The use of monensin or formaldehyde to control the digestion of the nitrogenous constituents of perennial ryegrass (Lolium perenne cv. Melle) and white clover (Trifolium repens cv. Blanca) in the rumen of cattle

Abstract

1. Pure swards of perennial ryegrass (Lolium perenne cv. Melle) and white clover (Trifolium repens cv. Blanca)were harvested daily as primary growth (grass in May, clover in June) or regrowths (clover only in July) and offered, in the long form, to growing cattle at a feeding rate of 22 g dry matter/kg live weight. With each forage, two treatments were compared with the untreated forage (C): monensin (100 g active ingredient/kg, 250 mg/d) addition to the rumen (treatment M) or formaldehyde (30 g/kg crude protein (nitrogen x 6.25)) application to the diet (treatment F). The objective of the experiment was to examine means of manipulating N metabolism in the rumen and the duodenal non-ammonia-N (NAN) supply derived from fresh forages. 2.The apparent digestion of ingested organic matter (g/kg) in the rumen was unaffected by treatment M (C 509, M 497) but was significantly ( P < 0.01) reduced by tieatment F (443). The extent of cellulose digestion in the rumen was not affected by any of the treatments imposed and the changes in organic matter digestion were due mainly to effects on N digestion and rumen microbial synthesis. On the untreated diets, duodenal NAN supply averaged 0.74 g/g N intake and treatment M caused a small but non-significant increase (M 0.79 g/g N intake).In contrast, the effect of treatment F was much larger (F 0.91 g/g N intake; P < 0.01). These differences were accompanied by corresponding reductions in rumen NH, concentrations (mg/l; C 350, M 310, F 220; P < 0.001).3. Of the increased flow of NAN to the small intestine observed on the white clover only diets with treatment F, 0.70 was accounted for by an increased net synthesis of microbial N, while treatment M had no effect on microbial N synthesis and a marginal reduction in feed N degradability only with the regrowth white clover diet. Treatment F reduced feed N degradability to a limited extent on both clover diets (C 0.82, M 0.81, F 0.77). No corresponding measurements were made for the ryegrass diets.4. It is concluded that the extensive loss of N from the reticulo-rumen of cattle fed on fresh forages can be reduced by the use of agents to reduce protein solubility. However, the study demonstrated that treatment F may in some circumstances increase N supply to the small intestine more through enhancing microbial N synthesis within the rumen than through increasing the passage of undegraded feed N to the small intestine. The use of monensin, to manipulate proteolytic or deaminative activity in the rumen, or both, was not found to confer any beneficial effects on duodenal-NAN supply.There have been several studies to evaluate the digestion of fresh forages and the nutrient supply arising from such diets (Beever et al. 1971(Beever et al. , 1976(Beever et al. , 1978b Ulyatt & Egan, 1979; VtritC et al. 1984). Recent experiments with growing cattle (Ulyatt et al. Beever et al. 1985 Beever et al. , 1986a have demonstrated that as the amount of nitrogen in the crop increases, considerable losses of N between mouth and duodenum (up to 0.40 of N...

Forage Nutritive Value of Various Amaranth Species at Different Harvest Dates

“…After 70 DAP, A. cruentus (Zimbabwe) had greater average UIP (36%) than the UIPs reported for alfalfa (Merchen and Satter, 1983; Charmley and Veira, 1990) and perennial ryegrass (Rooke et al, 1983; Rooke et al, 1987; Dawson et al, 1988). The percentage of UIP reported for white clover ( Trifolium repens ) (Beever et al, 1987) is also lower than that of A. cruentus (Zimbabwe) and A. cruentus (Rwanda) after 70 DAP. The comparison across species should be noted with some caution since these species were evaluated under different environmental conditions.…”

“…The concentration of UIP in different forages has been reported (Merchen and Satter, 1983; Mathers and Miller, 1981; Rooke et al, 1983; Charmley and Veira, 1990; Glenn et al, 1989; Beever et al, 1987). Mitchell et al (1997) reported UIP for switchgrass ( Panicum virgatum L.) and smooth bromegrass ( Bromus inermis L.) as 230 to 310 and 110 to 180 g kg −1 of total crude protein, respectively, and that warm‐season grasses generally had greater UIP because of their C 4 anatomy.…”

Effect of monensin on the specific activity of ammonia production by ruminal bacteria and disappearance of amino nitrogen from the rumen

“…Poos et al (24) reported that monensin caused an increased flow of amino acid nitrogen to the lower gut, but in other studies the flow of nonammonia nitrogen was only marginally increased (2). In some cases, the increased flow of plant amino acids was countered by a decreased flow of microbial protein (24).…”

Ruminal and postruminal digestion of dietary protein and starch in steers: 2.Multivariate model prediction of non-ammonia nitrogen and starch passage and digestibility

“…NAN passage to the duodenum on high quality forage diets is I to 2 glMI ME intake (Beever et al 1987). This figure is usually lower with high energy (feedlot) diets, because of reduced ruminal dilution rate (Owens et al, 1984).…”