Incorporation of Grass Straw Nuggets into Dairy Heifer Diets
D. J. Carroll, M. Gamroth, M. Keller, and K. E. Nickell
Department of Animal Sciences, Oregon State University, Corvallis, July 1996
RESEARCH QUESTION
Restrictions on field burning in Oregon have resulted in an abundance of grass seed straw. A process has been developed by Harvest Feed, Inc. where grass straw can be mixed with other feeds and compressed into a nugget. Feeding the nugget to dairy heifers located in the Willamette Valley would keep transportation costs low. The nutritional value of the nuggets for heifers is unknown.
The goal of this study was to feed grass straw nuggets to dairy heifers to evaluate performance, and to establish laboratory procedures so grass straw products can be evaluated for energy content.
LITERATURE SUMMARY
A 100% grass straw (Tall fescue) nugget and a 25:75% alfalfa hay to grass straw nugget was fed to beef steers in eastern Oregon by Tim DelCurto. The steers increased intake from 2 to 3.25% of their body weight when fed the 25:75% nugget compared to long stem fescue hay fed alone. The increased palatability of the grass straw in the form of the nugget encouraged us to test the feed with growing dairy replacement heifers.
STUDY DESCRIPTION
Six experiments were performed to evaluate a 60% grass straw nugget. 1) To test three methods of transitioning heifers to a nugget diet. 2) To evaluate the dry matter intake of two age groups of Holstein heifers. 3) To formulate nuggets that will meet the nutrient requirements of growing heifers and perform a digestion trial. 4) To run a performance trial to evaluate heifer growth for two age groups. 5) To develop standards from the digestion trial that can be used to establish in-vitro dry matter digestibility procedures in nutrition labs. 6) To test procedures for estimating energy density of poor quality forages.
APPLIED QUESTIONS
How do the heifers adapt to the nuggets?
The heifers take 3 or 4 days to return to previous dry matter intakes after being offered the nuggets for the first time.
What is the dry matter intake of the nuggets? Holstein heifers ate about 2% of their body weight on a daily basis; heifers on the various control diets ate from 2.1 to 2.3% on a body weight basis.
What was the energy (TDN) value of the nuggets? The nugget used in this project was 60% grass straw, 20% alfalfa hay and 20% by-product feed. The TDN was approximately 50% when calculated by the digestion trial. Estimate of TDN from the in-vitro dry matter digestibility assay was 50 to 53%; from the extensive laboratory assays developed by Weiss, the TDN was 61.5% and from the traditional ADF prediction equation used in forage analytical labs, the TDN was 65 to 69% TDN. In order of accuracy, the best estimate of TDN was the digestion trial, followed by the IVDMD assay, Weiss lab equations and ADF prediction equations.
Can this grass straw nugget be used to feed dairy heifers? The younger heifers (7 to 12.5 mo.) and the older heifers (15.3 to 22.1 mo.) had an average daily gain of 2.15 lbs on the nugget diet and 2.1 vs. 2.6 lbs on the control diet. Heifers on both diets met or exceeded industry standards for wither height and weight gain.
Turner, B., F. Conklin, D.J. Carroll, T. Cross, and T. DelCurto. 1995. Feeding Oregon's Grass Straw to Livestock: Economic and Nutritional Considerations. OSU Experiment Station Special Report 952. 61 p.
