Urinary Excretion Of Purine Derivatives Research Articles

Urinary purine derivatives excretion, rumen microbial nitrogen synthesis and the efficiency of utilization of recycled urea in Tibetan and fine-wool sheep

Urinary purine derivatives (PD) excretion, rumen bacterial purine bases and nitrogen (N) variations, estimated microbial N synthesis and the efficiency of utilization of recycled urea-N were determined in Tibetan and Gansu Alpine fine-wool sheep offered 4 diets with different N concentrations [11.0, 16.7, 23.1 and 29.2gN/kg dry matter (DM)] in 2 concurrent 4×4 Latin square designs. Urine output increased linearly with increasing dietary N concentration (P<0.001), and was lower in Tibetan than in fine-wool sheep (P<0.05). With an increase in dietary N, urinary PD and the components increased linearly (P<0.05), except for uric acid (P>0.10); however, the purine nitrogen index (PNI) decreased (P<0.001). For the lowest N diet, allantoin, total PD and PNI were greater in Tibetan sheep than in fine-wool sheep (linear dietary N×breed, P<0.05). As dietary N increased, rumen bacterial purine bases [ribonucleic acid (RNA) equivalent] decreased linearly (P<0.05), whereas total N content increased (P<0.05). Compared to fine-wool sheep, rumen bacteria of Tibetan sheep contained higher RNA and lower N content (P<0.01). Total microbial N production and microbial N from recycled urea-N increased linearly with dietary N but did not differ between breeds at low N diets (P>0.05). As a proportion of total microbial N synthesis or hepatic urea-N production, recycled urea-N was utilized more efficiently in Tibetan than in fine-wool sheep (P<0.05). These results suggest that Tibetan sheep are better able to cope with a low protein diet, which is characteristic of the Qinghai-Tibetan Plateau during the long-cold season, than are Gansu Alpine fine-wool sheep.

Performance and ruminal parameters of fattening Moghani lambs fed recycled poultry bedding.

This study investigated the effects of recycled poultry bedding (RPB) on performance and protozoa population, microbial enzyme activity and microbial protein synthesis (MPS) in rumen contents of fattening lambs. Thirty-six male Moghani lambs (31.4 ± 3.2 kg body weight) were fed iso-energetic and iso-nitrogenous diets containing 0, 70, 140 or 210 g/kg dry matter (DM) RPB in a balanced randomized design (9 lambs per treatment). Results showed that final body weight, DM intake, average daily gain and feed conversion ratio were unchanged (P > 0.05) by RPB inclusion. Total protozoa population and sub-family of Entoniniinae and Diplodiniiae were linearly decreased by RPB (L, P < 0.05). For rumen fibrolytic enzymes including carboxymethyl-cellulase, microcrystalline-cellulase and filter paper degrading activity, the extra cellular, cellular and total (extra cellular plus cellular fraction) activity were similar (P > 0.05) by feeding the experimental diets. Inclusion of RPB in the diet linearly decreased extra cellular and total α-amylase activity (L, P < 0.05), while cellular activity was unchanged (P > 0.05). The extra cellular activity of proteases tended to increase (L, P = 0.07) and their total and cellular activity increased (P > 0.05) in lambs fed RPB. Incorporation of RPB into the diet had no effect (L, P > 0.05) on urinary purine derivative excretion and MPS. In conclusion, inclusion of RPB up to 210 g/kg DM had no negative impact on performance, ruminal fibrolytic enzyme activity and MPS, while it increased rumen protease activity and decreased protozoa population in fattening Moghani lambs.

Technical note: Evaluation of urinary purine derivatives in comparison with duodenal purines for estimating rumen microbial protein supply in sheep.

A data set of individual observations was compiled from digestibility trials to examine the relationship between the duodenal purine bases (PB) flow and urinary purine derivatives (PD) excretion and the validity of different equations for estimating rumen microbial N (Nm) supply based on urinary PD in comparison with estimates based on duodenal PB. Trials (8 trials, = 185) were conducted with male sheep fitted with a duodenal T-type cannula, housed in metabolic cages, and fed forage alone or with supplements. The amount of PD excreted in urine was linearly related to the amount of PB flowing to the duodenum ( < 0.05). The intercept of the linear regression was 0.180 mmol/(d·kg), representing the endogenous excretion of PD, and the slope was lower than 1 ( < 0.05), indicating that only 0.43% of the PB in the duodenum was excreted as PD in urine. The Nm supply estimated by either approach was linearly related ( < 0.05) to the digestible OM intake. However, the Nm supply estimated through either of 3 published PD-based equations probably underestimated the Nm supply in sheep.

Effect of dietary Quebracho tannin extract on feed intake, digestibility, excretion of urinary purine derivatives and milk production in dairy cows

ABSTRACTThe aim of this study was to evaluate the effects of dietary Quebracho tannin extract (QTE) on feed intake, apparent total tract digestibility (ATTD), excretion of urinary purine derivatives (PD) and milk composition and yield in dairy cows. Fifty Holstein cows were divided into two groups. To reach a similar performance of both groups, cows were divided according to their milk yield, body weight, days in milk and number of lactations at the start of the experiment averaging 33.2 ± 8.2 kg/d, 637 ± 58 kg, 114 ± 73 d and 2.3 ± 1.6 lactations, respectively. The cows were fed a basal diet as total mixed ration containing on dry matter (DM) basis 34% grass silage, 32% maize silage and 34% concentrate feeds. Three dietary treatments were tested, the control (CON, basal diet without QTE), QTE15 (basal diet with QTE at 15 g/kg DM) and QTE30 (basal diet with QTE at 30 g/kg DM). Two treatments were arranged along six periods each 21 d (13 d adaptation phase and 8 d sampling phase). The ATTD of DM and organic matter were reduced only in Diet QTE30, whereas both QTE treatments reduced ATTD of fibre and nitrogen (N), indicating that QTE impaired rumen fermentation. Nevertheless, feed intake was unaffected by QTE. In Diet CON, urinary N excretion accounted for 29.8% of N intake and decreased in treatments QTE15 and QTE30 to 27.5% and 17.9%, respectively. Daily faecal N excretion increased in treatments CON, QTE15 and QTE30 from 211 to 237 and 273 g/d, respectively, which amounted to 39.0%, 42.4% and 51.7% of the N intake, respectively. Hence, QTE shifted N excretion from urine to faeces, whereas the proportion of ingested N appearing in milk was not affected by QTE (average 30.7% of N intake). Daily PD excretion as indicator for microbial crude protein (CP) flow at the duodenum decreased in treatment QTE30 compared with Diet CON from 413 to 280 mmol/d. The ratios of total PD to creatinine suggest that urinary PD excretion was already lower when feeding Diet QTE15. While there was no effect of Diet QTE15, treatment QTE30 reduced milk yield, milk fat and protein. Both QTE treatments reduced milk urea concentration, which suggest that ruminal degradation of dietary CP was reduced. In summary, adding QTE at dosages of 15 and 30 g/kg DM to diets of lactating dairy cows to improve feed and protein use efficiency is not recommended.

Assessment of dietary ratios of red clover and corn silages on milk production and milk quality in dairy cows.

Twenty-four multiparous Holstein-Friesian dairy cows were used in a replicated 3×3 Latin square changeover design experiment to test the effects of changing from corn (Zea mays) silage to red clover (Trifolium pratense) silage in graded proportions on feed intakes, milk production, and whole-body N and P partitioning. Three dietary treatments with ad libitum access to 1 of 3 forage mixtures plus a standard allowance of 4kg/d dairy concentrates were offered. The 3 treatment forage mixtures were, on a dry matter (DM) basis: (1) R10: 90% corn silage and 10% red clover silage, (2) R50: 50% corn silage and 50% red clover silage, and (3) R90: 10% corn silage and 90% red clover silage. In each of 3 experimental periods, there were 21d for adaptation to diets, and 7d for measurements. Diet crude protein intakes increased, and starch intakes decreased, as the silage mixture changed from 90% corn to 90% red clover, although the highest forage DM intakes and milk yields were achieved on diet R50. Although milk fat yields were unaffected by diet, milk protein yields were highest with the R 0250 diet. Whole-body partitioning of N was measured in a subset of cows (n=9), and both the daily amount and proportion of N consumed that was excreted in feces and urine increased as the proportion of red clover silage in the diet increased. However, the apparent efficiency of utilization of feed N for milk protein production decreased from 0.33g/g for diet R10 to 0.25g/g for diet R90. The urinary excretion of purine derivatives (sum of allantoin and uric acid) tended to increase, suggesting greater flow of microbial protein from the rumen, as the proportion of red clover silage in the diet increased, and urinary creatinine excretion was affected by diet. Fecal shedding of E. coli was not affected by dietary treatment. In conclusion, even though microbial protein flow may have been greatest from the R 0450 diet, optimum feed intakes and milk yields were achieved on a diet that contained a 1:1 DM mixture of corn and red clover silages.

Effects of dietary supplementation of rumen-protected folic acid on rumen fermentation, degradability and excretion of urinary purine derivatives in growing steers

ABSTRACTThe present experiment was undertaken to determine the effects of dietary addition of rumen-protected folic acid (RPFA) on ruminal fermentation, nutrient degradability, enzyme activity and the relative quantity of ruminal cellulolytic bacteria in growing beef steers. Eight rumen-cannulated Jinnan beef steers averaging 2.5 years of age and 419 ± 1.9 kg body weight were used in a replicated 4 × 4 Latin square design. The four treatments comprised supplementation levels of 0 (Control), 70, 140 and 210 mg RPFA/kg dietary dry matter (DM). On DM basis, the ration consisted of 50% corn silage, 47% concentrate and 3% soybean oil. The DM intake (averaged 8.5 kg/d) was restricted to 95% of ad libitum intake. The intake of DM, crude protein (CP) and net energy for growth was not affected by treatments. In contrast, increasing RPFA supplementation increased average daily gain and the concentration of total volatile fatty acid and reduced ruminal pH linearly. Furthermore, increasing RPFA supplementation enhanced the acetate to propionate ratio and reduced the ruminal ammonia N content linearly. The ruminal effective degradability of neutral detergent fibre from corn silage and CP from concentrate improved linearly and was highest for the highest supplementation levels. The activities of cellobiase, xylanase, pectinase and α-amylase linearly increased, but carboxymethyl-cellulase and protease were not affected by the addition of RPFA. The relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes increased linearly. With increasing RPFA supplementation levels, the excretion of urinary purine derivatives was also increased linearly. The present results indicated that the supplementation of RPFA improved ruminal fermentation, nutrient degradability, activities of microbial enzymes and the relative quantity of the ruminal cellulolytic bacteria in a dose-dependent manner. According to the conditions of this experiment, the optimum supplementation level of RPFA was 140 mg/kg DM.

Effects of rumen-protected folic acid on ruminal fermentation, microbial enzyme activity, cellulolytic bacteria and urinary excretion of purine derivatives in growing beef steers

This experiment was done to investigate the influences of supplementary rumen-protected folic acid (RPFA) on ruminal fermentation parameters, microbial enzyme activity, cellulolytic bacteria and urinary excretion of purine derivatives in growing beef steers. Eight ruminally fistulated Jinnan beef steers (398.4±1.9kg) were used in a repeated 4×4 Latin square experimental design. The treatments were: control (without RPFA), low RPFA (LRPFA), medium RPFA (MRPFA) and high RPFA (HRPFA) with 0, 0.6, 1.2 and 1.8g RPFA per steer per day, respectively. The dietary corn silage to concentrate ratio was 50:50 (dry matter [DM] basis). The dry matter intake was confined to 95% of voluntary intake. Mean ruminal pH was quadratically reduced with altering RPFA supplementation, and was the lowest for MRPFA and HRPFA, highest for the control, and intermediate for the LRPFA. Ruminal total VFA concentration was quadratically increased with increasing RPFA supplementation and was higher in MRPFA than in control. The ratio of acetate to propionate was quadratically increased due to the increased acetate concentration and the unchanged propionate concentration. Ruminal degradabilities of DM and neutral detergent fibre of corn silage, and DM and crude protein of concentrate mix increased quadratically with increasing RPFA supplementation. Ruminal enzyme activity of cellobiase, xylanase, pectinase and α-amylase quadratically increased and was higher in MRPFA than in control. The populations of B. fibrisolvens, R. albus, R. flavefaciens and F. succinogenes quadratically increased with altering the supplementary PRFA. Urinary excretion of purine derivatives quadratically increased with altering RPFA supplementation and was higher in HRPFA and MRPFA than in LRPFA and control. The results indicated that dietary supplements of RPFA improved ruminal fermentation, in situ ruminal degradation and urinary excretion of purine derivatives. It was suggested that the RPFA regulated the activity of rumen microbe or enzymes in a concentration-dependent manner. Under this experimental condition, the appropriate dose of RPFA was at 1.2g/d for steer.

Efficiency of rumen microbial protein synthesis in cattle grazing tropical pastures as estimated by a novel technique

The efficiency of microbial protein synthesis (EMPS) in cattle grazing a range of tropical pasture types was examined using a new method of intra-jugular infusion of chromium–EDTA to estimate urinary excretion of purine derivatives. Seven pasture types were studied in south-eastern Queensland, Australia, over a 13-month period. These included native tropical grass (C4) pasture (major species Heteropogon contortus and Bothriochloa bladhii) studied in the early wet, the wet–dry transition and the dry season; introduced tropical grass (C4) pasture (Bothriochloa insculpta) in the mid-wet season; two introduced tropical legume species (C3; Lablab purpureus and Clitoria ternatea); and the temperate-grass (C3) pasture, ryegrass (Lolium multiflorum). There was a large range in EMPS across pasture types, with a range of 26–209 g microbial crude protein per kilogram digestible organic matter intake (DOMI). Estimated rumen-degradable protein (RDP) supply (42–525 g/kg DOMI) was the major factor associated with EMPS across the range of pasture types studied. EMPS in steers grazing all tropical grass pastures was low (&amp;lt;130 g/kg DOMI) and limited by RDP supply. Negative linear relationships (P &amp;lt; 0.05) between EMPS and concentrations of both neutral detergent fibre and acid detergent fibre in extrusa were evident. However, non-fibre carbohydrate in extrusa, total non-structural carbohydrate concentration in plucked pasture leaf, rumen fluid and particle dilution rate, protozoal concentration in rumen fluid and rumen fluid pH were not correlated with EMPS. It was concluded that EMPS was well below 130 g microbial crude protein per kilogram DOMI when cattle grazed unfertilised, tropical grass pastures in south-eastern Queensland and that RDP was the primary limiting nutrient. High EMPS was associated with a very high RDP, vastly in excess of RDP requirements by microbes.

Ruminal fermentation, nutrient digestibility and microbial protein synthesis in sheep fed diets with different levels of date pulp

Four ruminally cannulated mature Kermani sheep (50 ± 2.3 kg and 40 ± 2.1 months old) were used in a 4 × 4 Latin square design to determine the effects of diets with different levels of date pulp (DP) on ruminal fermentation, nutrient digestibility and microbial protein synthesis. DP was replaced for wheat bran in diets at no DP (0 DP), 7 (7 DP), 14 (14 DP) and 21% (21 DP) of diet dry matter (DM) and were fed twice daily (0800 hours and 1800 hours). In this study, increasing the amount of DP in diets of sheep did not affect DM intake and apparent digestibility of nutrient (P &gt; 0.05). Inclusion of DP in diets increased ruminal pH linearly (P &lt; 0.05), but did not influence total volatile fatty acids and molar proportion of individual volatile fatty acids (P &gt; 0.05). Ruminal ammonia nitrogen concentration (6.04 vs 10.13 mmol/L), and blood urea nitrogen (8.59 vs 13.10 mg/dL) were affected by diets (P &lt; 0.05). Moreover, urinary nitrogen excretion was higher (P &lt; 0.05) for Control diet (no DP) than the 21 DP diet. In this study, urinary excretion of purine derivatives and microbial protein synthesis were affected by experimental diets (P &lt; 0.05). In conclusion, this study showed that DP at 14% can be used as an alternative feed resource in sheep nutrition especially in semiarid areas.

Effects of dietary crude protein and rumen-degradable protein concentrations on urea recycling, nitrogen balance, omasal nutrient flow, and milk production in dairy cows

The objective of this study was to determine how interactions between dietary crude protein (CP) and rumen-degradable protein (RDP) concentrations alter urea-nitrogen recycling, nitrogen (N) balance, omasal nutrient flow, and milk production in lactating Holstein cows. Eight multiparous Holstein cows (711±21kg of body weight; 91±17d in milk at the start of the experiment) were used in a replicated 4×4 Latin square design with a 2×2 factorial arrangement of dietary treatments and 29-d experimental periods. Four cows in one Latin square were fitted with ruminal cannulas to allow ruminal and omasal sampling. The dietary treatment factors were CP (14.9 vs. 17.5%; dry matter basis) and RDP (63 vs. 69% of CP) contents. Dietary RDP concentration was manipulated by including unprocessed or micronized canola meal. Diet adaptation (d 1–20) was followed by 8d (d 21–29) of sample and data collection. Continuous intrajugular infusions of [15N15N]-urea (220mg/d) were conducted for 4d (d 25–29) with concurrent total collections of urine and feces to estimate N balance and whole-body urea kinetics. Proportions of [15N15N]- and [14N15N]-urea in urinary urea, and 15N enrichment in feces were used to calculate urea kinetics. For the low-CP diets, cows fed the high-RDP diet had a greater DM intake compared with those fed the low-RDP diet, but the opposite trend was observed for cows fed the high-CP diets. Dietary treatment had no effect on milk yield. Milk composition and milk component yields were largely unaffected by dietary treatment; however, on the low-CP diets, milk fat yield was greater for cows fed the low-RDP diet compared with those fed the high-RDP diet, but it was unaffected by RDP concentration on the high-CP diets. On the high-CP diets, milk urea nitrogen concentration was greater in cows fed the high-RDP diet compared with those fed the low-RDP diet, but it was unaffected by RDP concentration on the low-CP diets. Ruminal NH3-N concentration tended to be greater in cows fed the high-CP diet compared with those fed the low-CP diet, and it was greater in cows fed the high-RDP diet as compared with those fed the low-RDP diet. Nitrogen intake and both total N and urea-N excretion in urine were greater for cows fed the high-CP diet compared with those fed the low-CP diet. However, N balance and urinary excretion of purine derivatives were unaffected by dietary treatment. Urea-N entry rate (UER) was greater in cows fed the high-CP diet compared with those fed the low-CP diet; however, UER was unaffected by dietary RDP concentration. The proportion of urea-N recycled to the gastrointestinal tract (as a percentage of UER) was greater in cows fed the low-CP diet compared with those fed the high-CP diet. In summary, reducing dietary CP concentration decreased urinary N excretion but had no effect on milk yield, thus resulting in an overall improvement in milk N efficiency.

The effect of dietary water soluble carbohydrate to nitrogen ratio on nitrogen partitioning and isotopic fractionation of lactating goats offered a high-nitrogen diet

The objective of this study was to investigate the relationship between nitrogen (N) partitioning and isotopic fractionation in lactating goats consuming diets with a constant high concentration of N and increasing levels of water soluble carbohydrate (WSC). Eight lactating goats were offered four different ratios of WSC : N in the diet. A two-period incomplete cross-over design was used, with two goats assigned to each treatment in each period. N balance measurements were conducted, with measurement of feed N intake and total output of N in milk, faeces and urine. Treatment, period and infusion effects were tested using general ANOVA; the relationships between variables were analysed by linear regression. Dietary treatment and period had significant effects on dry matter (DM) intake (g/day). DM digestibility (g/kg DM) and N digestibility (g/kg N) increased as the ratio of WSC : N increased in the diet. No treatment effect was observed on milk urea N concentration (g/l) or urinary excretion of purine derivatives (mM/day). Although dietary treatment and period had significant effects on N intake, the change of N intake was small; no effect was observed for N partitioning among faeces, milk and urine. Milk, plasma and faeces were enriched in 15N compared with feed, whilst urine was depleted in 15N relative to feed. No significant relationship was established between N partitioning and isotopic fractionation. This study failed to confirm the potential to use N isotopic fractionation as an indicator of N partitioning in dairy goats when diets provided N in excess to requirements, most likely because the range of milk N output/N intake and urinary N output/N intake were narrow.

Nitrate but not tea saponin feed additives decreased enteric methane emissions in nonlactating cows.

Tea saponin is considered a promising natural compound for reducing enteric methane emissions in ruminants. A trial was conducted to study the effect of this plant extract fed alone or in combination with nitrate on methane emissions, total tract digestive processes, and ruminal characteristics in cattle. The experiment was conducted as a 2 × 2 factorial design with 4 ruminally cannulated nonlactating dairy cows. Feed offer was restricted to 90% of voluntary intake and diets consisted of (DM basis): 1) control (CON; 50% hay and 50% pelleted concentrates), 2) CON with 0.5% tea saponin (TEA), 3) CON with 2.3% nitrate (NIT), and 4) CON with 0.5% tea saponin and 2.3% nitrate (TEA+NIT). Tea saponin and nitrate were included in pelleted concentrates. Diets contained similar amounts of CP (12.2%), starch (26.0%), and NDF (40.1%). Experimental periods lasted 5 wk including 2 wk of measurement (wk 4 and 5), during which intake was measured daily. In wk 4, daily methane emissions were quantified for 4 d using open circuit respiratory chambers. In wk 5, total tract digestibility, N balance, and urinary excretion of purine derivatives were determined from total feces and urine collected separately for 6 d. Ruminal fermentation products and protozoa concentration were analyzed from samples taken after morning feeding for 2 nonconsecutive days in wk 5. Tea saponin and nitrate supplementation decreased feed intake ( < 0.05), with an additive effect when fed in combination. Compared with CON, tea saponin did not modify methane emissions (g/kg DMI; > 0.05), whereas nitrate-containing diets (NIT and TEA+NIT) decreased methanogenesis by 28%, on average ( < 0.001). Total tract digestibility, N balance, and urinary excretion of purine derivatives were similar among diets. Ruminal fermentation products were not affected by tea saponin, whereas nitrate-containing diets increased acetate proportion and decreased butyrate proportion and ammonia concentration ( < 0.05). Under the experimental conditions tested, we confirmed the antimethanogenic effect of nitrate, whereas tea saponin alone included in pelleted concentrates failed to decrease enteric methane emissions in nonlactating dairy cows.

Influence of ruminal Quebracho tannin extract infusion on apparent nutrient digestibility, nitrogen balance, and urinary purine derivatives excretion in heifers

Six fully grown heifers (491kg body weight, standard deviation 35) fitted with ruminal cannulae received incremental dosages of a commercial Quebracho tannin extract (QTE) to investigate its effects on apparent total tract nutrient digestibilities, nitrogen balance, and purine derivatives excretion as an indicator of duodenal microbial crude protein flow. The basal diet comprised 2.6kg/d grass hay, 2.6kg/d concentrate feed, and 60g/d of a mineral premix (as-fed basis) and was offered in two equal meals. The QTE was administered at 0 (CON 1), 1, 2, 4, or 6% of the daily DM intake from the basal diet (i.e., 45g, 90g, 180g, and 270g/d; as-fed basis). For this, half of the daily QTE dosage was suspended in water and intraruminally infused during each feeding. All animals simultaneously received the same QTE dosage. Every period comprised 9d of adaptation and 6d of total urine and feces collection. Subsequent to highest QTE dosage, infusion was ceased and after 14d of adaptation, urine and feces were collected again for 10d (CON 2). The QTE infusions at ≥4% lowered apparent total tract organic matter digestibility (P≤0.045). The effects were more pronounced for neutral detergent and acid detergent fiber digestibilities which decreased from 0.718 and 0.626 without QTE to 0.590 and 0.493 at 6% QTE, respectively (P<0.001). Nitrogen excretion linearly decreased in urine (P=0.003) and linearly increased in feces (P<0.001) with incremental QTE dosages. Irrespective of the dosage level, nitrogen retention was higher with than without QTE infusion (P≤0.035). Urinary purine derivatives excretion declined from 103mmol/d at 1% QTE to 80mmol/d at 6% QTE (P<0.001), indicating a 36% decrease in estimated duodenal microbial crude protein flow. At QTE dosages of ≥4% of DM intake, reduced carbohydrate digestibility will lower energy supply to the host animal. The pronounced decrease in estimated microbial protein synthesis even at moderate QTE levels is unlikely to be compensated by the increase in rumen-escape protein. The QTE addition to ruminant diets might not improve protein supply and performance of cattle.

Effects of supplementing rare earth element cerium on rumen fermentation, nutrient digestibility, nitrogen balance and plasma biochemical parameters in beef cattle.

The objectives of the trial were to investigate the effects of supplementing rare earth element (REE) cerium (Ce) on rumen fermentation, nutrient digestibility, methane (CH4 ) production, nitrogen (N) balance and plasma biochemical parameters in beef cattle. Four Simmental male cattle, aged at 14 months, with initial liveweight of 355 ± 8 kg and fitted with permanent rumen cannulas, were used as experimental animals. The cattle were fed with a total mixed ration (TMR) composed of concentrate mixture and corn silage. Four levels of cerium chloride (CeCl3 ·7H2 O, purity 99.9%), that is 0, 80, 160 and 240 mg CeCl3 /kg DM, were added to basal ration in a 4 × 4 Latin square design. Each experimental period lasted 15 days, of which the first 12 days were for pre-treatment and the last 3 days were for sampling. The results showed that supplementing CeCl3 at 160 or 240 mg/kg DM increased neutral detergent fibre (NDF) digestibility (p < 0.05) and tended to increased acid detergent fibre (ADF) digestibility (p = 0.083). Supplementing CeCl3 at 80, 160 or 240 mg/kg DM decreased the molar ratio of rumen acetate to propionate linearly (p < 0.05). Supplementing CeCl3 at 160 or 240 mg/kg DM decreased total N excretion, urinary N excretion and increased N retention (p < 0.05), increased excretion of total urinary purine derivatives (PD) (p < 0.05) and decreased CH4 /kg DMI (p < 0.05). In conclusion, supplementing CeCl3 at 160 or 240 mg/kg DM in the ration of beef cattle increased the digestibility of NDF, decreased the molar ratio of rumen acetate to propionate, increased N retention and microbial N flow and decreased CH4 /kg DMI.

Response of urinary purine derivatives excretion to different levels of ruminal glucose infusion in heifers

This study investigated the response of urinary purine derivatives (PD) excretion to increasing levels of intraruminal glucose infusion to evaluate how well this indicator reflects induced changes in microbial crude protein flow. Four rumen-cannulated heifers (482 ± 25 kg body weight) were fed at maintenance energy level with a basal diet (on fresh matter basis) of 4 kg/d hay, 1.5 kg/d concentrate and 60 g/d minerals in two equal meals. The trial comprised a control period (Control I) without glucose infusion followed by four consecutive periods in which all animals received 125 g, 250 g, 500 g or 1000 g/d of glucose, respectively. For this, daily dosages of glucose and urea (90 g/d during all periods) were divided into three portions that were dissolved in water and directly administered into the rumen during morning and afternoon feedings and once during noon. After the highest glucose dosage, a second control period was carried out (Control II). Urinary PD excretion increased with glucose infusion of 125 g/d (71.4 mmol/d) and 1000 g/d (74.2 mmol/d) over the level at Control I (53.9 mmol/d (standard error of the mean (SEM) 3.4; p = 0.012). After withdrawing glucose infusion, PD excretion (79.0 mmol/d) did not return to Control I level (p = 0.001). In contrast, faecal nitrogen (N) excretions linearly increased with incremental glucose infusion (p < 0.001) from 33.9 g/d at Control I to 39.7 g/d (SEM 0.5) at 1000 g/d of glucose and were similar in Control I and II (p = 0.086). The contradicting responses in the excretions of faecal N and urinary PD to increasing glucose infusions highlight the limited accuracy of the PD excretion as a non-invasive indicator when incremental dosages of rapidly fermentable carbohydrates are supplied.

Influence of Condensed Tannins Supplementation through Leaf Meal Mixture on Urinary excretion of Purine Derivatives, Microbial Protein Synthesis and Performance ofHaemonchus contortusInfected Sheep

Study was carried out to assess the effect of condensed tannins (CT) containing leaf meal mixture (LMM) on feed intake, body weight changes, parasitic load, urinary excretion of purine derivatives (PD) and microbial protein synthesis (MP) in Haemonchus contortus infected sheep. Eighteen adult male sheep of similar age and body weight (25.03±1.52) were randomly divided into three groups (negative control; NC, infected control; C and treatment; T) of six each in a completely randomized block design (CRD) for a period of 90 days. Twelve H. contortus infected sheep were allocated into C and T groups, containing 0 and 1.5% of CT, respectively. Six non-infected sheep was taken in NC group to compare their performance with C group. Concentrate intake was significantly (P<0.000) lower in T group as compared to C group, while roughage intake did not differ significantly irrespective of groups. Final body weights were comparable (P<0.063) among all three groups. Faecal egg counts (FECs) were significantly (P<0.001) higher in C group as compared to T group. MP synthesis was calculated by estimating urinary excretion of PD through High performance liquid chromatography (HPLC). Total PD excretion, absorption of PD and Microbial nitrogen (MN) supply (g d−1) were comparatively (P<0.05) higher in T group than in the C group. It may be concluded that CT supplementation (1.5%) decreased H. contortus load in sheep by reducing FECs and has a potential benefits on protein nutrition by altering partitioning of nutrients towards higher microbial yield and absence of any depressing effect on rumen MN synthesis.

Shifting Eating Time Alters Rumen Dynamics in Once-daily Fed Dairy Cows

e objective was to establish e�怆ects of providing a total mixed ration (TMR) at either 0900 h or 2100 h on rumen fermentation and passage kinetics, and microbial protein biomass in lactating cows. Four multiparous and four primiparous Holstein cows were used in a cross- over design study with two 6-week periods, each with 3-week adaptation. Total urine was collected during a sampling week in each period to measure urinary excretion of purine derivatives to estimate microbial protein biomass. Rumen ammonia concentrations were lower in primiparous cows fed at 2100 h vs. 0900 h (10 vs. 11 mg/L, P<0.05). Rumen propionate was lower (26.5 vs. 28 mmol/L) and the acetate to propionate ratio was higher (2.1 vs. 1.9) in multiparous cow fed at 2100 h vs. 0900 h. Microbial protein estimates were not sgnficnty ��怆ected by eating time. Evening fed cows tended to realize a greater rumen volume than morning fed cows (107 vs. 90 L, P<0.01). �䀆erefore, feed delivery at 2100 h vs. 0900 h increased rumen volume and fermentation without sgnficnty ��怆ectng microbial protein synthesis.

Effects of crude protein level in the concentrate and time allotment on pasture on milk yield, urinary nitrogen, and purine derivative excretion in lactating Latxa ewes

This study assessed the influence of reducing the crude protein (CP) content (from 190 to 130 g/kg CP/kg) in the supplementary concentrate and time allotment on pasture (TAP) on the milk yield, bodyweight, and the urinary nitrogen (N) and purine derivatives (PD) in lactating Latxa ewes. Animals were reared in a production system that restricted the amount of time that ewes spent on pasture. In mid-April, at the start of the 42 days experiment, 40 dairy Latxa ewes were assigned to one of four groups on the basis of their initial milk yield, days in lactation (DIL), bodyweight (BW), and condition score; thereafter, each group grazed in its own fenced paddock. The experiment was based on a 2 × 2 factorial design that included two CP levels and two pasture grazing regimes: 4 h continuous grazing (CG) in the morning or 2 h grazing in the morning and 2 h in the afternoon (DG). Individual milk yield was recorded three times a week, and time spent grazing and BW was recorded weekly. In the middle (day 15–17; P1) and at the end (day 36–38; P2) of the experiment, urinary spot samples were collected using a catheter. At the end of the experiment, ewes were confined to metabolic cages and urine was collected. CP level of the concentrate was not correlated with time spent grazing; however, the ewes that were permitted access to pasture twice per day spent more time grazing (223 min/day vs 207 min/day, P &lt; 0.01) and were more efficient with their time (56 min/h grazing vs 52 min/h, P &lt; 0.05) than the ewes that were permitted access to pasture once per day. Concentrate CP levels were not correlated with milk yield or composition, although ewes that received the high protein (HP) lost more weight than did those that received the low protein (LP) concentrate. Concentrate CP level and TAP were not correlated with creatinine (CR) excretion rate (mean = 315 µmol/kg LW0.75 s.e. 0.0161). Urea-N was the largest component of urinary-N (68.7 s.e. 2.33%; P &gt; 0.05), and urea-N waste was higher in HP ewes (202.7 mmol/day) than it was in LP ewes (159.5 mmol/day) (s.d. 27.83; P &lt; 0.01). Ewes subjected to the DG regime had significantly (P &lt; 0.01) higher urinary PD excretion (23.6 vs 21.4 mmol/day s.d. 4.01; P &lt; 0.01), and tended (P &lt; 0.1) to excrete less urea-N (175.1 vs 188.3 mmol, s.d. 27.83) than did the CG ewes. A reduction in the CP in the supplementary concentrate led to a reduction in N waste without having a detrimental effect on performance or milk production.

Timing of eating a global orchestrator of biological rhythms: dairy cow nitrogen metabolism and milk fatty acids

Timing of eating is a multiscience biological rhythms discipline that orchestrates global animal and human chronophysiology and metabolism. The objective of this study was to establish biological rhythmic effects of providing a total mixed ration (TMR) at either 0900 h or 2100 h on rumen microbial protein biomass, nitrogen partitioning, and milk fatty acids in a lactating dairy cow model. Four multiparous and four primiparous Holstein cows were monitored in a cross-over design study with two 42-day periods. Each period consisted of 21-day adaptation and 21-day sampling and data collection. The TMR had a forage:concentrate ratio of 50.2:49.8 (dry matter based). Total urine and feces were collected during a sampling week in each period to measure nitrogen partitioning. Urinary excretion of purine derivatives was utilized to estimate microbial protein biomass. Provision of TMR at 2100 h vs. 0900 h increased nitrogen intake and milk yields of total fats and health-improving anti-cancer conjugated linoleic acids (CLA). Evening eating maintained normal rumen function and health as reflected in maintained microbial protein synthesis and milk proportions of total short, medium, and long chain fatty acids. Feeding at 2100 h instead of 0900 h decreased milk proportions of C10:0, C12:0, C12:1, C13:0, C13:1, and C18:3 n-3, and tended to decrease proportions of C8:0 and C18:1 trans-9, while increasing that of C18:0. Evening instead of morning eating reduced the proportion of nitrogen that was excreted via urine and feces and secreted in milk. Findings suggest that feed delivery at 2100 h vs. 0900 h improved nitrogen dynamics and metabolism. Reduced N excretion and increased milk yields of total fats and health-improving fatty acids (e.g. CLA) by evening eating possess environmental and life quality implications.

Effect of soybean roasting and monensin on microbial protein synthesis, ruminal parameters and plasma metabolites of lactating dairy cows

This study was conducted to evaluate the effects of inclusion of roasted whole soybean seed and monensin (MO) in the diets of lactating dairy cows on plasma metabolites, ruminal parameters, and microbial protein synthesised in the rumen. Four multiparous Holstein lactating dairy cows (third parity; 656 ± 55 kg of liveweight; 83 ± 10 days in milk; 35 ± 4 kg/day milk yield) were assigned to a balanced 4 × 4 Latin square design. Each experimental period lasted 21 days with 14 days of treatment adaptation and 7 days of data collection. The control diet (C) was a total mixed ration consisting of 40% forage and 60% concentrate mixture on a dry matter (DM) basis. These cows were randomly assigned to one of the four dietary treatments. The first treatment was the C diet of unprocessed whole soybean seed, second was the C diet supplemented with 24 mg of MO/kg of DM (M), the third was roasted whole soybean seed (R) and the fourth treatment was R diet supplemented with 24 mg of MO/kg of DM (RM). Urinary excretion of creatinine and purine derivatives, microbial protein synthesised in the rumen, rumen pH and rumen concentrations of volatile fatty acids and ammonia were similar among the dietary treatments (P &gt; 0.05). Orthogonal contrasts showed that the rumen concentration of acetate was lower in MO-supplemented cows than non-supplemented cows (P &lt; 0.05). Dietary treatments had no effects on plasma concentrations of glucose, total cholesterol, triglycerides and total protein (P &gt; 0.05). Plasma concentration of urea was significantly lower in cows fed with the RM diet compared with cows fed the C and M diets (P &lt; 0.05). In conclusion, dietary treatments had no effect on microbial protein synthesised in the rumen, plasma metabolites (except for plasma concentration of urea) and ruminal parameters of dairy cows.