caa a22 4500 388059729 CHVBK 20180307125117.0 cr unu---uuuuu 161130e199806 xx s 000 0 eng 10.1017/S1357729800009139 doi S1357729800009139 pii (NATIONALLICENCE)cambridge-10.1017/S1357729800009139 Evaluation of the spot urine sampling technique to assess urinary purine derivative excretion in lactating dairy cows [Elektronische Daten] The potential of the spot urine sampling technique as an alternative to performing a total urine collection was evaluated. Twelve multiparous Holstein-Friesian cows were given two experimental diets in a complete change-over design using two 14-day experimental periods. Experimental diets were either silage offered ad libitum with 7 kg fresh weight concentrate supplement as a single meal (SF), or a complete diet formulated from the same ingredients with a similar foragexoncentrate ratio (CD). Total urine collections were performed every 2 h on days 11 and 14 of each experimental period. Subsamples of urine were stored at 20°C and subsequently analysed by high-performace liquid chromatography. Daily allantoin and purine derivative (PD) excretion were highly correlated (r = 0·995, no. = 48, P < 0·001). PD and creatinine excretion during each 2-h interval depended on time of collection (PD, P < 0·001 and creatinine, P < 0·05) and on cow (P < 0·01) but were unaffected by sampling day or treatment. Diurnal variations in the molar ratio ofPD or allantoin to creatinine (PD/c and Ale, respectively) followed similar diurnal patterns as observed for PD and allantoin excretion. The data were used to assess the error of prediction of daily mean PD/c or Ale ratios. Three spot sampling regimens (based on the collection of four 4-h samples, three 8-h samples or two 12-h samples) and also on either single or 2-day urine collections were evaluated. Collection of multiple samples within a day was more reliable than collecting fewer samples over several days. Prediction errors were greater for SF compared with CD. Even the most intensive sampling regimen did not allow an acceptable prediction of daily mean PDIc or Ale ratio, minimum r values for PDIc and Ale ratios were 0·098, 0·136 and 0·547, 0·579 for SF and CD, respectively. Furthermore, daily mean PDIc and Ale ratios proved poor predictors of daily PD and allantoin excretion (r values of 0·69 and 0·72, respectively). Total urine collection appears necessary to assess accurately daily PD excretion in dairy cows. Copyright © British Society of Animal Science 1998 creatinine nationallicence dairy cows nationallicence feeding frequency nationallicence purines nationallicence Shingfield K. J. Grassland and Ruminant Science Department, Scottish Agricultural College, Auchincruive, Ayr KA6 5HW Offer N. W. Grassland and Ruminant Science Department, Scottish Agricultural College, Auchincruive, Ayr KA6 5HW Animal Science Cambridge University Press 66/3(1998-06), 557-568 1357-7298 66:3<557 1998 66 ASC https://doi.org/10.1017/S1357729800009139 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S1357729800009139 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shingfield K. J. Grassland and Ruminant Science Department, Scottish Agricultural College, Auchincruive, Ayr KA6 5HW NATIONALLICENCE 700 1- Offer N. W. Grassland and Ruminant Science Department, Scottish Agricultural College, Auchincruive, Ayr KA6 5HW NATIONALLICENCE 773 0- Animal Science Cambridge University Press 66/3(1998-06), 557-568 1357-7298 66:3<557 1998 66 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge