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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #156250
Title: EFFECTS OF PHASE FEEDING OF PROTEIN ON PERFORMANCE, BLOOD UREA NITROGEN, AND CARCASS CHARACTERISTICS OF FINISHING BEEF CATTLE

Author
item VASCONCELOS, J. - TAES
item GREEME, L. - TAES
item Cole, Noel
item MCCOLLUM, F. - TCE
item SILVA, J. - TAES

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/2/2004
Publication Date: 7/25/2004
Citation: Vasconcelos, J.T., Greeme, L.W., Cole, N.A., Mccollum, F.T., Silva, J.C. 2004. Effects of phase feeding of protein on performance, blood urea nitrogen, and carcass characteristics of finishing beef cattle [abstract]. Journal of Animal Science Supplement. 82(1):63-64

Interpretive Summary: Forty five crossbred steers (average initial BW = 423 kg) were trained to consume their daily feed from Calan® electronic gates feeders. Steers were blocked by weight and used in a randomized block design to determine the performance, blood urea nitrogen (BUN) and USDA carcass characteristics when fed different dietary CP strategies. A finishing diet containing 10% roughage (DM basis) was formulated to contain 13% CP (DM basis) and was fed ad libitum for 62 d. Supplemental CP was provided from an equal amount of N provided by urea and cottonseed meal (CSM). On d 62, the dietary CP was maintained at 13% or reduced to 11.5% (by removing equal amounts of N from urea and CSM) or no supplemental CP. At the time of the diet change, the average BW of steers was 536 kg. Steers were harvested when they had and estimate of 25 mm of external fat. On the day of harvest (d 109) the average BW was 585 kg. Reducing the CP content of the diet to 11.5% or no supplemental crude protein did not affect (P = 0.51) ADG of steers (1.12, 1.06 and .99 kg/d for no supplemental protein, 11.5% CP and 13% CP, respectively) from d 62 to 109. The ADG of steers was similar (P = 0.85) throughout the feeding period regardless of dietary CP treatment (1.49, 1.50 and 1.45 kg/d for no supplemental CP, 11.5% CP and 13% CP, respectively). No differences among treatments were detected for BUN concentrations on d 0, 62, and 109 (P = 0.65, P = 0.49, and P = 0.12, respectively). DMI (P = 0.81), external fat thickness (P = 0.30), ribeye area (P = 0.19), and percentage of internal fat (P = 0.27) were not different. These data suggest that dietary CP levels can be reduced to conserve N during the final stages of finishing without any reduction in ADG. Reducing supplemental CP from natural CP sources will also reduce dietary P intake and subsequent excretion.

Technical Abstract: Forty five crossbred steers (average initial BW = 423 kg) were trained to consume their daily feed from Calan® electronic gates feeders. Steers were blocked by weight and used in a randomized block design to determine the performance, blood urea nitrogen (BUN) and USDA carcass characteristics when fed different dietary CP strategies. A finishing diet containing 10% roughage (DM basis) was formulated to contain 13% CP (DM basis) and was fed ad libitum for 62 d. Supplemental CP was provided from an equal amount of N provided by urea and cottonseed meal (CSM). On d 62, the dietary CP was maintained at 13% or reduced to 11.5% (by removing equal amounts of N from urea and CSM) or no supplemental CP. At the time of the diet change, the average BW of steers was 536 kg. Steers were harvested when they had and estimate of 25 mm of external fat. On the day of harvest (d 109) the average BW was 585 kg. Reducing the CP content of the diet to 11.5% or no supplemental crude protein did not affect (P = 0.51) ADG of steers (1.12, 1.06 and .99 kg/d for no supplemental protein, 11.5% CP and 13% CP, respectively) from d 62 to 109. The ADG of steers was similar (P = 0.85) throughout the feeding period regardless of dietary CP treatment (1.49, 1.50 and 1.45 kg/d for no supplemental CP, 11.5% CP and 13% CP, respectively). No differences among treatments were detected for BUN concentrations on d 0, 62, and 109 (P = 0.65, P = 0.49, and P = 0.12, respectively). DMI (P = 0.81), external fat thickness (P = 0.30), ribeye area (P = 0.19), and percentage of internal fat (P = 0.27) were not different. These data suggest that dietary CP levels can be reduced to conserve N during the final stages of finishing without any reduction in ADG. Reducing supplemental CP from natural CP sources will also reduce dietary P intake and subsequent excretion.