87150
document
Feedlot performance and carcass characteristics of Holstein steers as affected by source of dietary protein and level of ruminally protected lysine and methionine . The objective of this study was to determine the effects of source of dietary CP and level of ruminally protected lysine and methionine ( RPLM ) on feedlot performance and carcass characteristics of Holstein steers during a growing-finishing trial ( 266 d ) . A total of 168 Holstein steers ( 182.7 +/- 27.5 kg ) were used in a completely randomized design experiment ( eight treatments ; three pens of seven steers/treatment ) . Steers were given ad libitum access to high-concentrate diets ( 13 % CP ) containing 71 % whole shelled corn , 10 % corn silage , 4 % condensed distillers solubles , and 15 % protein supplements ( DM basis ) . Treatments were arranged as a 2 x 4 factorial . The main factors were two sources of dietary CP and four levels of RPLM . The sources of dietary CP were soybean meal ( SBM ) or SBM and urea ( SBM-U ) . Urea-N replaced 50 % of SBM-N in the SBM-U diet . The levels of RPLM were 0 , 5 , 10 , and 15 g per steer daily . No interactions ( P > .10 ) between source of dietary CP and level of RPLM were observed for feedlot performance or carcass characteristics . Feedlot performance showed an advantage ( P < .10 ) to feeding SMB during the first 84 d of the trial and an advantage to feeding SBM-U during the last 98 d of the trial . However , feedlot performance for the whole trial and carcass characteristics ( except for fat thickness ) were not affected ( P > .10 ) by the source of dietary CP . Steers fed diets containing SBM-U had 12 % less ( P < .10 ) fat thickness than those fed diets containing SBM . Supplementation of diets with increasing levels of RPLM did not affect ( P > .10 ) ADG or carcass characteristics . However , DMI and gain : feed showed cubic ( P < .10 ) responses to increasing dietary level of RPLM . Supplementation of RPLM at the 10 g/d level improved gain : feed by 12 % during the last 98 d of the trial , and this was a direct response to the cubic effects of RPLM on DMI . Results suggest a cost advantage for replacing 50 % of SBM-N with that from urea in high-corn diets without negative effects on feedlot performance or carcass characteristics of growing-finishing Holstein steers with extended feeding periods ( 266 d ) . These types of diets seem to meet the amino acid requirements and are not limiting in lysine and methionine .
87151
Intervention_Physical
ad libitum access to high-concentrate diets
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Intervention_Pharmacological
( 13 % CP )
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Outcome_Other
effects
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Outcome_Other
feedlot performance
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Outcome_Mental
and
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Outcome_Other
carcass characteristics
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Outcome_Other
dietary CP
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Outcome_Other
Urea-N
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Outcome_Physical
dietary CP and level of RPLM
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Outcome_Other
carcass characteristics
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Outcome_Mental
.
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Outcome_Other
Feedlot performance
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Outcome_Other
feedlot performance
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Outcome_Physical
fat thickness
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Outcome_Physical
fat thickness
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Outcome_Other
cubic ( P < .10 ) responses
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Outcome_Physical
gain : feed
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Participant_Condition
Holstein
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Participant_Sex
steers
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Participant_Condition
Holstein steers
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Participant_Sample-size
168
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Participant_Condition
Holstein steers
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Participant_Condition
182.7 +/- 27.5 kg
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Participant_Condition
Holstein steers