Biohydrogenation of Fatty Acids and Digestibility of Fresh Alfalfa or Alfalfa Hay Plus Sucrose in Continuous Culture

Abstract

The pattern of biohydrogenation of fatty acids from fresh alfalfa or alfalfa hay supplemented with 3 concentrations (0, 4, and 8%) of sucrose was studied at a constant pH of 6.2. Four continuous culture fermenters were used in a 4 x 4 Latin square design to test the hypothesis that fresh forage would increase flow of vaccenic acid (VA) from the fermenters compared with the same forage in hay form and that this difference would be diminished by adding sucrose to the hay diet by changing the bacterial community profile. Effluent was collected from each of the 4 fermenters during the last 3 d of each 10-d period. Nutrient digestibility, volatile fatty acids (VFA), and fatty acids in the effluent were measured. Flow of bacterial organic matter (OM) and neutral and acid detergent fiber and acid detergent fiber digestibilities were higher for fresh alfalfa than alfalfa hay. True OM digestibility of alfalfa hay tended to linearly decrease with sucrose supplementation. However, microbial efficiency and flow of bacterial OM (g/d) linearly increased with sucrose addition. There was no change in total VFA concentration; however, proportion of acetate linearly decreased and proportion of butyrate linearly increased with sucrose addition. Fresh alfalfa increased total biohydrogenation of fatty acids compared with than hay. Vaccenic acid flow (mg/d) was much higher for fresh alfalfa compared with alfalfa hay (216 vs. 41) and VA was the predominant 18:1 isomer, followed by trans-13 18:1; however, sucrose had no effect on VA flow. The percentage of VA (of total trans-18:1) was not different between fresh alfalfa and hay, whereas percentage of trans-10 18:1 was much lower for fresh alfalfa. Therefore, the ratio of VA to trans-10 18:1 was higher for fresh alfalfa. Flow of trans-12 18:1 linearly increased, whereas flows of cis-12 and total cis-18:1 had quadratic responses to sucrose supplementation. Total biohydrogenation and biohydrogenation of linoleic and linolenic acids linearly decreased with sucrose; however, there was no effect of sucrose on total trans fatty acid flow. Sucrose may be more detrimental to the last step of biohydrogenation of VA. The effects of sucrose on biohydrogenation and concentration of VFA may have been caused by a shift in microbial population by mechanisms that are independent of pH.

Effect of the type of non-fibre carbohydrates in grass silage-based diets on in sacco ruminal degradability and protein value of lupin (Lupinus angustifolius L. cv. Sonet) seeds ground to different particle sizes

“…Th e lower content of the insoluble but potentially degradable fraction and the higher degradation rate of this fraction (P < 0.05) were characterized by degradation of seed NDF during incubation in the rumen of cows receiving diets with sucrose or pectin compared with that found out during incubation in the rumen of cows receiving diets with starch. Similarly, a reduction of susceptibility to digestion of lucerne hay NDF as the eff ect of dietary sucrose supplementation was observed in continuous culture fermenters by Ribeiro et al (2005). Th e infl uence of the type of non-fi bre carbohydrates included in the rations on the course of NDF degradation was reported by Alamouti et al (2009), who found out that the degradation of lucerne NDF in the early hours post feeding in sheep was aff ected by a signifi cant increase in rumen pH as a result of partial replacement of pectin by starch in the diets.…”

“…Th e rate of disappearance for sucrose was estimated to be 1200-1404%/h (Weisbjerg et al, 1998) and the starch of barley degrades in the rumen at a rate from 14 to 24%/h (Off ner et al, 2003). As shown by Ribeiro et al (2005) in continuous culture fermenters, the synchronism between the availability of energy from sucrose and soluble protein from lucerne hay caused a change in the bacterial activity. Th e authors gathered that the increase of sucrose from 0% to 8% improved the effi ciency of microbial protein synthesis from 36.7 to 56.4 g per kg of organic matter truly digested.…”

Influence of inoculated maize silage and sunflower oil on the in vitro fermentation, ciliate population and fatty acid outputs in the rumen fluid collected from sheep

“…LP added to grass silage diets was effective in increasing CLA concentrations and decreasing biohydrogenation of C18:2 and C18:3 while EF and LF had an opposite effect (Jalč et al, 2009a). The ensiling process does not reduce concentrations of PUFA and FA profiles in maize silage (Da Cruz et al, 2005;Ribeiro et al, 2005). Maize silage also has an impact on high TVA contents in RF of cattle (Or-Rashid et al, 2008b).…”

Replacing maize grain with dried citrus pulp in a concentrate feed for Jersey cows grazing ryegrass pasture

“…Pectin fermentation ceases under low ruminal pH, and there is no cumulative effect of lowered ruminal pH (Strobel & Russell, 1986;Allen, 2001). Sugar provides less carbon for VFA production per unit of mass compared with starch (Hall & Herejk, 2001) and increases the passage rate and production of MP (Sutoh et al, 1996;Ribeiro et al, 2005), essentially providing less OM for fermentation. Furthermore, rumen microorganisms are able to convert sucrose to glycogen for short-term energy storage (Hall & Weimer, 2007), temporarily reducing VFA production in the rumen (Oba, 2011) and thereby minimizing the potential negative effect on ruminal pH.…”

“…Despite the problems associated with feeding starches, it is practised widely because of the high energy content, which promotes milk production. Other non-fibre carbohydrates such as sugar and pectin (prevalent in various fruit wastes) have a more positive effect on the rumen environment (Hall & Herejk, 2001;Ribeiro et al, 2005) and maintain production when replaced in TMR systems (Leiva et al, 2000;Broderick et al, 2008). Dried citrus pulp is a by-product of the juicing industry (Bampidis & Robinson, 2006) and is high in sugar (208 g/kg dry matter (DM)) and pectin (150-200 g/kg DM) and low in starch (174 g/kg DM) (Miller-Webster & Hoover, 1998;Hindrichsen et al, 2004).…”