Effect of feeding frequency on diurnal variation in plasma and urinary purine derivatives in steers

Abstract

1992). Effect of feeding frequency on diurnal variation in plasma and urinary purine derivatives in steers. AbstractThe diurnal changes in plasma concentration and urinary excretion of purine derivatives (PD) were examined in four steers given their food in either one or two meals daily in two 18-day periods. In period 1, two steers were fed once daily (at 08.00 h) and the other two twice daily (at 08.00 and 16.00 h). In period 2, the treatments were switched. In the last 4 days of each period, plasma samples were taken from 08.00 to 24.00 h at 2 to 3 h intervals, and daily urine was collected in several 4 to 8h periods. With once daily feeding, allantoin concentration in plasma varied from 090 to 1-07 of the daily mean and with twice daily feeding, from 0-97 to 1-05 of mean. The coefficient of variation (CV) for total variation was 0-14. In urine, the concentration and hourly excretion of PD varied with sampling times (P < 0-05) but the ratio of PD to creatinine was relatively constant even for once-daily feeding (CV, 0-02 for measurements at different times). The CV for total variation in the ratio was 0-19. The results suggest that diurnal variation in plasma allantoin concentration and in the ratio of allantoin (or total PD) to creatinine are relatively small even for once daily feeding. It thus seems that these measurements in spot samples may be suitable for use as a simple index of microbial protein supply if they are correlated with the daily PD excretion. The results also indicate that measurements in samples of plasma and urine taken between 15.00 and 20.00 h tended to give a better representation of the daily mean.

Uso da creatinina como indicador da excreção urinária em ovinos

“…NSAHLAI et al (2000) não observaram efeito do horário de coleta em terneiros. Contudo, variações na concentração urinária de creatinina ao longo do dia, tanto em bovinos como em ovinos, também foram observadas por CHEN et al (1992), GONDA & LINDBERG (1994), CHEN et al (1995ae 1995b, SUSMEL et al (1995) e SHINGFIELD & OFFER (1998.…”

“…Em vários experimentos com bovinos, foi observado que a excreção diária desta molécula, como proporção do peso vivo, é relativamente semelhante entre os animais (VALADARES et al, 1997;RENNÓ et al, 2000;OLIVEIRA et al, 2001;SILVA et al, 2001). De outra forma, foi observado também que a relação entre a concentração dos derivados das purinas e creatinina em amostras pontuais de urina é relativamente constante ao longo do dia (CHEN et al, 1992;GONDA & LINDBERG, 1994;CHEN et al, 1995a). Com base nisto, tem sido sugerido o uso da concentração de creatinina em amostras pontuais de urina como um indicador da excreção urinária total dos animais.…”

Estimation of microbial protein supply in ruminant animals based on renal and mammary purine metabolite excretion. A review

“…A number of studies in ruminant species (Antoniewicz et al, 1981;Chen et al, 1992c;Gonda and Lindberg, 1994;Dewhurst et al, 1996;Valadares et al, 1999) have reported that spot sample PD/c ratios are little affected by diurnal variation and closely correlated with urinary PD excretion (Chen et al, 1995;Dapoza et al, 1999). In contrast, Puchala and Kulasek (1992) demonstrated the dependence of spot sample PD/c ratios on sampling time.…”

“…In cattle, the proportion of PDs excreted as allantoin is relatively constant ranging between 0.82 and 0.93 (Chen et al, 1990c(Chen et al, , 1992cVerbic et al, 1990;Giesecke et al, 1994;Shingfield and Offer 1998a,b;Valadares et al, 1999), while the remainder is excreted as uric acid, since bovine urine contains only trace amounts of xanthine and hypoxanthine (Susmel etal., 1994;Shingfield and Offer, 1999a). Pooling data from several dairy cow experiments (n -7) has also demonstrated This relationship indicates that for cattle, urinary PD excretion can be accurately predicted from measurements of allantoin alone, confirming the suggestions of Dewhurst et al (1996).…”

Elaboração de valores de referência urinários para elementos químicos essenciais e não essenciais em crianças brasileiras

“…Já em casos de diurese o contrário é observado (CHEN et al, 1992 Assim, a diferença causada pela diluição urinária pode levar a uma estimativa equivocada dos dados de concentração, especialmente quando a exposição ocorre em baixas doses.…”