Feed is an important end use of barley (Hordeum vulgare L.). Recent research has identified high starch content, low acid‐detergent fiber (ADF), low ruminal dry‐matter digestibility (DMD), and large particle size after dry rolling as desirable barley feed‐quality characteristics for beef cattle. Knowledge about the variation available may help barley breeders develop strategies for feed‐quality improvement. Our objective was to estimate the variation in feed‐quality characteristics in barley around the world. The spring barley core subcollection from the USDA‐ARS National Small Grains Collection was planted in 1995. Ruminal DMD of 1480 accessions was evaluated. Seventy‐three accessions, selected on variation in DMD, were planted in two field replications in 1996 and 1997. These 73 accessions were evaluated for starch, DMD, ADF, and particle size after dry rolling. The range in DMD was 82 to 621 g kg−1, with a mean of 398 g kg−1 (SD = 75 g kg−1). The ranges for other traits of the 73 selected accessions were 387 to 593 g kg−1 (starch); 15 to 96 g kg−1 (ADF); 187 to 510 g kg−1 (DMD); and 1118 to 1572 μm (particle size). Six‐row types had greater ADF and particle size (P < 0.001), lower starch, and DMD (P < 0.001), compared with 2‐row types. Starch was higher (P < 0.01), and ADF and DMD were lower (P < 0.01), for hulless than for hulled accessions. Substantial variation in the spring barley core collection for feed quality‐related characters could be exploited to develop barley cultivars for feed quality.

We conducted two experiments to determine the effects of monensin addition on digestion of high-concentrate diets based on corn or barley and to identify any interactions between grain source and monensin addition. A replicated in vitro experiment with a 2 x 4 factorial arrangement was used to evaluate monensin addition (0 or 72 mg/kg in vitro substrate) and grain source (corn, Gunhilde barley [GUN], Harrington barley [HAR], or Medallion barley [MED]). Triplicate tubes for each treatment were incubated for 0, 3, 6, 9, 12, 18, 24, and 30 h. Rate and extent of IVDMD were determined. Four ruminally and abomasally cannulated steers were used in a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments to test the effects of monensin addition (0 vs 270 mg x steer(-1) x d(-1)) and grain source (70% corn vs 80% Medallion barley). Diets were balanced to be isocaloric and isonitrogenous. An interaction (P < .10) was found between monensin addition and grain source for IVDMD during 3 through 9 h of incubation. Monensin increased the IVDMD of GUN and MED, but it decreased the IVDMD of HAR. Corn IVDMD was not affected by monensin addition. Steers fed Medallion barley had greater (P < .05) microbial protein synthesis, rate of in situ DM and starch disappearance, ruminal and postruminal digestion of starch, ruminal total VFA concentrations, and total tract digestion of DM, OM, and starch compared with steers fed corn. Monensin addition decreased (P < .10) ruminal digestion of feed N and ruminal proportions of acetate and butyrate and increased (P < .001) the ruminal proportion of propionate. No monensin x grain source interactions were observed for the variables measured in vivo.

No abstract

No abstract

No abstract