TY - JOUR
T1 - Ruminal peptide concentration required to optimize microbial growth and efficiency
AU - Fu, C. J.
AU - Felton, E. E.D.
AU - Lehmkuhler, J. W.
AU - Kerley, M. S.
PY - 2001/5
Y1 - 2001/5
N2 - Experimentation, with a single-phase continuous culture system operated at fractional dilution rates of 0.03 and 0.09 per hour and four cannulated crossbred steers (260 ± 20 kg) used in a 4 × 4 Latin square design, was conducted to determine the level of ruminally degradable protein (RDP) that maximized microbial efficiency (MOEFF), microbial nitrogen flow, and nutrient digestibility in the rumen. Treatments consisted of increasing diet RDP levels (from 3.5 to 17.5% RDP on a DM basis). The basal diet was corn with casein or soybean meal used as the source of RDP in the continuous culture experiment and animal study, respectively. Dietary nonstructural carbohydrate (NSC) ranged from 52 to 75% on a dry matter basis. Urea was added to ensure an adequate ammonia nitrogen source for microbial growth. The RDP levels did not affect true digestibility of dry matter and organic matter, ruminal pH, particulate passage rate, or liquid passage rate in the animal study. As RDP increased, bacterial nitrogen production increased linearly (P < 0.05) only for the 0.09/h dilution rate. Microbial efficiency was not influenced by RDP level. Ruminal peptide and NH3 N concentration increased linearly (P < 0.05) as RDP increased. Based on this experimentation, 1.8 mM peptide maximized MOEFF when ammonia nitrogen was not limiting (> 2 mg/dL). We concluded from this research that the RDP requirement of NSC-fermenting bacteria was lower than that currently fed in many diets.
AB - Experimentation, with a single-phase continuous culture system operated at fractional dilution rates of 0.03 and 0.09 per hour and four cannulated crossbred steers (260 ± 20 kg) used in a 4 × 4 Latin square design, was conducted to determine the level of ruminally degradable protein (RDP) that maximized microbial efficiency (MOEFF), microbial nitrogen flow, and nutrient digestibility in the rumen. Treatments consisted of increasing diet RDP levels (from 3.5 to 17.5% RDP on a DM basis). The basal diet was corn with casein or soybean meal used as the source of RDP in the continuous culture experiment and animal study, respectively. Dietary nonstructural carbohydrate (NSC) ranged from 52 to 75% on a dry matter basis. Urea was added to ensure an adequate ammonia nitrogen source for microbial growth. The RDP levels did not affect true digestibility of dry matter and organic matter, ruminal pH, particulate passage rate, or liquid passage rate in the animal study. As RDP increased, bacterial nitrogen production increased linearly (P < 0.05) only for the 0.09/h dilution rate. Microbial efficiency was not influenced by RDP level. Ruminal peptide and NH3 N concentration increased linearly (P < 0.05) as RDP increased. Based on this experimentation, 1.8 mM peptide maximized MOEFF when ammonia nitrogen was not limiting (> 2 mg/dL). We concluded from this research that the RDP requirement of NSC-fermenting bacteria was lower than that currently fed in many diets.
KW - Microbial Activities
KW - Peptides
KW - Rumen Fermentation
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U2 - 10.2527/2001.7951305x
DO - 10.2527/2001.7951305x
M3 - Article
C2 - 11374552
AN - SCOPUS:0035348075
SN - 0021-8812
VL - 79
SP - 1305
EP - 1312
JO - Journal of Animal Science
JF - Journal of Animal Science
IS - 5
ER -