Forb and Shrub Effects on Ruminal Fermentation in Cattle

Abstract

One experiment involving steers fed low-quality grass diets singly and mixed with native forbs, native shrubs, or alfalfa (Medicage sorival.) was conducted to compare the influence of these diets on ruminal fermentation. Native forbs used in our study were a 5050 mixture of scarlet globemallow (Splureralcea coccinea Nutt.) and leatherleaf croton (CrotonpoHsii Lam.); native shrubs were a 5050 mixture of fourwing saltbush (A&*lex canescens [Pursh.D and mountain mahogany (Cercocurpus montanus Raf.). Neither passage rate of indigestible neutral detergent fiber nor fluid passage rate differed (p>.lO) among the 4 diets. Ruminal pH did not differ (J9.10) among diets, and rumhral ammonia concentrations differed (P<.lO) inconsistently among diets, depending on time after feeding. Likewise, total rumhtal volatile fatty acid (VFA) concentrations did not differ (D.10) among diets. Except for butyrate [less (P<.O5) with alfalfa], proportions of individual VFA showed little difference among diets. Based on these data, adding forbs or shrubs with low-quality forage diets appears to elicit few changes in ruminal digesta kinetics and fermentation patterns compared to including alfalfa hay.There is considerable evidence that includingforbs and shrubs in cattle diets improves cattle performance during periods when grasses are dormant and low in quality (Holechek et al. 1989a). Several studies reviewed by Holechek et al. (1989a) show that leaves from forbs and shrubs contain more protein, phosphorus, and cell solubles than do grasses at comparable stages of maturity. In recent digestion trials with cattle , goats (Hunez-Hemandez et al. 1989), and sheep (Rafique et al. 1992), forage intake and nitrogen retention did not differ between palatable range shrubs and alfalfa (Me&ago sutiva L.) hay fed mixed into lowquality grass diets. However, these studies did not evaluate comparative ruminal fermentation characteristics of the shrub and alfalfa diets.Our objectives were to determine passage rate of indigestible, fiber, fluid passage rate, ruminal pH, ruminal ammonia (NH3) concentrations, and ruminal volatile fatty acid (VFA) proportions in beef steers fed a lowquality grass diet singly and in combination with forbs, shrubs, and alfalfa hay. Forbs and shrubs used in our study are common range components in New Mexico, and their use by cattle is well documented. Results from our study should provide a better understanding of how native range forbs and shrubs influence range cattle nutritional status.

The dissociation of the fluid and particle phase in the forestomach as a physiological characteristic of large grazing ruminants: an evaluation of available, comparable ruminant passage data

“…(1984), Prigge et al (1984), Dixon and Milligan (1985), McCollum and Galyean (1985), Merchen et al (1986), Funk et al (1987, Krysl et al (1987), Jacques et al (1989, Renecker and Hudson (1990), Tatman et al (1991), Arthun et al (1992), Spalinger et al (1993), Robbins et al (1995, citing Spalinger and Murden, unpublished article, read from graph), Kaske and Groth (1997), Behrend (2000), and the original dataset from Lechner-Doll et al (1990).…”

Effects of grass and browse consumption on the winter mass dynamics of elk

“…While we did not explore the physiological mechanism behind this result, others have revealed synergistic interactions between grass and browse in the digestive tract of elk (Baker and Hobbs 1987), and several species of domestic ruminants have also shown improved nutrition in response to mixed diets when feeding on dormant forages (RaWque et al 1988;Nunez-Hernandez et al 1991;Arthun et al 1992a, b;Bohnert et al 2002). Nitrogen intake has also been shown to positively aVect digestion and mass dynamics in several other ruminants consuming low-quality grass and browse (Arthun et al 1992b;Ngugi et al 1995;Bohnert et al 2002;Currier et al 2004;Schauer et al 2005), and increased nitrogen was correlated with reduced mass loss in elk (Table 1). However, nitrogen levels were only indirectly controlled in the original studies, and nitrogen content is often correlated with other measures of diet quality, such as digestibility, energy content and Wber fractions, all of which could aVect mass dynamics (McCorquodale 1993;Verheyden-Tixier et al 2008).…”