Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 30, 2007
Publication Date: August 1, 2007
Citation: Cole, N.A. 2007. Opportunities to enhance performance and efficiency through nutrient synchrony in concentrate-fed ruminants [abstract]. In: Journal of Animal Science Abstracts, from 2007 Joint Meeting of American Society of Animal Science, July 8-12, 2007, San Antonio, Texas, Volume 85, Supplement 1, p.125. Technical Abstract: Synchronization of the ruminal degradation of carbohydrates and crude protein (CP) is projected to increase ruminal microbial protein synthesis, and improve nitrogen (N) use efficiency. Attempts to synchronize the fermentation of dietary carbohydrates and CP have been met with mixed results, suggesting that either ruminal nutrient synchrony is not important or that N recycling to the rumen is offsets lack of synchrony. Nitrogen recycling is controlled by the concentrations of urea in the gut and blood, and the availability of fermentable energy in the gut. We hypothesized that N utilization could be improved by synchronizing the supply of nutrients in one segment of the gut with those in another segment (i.e., synchronize a ruminal N deficiency with a lower gut N excess, etc.) via oscillating the dietary CP between deficient and adequate concentrations. With corn-based diets and oil-seed based natural protein supplements, N retention has been greater in lambs or steers fed oscillating CP concentrations (at 48-h intervals) than in animals fed a constant CP percentage. Effects of oscillating CP on cattle performance have been variable and may depend upon the fermentability of the carbohydrate source (e.g., forage vs. grain, grain processing). In agreement with our hypothesis, Archibeque et al. (2007) reported that net portal uptake of urea was greater in lambs fed oscillating CP than in lambs fed constant CP concentrations. Nutrient intakes also need to be synchronized with the animals’ requirements. One method to adjust nutrient intake with requirements is via phase- feeding. Results of studies with dry-rolled corn-based diets indicate that dietary CP concentrations can be decreased late in the feeding period with no adverse effects on animal performance; however, results of studies using steam-flaked corn-based diets are less consistent, possibly due to differences in the aggressiveness of the implant program used. In conclusion, ruminal nutrient synchrony is theoretically a sound principle; however, it seems that N recycling may mitigate effects of asynchrony. Thus, methodologies that increase N recycling and/or increase the utilization of recycled N may benefit animal performance and the environment.