Plasma Urea Nitrogen Concentrations Research Articles

402 The effect of supplemental protein degradability and frequency of supplementation on nitrogen metabolism of beef cattle consuming low-quality forage

Abstract Rumen degradable protein (RDP) is required for cattle consuming low-quality forage to ensure adequate fiber digestion. However, in situations where cattle are not supplemented daily, supplementing RDP could overwhelm the nitrogen recycling mechanisms, leading to increased nitrogen excretion. The objective of this experiment was to determine the effect of rumen degradability and frequency of supplemental protein in beef cattle consuming low-quality forage. Treatments were arranged in a 2 × 2 factorial with protein degradability (68.5% or 32.8% RDP) and supplementation frequency (daily or biweekly) as the two factors. Ruminally cannulated Angus steers [n = 8; body weight (BW) = 328 ± 12.2 kg] were used in a Latin rectangle. The low RDP treatment was composed of 50% soybean hulls and 50% corn gluten meal (40.3% CP; 32.8% RDP), and the high RDP treatment consisted of 45.4% soybean hulls, 41.4% soybean meal, 4.1% urea, and 9.1% molasses (40% CP; 68.5% RDP). The biweekly steers were supplemented on d 0, 4, 7, 11, 14, 18, and 21 of each period. Steers were given ad libitum access to low-quality (7.4% CP) native grass hay. Daily blood samples were collected from d 14 to 17 at 0630 h and d 21 at -2, 3, and 7 h relative to supplementation. Rumen fluid samples were collected every 4 h on d 18 to 21. Daily NEFA concentrations decreased (P < 0.001) post-supplementation in the biweekly supplemented steers and then returned to baseline values, while the daily supplemented steers had no change. Hourly NEFA concentrations in steers supplemented with high RDP biweekly increased from 2 h pre-supplementation to 3 h post-supplementation (P < 0.001), then decreased at 7 h post-supplementation back to pre-supplementation concentrations. Plasma urea nitrogen (PUN) increased in biweekly high RDP supplemented steers 1 d after supplementation (P < 0.001) and decreased from d 15 to d 17. PUN concentrations increased from 2 h pre-supplementation through 7 h post-supplementation in both high RDP treatments, while low RDP treatments did not change (P < 0.001). Rumen fluid lactate and ammonia concentrations rapidly increased in the biweekly high RDP-supplemented steers in response to each supplementation (P < 0.001). There were spikes in ammonia concentrations for the daily high RDP treatment post-supplementation; however, they were smaller in magnitude compared with the biweekly high RDP. The low RDP treatments remained steady across all hours of ammonia sampling, where daily and biweekly supplemented steers decreased slightly in the time points following supplementation and then gradually increased. Rumen pH displayed drastic changes in the biweekly high RDP-supplemented group with values ranging from 6.99 to 5.97 (P < 0.001), but the low RDP treatments remained consistent. Supplementing biweekly with high RDP resulted in fluctuations in metabolites not observed in the other treatments, which could reduce forage utilization and increase nitrogen excretion.

Relationship between Plasma and Saliva Urea Nitrogen Concentrations in New Zealand Red Deer Calves (Cervus elaphus).

Red deer (Cervus elaphus), like other ruminants, excrete approximately 70% of the nitrogen they ingest. Developing ways in which to reduce the rate of loss, such as manipulating the diet or selecting for efficiency of growth, requires close monitoring of the plasma urea N (PUN) concentration which, in turn, requires a simple, safe, and reliable method for collecting samples. Saliva is easier to collect than blood, but the relationship between the salivary urea N (SUN) and the PUN is not known for red deer. This was therefore evaluated in two strains of mixed-sex red deer calves (Cervus elaphus): a phenotype with a high seasonality of growth (H, n = 10) and a phenotype with a low seasonality of growth (L, n = 13). Both phenotypes were divided into two groups, which were each offered one of two forage-based diets ad libitum: a medium-quality diverse treatment and a low-quality perennial ryegrass-white clover treatment. Blood and saliva samples for the determination of the PUN and SUN were collected at dawn every four weeks for five months (April to September 2022). There was a strong linear relationship between the PUN and SUN in the pooled sample (R2 = 0.65, p < 0.001). The estimations of the PUN were significantly improved by adding diet and the date of sampling into the model (p < 0.001), but not phenotype (p > 0.75). SUN represents a reliable index of the PUN, and collecting saliva therefore represents a simple and inexpensive alternative to collecting blood samples in studies of nitrogen metabolism in red deer.

Effect of S. cerevisiae strain KA500 supplementation on feed performance, feed efficiency, and digestion ability in feedlot buffaloes.

Live yeasts have favorable characteristics for use in animal feed, and may become a beneficial tool to improve digestive efficiency in buffaloes (Bubalus bubalis). The productive performance, feed efficiency, and digestion ability of buffaloes fed diets supplemented with yeast (Saccharomyces cerevisiae strain KA500) were evaluated. Eighteen male Murrah buffaloes, with initial weight 250 ± 31 kg (mean ± standard deviation), and aged approximately 12 months, were randomly assigned to one of two treatments. The treatments included experimental feed containing 10 g of the live yeast capable of forming 2 × 1010 colony forming units (CFU) and control (feed with no added yeast). The daily weight gain tended to be lower (p = 0.07) in buffaloes supplemented with yeast. There was a reduction in daily dry matter intake (DMI) and in % yield of live weight in buffaloes supplemented with yeast. There was no effect of live yeast supplementation on weight gain/kg dry matter intake, height at withers or rump, body condition score, total weight gain, carcass yield, plasma urea nitrogen concentrations, purine derivatives, and plasma glucose concentrations. The digestibility of dry matter (DM) and organic matter (OM) were lower (p < 0.05) with the supplementation of live yeast, although live yeast supplementation did not affect the digestibility of neutral detergent fiber (NDF) and non-NDF OM. The strain and dosage of live yeast used did not have a positive effect on buffalo performance and digestibility of dietary nutrients.

Dietary protein re-alimentation following restriction improves protein deposition via changing amino acid metabolism and transcriptional profiling of muscle tissue in growing beef bulls

This study aimed to develop a compensatory growth model using growing beef cattle by changing dietary protein and to investigate the underlying mechanisms of compensatory protein deposition in muscle tissue. Twelve Charolais bulls were randomly assigned to one of two groups with two periods: 1) a control group (CON) fed a 13% crude protein (CP) diet for 6 weeks; 2) a treatment group (REC) fed a 7% CP diet for 4 weeks (restriction period) and fed a 13% CP diet in the following 2 weeks (re-alimentation period). Growth performance, digestibility, nitrogen balance, targeted metabolomics of amino acids (AA) in plasma, and transcriptional profiling in muscle tissue were analyzed. Protein restriction decreased average daily gain (ADG; P < 0.05), while protein re-alimentation increased ADG relative to the CON (P < 0.05). Compared to the CON, REC reduced retained N (P < 0.05), and protein re-alimentation increased retained N and N utilization efficiency (P < 0.05), due to reduced urinary urea, hippuric acid, and creatinine excretions (P < 0.05). Ruminal NH3-N in the REC was lower than that in the CON in the protein re-alimentation period (P < 0.05). However, there was no difference in microbial protein and plasma urea nitrogen concentrations. Dietary protein restriction decreased plasma valine and aspartic acid concentrations relative to the CON (P < 0.05), and increased proline and 3-methyl-L-histidine concentrations (P < 0.05). After dietary protein re-alimentation, REC increased plasma citrulline concentrations (P < 0.05). The transcriptional profiling revealed that REC upregulated the AA transporter SLC3A1, and protein re-alimentation downregulated SLC7A8 in the muscle cell membrane. Within the muscle cell, upregulated cytosolic arginine sensor for mTORC1 subunit 2 (CASTOR2) inhibited protein synthesis by inhibiting the mammalian target of rapamycin complex 1 phosphorylation in the protein restriction period, while DNA-damage-inducible transcript 4 (DDIT4) activated the mTOR signaling pathway and promoted protein synthesis in the protein re-alimentation period. In summary, the targeted metabolomics and transcriptomics analyses demonstrated that protein re-alimentation following restriction can promote protein synthesis and reduce muscle breakdown by regulating AA metabolism and functional transcripts related to AA transporters and the mTOR signaling pathway.

97 Effects of crude protein content and supplementing probiotics in late gestation and lactation sow diets on performance of sows and suckling pigs

Abstract The objective of this study was to investigate the effects of crude protein (CP) content and supplementation with Bacillus-based probiotics (PRO) in late gestation and lactation sow diets on performance of sows and suckling pigs. Pregnant sows (n = 120; 60 gilts and 60 2+ parity) were assigned to 4 dietary treatments in a 2 x 2 factorial arrangement (2 CP levels, with or without probiotics) from d 85 of gestation to d 21 of lactation. The experiment was conducted in 4 consecutive periods (half sows and half gilts per period). The diets consisted of 1) a corn-soybean meal (SBM)-based low CP (LCP; 12% CP) diet; 2) LCP + 0.05% probiotic (LCP-PRO); 3) a corn-SBM-based high CP (HCP; 15% CP) diet; and 4) HCP + 0.05% probiotic (HCP-PRO). The diets were formulated for 2 phases: gestation (d 85 – 115) and lactation (d 1 – 21). Sow body weight (BW) and backfat thickness were recorded on d 85 and 111 of gestation and on d 1 and 21 of lactation. Sow blood and milk were sampled on d 1 and 21 of lactation to analyze plasma urea nitrogen (PUN) concentration, and milk fat, protein, and lactose, respectively. Data were analyzed using the PROC MIXED of SAS. The statistical model included diet as fixed effect and period as random effect. There were no significant effects of CP and PRO on sow BW or backfat thickness. There was an interaction (P &amp;lt; 0.05) between CP and PRO on the number of stillbirths, where the number of stillbirths did not differ between LCP and LCP-PRO groups, while the number decreased in sows fed HCP-PRO diet compared with HCP diet. Sows fed LCP diets had reduced (P &amp;lt; 0.05) PUN concentrations on d 1 and d 21 of lactation compared with those fed HCP diets. However, no difference was found in fat, protein, or lactose content in both colostrum (d 1) and milk (d 21). Piglets from the sows fed LCP diets showed heavier (P &amp;lt; 0.05) birth weights (1.58, 1.57, 1.53, and 1.52 kg for diets 1 to 4) than those in HCP groups, however, the average daily gain (ADG) of week 1 (188, 166, 187, and 187 g for diets 1 to 4) was less (P &amp;lt; 0.05) for piglets in LCP groups than HCP groups. No other effects were observed on piglet growth. In conclusion, CP and PRO did not affect sow BW and backfat thickness. There was an interaction effect of CP and PRO on reproductive performance, where stillbirths did not differ between LCP and LCP-PRO groups; however, stillbirths decreased with PRO in HCP diet. Moreover, feeding LCP diets to sows did not influence milk nutrient contents and overall growth performance in suckling piglets.

Total Replacement of Soybean Meal with Sundried Soymilk Residue in the Total Mixed Ration has a Negative Impact on Intake, Digestibility, and Milk Production in Dairy Goats.

This study aimed to evaluate whether total replacement of soybean meal (SBM) with sundried soymilk residue (SSR) in a total mixed ration (TMR) affects intake, digestibility, milk production, and blood metabolites in dairy goats. A total of 12 healthy Saanen dairy goats (40.12 ± 5.80 kg of BW) in midlactation (31.23 ± 10.12 days) were used in a randomized complete design (n = 4 goats/group). Dietary treatments were based on a TMR as follows: control TMR without SSR (CON) or SBM-based TMR with 50% or 100% of SSR replacing SBM (SSR-50 and SSR-100, respectively). All goats had ad libitum access to feed and clean water throughout the experiment. The dry matter (DM) intake decreased (p < 0.05) with the increasing replacement ratio of SBM and was lowest in the SSR-100 group. Similarly, organic matter (OM) digestibility was lowest (p < 0.05) in the SSR-100 group. However, the digestibility of DM, CP, NDF, and ADF did not change (p > 0.05) by dietary treatments. Compared with CON, the milk yield decreased significantly (p < 0.05) with increasing replacement ratio of SBM. In contrast, milk composition such as total solids, solids-not-fat, milk fat, lactose, protein, and pH were not influenced (p > 0.05) by feeding dietary SSR. Compared with other treatments, blood glucose concentration was lower (p < 0.05) in the SSR-100 group. In contrast, packed cell volume, glucose, and plasma urea nitrogen concentrations did not differ (p > 0.05). The results indicated that SSR could replace SBM in a TMR at less than 50%. Thus, the present study provides support for further investigation to enhance the utilization of soybean waste as an alternative protein source in the TMR for dairy goats and potentially other ruminants.

85 Evaluation of a Saccharomyces cerevisiae fermentation product on performance, plasma metabolites, rumen parameters, and fecal pathogen shedding in feedlot steers

Abstract The objective of the experiment was to evaluate a commercial Saccharomyces cerevisiae fermentation product (SCFP; NaturSafe, Dimond V, Cedar Rapids, IA) on performance, plasma metabolites, rumen parameters, and fecal pathogen shedding in feedlot steers. Crossbred steers (n = 61; 271 ± 48.1 kg) were sourced from 3 different research units at Oklahoma State University and assigned to 1 of 3 experimental treatments in a randomized complete block design. Steers were group housed in pens equipped with an automated individual feed intake system. Treatments consisted of a negative control (CON), CON with tylosin phosphate (TYL; 9.9 mg · kg-1 of diet DM), or CON with SCFP (1.63 g · kg-1 of diet DM). Body weight and feed efficiency did not differ among treatments (P ≥ 0.12). However, steers fed SCFP tended to have greater ADG from d 35 to 56 (P = 0.10). In addition, steers fed SCFP exhibited increased DMI from d 56 to 112 (P = 0.03), a tendency for increased DMI from d 112 to final (P = 0.07), and increased DMI overall (P = 0.05). There was no treatment × time interaction for pH, pH change, or lactate concentrations in rumen fluid (P ≥ 0.11), but all were impacted by time (P &amp;lt; 0.01). A treatment × time interaction (P &amp;lt; 0.01) was detected for fecal pH and fecal pH change, with the pH being greater in TYL fed steers on d 56 and in CON fed steers on the final day. Steers that consumed CON had a reduced fecal pH (P &amp;lt; 0.01) and steers consuming SCFP tended to have a reduced fecal pH (P = 0.08) from d 35 to 56 compared with TYL fed steers, while both CON and SCFP fed steers experienced an increase in fecal pH from d 56 to 112 (P &amp;lt; 0.01). A time effect was detected (P ≤ 0.04) for plasma glucose, lactate, urea nitrogen, and non-esterified fatty acid concentrations among treatment groups. A treatment × time interaction was observed (P &amp;lt; 0.02) for stx2 genes of Shiga toxin producing Escherichia coli (STEC) in individual fecal samples where SCFP and TYL fed steers tended to exhibit an increased concentration compared with CON fed steers on d 14, while on d 190 CON and SCFP fed steers exhibited an increased concentration compared with TYL fed steers. Overall, STEC, E. coli O157:H7, and Salmonella concentrations were all impacted by time (P &amp;lt; 0.001). This experiment suggests that SCFP could be utilized as a potential alternative to TYL in feedlot cattle without adversely affecting cattle performance. However, SCFP did not impact pathogen shedding. In addition, CON fed steers performed similarly to both SCFP and TYL fed steers.

Effects of increasing dietary arginine supply during the three first weeks after weaning on pig growth performance, plasma amino acid concentrations, and health status.

A total of 425 weaned pigs (Exp. 1: 225 pigs [5.8 ± 0.9 kg]; Exp. 2: 200 pigs [6.1 ± 1.2 kg]) were used to determine the optimal dietary standardized ileal digestible (SID) arginine (Arg) level in early nursery diets based on growth and health responses. The basal diet in Exp.1 was formulated to meet SID Arg recommendation (0.66%; NRC, 2012) and in Exp. 2, SID Arg was set to simulate current industry practices for feeding nursery pigs (1.15 %). Basal diets were supplemented with 0.3%, 0.6%, 0.9%, and 1.2% of l-arginine to provide five levels of dietary SID Arg. Experimental diets were fed during phases I (days 0 to 7) and II (days 8 to 21) with common diets until market. Feed disappearance and body weight (BW) were measured on days 7, 14, 21, and 43. Final BW was recorded at first removal of pigs for market. Pen fecal score was assigned daily from days 0 to 21. Plasma immunoglobulin A (IgA) was determined on days 0, 7, and 14 and amino acids (AAs) concentration and plasma urea nitrogen (PUN) on days 0 and 14. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of dietary Arg. Optimal SID Arg was determined by fitting the data with piecewise regression, using growth performance as the primary response variable. In Exp. 1, dietary Arg linearly increased (P < 0.1) BW, average daily gain (ADG), and gain to feed ratio (G:F) ratio on day 21, as well as reduced (χ2 = 0.004) the percentage of pigs that lost weight (PLW) in week 1 by 29%. Dietary Arg resulted in linear improvement (P = 0.082) of ADG for the overall nursery period and quadratic improvement (P < 0.1) of final BW at marketing. In Exp. 2, dietary Arg linearly increased (P < 0.05) ADG and average daily feed intake (ADFI) in week 1, BW and ADFI (P < 0.1) on day 14, as well as reduced (χ2 ≤ 0.001) PLW in week 1. From days 0 to 21, G:F was improved quadratically (P < 0.1). Dietary Arg linearly increased (P < 0.1) ADG and BW on day 43. Dietary Arg supplementation decreased the incidence (χ2 < 0.05) of soft and watery feces during the first weeks after weaning and lower concentration of plasma IgA on days 7 and 14. Dietary Arg linearly and/or quadratically influenced plasma AA concentrations (P < 0.05), including an increase in Arg, Leu, Phe, Val, citrulline, ornithine, and PUN concentrations. Overall, weaned pigs exhibit optimal nursery growth performance and health when provided with dietary SID Arg ranging from 1.5% to 1.9%. This dietary range contributes to a reduction in the occurrence of fall-back pigs and improvements in final BW at marketing.

Dietary crude protein time-dependently modulates the bacterial community and metabolites and changes dietary nutrient efficiency in growing pigs

The reduced nutrient digestibility of low-protein (LP) diets has been shown to be caused by the weakened fermentative capacity of the post-gut flora. The dynamic regulation of dietary protein contents on post-gut microbial population and fermentative metabolism is unclear. Twelve growing barrows (19.9 ± 0.8 kg) fitted with a T-cannula at the blind end of the cecum were randomly administered a high-protein (HP, 21.5% crude protein [CP]) diet or an LP (15.5% CP) diet for 28 d. The cecal content and feces were collected at d 1, 14, and 28 of the experiment for microflora structures and metabolite concentrations analysis. The nutrient digestibility coefficient and plasma biochemical parameters were also determined. Compared with the HP treatment, the LP treatment showed decreased plasma urea nitrogen concentration and apparent total tract digestibility of dry matter, gross energy, and CP (P < 0.01). In addition, urinary nitrogen losses, total nitrogen losses, and daily nitrogen retention in the LP treatment were lower than those in the HP treatment (P < 0.01), and the nitrogen retention-to-nitrogen intake ratio in the LP treatment was increased (P < 0.01). The HP group showed increased cecal total short-chain fatty acids (SCFA) concentration and fecal propionate, butyrate, and total SCFA concentrations (P < 0.05) on d 14 and 28, which may be mainly related to the elevated abundance of SCFA-producing bacteria, such as Ruminococcus, Lactobacillus, and Prevotella (P < 0.05). Probiotics, such as Bifidobacterium, Bacteroidales S24-7, and Rikenella, enriched in the LP treatment possibly contributed to reduced plasma endotoxin content. The differences in the abundances of almost all the above-mentioned flora appeared on d 28 but not d 14. Likewise, differences in the Simpson and Shannon indices and clustering patterns of the microbiota between treatments were also only observed on d 28. To sum up, in a time-dependent manner, the LP diet increased probiotics with gut-improving functions and decreased SCFA-producing bacteria, which may cause enhanced intestine health and reduced nutrient digestibility.

Differential voluntary feed intake and whole transcriptome profiling in the hypothalamus of young sheep offered CP and phosphorus-deficient diets.

A reduction in voluntary feed intake is observed in ruminants consuming nutrient-deficient diets, such as those with a low CP or P content, and has been attributed to active metabolic regulation, rather than a physical constraint. The hypothalamus is the key integrator of feed intake regulation in mammals. The objectives of this experiment were to (1) establish a model of metabolic feed intake regulation in ruminants consuming diets of variable CP and P content, and (2) determine key biochemical pathways and influential points of regulation within the hypothalamus. Merino wethers [n=40; 23.7±1.4kg liveweight (mean±SD)] were fed one of five dietary treatments (n=8/treatment) for 63days in individual pens. The treatments included targeted combinations of high (H) and low (L) CP (110 and 55g/kg DM) and high and low P (2.5 and 0.7g/kg DM) with 9MJ metabolisable energy (ME) per kg DM which were fed ad libitum (UMEI; unrestricted ME intake) resulting in four experimental diets (HCP-HP-UMEI, LCP-HP-UMEI, HCP-LP-UMEI and LCP-LP-UMEI). An additional nutritional treatment (HCP-HP-RMEI) restricted intake of the HCP-HP diet to an equivalent ME intake of wethers consuming the LCP-LP-UMEI treatment. Wethers offered the LCP-HP-UMEI, HCP-LP-UMEI and LCP-LP-UMEI treatments consumed 42, 32 and 49% less total DM (P≤0.05), respectively than the HCP-HP-UMEI treatment, and this was not attributable to any physical limitation of the rumen. Plasma concentrations of urea nitrogen and inorganic phosphate indicated that these nutrient deficiencies were successfully established. To assess potential mechanisms, RNA-seq was conducted on samples from the arcuate nucleus (ARC), ventromedial hypothalamus and lateral hypothalamus of the wethers, yielding a total of 301, 8 and 148 differentially expressed genes across all pairwise comparisons, respectively. The expression of NPY, AGRP and CARTPT, known for their regulatory role in mammalian feed intake regulation, had a similar transcriptional response in the ARC of wethers consuming nutrient-deficient treatments and those consuming a ME-restricted treatment, despite these wethers expressing behaviours indicative of satiated and hungry states, respectively. In addition, genes involved with glycolysis (TPI1), the citric acid cycle (CS, OGDH, GLUD1, GOT1) and oxidative phosphorylation (COX5A, ATP5MC1, ATP5F1B, ATP5MC3) were downregulated in the ARC of wethers fed a nutrient deficient (LCP-LP-UMEI) relative to the non-deficient (HCP-HP-UMEI) treatment. In summary, a model for voluntary feed intake restriction was established to determine genome-wide molecular changes in the hypothalamus of young ruminants.

Inhibiting the phosphatase activity of soluble epoxide hydrolase attenuates chronic kidney disease-induced calcific aortic valve disease in rats

Calcific aortic valve disease (CAVD) is the most frequent valvulopathy ultimaltely leading to aortic stenosis, one of the driving causes of an increased morbidity and mortality in aging and in patients with chronic kidney disease (CKD). Up to date, there is no available pharmacological treatment to prevent the development and progression of CAVD. Previous studies suggested that the bifunctional enzyme, soluble epoxide hydrolase (sEH), is involved in the regulation of cardiovascular calcification development. Our study aimed to investigate whether the phosphatase activity of sEH is involved in CAVD. Sprague Dawley sEH-P knocking rats (sEH-P KI) were generated using CRISPR/Cas9 method. Eighteen-week-old WT and sEH-P KI rats underwent subtotal nephrectomy (5/6Nx) to mimic CKD. These animals were afterword fed with a high-phosphate chow diet (1.8% phosphorus). In parallel, sham-operated animals on a standard diet (0.9% total phosphorus) served as controls. Twelve weeks after surgery, renal and cardiac parameters were determined and histological analysis of aortic valves was performed. Twelve weeks after surgery, the development of renal dysfunction in 5/6Nx + phosphate WT rats was shown by the augmentation in plasma creatinine and urea nitrogen concentrations and the decline in estimated glomerular filtration rate compared to sham-operated WT rats. These animals also displayed anemia, polyuria and polydipsia. The genetic inhibition of sEH-P did not allow to prevent these alterations. However, inhibiting sEH-P limited hydroxyapatite crystals deposition in the aortic valve of 5/6Nx + phosphate rats compared to 5/6Nx + phosphate WT rats (Fig. 1B, C), associated with a prevention of the decrease in intercusp distance and of the increase in aortic valve mean pressure gradient and in peak aortic valve velocity (Fig. 1A). In addition, left-ventricular diastolic (E/e′) and systolic dysfunction (fractional shortening) as well as cardiac fibrosis were prevented by sEH-P inhibition. Additional experiments on recombinant human and rat sEH allowed to demonstrate that sEH-P metabolizes pyrophosphate anions (PPi), a potent inhibitor of cardiovascular calcification, and that PPi degradation is efficiently prevented by sEH-P inhibition. Taking altogether, these results demonstrate that inhibition of sEH-P prevents aortic valve calcification and its hemodynamical consequences in the 5/6Nx + phosphate rat model, and may serve as a potential therapeutic strategy for the treatment of CAVD.

Short-term physiological responses to moderate heat stress in grazing dairy cows in temperate climate.

Even in temperate climate regions, an increase in ambient temperature and exposure to solar radiation can cause heat stress in lactating dairy cows. We hypothesised that grazing dairy cows exhibit short-term physiological changes due to increasing heat load under moderate climate conditions. Over two consecutive summers, 38 lactating Holstein dairy cows were studied in a full-time grazing system. Data were collected in 10 experimental periods of up to three consecutive days with a moderate comprehensive climate index (CCI). The individual animals' vaginal temperature (VT), heart rate, and locomotor activity data were automatically monitored with sensors. Blood samples and proportional whole milk samples were collected at afternoon milking. The concentrations of beta-hydroxybutyrate, glucose, non-esterified fatty acids, urea nitrogen, plasma thyroxine and triiodothyronine were analysed in blood plasma, and fat, protein, lactose, urea nitrogen, cortisol, Na+, K+, and Cl- concentrations were analysed in milk. The daily distribution of VT recordings greater than 39°C showed a circadian rhythm with a proportion of recordings of 2% and lower during the night and a percentage of 10% or higher in the afternoon. The cows' maximal daily vaginal temperature (VTMAX) between 0830 and 1430h was positively related to the mean daily CCI in the same time period (CCIMEAN; mean and SD 23.6±5.4°C). Cows with greater VTMAX had an increased mean heart rate, plasma glucose and milk cortisol concentrations and decreased concentrations of plasma thyroxine and triiodothyronine. The concentration of Na+ in milk was lower, and the concentration of K+ in milk tended to be higher in cows with increased VTMAX. For beta-hydroxybutyrate, non-esterified fatty acids and urea nitrogen concentrations in plasma and fat and lactose concentrations in milk no relationships were found in terms of increasing VT. For milk urea nitrogen and protein concentrations, the proportion of total variance explained by inter-individual or -period variance was high. In conclusion, changes observed in milk and blood likely reflected short-term physiological responses to moderate heat stress. In particular, milk cortisol and Na+ may be useful traits for timely monitoring of heat stress in individual cows because their inter-individual variances were relatively small and samples can be collected non-invasively.

Effects of crude protein and neutral detergent fiber percentages in the diet of Japanese Black steers on rumen fluid properties, blood biochemical properties, and carcass characteristics.

The effects of crude protein (CP) and neutral detergent fiber (NDF) percentages in the diet of Japanese Black steers on rumen fluid properties, blood biochemical properties, and carcass characteristics were examined. Twelve 13-month-old Japanese Black steers were used for this study and slaughtered at 30 months of age. Steers were assigned to a control group (n = 6) and test group (n = 6) and were fed a concentrate containing 12.9%-13.9% CP and 26.5%-29.8% NDF or 9.1%-9.6% CP and 29.9%-31.2% NDF, respectively. Lipopolysaccharide activity levels in rumen fluid were lower in the test group than in the control group. Plasma urea nitrogen concentration and activities of aspartate aminotransferase and γ-glutamyltransferase remained lower in the test group than in the control group. In contrast, plasma vitamin A concentrations remained higher in the test group than in the control group. Carcass characteristics did not significantly differ between the two groups. These results suggest that dietary CP and NDF percentages in feed for Japanese Black steers older than 13 months of age affected rumen fluid properties and blood biochemical properties, indicating a reduced load on the liver with a small effect on carcass characteristics.

Effects of branched-chain amino acids to lysine ratios in corn distillers dried grains with solubles containing diets on growth performance, plasma nitrogen profile, carcass traits, and economic analysis in growing-finishing pigs.

A study was conducted to identify the effects of standardized ileal digestible (SID) branched-chain amino acids (BCAA):lysine (Lys) ratios on the growth performance, plasma nitrogen (N) profile, carcass traits, and economic analysis of growing-finishing pigs fed diets with high corn distillers dried grains with solubles (cDDGS) inclusions. A total of 1,140 pigs (initial body weight [BW] = 28.7 ± 2.0 kg) were housed in 45 pens of 25 or 26 pigs and fed one of five diets in a randomized complete block design. Experimental diets were fed in four phases based on BW. Dietary treatments were a corn-soybean meal (SBM) based diet (PC), a corn-SBM-cDDGS-based diet (NC) with SID BCAA:Lys ratio of PIC (2020) recommendation and NC diets with SID BCAA:Lys ratios targeted for the 73% SID Val:Lys, 60% SID Ile:Lys, and 144% SID Leu:Lys during the growing phases (25 to 80 kg, Grow), targeted for the 78% SID Val:Lys, 70% SID Ile:Lys, and 160% to 170% SID Leu:Lys during the finishing phases (80 to 120 kg, finish), and both during the growing and finishing phases (Grow-Finish). One pig from each pen was bled at the end of 7 and 13 wk. After the 11-wk-feeding trial, pigs were sent to a commercial abattoir to investigate carcass traits. Pigs fed the Finish diet had a greater overall average daily gain (P < 0.05) than pigs fed the other cDDGS diets. Dietary treatments did not affect the hot carcass weight. However, feeding the Finish diet increased (P < 0.05) the iodine value of pork belly samples and decreased (P < 0.05) carcass yield. The plasma urea nitrogen (PUN) concentration at the end of the growing phase and plasma concentrations of Leu and Val were greater (P < 0.05) in pigs fed the Finish diet compared to the other cDDGS diets. Feeding pigs the cDDGS diets with different BCAA:Lys ratios had no difference in income over feed cost and income over feed and facility costs compared to the corn-SBM diet. Therefore, feeding pigs cDDGS diets with SID BCAA:Lys ratios adjusted for the previously determined finishing phase (from 80 to 120 kg of BW) recommendations by SBM inclusion supported growth performance and economic benefits equal to the corn-SBM diet.

Subchronic toxicity of oral deltamethrin in laying chickens.

Pyrethroid pesticides, with low toxicity to birds and mammals and short persistence in the environment, are widely used now. With the development of intensive poultry farming, pesticide application leads to residues in poultry products and pollution in ecological environment. The aim of the present study was to examine deltamethrin subchronic toxicity in laying chickens. One hundred and twelve laying chickens were randomly assigned to 14 groups including 13 groups medicated with deltamethrin (n = 8) and one unmedicated group used as control (n = 8). Tissue samples were collected during and after administration for weighing and histopathological analysis. A single dose of deltamethrin (20 mg·kg-1·BW·d) was administered orally to laying chickens for 14 days. The results showed that deltamethrin has no significant effect on the relative organ weight of laying chickens (p > 0.05). The activities of aspartate aminotransferase and cholinesterase in the plasma gradually decreased over time in the medicated group (p < 0.05). Plasma concentrations of urea nitrogen, uric acid, cholesterol, triglycerides, and creatinine significantly increased during treatment (p < 0.05), and significant liver damage and loss of intestinal villous epithelium were observed. The intestinal wall thickness, villus height, and crypt depth of laying chickens were altered by deltamethrin treatment. During treatment was withdrawn, the intestinal repair was more extensive than the liver repair.

Using whole cottonseed to replace dried distillers grains plus solubles and prairie hay in finishing beef cattle rations balanced for physically effective neutral detergent fiber

The objective of this experiment was to determine the effects of replacing prairie hay and dried distillers grains plus solubles with whole cottonseed (WCS) in diets balanced for physically effective NDF on the growth, intake, feed efficiency, carcass characteristics, and plasma metabolites of finishing beef cattle. Crossbred heifers (n = 103) and steers (n = 104) were blocked by BW within sex and randomly allocated to pens within block (6 pens per treatment) with 17 (n = 10 pens) or 18 (n = 2 pens) animals per pen. Pens were randomly allocated to experimental treatment: either a control diet (CON; prairie hay, dried distillers grains plus solubles, dry-rolled corn, and liquid supplement) or a WCS diet (CTN; WCS, dry-rolled corn, and molasses). A common vitamin and mineral supplement and urea were included in both diets at the same rate. Animals were slaughtered in 3 groups based on BW block. Cattle fed the CTN treatment tended to have a greater final BW (P = 0.10) and had greater overall ADG and G:F (P ≤ 0.05). There was no difference in overall DMI (P = 0.23). Fecal consistency scores were greater for cattle fed the CON treatment on d 42, at the beginning of the β-agonist feeding period, and at the final collection before slaughter (P ≤ 0.03). Cattle fed the CTN treatment had a more neutral fecal pH on d 140 and at the final collection (P < 0.01). No treatment × day interactions (P ≥ 0.70) were detected for plasma glucose, lactate, urea nitrogen, or nonesterified fatty acid concentrations. Cattle fed the CON treatment had greater plasma urea nitrogen concentrations (P < 0.001) and a tendency for a greater plasma lactate concentration (P = 0.06). A day effect was also observed for all plasma metabolites (P < 0.001). This experiment suggests that feeding WCS improves the growth and feed efficiency of cattle when replacing the roughage and byproduct protein and fat sources within a finishing diet.

Effects of dietary branched-chain amino acid supplementation on serum and milk metabolome profiles in dairy cows during early lactation.

The 3 branched-chain AA (BCAA), Val, Leu, and Ile, are essential AA used by tissues as substrates for protein synthesis and energy generation. In addition, BCAA are also involved in modulating cell signaling pathways, such as nutrient sensing and insulin signaling. In our previous study, dietary BCAA supplementation was shown to improve protein synthesis and glucose homeostasis in transition cows. However, a more detailed understanding of the changes in metabolic pathways associated with an increased BCAA availability is desired to fine-tune nutritional supplementation strategies. Multiparous Holstein cows (n = 20) were enrolled 28 d before expected calving and assigned to either the BCAA treatment (n = 10) or the control group (n = 10). Cows assigned to BCAA were fed 550 g/d of rumen-protected BCAA mixed with 200 g/d of dry molasses from calving until 35 DIM, whereas the cows assigned to the control were fed only 200 g/d of dry molasses. Serum samples were collected on d 10 before expected calving, as well as on d 4 and d 21 postpartum. Milk samples were collected on d 14 postpartum. From a larger cohort, we selected 20 BCAA-supplemented cows with the greatest plasma urea nitrogen concentration, as an indicator for greater BCAA availability, for the metabolomics analysis herein. Serum and milk samples were subjected to a liquid chromatography-mass spectrometry-based assay, detecting and measuring the abundance of 241 serum and 211 milk metabolic features, respectively. Multivariable statistical analyses revealed that BCAA supplementation altered the metabolome profiles of both serum and milk samples. Increased abundance of serum phosphocholine and glutathione and of milk Val, Ile, and Leu, and decreased abundance of milk acyl-carnitines were associated with BCAA supplementation. Altered phosphocholine and glutathione abundances point to altered hepatic choline metabolism and antioxidant balance, respectively. Altered milk acyl-carnitine abundances suggest changes in mammary fatty acid metabolism. Dietary BCAA supplementation was associated with a range of alterations in serum and milk metabolome profiles, adding to our understanding of the role of BCAA availability in modulating dairy cow protein, lipid, and energy metabolism on a whole-body level and how it affects milk composition.

347 Using Whole Cottonseed to Replace Dried Distillers Grains Plus Solubles and Prairie hay in Finishing Rations Balanced for Physically Effective Neutral Detergent Fiber

Abstract The objective of this experiment was to determine the effects of replacing hay and dried distillers grains plus solubles (DDGS) with whole cottonseed (WCS) in diets balanced for physically effective neutral detergent fiber (peNDF) on performance, carcass characteristics, and plasma metabolites of finishing cattle. Heifers (n = 103) and steers (n = 104) were blocked by sex and bodyweight (BW) and randomly allocated to pens within block (6 pens per treatment). Pens were randomly allocated to 1 of 2 experimental treatments: a control diet (CON; prairie hay, DDGS, dry-rolled corn, and liquid supplement), and a WCS diet (CTN; WCS, dry-rolled corn, and molasses). A vitamin and mineral supplement and urea were included in both diets at same rate. Data were collected on 14 d intervals through d 56, then every 28 d until harvest. Animals were harvested in 3 different groups based on BW block. Average daily gain (ADG) and gain to feed ratio (G:F) were greater for the CTN treatment overall (P ≤ 0.05), and the CTN treatment tended to have a greater final BW (P = 0.10). Fecal consistency score was greater for CON treatment on d 42, at beginning of the beta-agonist feeding period, and at the final collection (P ˂ 0.03). The CTN treatment had a more neutral fecal pH on d 140 and at the final collection (P ˂ 0.01). No treatment × day interaction (P ≥ 0.70) was detected for plasma glucose, lactate, or urea nitrogen (PUN) concentrations. The CON treatment had greater plasma lactate and PUN concentrations (P ˂ 0.01). A day effect was observed for all analyzed plasma metabolites (P ˂ 0.01). This experiment suggests that WCS improves growth performance and feed efficiency when replacing the roughage and byproduct protein and fat source within a finishing diet.

PSIII-A-7 Conditioning of Goats to Livestock Trailer: Effects on Physiological Stress Responses During Long-Distance Transportation

Abstract Meat goats are often transported long distances under commercial situations in the US. In a split-plot design, 168 twelve-month-old male Spanish goats were used to determine the effects of habituation to trailers on behavior and stress responses when transported for long periods. Animals were separated into two treatment (TRT) groups and maintained on two different paddocks. Concentrate supplement was fed to one group inside two livestock trailers (5.0 × 2.3 m each; habituated group, H), while the other group received the same quantity of concentrate, but not inside the trailers (non-habituated, NH). After 4 weeks of habituation period, goats were subjected to a 10-hour transportation stress in 4 replicates (n = 21 goats/replicate/TRT). Blood samples were collected prior to loading (Preload), 20 min after loading (0 h), and at 2, 4, 6, 8, and 10 h of transportation (Time). Behaviors of goats after loading were not affected by treatment. Plasma cortisol, glucose, and urea nitrogen concentrations and creatine kinase (CK) activities were significantly influenced by Time (P &amp;lt; 0.01). Plasma cortisol was not affected by TRT; however, glucose and CK in the H group tended to be lower than the NH group. Plasma non-esterified fatty acid (NEFA) concentrations were significantly lower (P &amp;lt; 0.01) in the H group than the NH group, likely in response to epinephrine release. There was a TRT × Time effect (P &amp;lt; 0.05) on CK activities, with the values increasing in the NH group and decreasing in the H group during the first two hours of transportation. Lymphocyte to neutrophil ratio also increased (P &amp;lt; 0.01) over transportation time. Habituation to trailer may be beneficial during long distance transportation of goats as indicated by certain physiological stress responses. Habituation may also facilitate the loading process, based on behavioral observations.

265 Effects of non-Starch Polysaccharide Degrading Enzymes + Lysophospholipids in Feeds with Varied ME Contents on Growth Performance and Nutrient Utilization of Pigs from 25 to 75 Kg BW

Abstract This study aimed to investigate efficacy of the combinational use of non-starch polysaccharide degrading enzymes (NSPase) and lysophospholipids (LPL) on growth performance and nutrient utilization in pigs fed feeds with varied metabolizable energy (ME) levels. Grower pigs (n = 270; 28.1 ± 0.6 kg BW) were allotted in a randomized complete block design with a 3 x 3 factorial arrangement of treatments fed for 51 d in 2 phases (30 and 21 d, respectively). Two factors were ME (3,260, 3,335, and 3,410 kcal/kg) and NSPase + LPL (ELPL at 0.00, 0.05, and 0.10%). Growth performance and backfat were measured. Blood was collected to measure plasma urea nitrogen (PUN) concentrations. Data were analyzed using the MIXED procedure on SAS 9.4. Increasing ME tended to increase (P = 0.066) ADG during Grower 2 and increased (P &amp;lt; 0.05) G/F during the overall period. Increasing ELPL supplementation increased (P &amp;lt; 0.05) both ADG and ADFI during Grower 2, whereas it tended to reduce (P = 0.084) G/F during the overall period. Supplemental effects of ELPL on increasing ADG was prominent (P &amp;lt; 0.05) at high ME content (3% above NRC requirement). Supplementation of ELPL tended to reduce (P = 0. 057) G/F during Grower 2 at low ME content (3% below NRC requirements). Backfat thickness and NEFA were not influenced by 2 factors. Increasing ME increased (P &amp;lt; 0.05) PUN during Grower 1 whereas increasing ELPL tended to increase (P = 0.077) PUN during Grower 2. In conclusion, supplementation of ELPL enhanced growth and feed intake of pigs from 50 to 75 kg BW, especially when dietary ME was above NRC requirement (3%) by fat supplementation (4%). These improvements may be due to increased nutrient utilization as indirectly indicated by increased PUN during fed status.