A Comparison of Purine Derivatives Excretion with Conventional Methods as Indices of Microbial Yield in Dairy Cows (original) (raw)
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Animal Feed Science and Technology, 1998
In the frame of a feeding experiment with three periods, balance trials were carried out with 18 double-muscled Belgian White±blue bulls, allocated to one of four feeding regimes. The ration consisted of maize silage and concentrate in the ratio of 35:65 on DM basis. Six concentrates were formulated to supply three levels of protein and energy. The three periods corresponded to distinct live weight intervals of 360±460, 460±570 and 570±680 kg. In the first feeding regime, low protein and intermediate energy level were given during the whole trial; in the second regime, protein level decreased at a constant intermediate energy level; in the third regime, the energy level increased at a constant high protein level; in the fourth regime, protein level decreased simultaneously with an increase in the energy level. Total daily intake varied from 6.2 to 9.7 kg for dry matter (DM), from 65 to 106 MJ for metabolisable energy (ME) and from 719 to 1326 g for crude protein (CP) (50 animal observations). At the end of each period, the excretion of the purine derivatives (PD), allantoin and uric acid, was measured after total urine collection during 4 days to estimate microbial nitrogen supply to the duodenum (MN PD ). The effect of the intake of DM, organic matter (OM), digestible OM (DOM), digestible carbohydrates (DCHO), total digestible nutrients (TDN), rumen fermentable OM (FOM), metabolisable energy (ME), fermentable ME (FME), CP, digestible CP (DCP) and rumen degradable protein (RDP) on PD and MN PD was examined. Further, the relationship of MN PD to MN, calculated according to different systems, was examined. The amount (meanAESD) of allantoin excreted in urine was 147AE23 mmol day À1 and of uric acid 11AE3 mmol day À1 . The MN PD amounted to 97AE21 g day À1 , varying from 57 to 154 g day À1 , and significantly Animal Feed Science and Technology 75 (1998) 93±109 Elsevier Science B.V. All rights reserved PII S 0 3 7 7 -8 4 0 1 ( 9 8 ) 0 0 2 0 1 -6 increased with all measures of nutrient intake. The correlation coefficients, ranging from 0.45 for DCP to 0.57 for DOM and FME, were, however, not significantly different. MN PD showed a larger variation and was on average lower than the potential MN values calculated from the intake of FOM (108AE13 g day À1 ), DCHO (141AE16 g day À1 ) and FME (109AE13 g day À1 ), similar to that calculated from the intake of RDP (99AE14 g day À1 ) and higher than the MN value calculated from the intake of TDN (84AE11 g day À1 ). The correlations of MN PD to the calculated MN values ranged from 0.47 for MN FOM to 0.59 for MN FME , but were not significantly different. # 1998 Elsevier Science B.V.
Journal of Dairy Science, 2006
Four mature Holstein-Friesian dairy cows were used in a 4 × 4 Latin square changeover design experiment made up of four 4-wk periods to investigate the relationship between microbial protein flow to the duodenum and excretion of purine derivatives (PD) in the urine. Four dietary treatments based on ad libitum access to ryegrass silage were offered, with a standard dairy concentrate included at different forage:concentrate (F:C) ratios, calculated on a dry matter basis: 80:20, 65:35, 50:50, and 35:65. Feed intakes increased as the proportion of concentrate in the diet increased, despite a concurrent decrease in silage intake. Increased feed intake led to increased nutrient flow to the duodenum. Milk yields increased as the diet F:C ratio decreased, with cows offered the 35:65 diet yielding nearly 8 kg/d more milk than cows offered the 80:20 diet; the concentrations of milk fat decreased and milk protein increased with a decreasing F:C ratio. Purine derivative excretion in the urine increased with an increasing proportion of concentrate in the diet, and there was a strong linear relationship between total PD excretion (allantoin and uric acid) and microbial N flow to the duodenum: microbial N (g/d) = 19.9 + 0.689 × total PD (mmol/d); R = 0.887. This strengthens the case for using PD excretion as a noninvasive marker of microbial protein flow from the rumen in dairy cows.
British Journal of Nutrition, 1996
The present study compares estimates of rumen microbial-N production derived from duodenal flow measurements (15N and purine bases) with those from measurements of the urinary excretion of purine derivatives. Four Rasa Aragonesa ewes fitted with simple cannulas in the rumen and proximal duodenum were used. Four diets consisting of 550 g lucerne (Medicago sativa) hay/d as sole feed or supplemented with 220, 400 and 550 g rolled barley grain/d were given in a 4 x 4 random factorial arrangement. Duodenal digesta flows were determined by the dual-phase marker technique during continuous intraruminal infusions of Co-EDTA and Yb-acetate. Microbial contribution to the non-NH3N (NAN)flow was estimated from 15N enrichment and purines: N ratio in duodenal digesta and bacterial fractions isolated from the rumen content. Whole tract organic matter (OM) digestibility and duodenal flow of OM and NAN increased (P<0·001) with the level of barley supplementation. Digestible OM intake ranged from ...
Urinary excretion of purine derivatives and prediction of rumen microbial outflow in goats
Livestock Production Science, 2002
The present study examined the relationship between duodenal flow of purine bases and urinary excretion of their derivatives (i.e., Allantoin, uric acid, xanthine and hypoxanthine) in selected milk goats. Three adult Granadina goats fitted with a T-shaped cannula in the abomasum were used to determine the endogenous contribution to renal excretion of purine derivatives and urinary recovery of abomasaly infused purine bases as yeast-RNA. Animals were fed alfalfa at maintenance 0.75 level. The endogenous contribution of purine derivatives was determined at fasting (11.34 mg N / W or 202.2 0.75 mmol / W ) and it was similar to that obtained in sheep but lower than that reported in cattle. Urinary PD excretion responded linearly to incremental supply of purine bases throughout the abomasal cannula, these recovery (%) averaged 76. Xanthine oxidase activities in goat tissues were, in plasma 0.001 (S.E. 0.0001) i.u. / ml, in liver 0.12 (S.E. 0.021) i.u. / g and in duodenum 0.0009 (S.E. 0.00026) i.u. / g. Again, activities were lower than those detected in cows but close to values determined in sheep. A similar response model between both species (sheep and goat) is suggested.
Journal of Dairy Science, 1997
Five multiparous, ruminally cannulated Holstein cows (two lactating and three dry) weighing (X +/- SD) 667 +/- 35 kg were used to study the effect of abomasal purine infusion on the excretion of purine derivatives. Cows were fed corn silage four times daily at 90% of ad libitum intake (X = 9.16 kg of dry matter/d). Purines were infused into the abomasum as brewer&amp;#39;s yeast suspensions in five incremental amounts (0 to 380 mmol/d) during five experimental periods according to a 5 x 5 Latin square design. Periods were 7 d; purine infusions were conducted during the last 4 d, and urine was collected during the last 3 d of each period. Ruminal purine outflow in all cows was measured during an experimental period immediately preceding and immediately following the five infusion periods and in each cow during the 0-mmol/d infusion period of the experiment. The relationship between total (milk plus urine) daily excretion of purine derivatives (allantoin plus uric acid) and total (abomasal infusion plus ruminal outflow) daily purine flow was quantified by linear regression analysis and was described by the relationship: Y = 0.856X + 103 (r2 = 0.93). The slope (0.856) indicated that 86% of purines that reached the omasum were excreted as purine derivatives. In the two lactating cows, urinary purine derivatives accounted for 98.4% of the total purine derivatives that were excreted. Ruminal flow of microbial CP can be estimated from the CP:purine ratio of ruminal microorganisms and the excretion of purine derivatives.
Feasibility of using total purines as a marker for ruminal bacteria
Journal of Animal Science, 1999
A procedure for measuring total purine content of mixed ruminal bacteria was adapted for use in the determination of purines in pure cultures of ruminal bacteria. Recovery of adenine and guanine, alone or in mixture, was quite variable. The problem was traced to solubility of the silver salt of adenine in the acid wash solution. When the precipitating solution was used as the wash, recovery of the purines was over 97%. Recovery of a 1:1 mixture of adenine and guanine added to yeast RNA was 100.6 ± 3.2%. Purine, protein, and bacterial concentrations were determined for 10 pure cultures of ruminal bacteria: Butyrivibrio fibrisolvens, D16f, H10b, and H17c; Fibrobacter succinogenes B21a; Lachnospira multiparus D25e; Lactobacillus lactis ARD26e; Prevotella ruminicola H15a; Ruminococcus albus 7; Ruminococcus flavefaciens B34b; and Streptococcus bovis ARD5d. The CV for the most-probablenumber (MPN) assay (bacterial concentrations), purine analysis, and protein analysis were 55.86, 5.25 and