The nutritive value of silages Digestion of organic matter, gross energy and carbohydrate constituents in the rumen and intestines of sheep receiving diets of grass silage or grass silage and barley

Abstract

I .Two experiments were conducted to study the digestion of organic matter, gross energy and carbohydrate constituents in the rumen, small intestine and caecum and colon of sheep given grass silage diets. Three silages made from perennial ryegrass (Lolium perenne) with formic acid as an additive were used. One was made from first-harvest grass in the spring and the others from regrowth grass cut from a single sward in either early autumn or late autumn. Expt I involved a comparison between the spring silage given alone or supplemented with barley (silage: barley, 4: i dry matter (DM) basis). Expt 2 involved a comparison between the early-cut and late-cut autumn silages.2. In Expt I , supplementation of the silage with barley resulted in a non-significant (P > 0.05) reduction in the proportion of digestible energy (DE) and digestible organic matter digested in the rumen and an increase in the proportions digested in the small intestine. There were also pronounced effects of barley on ruminal cellulolysis and the proportion of digestible cellulose broken down in the rumen was reduced (P < 0 . 0 5 ) from 0.90 to 0.77. There was an increased passage of a-linked glucose polymers to the duodenum but even with the supplemented diet 0.91 of the dietary polymers were digested in the rumen. The molar proportion of propionic acid in the rumen tended to be reduced and there were increases in the proportions of butyric acid (P < 0.01) and acetic acid.3. In Expt 2 , the digestibility of organic matter, gross energy and cellulose in the early-cut silage was higher (P < 0.01) than in the late-cut silage but there were no significant (P < 0.05) differences between silages in the sites of digestion of these constituents. However, the molar proportion of acetic acid in the rumen was higher (P < 0.01) and the molar proportion of propionic acid was lower (P < 0.01) with the late-cut silage than with the early-cut silage.4. The results are discussed in relation to the voluntary intake and utilization of high-digestibility silages.In calorimetric studies of energy metabolism in sheep Kelly & Thomas (1978) examined the utilization of the energy of three perennial ryegrass (Lolium perenne) silages prepared using formic acid as an additive. One silage was made from first harvest grass in the spring and the others were from regrowth cut either early or late in the autumn. Each silage was given as a sole food and the spring and late-cut autumn silages were also given supplemented with barley. The experiments reported here were to study the sites of digestion of organic matter, gross energy and carbohydrates in sheep given silage diets similar to some of those used by Kelly and Thomas (1978). The object was to provide a fuller understanding of the effects of barley supplementation and of the maturity of the grass ensiled on the digestion processes, and to investigate whether differences between silages in the efficiency of utilization of metabolizable energy for fattening (kf), observed in the earlier experiments, could be related to the pa...

An examination of the effect of method and level of concentrate feeding on milk production in dairy cows offered a grass silage-based diet

“…This is in agreement with observations by Thomas and Chamberlain (1982) and Rooke et al (1985). This is in agreement with observations by Thomas and Chamberlain (1982) and Rooke et al (1985).…”

Reticulo-rumen Fermentation in Dairy Cows Fed 12 Times Daily with 4 types of Roughages Supplemented with Straw and Concentrates

“…The apparent lack in the present experiment of an increase in the molar proportion of propionate in the rumen fluid when feeding more starch has also been seen by Mathers & Miller (1981), Norton et al (1982) and by Thomas et al (1980). Mathers & Miller (1981) found no change in the molar proportion of propionate in the rumen fluid of sheep by gradual substitution of an all lucerne diet with an all rolled barley diet, fed at 2 hourly intervals.…”

“…The molar proportion of acetate or propionate was not affected by the content of starch in the ration. Thomas et al (1980) fed sheep twice daily with spri,ng grass silage plus barley in the proportion 4 : 1 on dry matter basis and found the molar proportions to be 60% acetate, 25% propionate and 12% butyrate and only the butyrate were affected significantly by the barley supplementation.…”

The effects of forage preservation method and proportion of concentrate on nitrogen digestion and rumen fermentation in cattle

“…As in the present experiment, the rate of synthesis has improved with moderate addition of barley to a silage diet (Thomas et al,, 1980b;Rooke et al, 1985), whereas a further substitution has gradually reduced the efficiency (Harstad and Vik-Mo, 1985). Similarly, Hagemeister el al, (1980) reported a tendency towards a lower protein synthesis with rations containing very low (0-20%) or high (70-100%) proportions of concentrate.…”