Growth efficiency and digestibility of heated protein fed to growing ruminants.
Four trials were conducted to evaluate digestibility and growth efficiency caused by feeding heat-damaged protein. In Trial 1, 60 lambs (18.6 kg) were fed diets containing corn gluten meal (CGM) at five levels either of control (CGM-C) or heat-damaged (CGM-H), along with urea as the main supplemental N source. Efficiency of protein used for growth was determined by the slope-ratio technique. The heat damage to CGM decreased (P < .001) protein efficiency by 46%. In Trial 2, diets with the three highest CGM levels from Trial 1 were fed to 18 of the same lambs in a digestion trial. True N digestibility (TND) was 108% for CGM-C and was decreased (P < .05) 22% by heat damage. In Trial 3, 90 growing cattle (219 kg) were individually fed one of three protein supplements for 56 d. The protein supplement contained either a control source of dried distillers grains (DDG-C) or a heat-damaged source (DDG-H) at five levels, and a urea treatment was used as a negative control. Protein efficiency of DDG protein determined by the slope-ratio technique was decreased (P < .05) 34% by heat damage. In Trial 4, four yearling heifers (265 kg) were used in a 4 x 4 Latin square design to determine N digestibility of three diets used in Trial 3 (plus a diet not reported herein). True N digestibility averaged 98% for DDG-C and was decreased 7% by heat damage. These data suggest that some of the N in heat-damaged protein was absorbed postruminally but was not used for growth by growing ruminants.
Nakamura
T
T
Department of Animal Science, University of Nebraska, Lincoln 68583-0908.
Klopfenstein
T J
TJ
Gibb
D J
DJ
Britton
R A
RA
D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000254:growth & development* / Q000502:physiology; D004044:Dietary Proteins / Q000008:administration & dosage*; D004063:Digestion; D005260:Female; D005527:Food, Fortified; D006358:Hot Temperature; D008297:Male; D009584:Nitrogen / Q000008:administration & dosage / Q000378:metabolism; D009753:Nutritive Value; D012756:Sheep / Q000254:growth & development* / Q000502:physiology; D014508:Urea / Q000008:administration & dosage; D015430:Weight Gain; D003313:Zea mays
D004044:Dietary Proteins; D014508:Urea; D009584:Nitrogen