kg−1 with increasing dietary fat level. The results of the study indicate that dietary fat from canola screenings at levels up to 100 g kg−1 can be fed to growing steers without detrimental effects on feed intake. Key words: Canola screenings, fat, intake, nutrient utilization, steers.