caa a22 4500 388062266 CHVBK 20180307125124.0 cr unu---uuuuu 161130e199804 xx s 000 0 eng 10.1079/BJN19980062 doi S0007114598000634 pii (NATIONALLICENCE)cambridge-10.1079/BJN19980062 Urinary excretion of purine derivatives as an index of microbial-nitrogen intake in growing rabbits [Elektronische Daten] Three experiments were carried out to establish a response model between intake and urinary excretion of purine compounds. In Expt 1 the relationship between the intake of purine bases (PB) and the excretion of total purine derivatives (PD) was determined in seven growing rabbits with a mean initial live weight (LW) of 2·03 (SE 0·185) kg, aged 70 d, each fitted with a wooden neck collar to prevent caecotrophagy. They were fed on five experimental diets formulated with different levels of nucleic acids (0·00, 3·75, 7·50, 11·25, 15·00 g yeast-RNA/kg diet). The relationship between intake of purine (x, μmol/kg W0·75) and total urinary PD excretion (y, μmol/kg W0·75), y = 0·56 + 0·67x (r2 0·86; RSD 0·338), indicated that about 70% of duodenal PB were recovered as urinary PD and that the endogenous contribution was constant and independent of dietary PB supply. Endogenous excretion of PD (allantoin and uric acid) was measured in a second experiment using six rabbits fed on a purine-free diet and fitted with neck collars to avoid caecotrophagy. Basal daily urinary excretion values for allantoin and uric acid were 532 (SE 33·9) and 55 (SE 7·3) μmol/kg W0·75 respectively; xanthine and hypoxanthine were not found in urine samples and therefore the sum of allantoin and uric acid should comprise the total excretion of PD (588 (SE 40·1) μmol/kg W0·75). The xanthine oxidase (EC 1·2.3·2) activity in plasma, liver, duodenum, jejunum and kidney was measured in a third experiment. The activities of xanthine oxidase in duodenal and jejunal mucosa, liver and kidney were: 0·61 (SE 0·095), 0·37 (SE 0·045), 0·035 (SE 0·001) and 0 units/g fresh tissue respectively and in plasma 2·96 (SE 0·094) units/1. The results show that urinary excretion of PD may be a useful tool to estimate duodenal PB input and microbial protein intake once the relationship between PB and N has been established in caecal micro-organisms. Copyright © The Nutrition Society 1998 Purines nationallicence Xanthine oxidase nationallicence Rabbit nationallicence Balcells J. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain Ganuza J. M. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain Pérez J. F. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain Martín-Orúe S. M. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain González Ronquillo M. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain British Journal of Nutrition Cambridge University Press 79/4(1998-04), 373-380 0007-1145 79:4<373 1998 79 BJN https://doi.org/10.1079/BJN19980062 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1079/BJN19980062 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Balcells J. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain NATIONALLICENCE 700 1- Ganuza J. M. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain NATIONALLICENCE 700 1- Pérez J. F. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain NATIONALLICENCE 700 1- Martín-Orúe S. M. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain NATIONALLICENCE 700 1- González Ronquillo M. Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain NATIONALLICENCE 773 0- British Journal of Nutrition Cambridge University Press 79/4(1998-04), 373-380 0007-1145 79:4<373 1998 79 BJN CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge