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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #410911

Research Project: Strategies to Manage Feed Nutrients, Reduce Gas Emissions, and Promote Soil Health for Beef and Dairy Cattle Production Systems of the Southern Great Plains

Location: Livestock Nutrient Management Research

Title: Technical Note: Optimization of indigestible neutral and acid detergent fiber measurement protocols

item Beck, Matthew - Matt
item GRIFFIN, MACKENZIE - Colorado State University
item PROCTOR, JARRET - Texas A&M University
item FOSTER, RYAN - Texas A&M University
item LONG, NATHAN - Texas A&M University
item SMITH, JASON - Texas A&M Agrilife
item GOUVÊA, VINICIUS - Texas A&M Agrilife

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2024
Publication Date: 3/27/2024
Citation: Beck, M.R., Griffin, M.L., Proctor, J.A., Foster, R., Long, N.S., Smith, J.K., Gouvêa, V.N. 2024. Technical Note: Optimization of indigestible neutral and acid detergent fiber measurement protocols. Applied Animal Science. 40(2):124-131.

Interpretive Summary: Estimations of dry matter digestibility are important in ruminant nutrition research as it influences intake, performance, and environmental impacts. Dry matter digestibility is commonly estimated using internal marker concentration in diet and feces. Indigestible neutral (INDF) and acid detergent fiber (IADF) are internal markers that are commonly used. These markers can be measured by ruminally incubating samples. A previous experiment demonstrated that a hydrochloric acid and pepsin pre-digestion (PD) of diets improved the recovery rate of IADF. However, to date there has been no investigation into using a PD when measuring INDF content. Furthermore, no experiment has assessed different ruminal incubation lengths with or without a PD of diets when measuring INDF or IADF. As such, researchers from ARS (Bushland, TX), Colorado State University, Texas A&M University, and Texas A&M AgriLife aimed to optimize INDF and IADF measurement protocols. We determined that with a PD of diet samples, a 120 hour ruminal incubation length was adequate for measuring INDF and IADF. Additionally, without a PD, a 288 hour ruminal incubation lengths are needed.

Technical Abstract: Objective: The objective of this experiment was to evaluate using a diet pre-digestion (PD) of HCl and pepsin along with different ruminal incubation lengths to determine indigestible neutral and acid detergent fiber (INDF and IADF, respectively) content for diet and fecal samples. Materials and Methods: Diet and total fecal collection samples from steers fed a starter or a finisher diet were collected from a larger experiment. Diet samples either underwent PD or not (NPD). Then, diet and fecal samples were ruminally incubated for 72, 96, 120, or 288 h. After incubation, NDF or ADF protocols were conducted to determine INDF and IADF. Results and Discussion: For PD, a 120-h ruminal incubation length was needed to achieve fecal recoveries that were not different (P = 0.33) from 100% for all marker by diet combinations. For NPD, a 288-h incubation was required to achieve 100% fecal recovery for most diet by marker combinations. When DM digestibility (DMD) was calculated for PD, 120-h incubations resulted in the highest agreement (CCC = 0.90) with observed DMD for INDF and IADF. When NPD, a 288-h incubation was needed to achieve estimates of DMD with excellent agreement (CCC = 0.89) for INDF and IADF. Implications and Applications: Based on these results, PD followed by a 120-h ruminal incubation shortens time requirements and provides acceptable measurements of INDF and IADF concentrations in feeds and feces. For NPD a 288-h ruminal incubation length is required.