Influence of pressed beet pulp and concentrated separator byproduct on intake, gain, feed efficiency, and carcass composition of growing and finishing beef steers

¹ Department of Animal and Range Sciences North Dakota State University, Fargo 58105

^* To whom correspondence should be addressed. E-mail: Marc.Bauer{at}ndsu.edu.

	Abstract

The objectives of this experiment were to determine a NE value for pressed beet pulp and the value of concentrated separator byproduct (de-sugared molasses) as a ruminal N source in growing and finishing diets for beef cattle. One hundred forty-four crossbred beef steers (282 ± 23 kg initial BW) were used in 2 experiments (growing and finishing). A randomized complete block design was used with a 3 x 2 factorial arrangement (level of pressed beet pulp and inclusion of concentrated separator byproduct) of treatments for both studies. Steers were blocked by BW and allotted randomly to 1 of 6 treatments. The growing study control diet contained 49.5% corn, 31.5% corn silage, 10.0% alfalfa hay, and 9.0% supplement (DM basis). Pressed beet pulp replaced corn at 0, 20, or 40% of dietary DM and concentrated separator byproduct replaced corn and urea at 10% of dietary DM. The growing study lasted 84 d. Initial BW was an average of 2-d BW following a 3-d restricted feeding period (1.75% of BW) of 50% alfalfa hay and 50% corn silage (DM basis). Growing study final BW was an average of 2-d BW following a 3-d restricted feeding period (1.75% of BW) of 31.5% corn silage, 10.0% alfalfa hay, 25.0% dry-rolled corn, 20.0% pressed beet pulp, 5.0% concentrated separator byproduct, and 8.5% supplement (DM basis). Following the growing study, steers were weighed (415 ± 32 kg), re-randomized, and allotted to 1 of 6 finishing diets. The control diet for the finishing study included 45% dry-rolled corn, 40% high moisture corn, 5% brome hay, 5% pressed beet pulp, and 5% supplement. Pressed beet pulp replaced high moisture corn at 5.0, 12.5, and 20.0% of the dietary DM and concentrated separator byproduct replaced high moisture corn and supplement at 10.0% of diet DM. Steers were slaughtered on d 83 or 98 of the study. In the growing study, addition of pressed beet pulp to growing diets linearly decreased (P = 0.001) DMI and ADG and inclusion of 10% concentrated separator byproduct decreased (P = 0.001) G:F. Increased levels of pressed beet pulp in finishing diets caused a linear decrease (P = 0.001) in ADG and tended (P = 0.06 and 0.07 for kg/d and % of BW, respectively) to quadratically decrease DMI. Whereas, addition of concentrated separator byproduct increased (P = 0.02 and 0.001 for kg/d and % of BW, respectively) DMI. Apparent NEg of pressed beet pulp was 94.2% that of corn in the growing study and 81.5% that of corn in the finishing study.

Key Words: pressed beet pulp, concentrated separator byproduct, cattle, feedlot