Abstract
ObjectiveThis study was conducted to evaluate changes in nutritional value and in situ dry matter (DM) degradability of oak and pine wood before and after steam-digestion process (60 min/160°C/6 atm) and feeding effect of the oak roughage on performance and behavior of Hanwoo steers.MethodsChemical composition and tannin concentration were analyzed for oak and pine trees before and after the pretreatment. In situ DM and effective degradability of these samples were assessed using a nylon bag method. In vivo trial was performed to estimate animal performance and behavior, using steers fed total mixed ration (TMR) diets containing 0% (control), 25% (OR-25), and 50% (OR-50) of the oak roughage. Eighteen steers were allocated into nine pens (2 steers/pen, 3 pens/treatment) for 52 days according to body weight (BW) and age.ResultsBy the steam-digestion treatment, the neutral detergent-insoluble fiber was decreased from 86.5% to 71.5% for oak and from 92.4% to 80.5% for pine, thereby increasing non-fiber carbohydrate. In situ DM degradability of treated oak reached 38% at 72 h, whereas that of untreated oak was only 11.9%. The 0 h degradability of the treated pine increased from 5.9% to 12.1%, but the degradability was unchanged thereafter. Animal performance including BW, average daily gain, DM intake, and feed conversion ratio was not different among control and oak treatments. No differences were detected in animal behavior such as lying, standing, rumination, drinking, and eating, except walking. Walking was higher in control than oak treatments with numerically higher eating and lower lying times, probably due to bulkier characteristics of rice straw in the diet.ConclusionThis study demonstrates that the oak roughage can be substituted for 50% of total forage or 100% of rice straw in TMR diets at early fattening stage of Hanwoo steers.
Highlights
In Korea, approximately 70% of the land is mountainous and is not suitable for producing forages due to concentrated precipitation along with high temperature during the summer and very cold weather in winter
Low concentrations of ash were noted for U-O, T-O, U-P, and T-P (0.91%, 0.76%, 0.36%, and 0.36%, respectively) compared to rice straw (16.7%), which is favorable in terms of intake and digestibility
The neutral detergent-insoluble fiber (NDF) values of oak were decreased from 86.5% to 71.5% by the steam digestion-milling process, and those of pine decreased from 92.4% to 80.5%
Summary
In Korea, approximately 70% of the land is mountainous and is not suitable for producing forages due to concentrated precipitation along with high temperature during the summer and very cold weather in winter. The proportion of rice straw in domestic forage is 45%, while the supply of rice straw is expected to decrease due to continuous decline in rice demand and increase in rice productivity [1]. It is necessary to search and develop roughage substitutes when the price of imported forage increases, or the supply of rice straw is insufficient. Vast amount of thinning woods is produced annually through the Forest Management Project, estimating approximately 1.3 million m3 [2].
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