Excretion Of Purine Derivatives Research Articles

Supplementing flaxseed meal with sucrose, flaxseed oil, or both: Effect on milk enterolactone, ruminal microbiota profile, production performance, and nutrient utilization in dairy cows

Flaxseed is the richest source of secoisolariciresinol diglucoside, which is converted by ruminal microorganisms primarily to the mammalian lignan enterolactone. Our objective was to investigate the effect of diets containing soybean meal or flaxseed meal (FM) supplemented with sucrose, flaxseed oil, or both on milk enterolactone concentration and yield, diversity and relative abundance of ruminal bacterial taxa, ruminal fermentation profile, production performance, milk fatty acid (FA) yield, and nutrient utilization in dairy cows. Sixteen Holstein cows [8 multiparous (4 ruminally-cannulated) and 8 primiparous] averaging (mean ± SD) 134 ± 54.1 DIM and 679 ± 78.9 kg of BW in the beginning of the study were assigned to treatment sequences in a replicated 4 × 4 Latin square design. Each experimental period lasted 25 d with 18 d for diet adaptation and 7 d for data and sample collection. Diets were formulated to contain a 60:40 forage:concentrate ratio and included (DM basis): 1) 8% soybean meal and 23% ground corn (SBM), 2) 15% FM, 10.7% ground corn, and 5% sucrose (FLX+S), 3) 15% FM, 15.4% ground corn, and 3% flaxseed oil (FLX+O), and 4) 15% FM, 10.2% ground corn, 5% sucrose, and 3% flaxseed oil (FLX+SO). Compared with SBM, the concentration and yield of milk enterolactone increased in cows fed the FM diets, but did not differ among FLX+S, FLX+O, and FLX+SO. The relative abundances of the phyla Firmicutes, Verrucomicrobiota, and Actinobacteriota and those of the bacterial genera Lachnospiraceae NK3A20 group, Eubacterium coprostanoligenes group, Anaeromusa-Anaeroarcus, WCHB1-41, and p-251-o5 decreased, whereas Prevotella and NK4A214 group increased when comparing SBM against at least 1 diet containing FM. Furthermore, the relative abundances of Firmicutes and Actinobacteriota and those of Prevotella, Lachnospiraceae NK3A20 group, Eubacterium coprostanoligenes group, Acetitomaculum, Lachnospiraceae unclassified, NK4A214 group, and Anaeromusa-Anaeroarcus changed (increased or decreased) across the FLX+S, FLX+O, and FLX+SO diets. However, all these changes in the relative abundance of the ruminal bacterial taxa were not conclusively associated with the effect of diets on milk enterolactone. Diets did not affect ruminal pH and concentrations of NH3-N and total VFA. Dry matter intake and yields of milk, milk fat, and milk true protein all decreased in cows fed FLX+O or FLX+SO. Yields of milk total odd-chain FA, branched-chain FA, total < 16C FA, and total 16C FA all decreased with feeding FLX+O and FLX+SO. The apparent total-tract digestibilities of DM and OM were lowest in the FLX+S and FLX+O diets, with CP and ADF digestibilities lowest in cows receiving FLX+S or FLX+O, respectively. Urinary excretion of total N was lowest with feeding SBM. Contrarily, diets did not affect the urinary excretion of total purine derivatives. In brief, despite the effect of diets on the relative abundance of several ruminal microbiota phyla and genera, we were unable to conclusively associate these changes with increased milk enterolactone in FM-containing diets versus SBM.

Dietary supplementation with live or autolyzed yeast: Effects on performance, nutrient digestibility, and ruminal fermentation in dairy cows

This study was conducted to evaluate the effects of live or autolyzed yeast supplementation on dairy cow performance and ruminal fermentation. Two experiments were conducted to evaluate performance, feed sorting, total-tract apparent digestibility of nutrients, purine derivatives excretion, N utilization, ruminal fermentation, and abundance of specific bacterial groups in the rumen. In Exp. 1, 39 Holstein cows (171 ± 40 d in milk and 32.6 ± 5.4 kg/d milk yield) were blocked according to parity, days in milk, and milk yield and randomly assigned to the following treatments: Control (CON); autolyzed yeast (AY) fed at 0.625 g/kg DM (Levabon, dsm-firmenich); or live yeast (LY) fed at 0.125 g/kg DM (Vistacell, AB Vista). Cows were submitted to a 2-wk adaptation period followed by a 9-wk trial. In Exp. 2, 8 ruminal cannulated Holstein cows (28.4 ± 4.0 kg/d milk yield and 216 ± 30 d in milk), of which 4 multiparous and 4 primiparous, were blocked according to parity and enrolled into a 4 × 4 Latin square experiment with 21 d-periods (the last 7 d for sampling). Cows within block were randomly assigned to treatments sequences: control (CON2); live yeast (LY) using the same product and dietary concentration as described in Exp. 1; or autolyzed yeast fed at 0.625 g/kg DM (AY) or 0.834 g/kg DM (AY2). In Exp. 1 and 2, nutrient intake and total-tract apparent digestibility were not affected by treatments. Sorting for long feed particles (>19 mm) tended to be greater in cows fed yeast supplements than CON in Exp.1. Efficiency of N conversion into milk N was increased when feeding yeast supplements in Exp. 1. 3.5% Fat-corrected milk yield tended to be greater in cows fed yeast supplements than CON. Feed efficiency was increased when yeast supplements were fed to cows in relation to CON in Exp. 1. In Exp. 2, yield of fat-corrected milk and fat were greater in cows fed yeast supplements compared with CON2. Uric acid concentration and output in urine were increased when feeding yeast supplements when compared with CON2. Neither ruminal pH nor total volatile fatty acids were influenced by treatments. The current study did not reveal treatment differences in ruminal abundance of Anaerovibrio lipolytica, genus Butyrivibrio, Fibrobacter succinogenes, Butyrivibrio proteoclasticus, or Streptococcus bovis. Yeast supplementation can increase feed efficiency without affecting nutrient intake and digestibility, ruminal volatile fatty acid concentration, or ruminal abundance of specific bacterial groups. Supplementing live or autolyzed yeast, regardless of the dose, resulted in similar performance.

Replacing the forage portion of the ration with triticale hay improves the performance of Holstein dairy cows

The aim of the present study was to assess the effect of replacing the forage portion (alfalfa, corn silage, and barley straw) in the diet of lactating Holstein cows with triticale hay (TH, × Triticosecale L.) on DMI, digestibility, ruminal fermentation variables, estimated microbial-N synthesis (EMNS), and milk production and composition. Eight Holstein cows were used in a replicated Latin square design (two 4 × 4 squares) with four 28-d periods and 4 treatments, including a TH-free diet (control), and diets replacing 33%, 66%, and 100% of the forage portion with TH. Cows were fed ad libitum with 10% carryover during the experimental periods. Intakes and in vivo digestibilities of dry matter, organic matter, crude protein, and ash-free neutral detergent fiber, rumen pH, ammonia-N, total and individual short-chain fatty acids, protozoa, and bacteria populations were evaluated using specific methods. Moreover, in vitro total gas and methane release and in vivo urinary purine derivatives, EMNS, milk production, and composition were measured. The results showed that TH diets lowered DMI, compared with the control. Apparent digestibilities of DM, OM, CP, and NDF increased with dietary TH inclusion. The addition of TH instead of the diet forage portion increased in vivo rumen pH; acetic, propionic, valeric, and isovaleric acids concentrations; cellulolytic bacteria number; and in vitro gas production. In vivo rumen ammonia-N, short-chain fatty acids, butyric acid, in vivo and in vitro total protozoa and Entodiniinae numbers, and in vitro methane production decreased with increasing dietary levels of TH instead of the forage portion. The dietary addition of TH did not affect milk yield, protein, and lactose, but increased fat-corrected milk, milk fat, fat-corrected milk:DMI ratio, and milk yield:DMI ratio. Milk urea N decreased, but urinary purine derivatives excretion and EMNS increased with increasing levels of TH in the diet. For variables with significant changes, except for isovaleric acid, there was a linear response of animals to increasing levels of TH in the diet. Results suggest that TH, which is grown with less water compared with alfalfa, corn forage, and straw, is a potential alternative to those forages by increasing milk production efficiency, milk fat, and decreasing methane emission.

Chitosan associated with technical cashew nut shell liquid in supplements for grazing beef steers: nitrogen balance and rumen metabolism

ABSTRACT The aim of this study was to evaluate the inclusion of the chitosan (CHI) and technical cashew nutshell liquid (CNSLT) on nitrogen metabolism and ruminal fermentation on pasture system. Five steers (5 × 5 Latin square); kept of Marandu grass and supplemented daily by up to 0.4% BW. The experimental diets were: CON (mineral supplement); PRO (protein supplement); CHI supplementation; CNSLT supplementation and CC (CHI + CNSLT supplementation). Animals supplemented with CNSLT showed a reduction of pasture intake. The combination CC increased the intake of supplement. Steers supplemented with the combination of CNSLT, and CHI showed a higher supplement intake. The ruminal pH for the animals that received the combination of CNSLT and CHI, showed the lowest values. CHI decreased rumen acetate concentration, and increased propionate. Animals fed CC had a higher concentration of short-chain fatty acids (SCFA) and a reduced value for purines. CNSLT increased the excretion of total purines, microbial nitrogen synthesis and crude protein. Animals that received CC showed higher urinary excretion of N compared to the other treatments. The CHI + CNSLT proved to be favourable, with a higher total concentration of SCFA and positive effect on nitrogen balance.

Starter protein content and supplemental soybean oil or hydrogenated palm fatty acids in Holstein dairy calves: growth performance, protozoa population, and nitrogen utilization efficiency

The study hypothesized that a 24% protein starter diet supplemented with inert fat (palm fatty acids; PLFs) instead of triglyceride-rich soybean oil (SBO) would promote the growth of dairy calves. The effects of different protein contents (20 vs 24% CP) and fat sources (SBO vs PLF at 2.5% DM) on growth, digestibility, blood metabolites, rumen protozoa and urinary nitrogen in dairy calves were investigated. A total of 52 female dairy calves (mean age 3 days and BW 40.7 kg) were allocated to the following treatments in a completely randomized design: (1) 20% CP starter diet supplemented with SBO (20CP-SBO), (2) 20% CP starter diet supplemented with PLF (20CP-PLF), (3) 24% CP starter diet supplemented with SBO (24CP-SBO), and (4) 24% CP starter diet supplemented with PLF (24CP-PLF). Calves were weaned on day 53, and the study ended on day 73. The 24CP diets enhanced starter feed intake, average daily gain (ADG), withers height, hip width, organic matter (OM) digestibility, and preweaning blood glucose compared to the 20CP diets. In contrast, SBO supplementation reduced feed intake, ADG, withers height, OM and CP digestibility, and pre- and postweaning blood glucose and beta-hydroxybutyrate levels, while increasing preweaning aspartate aminotransferase, compared to PLF. SBO supplementation led to lower urinary excretion of purine derivatives and microbial protein synthesis postweaning, and a reduction in protozoa population both pre- and postweaning. Calves fed PLF had higher starter intake than those fed SBO, regardless of the diet being 20CP or 24CP. Calves fed the 24CP-PLF diet had the highest ADG, while calves fed the 20CP-SBO diet had the lowest ADG. Calves fed the 20CP-SBO diet had lower feed efficiency than calves fed the other diets during the preweaning period and throughout the experimental period. Calves fed the 24CP-PLF diet had higher hip heights at weaning and on day 73 than calves fed the other diets. Calves fed the 20CP-SBO diet had lower neutral detergent fiber digestibility than calves fed the other diets. Calves fed the 24CP-SBO diet had higher postweaning blood urea nitrogen concentration than calves fed the other diets. Feeding the 20CP-SBO diet to dairy calves decreased urinary allantoin excretion and rumen microbial protein synthesis but increased urinary nitrogen excretion during the preweaning period. Our results suggest that PLF is more suitable than SBO in calf diets, especially when calves fed 24% CP, possibly due to improved nutrient digestibility.

Estimating Microbial Protein Synthesis in the Rumen-Can 'Omics' Methods Provide New Insights into a Long-Standing Question?

Rumen microbial protein synthesis (MPS) provides at least half of the amino acids for the synthesis of milk and meat protein in ruminants. As such, it is fundamental to global food protein security. Estimating microbial protein is central to diet formulation, maximising nitrogen (N)-use efficiency and reducing N losses to the environment. Whilst factors influencing MPS are well established in vitro, techniques for in vivo estimates, including older techniques with cannulated animals and the more recent technique based on urinary purine derivative (UPD) excretion, are subject to large experimental errors. Consequently, models of MPS used in protein rationing are imprecise, resulting in wasted feed protein and unnecessary N losses to the environment. Newer 'omics' techniques are used to characterise microbial communities, their genes and resultant proteins and metabolites. An analysis of microbial communities and genes has recently been used successfully to model complex rumen-related traits, including feed conversion efficiency and methane emissions. Since microbial proteins are more directly related to microbial genes, we expect a strong relationship between rumen metataxonomics/metagenomics and MPS. The main aims of this review are to gauge the understanding of factors affecting MPS, including the use of the UPD technique, and explore whether omics-focused studies could improve the predictability of MPS, with a focus on beef cattle.

Inclusion of sorghum grain rich in condensed tannins in the diet of steers did not affect the nitrogen utilization efficiency but increased the urine nitrous oxide emissions1

The objectives of this study which included two experiments were to investigate the effects of dietary inclusion of sorghum grain rich in condensed tannins (CT) [18.9 g kg-1 dry matter (DM)] on nitrogen (N) metabolism and urine nitrous oxide (N2O) emissions of beef steers. In experiment 1, six Limousin × Luxi steers with an initial body weight of 245 ± 18.70 kg liveweight were used as the experimental animals. Three levels of sorghum grain, i.e. 0, 167 and 338 g kg-1 DM were included in diets as experimental treatments. The animals and the treatments were randomly assigned to a replicated 3 × 3 Latin square design. In experiment 2, a static incubation technique was used to determine the N2O emissions of the urine samples collected in experiment 1. The results of experiment 1 showed that dietary inclusion of sorghum grain linearly increased the faecal N excretion (P = 0.001), the total N excretion (P = 0.010) and the faecal N to N intake ratio (P = 0.021), but did not affect the N retention and the N utilization efficiency (P > 0.10). The plasma metabolomic data showed that dietary inclusion of sorghum grain increased the relative concentrations of phenolic acid (N1,N5,N10-tris-trans-p-coumaroylspermine and prenyl cis-caffeate) and carnitine (3-hydroxyisovalerylcarnitine and linoelaidyl carnitine). The results also showed that dietary inclusion of sorghum grain linearly increased the urinary urea excretion (P = 0.010) and decreased the urinary excretion of purine derivatives (P = 0.041) as well as the estimated rumen microbial N flow (P = 0.012) based on urinary purine derivatives. The results of experiment 2 showed that including sorghum grain in the diet linearly increased the average concentrations of NH4+-N (P = 0.012), NO2--N (P = 0.009), NO3--N (P = 0.001) and the total inorganic N (P < 0.001) in the soil enriched with urine samples. The urine sample N2O-N flux (P = 0.001), the estimated steer urine N2O-N flux (P = 0.021) and the N2O-N to urinary N ratio (P = 0.038) linearly increased with increasing inclusion of sorghum grain in the diet. In conclusion, dietary inclusion of sorghum grain containing high CT at 167 and 338 g kg-1 DM did not affect the N retention rate of steers but increased the urine N2O-N emissions by 5.7% and 31.4%, respectively. For reducing N2O emissions to the environment, high levels of sorghum grain are not suggested to be included in the ration of steers.

Effect of supplementing bacterial probiotics on microbial protein synthesis, blood indices and rumen ciliate protozoa population of lactating crossbred cattle in Nepal

In recent times, the dairy industry in Nepal has been recognized as a burgeoning agro-industry, successfully meeting the domestic demand for fluid milk. Nevertheless, further efforts are necessary to achieve self-sufficiency in dairy products. To enhance milk production, alongside breed improvement and health management initiatives, nutritional interventions have been identified as crucial. In this context, a study was conducted in Rampur, Chitwan, focusing on the supplementation of diverse strains of bacterial probiotics in lactating crossbred cattle to evaluate their effects on microbial protein synthesis, animal health assessed through blood indices, and changes in rumen fauna. The findings of the study revealed that the inclusion of bacterial probiotics resulted in notable improvements in the overall excretion of purine derivatives. Specifically, the individual excretion of allantoin, xanthine, and hypoxanthine significantly increased (p&lt;0.01) in the group supplemented with Lactobacillus acidophilus, while uric acid levels remained unchanged. Consequently, microbial nitrogen supply and absorption also showed a significant increase within the same group. However, blood hematological and biochemical parameters remained unaffected across all treatment groups. Moreover, the supplementation did not induce any notable changes in the individual or overall population of rumen ciliate protozoa. The study underscores that the use of L. acidophilus can enhance the overall protein economy of the rumen, thus potentially reducing production costs by substituting expensive sources of dietary protein for lactating crossbred dairy cows.

The type of lipid supplement has crucial implications for forage particle size in calf starter diets

BackgroundForage inclusion in starters of young dairy calves has become an acceptable strategy in the last decade. To compensate for the lower energy provided by forage, concurrent lipid supplementation can be proposed. However, ruminal microbial activity and forage digestibility may be decreased by lipid supplementation. We hypothesized that the composite effect of forage and lipid supplements may be dependent on forage particle size and the type of lipid supplement. Therefore, we evaluated the effect of long (LP; geometric mean, 4.97 mm) vs. short alfalfa hay particle sizes (SP; geometric mean, 1.26 mm) with either soybean oil (SBO) or palm fatty acids (PLF) as lipid source in a 2 × 2 factorial design with treatments SP-SBO, SP-PLF, LP-SBO, and LP-PLF. Treatments (n = 13 with 6 males and 7 females each) were offered to Holstein calves (3 days old) with equal amounts of lipid (25 g/kg DM) throughout the experimental period. The milk offering scheme (d 1 to 53) was equal for all groups. Data collection continued until 20 d post-weaning.ResultsInteraction between forage particle size and lipid supplement was significant for the following readouts: the highest and lowest starter intakes during the pre-weaning period occurred in LP-PLF and LP-SBO, respectively. This was associated with similarly contrasting changes in average daily gain (ADG) during the post-weaning period, body weight at the end of experiment, withers height, digestibility of organic matter and neutral detergent fiber, and blood serum concentrations of glucose, beta-hydroxybutyrate, and insulin during the pre-weaning period. During both pre- and post-weaning periods, the highest and lowest urinary excretion of allantoin and total purine derivatives, representing microbial protein synthesis, were observed in LP-PLF and LP-SBO, respectively, indicating that those diets were most and least favorable for rumen development. Irrespective of forage particle size, supplemental SBO vs. PLF increased serum malondialdehyde as an oxidative stress indicator across periods, increased blood urea nitrogen and feed efficiency in the pre-weaning period, and reduced hip height during the post-weaning period.ConclusionsIt can be concluded that feeding a rumen-inert, mostly saturated fatty acid source with alfalfa hay as long particle size is recommended with view on performance, whereas a combination soybean oil rich in unsaturated fatty acids should not be provided to milk-fed Holstein calves together with long particle forage. Feeding soybean oil and alfalfa hay as long particles is not advisable mainly due to lower starter consumption and impaired development of ruminal function. If dietary supplementation of soybean oil is applied, incorporation of forage as small particles should be preferred to support rumen development.

Including 8 hours of access to alfalfa in 1 or 2 grazing sessions in dairy cows fed a partial mixed ration: Effects on intake, behavior, digestion, and milk production and composition

The aim of this study was to evaluate the inclusion of alfalfa grazing during 8 h continuous or partitioned in 2 separated sessions of 4 h after each milking, on nutrient intake, digestibility, ruminal fermentation, feeding behavior, milk production, milk composition, and milk fatty acid profile, in late-lactation cows fed a partial mixed ration (PMR). Twelve dairy cows (193 ± 83 d in milk, 584 ± 71 kg of body weight) were housed in individual outdoor pens and assigned to treatments according to a 3 × 3 Latin square design replicated 4 times. The treatments were as follows: (1) control (T0), cows were fed a total mixed ration (TMR) provided ad libitum 20.0% crude protein (CP), 32.2% neutral detergent fiber (NDF); (2) fed a diet combining a PMR which had the same ingredient composition as the TMR (60% of ad libitum intake) + 1 session of 8 h of pasture (T8), continuous grazing alfalfa (Medicago sativa; 20.6% CP, 35.8% NDF) after the p.m. milking; and (3) PMR (60% of ad libitum intake) + 2 daily sessions of 4 h of access to pasture after each milking (T4+4). The experiment lasted 57 d and was divided into 3 periods of 19 d each. The first 12 d of each period was used for diet adaptation, and the last 7 d was used for data collection. No differences among treatments were observed for any of the productive variables, feeding efficiency, or purine derivatives excretion. Cows in T0 had greater intake and apparent digestibility of dry matter, organic matter, and nonfibrous carbohydrates compared with T4+4 and T8. Compared with T0, alfalfa grazing increased the concentration of C18:1 trans-11 and decreased those of C16:0 and C17:0 in milk fat. Cows in T4+4 consumed 1.1 more kg DM/d of alfalfa and N provided by alfalfa in the diet was 3 percentage points higher compared with T8 cows (266 vs. 229 g/d, respectively). In addition, T4+4 cows had a greater daily range of ruminal pH than T8 (0.73 vs. 0.93), and the highest concentrations of NH3-N were recorded during the a.m. grazing session while in T8 cows it occurred during the night. In conclusion, including 8 h of alfalfa grazing in T8 and T4+4 treatments allowed the substitution between 35.8 and 38.7% of the total dry matter intake (DMI) of a PMR (with a similar CP concentration to alfalfa) for pasture, maintaining milk solids production and increasing the C18:1 trans-11 of milk fat compared with a TMR in mid late-lactation cows. In an herbage plus PMR diet, splitting the 1 continuous grazing session of 8 h into 2 sessions of 4 h increased the proportion of energy and N provided by alfalfa pasture and reduced PMR intake, without modifying the total nutrient intake or productive performance of cows.

Effect of nitrate supplementation, dietary protein supply, and genetic yield index on performance, methane emission, and nitrogen efficiency in dairy cows

The objective was to investigate the effect of nonprotein nitrogen source, dietary protein supply, and genetic yield index on methane emission, N metabolism, and ruminal fermentation in dairy cows. Forty-eight Danish Holstein dairy cows (24 primiparous cows and 24 multiparous cows) were used in a 6 × 4 incomplete Latin square design with 4 periods of 21-d duration. Cows were fed ad libitum with the following 6 experimental diets: diets with low, medium, or high rumen degradable protein (RDP):rumen undegradable protein (RUP) ratio (manipulated by changing the proportion of corn meal, corn gluten meal, and corn gluten feed) combined with either urea or nitrate (10 g NO3-/kg of dry matter) as nonprotein nitrogen source. Samples of ruminal fluid and feces were collected from multiparous cows, and total-tract nutrient digestibility was estimated using TiO2 as flow marker. Milk samples were collected from all 48 cows. Gas emission (CH4, CO2, and H2) was measured by 4 GreenFeed units. We observed no significant interaction between dietary RDP:RUP ratio and nitrate supplementation, and between nitrate supplementation and genetic yield index on CH4 emission (production, yield, intensity). As dietary RDP:RUP ratio increased, intake of crude protein, RDP, and neutral detergent fiber and total-tract digestibility of crude protein linearly increased, and RUP intake linearly decreased. Yield of milk, energy-corrected milk, and milk protein and lactose linearly decreased, whereas milk fat and milk urea nitrogen concentrations linearly increased as dietary RDP:RUP ratio increased. The increase in dietary RDP:RUP ratio resulted in a linear increase in the excretion of total purine derivatives and N in urine, but a linear decrease in N efficiency (milk N in % of N intake). Nitrate supplementation reduced dry matter intake (DMI) and increased total-tract organic matter digestibility compared with urea supplementation. Nitrate supplementation resulted in a greater reduction in DMI and daily CH4 production and a greater increase in daily H2 production in multiparous cows compared with primiparous cows. Nitrate supplementation also showed a greater reduction in milk protein and lactose yield in multiparous cows than in primiparous cows. Milk protein and lactose concentrations were lower for cows receiving nitrate diets compared with cows receiving urea diets. Nitrate supplementation reduced urinary purine derivatives excretion from the rumen, whereas N efficiency tended to increase. Nitrate supplementation reduced proportion of acetate and propionate in ruminal volatile fatty acids. In conclusion, no interaction was observed between dietary RDP:RUP ratio and nitrate supplementation, and no interaction between nitrate supplementation and genetic yield index on CH4 emission (production, yield, intensity) was noted. Nitrate supplementation resulted in a greater reduction in DMI and CH4 production, and a greater increase in H2 production in multiparous cows than in primiparous cows. As the dietary RDP:RUP ratio increased, CH4 emission was unaffected and RDP intake increased, but RUP intake and milk yield decreased. Genetic yield index did not affect CH4 production, yield, or intensity.

Renal function, sex and age influence purines and pyrimidines in urine and could lead to diagnostic misinterpretation

Glomerular filtration rate (GFR) is commonly used in clinical practice for the diagnosis and follow-up of chronic kidney disease. Screening for inborn errors of metabolism (IEM) is based on analysis of biomarkers in urine, reported by their ratio to urinary creatinine (crn). Impaired renal function may complicate the interpretation of several biomarkers used for screening of IEM. Our goal was to investigate the influence of kidney function, in terms of measured GFR (mGFR) on purines and pyrimidines in urine, in addition to the relationship to sex, age, pH and ketosis. Children (n = 96) with chronic kidney disease (CKD), in different CKD stages, were included. Urine samples were obtained prior to the injection of iohexol. Serum samples at 7 time-points were used to calculate mGFR based on iohexol plasma clearance. The association with sex, age, ketosis and pH was examined in samples of the laboratory production from 2015 to 2021 (n = 8192). Age was a highly significant covariate for all markers. GFR correlated positively to several purines and pyrimidines; the ratios hypoxanthine/crn, xanthine/crn and urate/crn (p = 2.0 × 10−14, < 3 × 10−15 and 7.2 × 10−4, respectively), and the ratios orotic acid/crn, uracil/crn, and carbamyl-β-alanine/crn (p = 0.03, 1.4 × 10−6 and 0.003, respectively). The values of urate/crn, xanthine/crn, uracil/crn, and carbamyl-β-alanine/crn were higher in females above 16 years of age. Ketosis and pH influenced some markers. In conclusion, decreased renal function interferes with the excretion of urinary purines and pyrimidines, and this could change decision limits substantially, e.g. result in false negative results in Lesch-Nyhan syndrome. SynopsisGFR influences purines and pyrimidines in urine.Clinical Trial Registration: ClinicalTrials.gov, Identifier NCT01092260, https://clinicaltrials.gov/ct2/show/NCT01092260?term=tondel&rank=2

Feeding phytogenic ingredients combined or not with Lithothamnium calcareum and a mycotoxin binder to lactating cows: Effects on performance, nutrient digestibility, physiological parameters, and nitrogen excretion

A study was conducted to evaluate the effects of phytogenic feed additives combined or not with buffer compounds and a mycotoxin binder on performance, nutrient digestibility, N utilization, and purine derivatives excretion in lactating cows. Thirty-six Holstein (162 ± 76 days in milk and 32.6 ± 5.57 kg/d milk yield) cows were blocked (n = 12) according to parity, days in milk, and milk yield and were randomly assigned to the following treatments: control (CON), no feed additive; phytogenic feed additive at 5 g/d (PA); and PA + 140 g of buffer compounds (Lithothamnium calcareum, NaHCO3, and MgO) + 25 g/d of a mycotoxin binder (PABB). The PFA mixture contained pepper oleoresin and extracts of cinnamon, pepper, onion, grape seed, Curcuma sp., and Quillaja sp. Treatments were provided mixed into minerals. Cows were allowed a 2 wk-covariate period, and treatments were applied for the following 9 wks. Tukey’s test was used to determine differences between treatment groups. Dry matter (DM) intake was greater (P < 0.001) when feeding phytogenic additives, either PA or PABB, in comparison with CON. Similar nutrient intake was observed between PA and PABB groups. Digestibility of DM was greater (P = 0.047) in cows fed PA than CON but did not differ from those fed PABB. Milk yield was greater (P = 0.041) in cows fed PA than CON group, whereas PA and PABB had similar production values (32.1, 33.6, and 32.8 kg/d for CON, PA, and PABB, respectively). Fat production was increased (P = 0.002) when feeding feed additives. Milk protein concentration was greater (P = 0.043) in PABB-cows than both PA and CON groups. There was no evidence for treatment effects on milk urea nitrogen concentration, feed efficiency, or serum concentrations of glucose and urea-N. The heart rate was lower (P = 0.026) in CON group than PA or PABB during the morning period evaluation. Skin temperature of the face region was elevated (P = 0.040) in cows fed PABB than CON during the morning period. Milk N secretion tended to be greater (P = 0.096) in cows fed treatments with phytogenic additives (PA and PABB) than CON. Relative N excretion (g/kg of N intake) in urine, feces, and milk were not affected by treatments. Urinary purine derivatives daily excretion was similar among treatments. Phytogenic feed additives improve performance of cows, whereas providing a blend of buffer components and mycotoxin binder may increase milk protein concentration.

Effects of substituting sericea lespedeza for lucerne on nutrient digestibility and utilization in feedlot lambs

The current study evaluated the effects of dietary increments of sericea lespedeza (SL, Lespedeza juncea var. sericea) as a substitute for lucerne (Medicago sativa L.) in lamb finishing diets on nutrient intake and digestibility, rumen fermentation, microbial nitrogen (N) supply, N balance, and N utilization efficiency. Following a completely randomized design, 25 Dohne Merino intact male lambs (4–5 months old) with an average initial weight of 28.2 ± 1.74 kg were equally assigned to five dietary treatments containing 0, 62.5, 125, 187.5 and 250 g SL per kg diet as replacement for lucerne in total mixed rations. The lambs were acclimatized to the diets and environment for 21 days before data collection during a 5-day period. Daily, the feed offered, refusals and total fecal matter were weighed to determine nutrient intake and digestibility, while urine was collected for the determination of urine nitrogen and purine derivatives excretion. At the end of the data collection period, lambs were humanely slaughtered, and the rumen was opened to determine ruminal pH, and collect representative samples of rumen fluid to determine ruminal fermentation parameters. Dietary increments of SL had no influence (P > 0.05) on the lambs’ nutrient intake except for neutral detergent fiber (aNDFom) intake which increased linearly (P ≤ 0.05) with SL inclusion. As SL increased in the diets, the apparent total tract digestibility of dry matter, organic matter, crude protein, aNDFom, and ether extract linearly declined (P ≤ 0.05). The concentrations of butyrate, valerate, and iso-valerate were quadratically (P ≤ 0.05) influenced by dietary inclusion of SL with maximum concentrations observed at the 125 g SL/kg inclusion level. Dietary inclusion of SL had no influence (P > 0.05) on purine derivatives excretion, microbial N supply, N balance, and N utilization efficiency. Overall, replacing lucerne with SL up to 250 g/kg in lamb finishing diets had no detrimental effects on nutrient intake and utilization.

Feeding amylolytic and proteolytic exogenous enzymes: Effects on nutrient digestibility, ruminal fermentation, and performance in dairy cows

Exogenous enzymes are added to diets to improve nutrient utilization and feed efficiency. A study was conducted to evaluate the effects of dietary exogenous enzyme products with amylolytic (Amaize, Alltech) and proteolytic (Vegpro, Alltech) activity on performance, excretion of purine derivatives, and ruminal fermentation of dairy cows. A total of 24 Holstein cows, 4 of which were ruminally cannulated (161 ± 88 d in milk, 681 ± 96 body weight, and 35.2 ± 5.2 kg/d of milk yield), were blocked by milk yield, days in milk, and body weight, and then distributed in a replicated 4 × 4 Latin square design. Experimental periods lasted 21 d, of which the first 14 d were allowed for treatment adaptation and the last 7 d were used for data collection. Treatments were as follows: (1) control (CON) with no feed additives, (2) amylolytic enzyme product added at 0.5 g/kg diet dry matter (DM; AML), (3) amylolytic enzyme product at 0.5 g/kg of diet DM and proteolytic enzyme product at 0.2 g/kg of diet DM (low level; APL), and (4) amylolytic enzyme products added at 0.5 g/kg diet DM and proteolytic enzyme product at 0.4 g/kg of diet DM (high level; APH). Data were analyzed using the mixed procedure of SAS (version 9.4; SAS Institute Inc.). Differences between treatments were analyzed by orthogonal contrasts: CON versus all enzyme groups (ENZ); AML versus APL+APH; and APL versus APH. Dry matter intake was not affected by treatments. Sorting index for feed particles with size <4 mm was lower for ENZ group than for CON. Total-tract apparent digestibility of DM and nutrients (organic matter, starch, neutral detergent fiber, crude protein, and ether extract) were similar between CON and ENZ. Starch digestibility was greater in cows fed APL and APH treatments (86.3%) compared with those in the AML group (83.6%). Neutral detergent fiber digestibility was greater in APH cows compared with those in the APL group (58.1 and 55.2%, respectively). Ruminal pH and NH3-N concentration were not affected by treatments. Molar percentage of propionate tended to be greater in cows fed ENZ treatments than in those fed CON. Molar percentage of propionate was greater in cows fed AML than those fed the blends of amylase and protease (19.2 and 18.5%, respectively). Purine derivative excretions in urine and milk were similar in cows fed ENZ and CON. Uric acid excretion tended to be greater in cows consuming APL and APH than in those in the AML group. Serum urea N concentration tended to be greater in cows fed ENZ than in those fed CON. Milk yield was greater in cows fed ENZ treatments compared with CON (32.0, 33.1, 33.1, and 33.3 kg/d for CON, AML, APL, and APH, respectively). Fat-corrected milk and lactose yields were higher when feeding ENZ. Feed efficiency tended to be greater in cows fed ENZ than in those fed CON. Feeding ENZ benefited cows' performance, whereas the effects on nutrient digestibility were more pronounced when the combination of amylase and protease was fed at the highest dose.

Feeding reduced levels of trace minerals in proteinate form and selenium-yeast to transition cows: Performance, trace minerals, and antioxidant status, peripheral neutrophil activity, and oocyte quality

An experiment was conducted to evaluate the effects of inorganic trace minerals (TM) and reduced levels of TM by using proteinate forms of Co, Zn, Mn, and Cu, and Se-yeast in diets of transition cows on performance, TM concentrations in colostrum, plasma, and liver, blood metabolites, antioxidant status, peripheral neutrophil activity, and oocyte quality. Thirty-two Holstein cows (22 multiparous and 10 primiparous cows) were enrolled in this study from 30 d before the expected calving date to 56 DIM. Cows were blocked according to body condition score, parity, and previous milk yield and randomly assigned to one of the following treatments: control (CON), with TM (Zn, Cu, Mn, and Co) supplied in form of sulfate and Se as sodium selenite to meet or exceed requirement estimates of the National Research Council; and proteinate trace minerals (PTM), with TM supplied bound with AA and peptides at 50% of CON levels and inorganic Se replaced with Se-yeast at 100% of CON level. Treatments were supplied until 56 DIM. Eight cows were removed from the study because of early calving (n = 3) or health issues (n = 5); thus, data of 24 cows (16 multiparous and 8 primiparous cows) were used in the statistical analysis. No differences between treatments were detected on nutrient intake or digestibility. Total excretion of purine derivatives was decreased when feeding PTM during the prepartum period. Feeding reduced levels of TM in proteinate form resulted in greater yield of milk (27.7 and 30.9 kg/d for CON and PTM, respectively) and protein (0.890 and 0.976 kg/d) between wk 5 and 8 of lactation. No treatment differences were detected for feed efficiency, milk somatic cell count, and milk urea nitrogen. Cows fed PTM had lower milk fat concentration during the 56 d of evaluation (4.08 and 3.74% for CON and PTM, respectively). Selenium concentration was greater in colostrum of cows fed PTM compared with CON (48.5 and 71.3 µg/L for CON and PTM, respectively), whereas Zn, Cu, and Mn concentrations were not different. Cows fed PTM showed lower liver Cu concentration compared with CON (51.4 and 73.8, respectively). Plasma concentrations of Mn and Zn were lower, but plasma Se concentration tended to be higher with PTM treatment. Feeding PTM resulted in greater blood concentrations of urea-N (16.6 and 18.2 mg/dL for CON and PTM, respectively) and β-hydroxybutyrate (0.739 and 0.940 mmol/L). Counts of lymphocytes were higher with PTM but counts of monocytes were lower in complete blood cell count. No differences were observed in serum concentrations of superoxide dismutase and glutathione peroxidase. No differences were detected in phagocytosis and oxidative burst potential of neutrophils after incubation with bacteria. Cows fed PTM had fewer viable oocytes per ovum pick-up in comparison with CON (8.00 and 11.6). Feeding PTM to transition cows may sustain performance without altering neutrophil activity despite some alterations in blood TM concentrations. More studies should be performed to evaluate production and fertility measurements when reducing TM dietary levels by using proteinate forms and Se-yeast with larger number of animals.

Trichostrongylus colubriformis infection damages intestine brush board cells and could negatively impact postabsorptive parameters of Santa Ines lambs

This study aimed to evaluate histological, digestive and postabsorptive physiological parameters in Santa Ines lambs infected with Trichostrongylus colubriformis and fed different levels of phosphorus. Therefore, eighteen Santa Ines, castrated male, six-month old, healthy lambs (initial body weight 22.4 ± 2.7 kg) were distributed in one of four treatments arranged in a 2 × 2 split-plot arrangement: Sufficient dietary P level and uninfected (SPui; n = 4), Sufficient dietary P level and infected (SPi; n = 5), Deficient dietary P level and uninfected (DPui; n = 4), Deficient dietary P level and infected (DPi; n = 5). Infected lambs received, orally, a single pulse dose of 40.000 T. colubriformis infective larval stage (L3). Animals were fed Tifton 85 hay (Cynodon ssp.; 60%), and cassava meal and maize gluten meal (40%). Measurement of nutrient apparent digestibility and nitrogen metabolism were performed in individual metabolic stalls. To achieve the trial results, it was measured methane emissions in respiratory chambers, urine purine derivatives, ruminal short-chain fatty acids (SCFA), histological cuts of duodenal mucosal tissues and passage rates fluxes, analyzed by external (Yb, Cr, and Co) and internal (iNDF) markers. Statistical procedures were performed in R studio. The fixed main effects of treatment and the interactions were tested by ANOVA, and means compared by Duncan's test at 5% significance. Apparent digestibility was not affected by treatments, however, nitrogen retained decreased (P < 0.01) and urinary nitrogen losses increased (P < 0.01) in infected animals. Small intestine digesta content, empty segment weight, and length were higher in infected animals (P < 0.05). Passage rate was not majorly affected by infection or dietary P levels. Methane emissions, SCFA concentrations, and purine derivative excretion were also not affected by treatments. Regarding the histology, the vilosity weight (P < 0.05), and crypt depth (P < 0.01) decreased in infected animals. In conclusion, T. colubriformis infection can damage intestinal mucosa and affect nitrogen metabolism, but did not affect the digesta transit, and nutrient digestibility. The P dietary levels did not promote any modification in GIT physiological parameters tested in this study.

Feeding incremental amounts of ground flaxseed: effects on diversity and relative abundance of ruminal microbiota and enteric methane emissions in lactating dairy cows.

We evaluated the effects of incremental amounts of ground flaxseed (GFX) on diversity and relative abundance of ruminal microbiota taxa, enteric methane (CH4) emissions, and urinary excretion of purine derivatives (PD) in lactating dairy cows in a replicated 4 × 4 Latin square design. Twenty mid-lactation Jersey cows were used in the study. Of these 20 cows, 12 were used for ruminal sampling, 16 for enteric CH4 measurements, and all for spot urine collection. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Diets were formulated by replacing corn meal and soybean meal with 0%, 5%, 10%, and 15% of GFX in the diet's dry matter. Ruminal fluid samples obtained via stomach tubing were used for DNA extraction. Enteric CH4 production was measured using the sulfur hexafluoride tracer technique. Diets had no effect on ruminal microbiota diversity. Similarly, the relative abundance of ruminal archaea genera was not affected by diets. In contrast, GFX decreased or increased linearly the relative abundance of Firmicutes (P < 0.01) and Bacteroidetes (P < 0.01), respectively. The relative abundance of the ruminal bacteria Ruminococcus (P < 0.01) and Clostridium (P < 0.01) decreased linearly, and that of Prevotella (P < 0.01) and Pseudobutyrivibrio (P < 0.01) increased linearly with feeding GFX. A tendency for a linear reduction (P = 0.055) in enteric CH4 production (from 304 to 256 g/d) was observed in cows fed increasing amounts of GFX. However, neither CH4 yield nor CH4 intensity was affected by treatments. Diets had no effect on the urinary excretion of uric acid, allantoin, and total PD. Overall, feeding GFX decreased linearly the relative abundance of the ruminal bacterial genera Ruminococcus and Clostridium and enteric CH4 production, but no change was seen for CH4 yield and CH4 intensity, or urinary excretion of total PD, suggesting no detrimental effect of GFX on microbial protein synthesis in the rumen.

Dietary replacement of soybean meal with heat-treated soybean meal or high-protein corn distillers grains on nutrient digestibility and milk composition in mid-lactation cows.

Lactation diets dependent on rumen undegradable protein (RUP) sources derived from soybean meal (SBM) products are generally high in Lys and poor in Met. We conducted an experiment to evaluate the effects of increasing dietary RUP and altering digestible AA supply by inclusion of heat-treated soybean meal (HTSBM) or high-protein corn dried distillers grains with soluble (DDGS) on performance in mid-lactation dairy cows. Twenty-four Holstein cows (200 ± 40 d in milk and 30.0 ± 3.92 kg/d of milk yield) blocked according to parity, milk yield, and days in milk were used in a 3 × 3 Latin square design experiment with 21-d periods. Treatments were (1) control (CON), a diet with 6.0% RUP containing 15.9% SBM as the main protein source; (2) HTSBM, a diet with 6.7% RUP containing 4.4% HTSBM partially replacing SBM; and (3) high-protein DDGS (FP; FlexyPro, SJC Bioenergia), a diet with 6.9% RUP containing 5.34% FP partially replacing SBM and ground corn. Diets had similar crude protein (16.9%) and net energy of lactation. Data were submitted to ANOVA using the mixed procedure of SAS software (SAS Institute Inc.). Treatment differences were evaluated using orthogonal contrasts: (1) increasing RUP (SBM vs. HTSBM + FP) and (2) altering digestible AA supply (HTSBM vs. FP). Cows fed HTSBM and FP had greater intake (values in parentheses represent treatment means of CON, HTSBM, and FP, respectively) of neutral detergent fiber (7.14, 7.35, and 7.69 kg/d), crude protein (4.27, 4.37, and 4.51 kg/d), and ether extract (0.942, 0.968, and 1.04 kg/d) compared with cows fed CON. Feeding FP resulted in greater intake of neutral detergent fiber and ether extract compared with HTSBM. Cows fed HTSBM and FP had lower sorting index for feed particles <4 mm than cows fed CON (1.029, 1.008, and 1.022). Feeding FP resulted in greater intake of feed particles <4 mm compared with HTSBM. Treatments containing HTSBM or FP tended to decrease organic matter digestibility (72.4, 71.2, and 71.1%), but no other effects were detected in digestibility of neutral detergent fiber, crude protein, or ether extract. No evidence for differences among treatments was detected in excretion of purine derivatives in milk and urine. Milk yield was greater in cows fed HTSBM or FP than in cows fed CON (28.0, 28.9, and 28.8 kg/d, respectively). Cows fed HTSBM or FP tended to have greater energy-corrected milk and protein yield compared with those fed CON. Milk protein concentration was greater in DDGS cows than those in the HTSBM group (3.45 and 3.40%, respectively). No differences were detected in milk fat yield and concentration, milk urea nitrogen, feed efficiency, or serum concentrations of urea and glucose. Overall, increasing dietary RUP by feeding HTSBM or FP improved intake of nutrients and milk yield without affecting feed efficiency. Altering digestible AA supply while maintaining similar dietary RUP had negligible effects on performance of cows.

Estimation of microbial protein synthesis in the rumen of growing lambs based on the purine derivative excretions and the dietary forage-to-concentrate ratio.

Estimating microbial protein synthesis (MPS) in the rumen of growing lambs based on the urinary excretion of purine derivatives (PDs) and forage to concentrate (F/C) ratio. 36 similar-growing male lambs (weight 32.53 ± 1.90 kg; age 93 ± 6.63 days) were used in a completely randomized design with four groups: a) the 20-80 F/C ratio (dry hay 10% + wheat straw 10%), b) the 20-80 F/C ratio (dry hay 0% + wheat straw 20%), c) the 10-90 F/C ratio (dry hay 5% + wheat straw 5%), d) and the 10-90 F/C ratio (dry hay 0% + wheat straw 10%) with nine replicates. Total PD and rumen MPS synthesized increased (10.98 vs. 13.25 mmol/day and 59.45 vs. 71.80 gm/day) in group d compared to group a. Dry organic matter intake (0.869 kg/day), fermentable dry organic matter (0.563 kg/day), and microbial nitrogen (N) yield (11.48 gm/day) of group d were at the maximum, but in terms of gN/kg dry organic matter (22.37 gm/kg), the mean of group c was higher than others. Increasing the level of food concentrate and the gradual removal of alfalfa from the diet increased the excretion of PD and MPS in the rumen. It was also found that urinary PD monitoring is an accurate indicator for the estimation of MPS.