Ammonia levels on <i>in vitro</i> degradation of fibrous carbohydrates from buffel grass

Abstract

This study was carried out to examine the degradation dynamics of neutral detergent fibre (NDF) and the profile of volatile fatty acids that originate from the fermentation of buffel grass (Cenchrus ciliaris, L.) with various levels of ammonia in the growth medium. The treatments consisted of six levels of ammonia in the growth medium (0, 5, 10, 15, 20 and 30 mg/dL), which were obtained by adding urea. These in vitro incubation times were evaluated in three replicates per time for 0, 3, 6, 9, 12, 24, 36, 48, 72 and 96 hours. Rumen concentrations of acetate and propionate responded quadratically to the ammonia levels. The treatment with 15 mg/dL of ammonia nitrogen in the rumen fluid provided mean acetate and propionate contents of 57.6 mM and 23.1 mM, respectively. Urea addition elevated the degradation rate of potentially degradable fraction of NDF (pdNDF) from 2.5% to 20.1% in comparison with the treatment without urea and to a reduction in estimated discrete lag time from 0.34 to 2.31 hours. Urea supplementation increased the specific microorganism growth rate from 2.6% to 20.1%. At the end of the incubation trial, NDF degradation showed a quadratic response, with maximum value obtained at 17.76 mg/dL of ammonia in the rumen fluid. Urea improves the degradation dynamics of NDF from deferred buffel grass and increases the concentrations of acetate and propionate.

Goats fed with non-protein nitrogen: ruminal bacterial community and ruminal fermentation, intake, digestibility and nitrogen balance

“…The increase in the ammoniacal nitrogen (N-NH 3 ) provided by NPN infusion corroborates a previous in vitro study which showed a linear increase of N-NH 3 in a medium containing buffel grass and different concentrations of nitrogen ammonia (Santana Neto et al, 2019). Interestingly, no changes in other ruminal parameters were observed in our study (pH, acetate, propionate, butyrate and total VFA).…”

“…Pires et al (2016) reported a 20% increase in the NDF degradation rate at 15 mg/dl N-NH 3 in the rumen fluid, compared to the treatment without N-NH 3 . Santana et al (2019) also observed that an N-NH 3 concentration of 17.76 mg/dl maximized NDF degradation from buffel grass by goat rumen microorganisms.…”

“…VFA production and NDF digestibility even in non-supplemented animals (Table 2) suggest that the microorganisms in the caprine rumen are able to grow and maintain fermentation and metabolic processes when fed buffel grass only. This is corroborated by the fact that in vitro fibre degradation of buffel grass and ruminal microorganism growth were shown to occur even in the absence of NPN supplementation, when N-NH 3 concentration was only 1.63 mg/dl (Santana Neto et al, 2019). Stefański et al (2020) also observed that when ruminal ammonia content is low, ruminal bacteria are more efficient in the use of extracellular nitrogen, and that the fermentation and synthesis processes are maintained.…”

“…The limited nitrogen content impairs the use of fibre carbohydrates by ruminal microorganisms and, consequently, animal performance is reduced (Paulino et al, 2008). In the specific case of the xerophilous forage buffel grass, cuttings or grazing is followed by fast growth, finishing its regrowth cycle (Santana Neto et al, 2019). This fast growth results in a low lignin synthesis; therefore, neutral detergent fibre is low in lignin and fibre digestibility can be high even though the protein content is low (Pinho et al, 2013).…”

Utilization of marigold leaves (Tagetes erecta L.) in rations and their effect on rumen enzyme activity, fermentation parameters, methane emission, and nutrient digestibility in vitro

“…Previous studies, such as McDonald et al [49] , have illustrated that the concentration of NH 3 –N in ruminal fluid typically ranges from 8.5 to 30 mg/100 ml. However, it is worth noting that excess NH 3 –N exceeding 50 mg NH 3 –N/l does not significantly impact microbial protein synthesis and is ultimately excreted, as indicated by Neto et al [50] .…”