Evaluation of milk allantoin excretion as an index of microbial protein supply in lactating dairy cows

Abstract

The potential of milk allantoin as an index ofmicrobial protein supply was evaluated in two experiments conducted with 12 multiparous Holstein-Friesian dairy cows that examined the effects of altering the supply of metabolizable energy (ME) and fermentable metabolizable energy (FME). In the first experiment, late lactation cows received a 14·3 kg dry matter (DM) per day basal diet consisting of (g/kg DM) chopped barley straw (415), soya-bean meal (322), molassed sugar-beet pulp (197), molasses (33), urea (17) and a vitamin and mineral supplement (17) for a 21-day co-variance period. During four 16-day periods, six treatments were allocated randomly to cows, consisting of potato starch (1, 2 or 3 kg DM per day) or fat supplements (0·64, 1·27 or 1·91 kg DM per day). In the second experiment, early lactation cows received 40 kg/day (fresh weight, (FW)) of silage (307 g/kg toluene-corrected dry matter, 149 g/kg DM crude protein and 11·6 MJ/kg ME). During three 21-day periods, four treatments were evaluated consisting of supplements of either 4·1 (LI) or 8·1 (12) kg fresh weight per day of a low fat concentrate (acid hydrolysis ether extract (AHEE) 45 g/kg DM) or 3·8 (HI) or 7·5 (H2) kg fresh weight per day of a high fat concentrate (AHEE 110 g/kg DM). Both experiments showed individual cow milk allantoin concentration or excretion to be poorly correlated with urinary purine derivative excretion or calculated microbial protein supply. Use of treatment mean (TM) values dramatically improved these relationships. For pooled TM (no. = 10) values from both experiments, close relationships existed between milk allantoin excretion and concentration with milk yield (r values 0·991 and 0·883, respectively). Auto-correlation with milk yield appeared to account for milk allantoin excretion and concentration being highly correlated with urinary purine derivative excretion (r values 0·908 and 0·934, respectively) and calculated microbial protein supply (r values 0·938 and 0·945, respectively). Current experimental data indicates that measurement of milk allantoin is not a reliable indicator of microbial protein supply for individual cows.

Chemical markers for rumen methanogens and methanogenesis

“…The technique depends on assumptions about the degradation of dietary purines, the purine content of rumen microbes, the endogenous contribution of purine derivatives from turnover within animal tissues and losses of purine derivatives through other routes (e.g. milk; Shingfield and Offer, 1998).…”

Utilization of nitrogen in cows consuming wet distillers grains with solubles in alfalfa and corn silage-based dairy rations

“…Urine samples were analyzed for N (Leco FP-528, Leco Corp.). Urinary creatinine and purine derivatives (PD) were analyzed by HPLC (Waters Corp., Milford, MA) according to the procedures of Shingfield and Offer (1998). Urinary creatinine has been validated as a marker to estimate urine volume (Valadares et al, 1999;Leonardi et al, 2003).…”

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

“…However, these estimates are subject to criticism due to a lack of specificity of colorimetric based methods used for the quantification of allantoin in milk and urine. Use of more specific and sensitive analytical methods based on high performance liquid chromatography have indicated that mammary secretion accounts for proportionately between 0.006-0.03 of urinary allantoin excretion in ruminant species (Giesecke et al, 1994;MartinOnie etal., 1996;Gonda and Lindberg, 1997;Shingfield and Offer, 1998b). Secretion of uric acid in milk has been reported to account for proportionately 0.03 and 0.17 of urinary excretion in cows (Giesecke et al, 1994;Valadares et al, 1999) and sheep (Martin-Orue et al, 1996), respectively.…”

“…Gonda and Lindberg (1997) working with dairy cows, were also unable to identify a consistent relationship between urinary and milk allantoin excretion. Shingfield and Offer (1998b) attempted to evaluate the potential of milk allantoin in two experiments using diets formulated to supply different amounts of metabolisable and fermentable energy, that were assumed to cause differences in MP supply. Excretion and concentration of allantoin in milk was found to be closely correlated with urinary PD excretion, based on mean treatment values, but not when based on individual cow measurements (Figure 7), a finding attributed to mutual correlation of these parameters with milk yield.…”

“…Excretion and concentration of allantoin in milk was found to be closely correlated with urinary PD excretion, based on mean treatment values, but not when based on individual cow measurements (Figure 7), a finding attributed to mutual correlation of these parameters with milk yield. Since the prediction of urinary PD excretion was not improved by milk allantoin measurements, compared to that of milk yield alone, Shingfield and Offer (1998b) concluded that the secretion of allantoin appears to be of little value for the assessment of MP supply. These findings are consistent with those of Lebzien et al (1993) indicating that estimates of MP supply based on 15 N were less well correlated with milk allantoin excretion (r value 0.711; Figure 8) than dietary energy intake (r value 0.916).…”