In vitro microbial digestion of straw cell wall polysaccharides in response to supplementation with different sources of carbohydrates

Abstract

The effect of carbohydrate supplementation on microbial fibre digestion was studied in vitro, by measuring the disappearance of cell wall monosaccharides, bacterial adhesion (mmol purine bases per g residue), and total (per g residue) and bacterial (per mmol purine bases) polysaccharidase activity. Straw cell walls (CW, 0.5% w/v) were cultured in medium supplemented with (0.275% w/v) or without starch, a sugar mixture, or pectin. Supplementation with these constituents did not cause a drop in pH below 6.1, and increased all parameters investigated with the exception of bacterial polysaccharidase activity, which was higher for CW cultures, suggesting a higher proportion of fibrolytic bacteria in the adherent population. By comparison with starch and sugar, pectin supplementation resulted in a lower proportion of residual sugars remaining from cell walls after 60 and 72 h (P < 0.05), which resulted in greater bacterial adhesion after 8 and 12 h (P < 0.05) and higher total cellulase activity after 8 h (P < 0.01). This was perhaps because pectin may cover particle surfaces, protecting the digestive area from external factors, or may act as a substrate for cellulolytic bacteria. The lack of differences in bacterial enzymatic activities suggests the absence of qualitative or quantitative differences in the adherent fibrolytic population.

Short communication: Growth performance, nutrient digestibility and blood parameters of fattening lambs fed diet replacing corn with orange pulp

“…There was a linear effect of replacing corn with OP on NDF digestibility, however, ADF digestibility showed a quadratic effect with the level of replacement, described by the equation Y=−0.018X 2 +2.7X+583 (R 2 =0.90 p<0.001) and the maximum estimated value for replacement was 75.3%. The positive effect of replacing starchy concentrates by feeds rich in easily degradable cell walls such as OP has generally been associated with a more favorable rumen environment for cellulolytic bacteria; thus an improvement in forage degradability (Barrios-Urdaneta et al, 2000). Increased rumen pH in lambs fed OP in the current study proved these findings (Table 2).…”

“…However, the inclusion of high levels of starch decreases rumen pH (Carro et al, 2000) which may affect the function of rumen cellulolytic bacteria (Stritzler et al, 1998), thus decreasing rumen cell wall fermentation, digestibility and feed intake (Castrillo et al, 1991). Replacement of starch with pectin appears to improve rumen function because of reduced negative associative effects (Barrios-Urdaneta et al, 2000). Citrus pulp has a high concentration of pectin, which leads to a fast rumen fermentation, releasing energy for a rapid microbial growth.…”

Black gram (Vigna Mungo L.) foliage supplementation to crossbred cows: effects on feed intake, nutrient digestibility and milk production

“…One of the strategies to manipulate the rumen environment is supplementation, particularly when poor quality roughages are fed. The principal objective of supplementation is to increase the supply of nutrients, mainly energy and protein, such as to create favourable conditions in the rumen which result in enhanced fermentation of basal roughage and thus, improve animal performance [3,4]. Use of unconventional feed resources to develop least cost ration has been increasing for sustainable livestock farming.…”

Proximate composition, phytochemicals, minerals and antioxidant activities of Vigna mungo L. seed coat

“…Large quantities of pulse husks are available as by-product and are available to the extent of 3 million tonnes in India per annum [9]. The principle objective of supplementation is to increase the supply of nutrients, mainly energy and protein, which enhance the basal roughage in rumen [10].…”