Loading...
Please wait, while we are loading the content...
Similar Documents
Effects of ruminally-degradable starch and ruminally-degradable protein levels on urea-nitrogen recycling , microbial protein synthesis , and nitrogen balance in beef heifers
| Content Provider | Semantic Scholar |
|---|---|
| Author | Baker, Kevin McKinnon, John J. McAllister, Tim A. Mutsvangwa, Timothy Wood, Katie M. McEwen Smith, Trevor K. Mandell, Ira B. Yiannikouris, Alexandros Swanson |
| Copyright Year | 2009 |
| Abstract | The objective of this study was to determine the effects of dietary levels of ruminally-degradable starch (RDS) and ruminally-degradable protein (RDP) on urea-N recycling to the gastrointestinal tract (GIT), microbial protein synthesis and N balance of beef heifers. Four ruminallyand duodenally-cannulated beef heifers (723 ± 57 kg BW) were used in a 4 × 4 Latin square design with a factorial arrangement of dietary treatments and 23-d periods. Dietary treatments were 2 levels (DM basis) of RDS (30% vs. 70%) and 2 levels of RDP (36% vs. 52%). Levels of RDS were manipulated by feeding whole or steam-rolled corn. All diets contained 10% CP (DM basis). Jugular infusions of [15N15N]-urea (220 mg/d) were conducted for 4 d (d 18-22), with total collection of feces and urine to estimate urea-N kinetics. Both N intake and N balance were unaffected by diet (P > 0.05), however, ruminal NH3-N concentrations were greater (P = 0.01) in heifers fed high RDP as compared to those fed low RDP (8.6 vs. 6.3 mg/dL). Endogenous production of urea-N (UER; 129.6 to 152.8 g/d) and urea-N transfer to the GIT (GER; 72.4 to 93.5 g/d) were similar across diets; however, there was a tendency for a RDS × RDP interaction for UER (P = 0.11) and UER (P = 0.10). The amount of urea-N returned to the ornithine cycle (ROC; 69.6 g/d vs. 61.9 g/d) tended (P = 0.08) to be greater in heifers fed high RDP compared to those fed low RDP. Feeding a high level of RDP increased (P = 0.03) microbial N supply to the duodenum compared to feeding low RDP. In summary, at a low dietary CP level (10%), feeding high RDP tended to increase the amount of urea-N returned to the ornithine cycle and increased microbial N supply to the doudenum compared to feeding low RDP. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.jtmtg.org/JAM/2009/abstracts/0228.PDF |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
