Effect of level and origin of rumen degradable nitrogen on rumen microbial growth and nitrogen utilisation efficiency of animals fed maize silage at maintenance

Abstract

-Isoenergetic maize silage diets, fed at maintenance to 24 suckling cows (Exp. 1) and to 3 (Exp. 2) or 4 (Exp. 3) rumen fistulated sheep, were compared with a urea and controlled release NPN diet (Exps. 1 and 2) and with a protein-N supplemented diet (Exp. 3). Supplementation increased blood urea concentrations (44.7 ± 22.3 vs. 97.6 ± 23.7 mg urea-N . L -1 ) (Exp. 1) and renal urea excretion (2.5 ± 1.1 vs. 7.6 ± 1.8 g urea-N . d -1 ) (Exps. 2 and 3), whereas blood allantoin concentrations (286.7 ± 77.0 µmol . L -1 ) (Exp. 1) and renal excretion of purine derivatives (357.6 ± 90.7 mg purine-N . d -1 ) (Exps. 2 and 3) were not affected, indicating additional N supplementation did not improve rumen microbial growth. However, some deficiency of rumen degradable N might occur in non supplemented diets as suggested by the reduced rumen NH 3 -N and RNA concentrations (868 ± 270 vs. 1466 ± 466 mg RNA . kg -1 rumen contents).

Black soldier fly as dietary protein source for broiler quails: apparent digestibility, excreta microbial load, feed choice, performance, carcass and meat traits

“…The amino acid concentration of H was analysed by EPTA NORD srl (Via Padova, Conselve, Italy, internal method). CP content of excreta was corrected for uric acid content which was analysed according the procedure described by Fievez et al (2001) with the following modifications: the HPLC was an Agilent 1200 series (Agilent Technologies, Santa Clara, CA, USA), provided by a degasser, auto sampler, quaternary pump, column oven and diode-array detector. A 25 cm reversed phase column, 4.6 mm internal diameter and 5 μm particle size was used (Supelcosil LC-18 Supelco cat.…”

Methane emissions from the rumen of sheep fed a mixed grass-clover pasture at two fertilisation rates in early and late season

“…Prior to the start of the urine and faeces collection, sheep were removed from the metabolic cages, which were completely cleaned. Urine and faeces were then collected separately during 24 h, as described by Fievez et al (2001a). After 24 h collection, fresh faecal material was weighed and a representative subsample (10 to 20%) was taken.…”

“…Purine derivatives (allantoin, uric acid, hypoxantine and xantine) were determined in the urine samples as described by Fievez et al (2001a).…”

Effect of N fertilisation rate, energy supplementation and supplementation strategy on efficiency of N utilisation in the sheep rumen

“…Each experimental period, 4 total urine and faeces collections were performed during 24 h. After dilution (Fievez et al, 2001a), a representative urine sample was stored for analysis of urinary excretion of purine derivatives (Fievez et al, 2001a) and urea after transformation to NH 3 . For the latter, H 2 O (1.25 ml) and urease buffer (2.5 ml) were added to a subsample (1.25 ml) of the stored urine samples.…”

“…V) (van Vuuren et al, 1993), which is in accordance with the reduced rumen microbial growth rates associated with maize silage diets (Tab. IV) (Vérité et al, 1987;Fievez et al, 2001a).…”