In Situ Assessment of Degradability of Organic Matter in the Rumen of the Dairy Cow

Abstract

This study analyzed the relationships among the effective degradabilities of organic matter (OM) in feedstuffs, which were assessed separately by an in situ method and a direct in vivo measurement of the rumen degradation of OM in the diets of Holstein dairy cows. For this comparison, 80 individual data points were used from studies of dairy cows that were in midlactation and that had been cannulated in the rumen and abomasum. In vivo evaluation of the true degradability of OM in the rumen was based on rare earth digesta markers. Purine N served as a microbial marker. Feed samples were incubated in the rumens of dairy cows for 3, 6, 9, 12, 24, 48, and 72 h, and effective rumen degradation was calculated from the percentage of residual OM for rumen outflow rates of 4, 6, and 8%/h. Evaluations of rumen degradability of OM by the in situ method were correlated with actual in vivo measurements of rumen degradability of OM (r2 = 0.31, 0.34, and 0.37; SE of the estimate = 4.1, 4.0, and 3.9%, respectively). We concluded that the in situ method is a useful tool for providing reliable estimates of rumen degradability of OM in dairy cows.

In Sacco and In Vitro Organic Matter Degradability (OMD) Of Selected Semi Arid Browse Forages

“…This may have been due to the low rate of degradation constant 'c' as [38] with the potential degradability of dry matter in browse plants. Potential degradability values reported for roughages [34] were similar to what obtained in this investigation. Effective degradability values reported for organic matter in the leaves studied showed this nutrient to be well degraded in situ at an outflow value of 0.12.…”

“…On the contrary the least 'a' value recorded in Maerua angolensis indicates that this browse forage may be composed of slow degrading carbohydrates, likely to affect the efficiency of microbial protein synthesis [36]. Nevertheless, the organic matter solubility range reported in the shrub and tree leaves of this of this study (2.23 to 16.12%) were within the range reported in some roughage [34]. The insoluble but degradable organic matter frraction 'b' was high in the plant leaves compared to values reported for some multipurpose tree species [37].…”

“…This is in view of the fact that microbial protein synthesis is highly dependent on availability of rumen degradable organic matter [33] are of the view that rate of nitrogen and carbohydrate degradation especially from forage and concentrate mixtures, increase the efficiency of microbial protein synthesis due to improved rumen environment for the growth of more diverse bacteria species. The shrub and tree leaves used in this study varied in organic matter degradation characteristics, Readily soluble fraction of organic matter in the test leaves was observed to be highest 16.12% in both Cassia sieberiana.This may be due to the presence of degradable carbohydrates, particularly the non-structural ones and NDF proteins and fat, components that may make organic matter readily degradable in situ in the rumen [34]. In this regard, feeding diets with at least 12% protein may be necessary to maximize organic matter fermentation in the rumen [35].…”

Relationship between chemical composition and in situ rumen degradation characteristics of maize silages in dairy cows

“…Information on the relationship between chemical composition and in situ rumen degradation characteristics of dry matter (DM), organic matter (OM), CP, starch and neutral detergent fiber (NDF) of maize silages in the scientific literature is scarce. Several in situ studies have been conducted on maize silages to determine the effect of individual factors such as maturity stage (Johnson et al, 1999;Di Marco et al, 2002;Jensen et al, 2005), chop length (Fernandez et al, 2004) and ensiling (González et al, 2010) of maize crop on the rumen degradation of specific nutrients like DM (Von Keyserlingk et al, 1996), OM (Arieli et al, 1998), CP (Von Keyserlingk et al, 1996;Shannak et al, 2000), starch (Fernandez et al, 2004;Hindle et al, 2005) and NDF (Varga and Hoover, 1983;Stensig et al, 1994;Jensen et al, 2005). In addition, often in these studies only a limited number (n = 1 to 12) of samples were investigated and compared with other feedstuffs.…”

In sacco degradation of Tephrosia candida and Leucaena leucocephala in mixtures with Panicum maximum using fistulated West African dwarf sheep

“…The use of in sacco feed evaluation method (Ørskov and MacDonald, 1979) has the unique advantage of not only furnishing information on the extent of nutrient release of a feed, but also providing a rapid estimate of the rate at which such nutrient is released (Ørskov et al, 1980). The method has proved to be a reliable means of predicting the digestibility of feedstuffs in the rumen (Ariel et al, 1998). The present study was undertaken to assess the in sacco degradability of T. candida and L. leucocephala when fed as mixtures with Panicum maximum, in the rumen of WAD sheep.…”