In situ rumen degradation characteristics of sixty cultivars of barley grain

Abstract

In situ rumen degradation characteristics of sixty cultivars of barley grain. Can. J. Anim. Sci. 80: 691-701. Our objectives were to determine the extent of genetic variability in the rate and extent of ruminal digestion among 60 cultivars of barley, and to evaluate the correlations between ruminal digestion characteristics and chemical composition and test weight of barley cultivars. Barley samples were ground through a 2-mm screen, and bags containing 1 g of ground grains were incubated in the rumen of three late-lactation Holstein cows with rumen cannulae for 0, 1, 2, 4, 8, 12, 16, and 24 h. The rate and extent of ruminal digestion were estimated. The insoluble DM fraction ranged from 33.4 to 56.4%, the degradable DM fraction ranged from 34.1 to 60.2%, and the rate of degradation of DM ranged from 0.200 h -1 to 0.624 h -1 . Hulled barley cultivars had lower (P < 0.05) soluble and degradable fractions than hulless cultivars. The soluble fraction was positively correlated to starch content of barley cultivars (P = 0.01) and the degradable fraction was correlated to the test weight and CP content (P < 0.01). The observed variability in the ruminal digestion characteristics of barley cultivars indicates that genetic selection holds promise as a means of enhancing the nutritional quality of barley for ruminants. We also observed that 70% of the variation in digestibility could be explained by measures of bulk density, starch content, and kernel weight. La fraction soluble marquait une corrélation positive avec la teneur en amidon du grain (P = 0,01) et la fraction dégradable avec le poids spécifique et avec la teneur en PB (P < 0,01). À partir de la variabilité observée des caractères de digestion ruminale des divers cultivars d'orge, on peut conclure que la sélection génétique offre des possibilités d'améliorer la qualité nutritionnelle de l'orge pour les ruminants. Nous avons constaté en outre que 70 % des variations de la digestibilité pourraient s'expliquer par la densité apparente, par la teneur en amidon et par le poids individuel du grain.

Effects of bulk density, precision processing and processing index on in vitro ruminal fermentation of dry-rolled barley grain

“…Differences in the nutritional characteristics within and among barley varieties have been reported (Molina-Cano et al, 1997;Khorasani et al, 2000). The range of values for the chemical composition in this study is similar to those reported earlier (Yang et al, 2000;Ramsey et al, 2001) and tabular values in NRC (2001).…”

Adjusting roller settings based on kernel size increased ruminal starch digestibility of dry-rolled barley grain in cattle

“…Processing improves digestibility of barley grain, and the effects of various processing methods on cattle performance have recently been reviewed (Dehghan-Banadaky et al 2008). Barley grain varies considerably in its physical characteristics; Khorasani et al (2000) reported that the weight of 1000 kernels ranged from 42.9 to 53.9 g among 60 cultivar lots. Kernel uniformity is influenced by barley variety as well as growing conditions.…”

QTL associated with barley (Hordeum vulgare) feed quality traits measured through in situ digestion

“…The first, in vivo, is characterised by feeding animals with known amounts of sample and measuring faecal output (Matsushima 1979). Although in vivo analysis is accurate and has been extensively used, it is expensive and requires a large amount of grain for the evaluation of a small number of samples (Khorasani et al 2000). The second method, an in vitro approach, determines digestibility by simulating ruminal chemistry and enzymatic reactions (McDonald et al 1995).…”

“…The third method is an in situ technique, which involves the insertion of multiple non-digestible porous nylon bags, filled with grain samples, into the rumen of cannulated animals. This allows the amount of dry matter digested within the bag to be measured over a set period (Herrera-Saldana et al 1990;Khorasani et al 2000) and provides data from within the rumen itself. Ruminal digestion of incubated samples in the nylon bag can be affected by a number of factors, such as bag and sample size, bag material, pore size, sample processing, animal diet, feeding level and frequency, bag insertion and removal procedures, location of the bag in the rumen, rinsing procedure, microbial correction and incubation time.…”