Site and extent of starch degradation in the dairy cow – a comparison between in vivo, in situ and in vitro measurements

Abstract

Prediction of the supply of glycogenic precursors to dairy cows and the site of degradation of wheat, maize and potato starch (PS) were determined in an in vivo experiment and the results were compared with data obtained from experiments involving in situ nylon bag and in vitro gas production techniques. In a Latin square design experiment four lactating dairy cows fitted with a rumen cannula and T-piece cannulae in the duodenum and terminal ileum, received either a low-starch control diet or diets in which sugar beet pulp in the concentrate mixture had been replaced by wheat, maize or PS. Starch from the different sources was almost completely degraded in the total gastrointestinal tract. For all starches, the rumen was the main site of degradation in vivo. No digestion of PS in the small intestine was observed. In situ results suggested that 14% of wheat starch (WS), 47% of maize starch and 34% of PS escaped rumen fermentation. According to the gas production technique WS ferments quickest and potato slowest. PS had a low degradability during the first 8 (gas production) to 11 (in situ) h. However, according to both in vitro and in vivo measurements rumen degradability of PS was high. The results suggest that in situ and in vitro techniques should be performed in animals that have adapted to starch source to provide a more accurate simulation of the in vivo situation.

Effect of induction of subacute ruminal acidosis on milk fat profile and rumen parameters

“…Wheat and sugar beat pulp contained 557 and 5 g/kg of DM starch, respectively, with 52 and 0 g/kg of DM bypass starch, respectively (CVB, 2007). Wheat starch degradation in the rumen was 89.6% in a study by Hindle et al (2005). Water intake, DMI, and milk yield were recorded daily.…”

Relationship between in vitro and in vivo methane production measured simultaneously with different dietary starch sources and starch levels in dairy cattle

“…Above all, in vitro and in vivo studies are usually performed separately under different conditions and there is a lack of direct in vitro-in vivo comparison, which is essential to demonstrate the robustness or effectiveness of the in vitro GP technique in simulating rumen fermentation. Hindle et al (2005) compared the in vitro and in vivo starch degradation from different sources and found a discrepancy between the in vivo starch degradation and that estimated from an in vitro GP experiment in which the donor animals were not adapted to the diets with the same starch source. The authors suggested in vitro GP could provide a more accurate simulation of the in vivo fermentation of potato starch if the donor animals are adapted to a diet including this starch source.…”

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.…”