Feeding Dairy Cows: In Vitro NDF Digestibility

Introduction

This fact sheet has been developed to support the implementation of the Natural Resources Conservation Service Feed Management 592 Practice Standard. The Feed Management 592 Practice Standard was adopted by NRCS in 2003 as another tool to assist with addressing resource concerns on livestock and poultry operations. Feed management can assist with reducing the import of nutrients to the farm and reduce the excretion of nutrients in manure.

The Natural Resources Conservation Service has adopted a practice standard called Feed Management (592) and is defined as “managing the quantity of available nutrients fed to livestock and poultry for their intended purpose”. The national version of the practice standard can be found in a companion fact sheet entitled “An Introduction to Natural Resources Feed Management Practice Standard 592”. Please check in your own state for a state-specific version of the standard.

Conclusions reached regarding in vitro neutral fiber digestibility (IVNDFD) and its impact on lactation performance in a literature review for a symposium presentation at the 2006 ADSA/ASAS Annual Meeting (Shaver, 2006) were as follows:

• IVNDFD has been related to > milk production across an array of different forages.

• Milk production response to IVNDFD is thru DMI, and not energy density.

• DMI and milk production responses to IVNDFD > in higher producing cows.

• Benefits of brown midrib corn & sorghum silages for IVNDFD, DMI, and milk production have been observed consistently.

• More IVNDFD/in vivo research is needed with legumes & other grasses.

• Increased IVNDFD has not been fully exploited by researchers in trials attempting to maximize dietary forage or optimize forage mixtures, or by field nutritionists feeding higher forage diets with the aim of improving cow health.

Please check this link first if you are interested in organic or specialty dairy production

IVNDFD Analysis

Several commercial testing laboratories offer wet chemistry IVNDFD measurements. Ranges for IVNDFD of forages are presented in Table 1. The IVNDFD values are highly variable among and within forage types. Introduction of low-lignin, brown midrib hybrids for production of corn and sorghum silages has widened the variation in IVNDFD for these forage types (Oba and Allen, 1999b). NIRS calibrations for predicting IVNDFD on hay-crop forage and corn silage samples are available at some commercial forage testing laboratories. However, Lundberg et al. (2004) found poor prediction by NIRS of legume-grass silage and corn silage IVNDFD. It is hoped that NIRS calibration equations can be improved upon in the future.

The NRC (2001) recommended a 48-h IVNDFD for use in the NRC (2001) model, and for that reason we used 48-h IVNDFD measurements in MILK2000 (Schwab et al., 2003). However, debate continues within the industry about the appropriateness of 48-h vs. 30-h IVNDFD measurements. Some argue that the 30-h incubation better reflects ruminal retention time in dairy cows (Oba and Allen, 1999a) and that most of the in vivo trials that have evaluated effects of varying IVNDFD on animal performance also performed 30-h IVNDFD measurements (Oba and Allen, 2005). Labs and their customers also like the faster sample turn around that is afforded by the 30-h incubation time point. For that reason, and also for improved lab operation efficiency, a 24-h incubation time point is being employed by some labs. However, some argue that the 48-h incubation time-point is less influenced by lag time and rate of digestion, and thus is more repeatable in the laboratory (Hoffman et al., 2003). Hoffman et al. (2003) provided data on the relationship between 30- and 48-h IVNDFD measurements that showed a strong positive relationship (r-square = 0.84). But, the lab average at a specific incubation time point and the relationship between incubation time points within a lab can be highly variable among labs making the development of a universal incubation time point adjustment equation difficult. The average lignin-calculated corn silage NDF digestibility in the NRC (2001) is 59%. This reference point is important for adjustment of IVNDFD values from different labs and varying incubation time points so that the resultant TDN and NEL values are comparable to NRC (2001) values.

Average IVNDFD values for selected high-fiber by-product feeds (Peter Robinson, CA-Davis, personal communication) are presented in Table 2. The IVNDFD values are highly variable among these high-fiber by-product feeds. The IVNDFD values for these high-fiber by-product feeds were poorly related to lignin-calculated (NRC, 2001) NDF digestibility. High digestible NDF (dNDF; % of DM) for soy hulls and beet pulp relative to other high-fiber by-products suggest a high potential for using these ingredients at reasonable inclusion rates to partially replace forage with low fiber digestibility to increase diet dNDF. Monitoring and maintaining effective NDF in the diet is critical when employing this feeding strategy.

The distribution of 48-h IVNDFD for high-group TMR samples from commercial dairies analyzed at the University of Wisconsin Forage Testing Laboratory (Marshfield, WI; Hoffman, 2003) is presented in Figure 1 with an average IVNDFD of 57.2% of NDF. The IVNDFD range for these high-group TMR samples is wide and raises concern over intake limitations on the low end and lack of effective fiber on the high end. Analyzing for IVNDFD offers another tool for troubleshooting fiber status of dairy cattle diets.

Figure 1. Distribution of 48-h IVNDFD (% of NDF) in data set of 377 high-group TMR samples from commercial dairies analyzed at UW Soil & Forage Analysis Lab, Marshfield, WI (Hoffman, 2003).

References

• Allen, M., and M. Oba. 1996. Fiber digestibility of forages. Pages 151-171 in Proc. MN Nutr. Conf. Bloomington, MN.
• Arieli, A., and G. Adin. 1994. Effect of wheat silage maturity on digestion and milk yield in dairy cows. J. Dairy Sci. 77: 237-243.
• Aydin, G., R. J. Grant, and J. O’Rear. 1999. Brown midrib sorghum in diets for lactating dairy cows. J. Dairy Sci. 82: 2127-2135.
• Bal, M. A., R. D. Shaver, H. Al-Jobeile, J. G. Coors, and J. G. Lauer. 2000. Corn silage hybrid effects on intake, digestion, and milk production by dairy cows. J. Dairy Sci. 83: 2849-2858.
• Chase, L. E. 2003. Update on forage digestibility. Page 25 in Proc. 2003 Dealer Seminars. Cornell Univ. Coop. Ext. Anim. Sci. Mimeo Series. No. 223.
• Chow, L., M. Oba, V. Baron, and R. Corbett. 2006. Effects of advanced in vitro fiber digestibility of barley silage on dry matter intake and milk yield of dairy cows. J. Dairy Sci. 89(Suppl.1):263(Abstr.).
• Dado, R. G., and M. S. Allen. 1996. Enhanced intake and production of cows offered ensiled alfalfa with higher neutral detergent fiber digestibility. J. Dairy Sci. 79: 418-428.
• Dhiman, T. R., and L. D. Satter. 1997. Yield response of dairy cows fed different proportions of alfalfa silage and corn silage. J. Dairy Sci. 80: 2069-2082.
• Grant, R. J., S. G. Haddad, K. J. Moore, and J. F. Pedersen. 1995. Brown midrib sorghum silage for midlactation dairy cows. J. Dairy Sci. 78: 1970-1980.
• Hoffman, P. C. 2003. New developments in analytical evaluation of forages and total mixed rations. Proc. Symposium & Joint Mtg. Of WI Prof. Nutrient Applicators, WI Custom Operators, and WI Forage Council. WI Dells, WI.
• Hoffman, P. C., Lundberg, K. L., L. M. Bauman, and R. Shaver. 2003. In vitro NDF digestibility of forages: The 30 vs. 48 hour debate. Univ. of WI Extension Focus on Forage Series. Vol. 5, No. 16. http://www.uwex.edu/ces/crops/uwforage/30vs48-FOF.htm.
• Hoffman, P. C., S. J. Sievert, R. D. Shaver, D. A. Welch, and D. K. Combs. 1993. In situ dry matter, protein, and fiber degradation of perennial forages. J. Dairy Sci. 76: 2632-2643.
• Kendall, C., and D. K. Combs. 2004. Intake and milk production of cows fed diets that differed in dietary NDF and NDF digestibility. J. Dairy Sci. 87(Suppl.1):340(Abstr.).
• Ivan, S. K., R. J. Grant, D. Weakley, and J. Beck. 2005. Comparison of a Corn Silage Hybrid with High Cell-Wall Content and Digestibility with a Hybrid of Lower Cell-Wall Content on Performance of Holstein Cows. J. Dairy Sci. 2005 88:244-254.
• Llamas-Lamas, G., and D. K. Combs. 1990. Effect of Alfalfa Maturity on Fiber Utilization by High Producing Dairy Cows. J. Dairy Sci. 73: 1069-1080.
• Lundberg, K. L., P. C. Hoffman, L. M. Bauman, and P. Berzaghi. 2004. Prediction of forage energy content by near infrared reflectance spectroscopy and summative equations. Prof. Anim. Sci. 20:262-269.
• Mertens, D. R., H. G. Jung, M. L. Raeth-Knight, and J. G. Linn. 2005. Impact of alfalfa hay neutral detergent fiber concentration and digestibility on Holstein dairy cow performance: I. Hay analyses and lactation performance – USDFRC. J. Dairy Sci. 88(Suppl.1):250(Abstr.).
• National Research Council. 2001. Nutrient Requirements of Dairy Cattle. 7th rev. ed. Natl. Acad. Sci., Washington, DC.
• Oba, M. and M. S. Allen. 2000. Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 1. Feeding behavior and nutrient utilization. J. Dairy Sci. 83:1333-1341.
• Oba, M. and M. S. Allen. 1999a. Effects of brown midrib 3 mutation in corn silage on dry matter intake and productivity of high yielding dairy cows. J. Dairy Sci. 82:135-142.
• Oba, M. and M. S. Allen. 1999b. Evaluation of the importance of the digestibility of neutral detergent fiber from forage: effects on dry matter intake and milk yield of dairy cows. J. Dairy Sci. 82:589-596.
• Oliver, A. L., R. J. Grant, J. F. Pedersen, and J. O’Rear. 2004. Comparison of brown midrib-6 and -18 forage sorghum with conventional sorghum and corn silage in diets of lactating dairy cows. J. Dairy Sci. 87: 637-644.
• Raeth-Knight, M. L., J. G. Linn, H. G. Jung, D. R., Mertens, and P. R. Peterson. 2005. Impact of alfalfa hay neutral detergent fiber concentration and digestibility on Holstein dairy cow performance: II. Lactation performance – St. Paul. J. Dairy Sci. 88(Suppl.1):250(Abstr.).
• Ruiz, T. M., E. Bernal, C. R. Staples, L. E. Sollenberger, and R. N. Gallaher. 1995. Effect of dietary neutral detergent fiber concentration and forage source on performance of lactating cows. J. Dairy Sci. 78: 305-319.
• Schwab, E. C., R. D. Shaver. J. G. Lauer, and J. G. Coors. 2003. Estimating silage energy value and milk yield to rank corn hybrids. J. Anim. Feed Sci. Technol. 109:1-18.
• Shaver, R. D. 2006. Forage intake, digestion and milk production by dairy cows. J. Dairy Sci. 89(Suppl.1):298(Abstr.).
• Tessmann, N. J., H. D. Radloff, J. Kleinmans, T. R. Dhiman, and L. D. Satter. 1991. Milk production response to dietary forage:grain ratio. J. Dairy Sci. 74: 2696-2707.
• Tine, M. A., K. R. Mcleod, R. A. Erdman, and R. L. Baldwin, VI. 2001. Effects of brown midrib corn silage on the energy balance of dairy cattle. J. Dairy Sci. 84: 885-895.

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Disclaimer

This fact sheet reflects the best available information on the topic as of the publication date. Date 5-25-2007

This Feed Management Education Project was funded by the USDA NRCS CIG program. Additional information can be found at Feed Management Publications.

This project is affiliated with the Livestock and Poultry Environmental Learning Center.

Project Information

Detailed information about training and certification in Feed Management can be obtained from Joe Harrison, Project Leader, jhharrison@wsu.edu, or Becca White, Project Manager, rawhite@wsu.edu.

Author Information

Randy Shaver
Professor and Extension Dairy Nutritionist
Department of Dairy Science
College of Agricultural and Life Sciences
University of Wisconsin – Madison
University of Wisconsin – Extension

Reviewer Information

Jim Barmore – Nutrition Consultant
Pat Hoffman – University of Wisconsin

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