A quantitative study on arginine catabolism by mixed ruminal bacteria,protozoa and their mixture in vitro

The catabolism of arginine (Arg) by mixed rumen bacteria (B), mixed rumen protozoa (P), and their mixture (BP) was quantitatively investigated in an in vitro system in order to confirm the metabolic pathway of Arg and provide basic information for enzymatic and molecular studies as well as an understanding of the quantitative distribution of metabolites. Rumen microbial suspensions (B, P, and BP) collected from fistulated goats were anaerobically incubated with or without 1 mmol/L Arg at 39°C for 12 h. Arg and other related compounds such as citrulline (Cit), ornithine (Orn), proline (Pro) and 5‐aminovaleric acid (5AV) in both supernatant and hydrolyzates of B, P, and BP suspensions were analyzed by HPLC. The metabolic pathways of Arg in mixed rumen bacteria and mixed rumen protozoa were considered to be as follows: rumen bacteria, Arg → Cit → Orn → Pro → 5AV → VFAs + NH₃; rumen protozoa, Arg → Cit → Orn → Pro → 5AV. The disappearance of Arg (1 mmol/L) was approximately 52.9 and 88.2% in B, 33.9 and 55.6% in P, and 52.8 and 85.2% in BP during 6 and 12 h incubations, respectively. When expressed in units of ‘per gram (g) of microbial nitrogen (MN)’, the net degradation rate of Arg in BP (50.3 µmol/g MN/h) was approximately 46% lower than that of B during a 12 h incubation period. The presence of protozoa tended to inhibit the production of Orn from Cit and the production of 5AV from Pro which were thought to be rate‐limiting steps of Arg metabolism in rumen microorganisms. As a result, protozoa appeared to have a saving effect on Arg metabolism, that is, protozoa protected Arg from wasteful exhaustion in the rumen.     

Synthesis of citrulline from ornithine by the small intestinal mucosa of cattle

Three segments of cattle small intestine (duodenum, upper jejuno‐ileum and lower jejuno‐ileum) were examined in an in vitro system for activity of ornithine carbamoyltransferase (OCT; EC 2.1.3.3) which is involved in the synthesis of citrulline (Cit) from ornithine (Orn). The mucosa of the three segments of small intestine was collected from Japanese black cattle, homogenized and then centrifuged. The supernatant fraction was used as the crude OCT enzyme solution. The OCT activity was assayed by the production of Cit from Orn determined directly by HPLC. The optimal pH and temperature for OCT activities in the duodenum, upper jejuno‐ileum and lower jejuno‐ileum of cattle small intestine were 7.47 and 39°C. Little difference was observed between the three segments. The OCT activity in cattle kidney was also examined for comparison, and almost no activity was found. The OCT activities in crude enzyme solutions of the three segments of small intestine were stable for up to one month of storage at ?20°C in Tris HCl buffer solution. Finally, the role of the small intestine in supplying Cit as a precursor for arginine synthesis in cattle kidney was discussed.     

Biosynthesis of arginine from citrulline and related compounds by mixed ruminal bacteria, protozoa and their mixture in vitro

Biosynthesis of arginine (Arg) from citrulline (Cit), ornithine (Orn), proline (Pro), and 5-aminovaleric acid (5AV) by mixed rumen bacteria (B), protozoa (P), and their mixture (BP) was quantitatively investigated in an in vitro system from the standpoint of protein nutrition in ruminants. Rumen microorganisms, collected from ruminally fistulated goats, were anaerobically incubated with or without 1 mmol/L each of substrates at 39°C for 12 h. Arginine and other related compounds, produced in both supernatants and acid-hydrolyzates of microorganisms in B, P, and BP suspensions, were analyzed by high-performance liquid chromatography. Arginine production from Cit in BP, when expressed with a unit of 'μmol/g microbial nitrogen', was approximately 70% and 94% higher than that in B and P, respectively, in a 12-h incubation period. In the case of Orn, the values were approximately 30% and 75%. Both rumen bacteria and protozoa could produce Cit and Orn from Pro, so it is assumed that they can produce Arg from Pro. Rumen protozoa were unable to degrade 5AV and it was the final product in the metabolism of Cit, Orn and Pro in P suspension. A trace amount of Orn and Pro produced from 5AV in B and BP suspensions indicated that the reversible reaction of 5AV formation was performed only by rumen bacteria. This is the first quantitative report on Arg biosynthesis from its precursors by rumen microorganisms.     

Urea cycle metabolism: effects of supplemental ornithine or citrulline on performance, tissue amino acid concentrations and enzymatic activity in young pigs fed arginine-deficient diets

Two experiments were conducted with young pigs to determine the efficacy of ornithine (Orn) or citrulline (Cit) as precursors of arginine (Arg). In Exp. 1, pigs were individually fed an Arg-deficient, semipurified diet (.18% Arg) supplemented with .3% Arg or an equimolar quantity of Orn or Cit. Supplemental Arg or Cit increased rate and efficiency of weight gain, but Orn addition was without effect. Free Arg in plasma 3 h post-prandial was increased by addition of either Arg or Cit to the basal diet. Liver Arg was elevated by dietary addition of Arg, Orn or Cit; kidney Arg and Orn were elevated only in pigs receiving supplemental Cit. Arginine or Cit addition to the diet increased Arg concentration in muscle tissue, but muscle Orn was unresponsive to any of the supplements fed. In Exp. 2, pigs were again fed the Arg-deficient, semipurified diet supplemented with .3% Arg or four times an isomolar quantity of ornithine. Arginine addition to the diet increased weight gain and feed efficiency, while Orn supplementation was without effect. Plasma Orn was increased by excess Orn, while plasma Cit was unaffected by supplemental Arg or Orn. Moreover, excess Orn increased free Orn and proline (Pro) in liver, kidney and muscle. Free Cit, however, increased only in liver from feeding excess Orn. In addition, excess Orn decreased both plasma ammonia and free glutamine (Gln) concentration in brain. Arginase activity was roughly 10, 40 and 100 times greater in hepatic tissue than in renal cortex, renal medulla or intestinal mucosa, respectively, while hepatic ornithine transcarbamoylase (OTC) activity was about 15 times greater than the activity present in mucosa tissue. Renal OTC activity was too low to be accurately measured.     

Response of meat chickens to different sources of arginine in low-protein diets

Arginine activity in broiler diets can be supplied by L-arginine (Arg), guanidinoacetic acid (GAA) and L-citrulline (Cit), all of which are commercially available. This study was conducted to assess the effects of Arg source and level on broiler performance, nutrient digestibility and carcass parameters. Day-old Ross 308 cockerels (n = 768) were assigned to one of eight dietary treatments using a completely randomized design: normal protein (NP), low protein deficient in Arg (LP) and LP with two levels of either Arg (0.238% and 0.476%), GAA (0.309% and 0.618%) or Cit (0.238 and 0.476%). The LP was 5 percentage points lower in protein level than the NP. Wheat, sorghum, soya bean meal, canola meal, and meat and bone meal-based diets were fed over three feeding phases to 6 replicate floor pens with 16 birds each. Compared to NP, birds fed LP had reduced feed intake (FI, p < 0.001), reduced body weight gain (BWG, p < 0.001) and increased feed conversion ratio (FCR, p < 0.001) from day 0 to day 35. Additions of Arg or Cit to the LP at both levels resulted in increased BWG and reduced FCR (p < 0.05). Birds fed LP with GAA added had lower FCR (p < 0.05) but not higher BWG (p > 0.05) compared with the LP observed from day 0 to day 35. Supplementation of Arg, Cit and the low level of GAA to LP resulted in increased carcass yield, bone length, diameter and ash (p < 0.05) but did not increase ileal energy or nitrogen digestibility (p > 0.05). The findings indicate that Cit is an efficacious source of Arg activity in Arg-deficient diets.     

Quantitative studies of the in vitro production of pipecolic acid by rumen protozoa and its degradation by rumen bacteria

An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species‐enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L‐lysine (1.0 mmol/L L‐Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L‐Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L‐Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D‐Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D‐Lys, though at a lower rate (1/3) compared with L‐Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L‐ or D‐Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D‐Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen‐produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.     

Response of laying hens to L-arginine,L-citrulline and guanidinoacetic acid supplementation in reduced protein diet

A study was conducted with Hy-Line Brown laying hens to examine the effects of reduced protein diet, deficiency of arginine (Arg), and addition of crystalline Arg, citrulline (Cit) and guanidinoacetic acid (GAA) as substitutes for Arg. Hen performance, egg quality, serum uric acid, liver and reproductive organ weights, and energy and protein digestibility were measured using a completely randomized design with 5 treatments. Treatments were a standard diet (17% protein diet; SP), a reduced diet (13% protein diet deficient in Arg; RP) and RP with added Arg (0.35%, RP-Arg), GAA (0.46% equivalent to 0.35% Arg, RP-GAA) or Cit (0.35%, RP-Cit) to the level of SP. It was hypothesized that performance would decrease with Arg deficient RP diet and the addition of GAA or Cit in RP would allow birds to perform similar or greater than Arg-added RP treatment. The experiment was conducted from 20 to 39 wk of age but the treatment effect was seen only after 29 wk of age. The birds offered RP had reduced egg and albumin weights (P < 0.01), lower yolk color score (P < 0.01), lower protein intake and excretion (P < 0.01) than those offered SP. When Arg or Cit were added to RP to make them equivalent to SP, feed intake (FI) and egg production were not different than those of RP (P > 0.05). The birds offered RP-GAA decreased FI and egg production (P < 0.01) compared to those offered RP. The addition of Arg, Cit or GAA to the RP had no effect on egg quality parameters, protein and energy digestibilities (P > 0.05). However, birds offered the RP-Cit diet tended to have higher Haugh unit (P = 0.095) and lower shell breaking strength (P = 0.088) compared to all other treatments while those offered RP-GAA had higher energy digestibility (P < 0.05) than all other groups but RP. The limited performance response of hens fed RP with added Arg, GAA, or Cit may be due to deficiency of some other nutrients in RP such as phenylalanine, potassium or non-essential amino acids and other components of soybean meal in the diet.     

精氨酸在体内和体外试验中对鲤鱼免疫力的影响

本试验采用体外和体内2种方法来研究精氨酸(Arg)对鲤鱼免疫力的影响。体外试验中,在培养基中分别添加0、0.5、1.0、1.5和2.0mmol/L的Arg,将肾脏白细胞培养不同的时间段后测定增殖指数、呼吸爆发活力、吞噬活力和杀菌率。体内试验中,将平均体重37g的鲤鱼随机分为5组,每组3个重复,每个重复10条,分别体内注射0、25、50、100和200 mg/kg鱼体重的Arg,商业饲料投喂2周,进行肾脏白细胞增殖指数、呼吸爆发活力和吞噬活力的测定,以及血清和肝胰脏一氧化氮(NO)含量、一氧化氮合成酶(NOS)活性及血清白蛋白(ALB)含量的测定。体外试验结果表明:添加Arg能够提高肾脏白细胞的增殖指数、呼吸爆发活力、吞噬活力和杀菌率。培养12和24h后,1.0、1.5和2.0mmol/L Arg组肾脏白细胞增殖指数显著高于0mmol/L Arg组(P0.05);培养6、12和24h后,1.0mmol/L Arg组肾脏白细胞呼吸爆发活力显著高于0mmol/L Arg组(P0.05);培养12和24h后,1.0、1.5和2.0mmol/L Arg组肾脏白细胞吞噬活力显著高于0mmol/L Arg组(P0.05);培养18h后,1.0、1.5和2.0 mmol/L Arg组肾脏白细胞杀菌率显著高于0 mmol/L Arg组(P0.05)。体内试验结果表明:50、100和200 mg/kg Arg组肾脏白细胞呼吸爆发活力、吞噬活力和增殖指数显著高于0mg/kg Arg组(P0.05);100和200mg/kg Arg组血清ALB和NO含量显著高于0 mg/kg Arg组(P0.05),50、100和200mg/kg Arg组血清NOS活性显著高于0mg/kg Arg组(P0.05);50、100和200mg/kg Arg组肝胰脏NO含量显著高于0mg/kg Arg组(P0.05),25和50mg/kg Arg组肝胰脏NOS活性显著高于0mg/kg Arg组(P0.05)。由此可见,Arg提高了鲤鱼肾脏白细胞的免疫力,体外试验表明Arg的适宜浓度为1.0mmol/L。正常摄食情况下,Arg在鲤鱼体内注射适宜浓度为50~100mg/kg。     

奶牛十二指肠乙状弯曲扭转造成梗阻的29例报告

[目的]探究奶牛十二指肠乙状弯曲扭转(DSFV)的临床特点,以评估手术的临床预后。[方法]回顾性病例系列研究。评估动物:29头荷斯坦牛(28头奶牛,1头公牛)。过程:利用搜集的病例分析病史、特征描述、临床症状、治疗经过、术中所见以及结果。[结果]对2006年12月至2010年8月间29头患有十二指肠乙状弯曲扭转奶牛的评估研究,有20头奶牛在最初评估前1d到两年做过网膜固定术或幽门固定术,奶牛在右侧腹壁第10和12肋间区域和背部听诊与叩诊时有‘钢管音’,伴有心动过速、轻度脱水、体温不高、血液生化指标有严重低血钾(均数mean±标准差SD,2.9±0.5mmol/L;中位数median,3.1mmol/L;全距range,2.08—3.92mmol/L)、低血氯(均数mean,69.7±11.1mmol/L;中位数median,71.1mmol/L;全距range,49.1-94.1mmol/L)、代谢性碱中毒(均数mean total CO2,44.5±7.4mmol/L;中位数median,45.3mmol/L;全距range,31.5-59.6mmol/L)和高胆红素血症(均数mean,32.4±29.0μmol/L;中位数median,20.5μmol/L;全距range,7.8-107μmol/L)。术中所见包括紧靠背部而变位的空的十二指肠后段和鼓气的十二指肠前段,以及紧紧缠绕在十二指肠乙状弯曲部而肿胀的皱胃和胆管。按压十二指肠前段,如果后段仍有胀气,可成功人工整复。评估中,22头奶牛成功治愈,7头在术后4d内死亡。[结论]临床上该病与奶牛皱胃扭转(AV)的症状十分相似,当在右侧背部的病灶区听到"钢管音",并有严重的低血钾和低血氯、胆红素浓度增高、且有皱胃固定术病史者,则基本能够诊断为十二指肠乙状弯曲扭转。手术整复后,临床预后良好。     

黑龙江省常用粗饲料对肉牛瘤胃内环境的影响研究

[目的]针对黑龙江省肉牛养殖中羊草、玉米秸秆、玉米青贮和玉米秸秆微贮4种常用粗饲料的营养成分特性和饲喂特点,研究其对瘤胃内的PH值和NH3-N、VFA浓度的动态变化规律,进一步为我国北方寒区肉牛养殖中的粗饲料的合理搭配与利用提供一定的理论基础。[方法]选择4头装有永久性瘤胃瘘管的西门塔尔肉用公牛,采用4×4拉丁方试验设计,日粮精粗比为30∶70。[结果]各试验组pH值均在5.5～7.52的正常范围内,各组在同一时间点pH值差异不显著(P0.05);NH3-N浓度从本试验从平均值来看,青贮组、微贮组和羊草组均低于秸秆组,分别低27%、5%和4.12%,表明三组饲料能氮释放更加合理,其中青贮组和羊草组NH3-N平均值最低,表明在肉牛饲养中青贮和羊草是较好的粗饲料来源;本试验中青贮组和羊草组的TVFA含量同样最高,为78.64 mmol/L、79.68mmol/L,分别比秸秆组高6.75mmol/L和7.79mmol/L,表明饲喂青贮和羊草能为反刍动物提供更多能量,尤其是丙酸含量的提高有利于反刍动物体内脂肪的蓄积。[结论]饲喂青贮和羊草有利于肉牛育肥,玉米秸秆微贮可以作为补充粗饲料来源。     

Duodenal obstruction caused by duodenal sigmoid flexure volvulus in dairy cattle: 29 cases (2006-2010)

Objective-To characterize duodenal sigmoid flexure volvulus (DSFV) and determine the prognosis for affected cattle undergoing surgery. Design-Retrospective case series. Animals-29 dairy cattle. Procedures-The medical records were analyzed for history, signalment, clinical signs, medical management, surgical findings, and outcome. Results-29 cattle were determined to have DSFV between December 2006 and August 2010. Twenty cattle had had an omentopexy or pyloropexy performed 1 day to 2 years before initial evaluation. Cattle were afebrile, tachycardic, and moderately dehydrated, with a small zone of percussion with a ping at the 10th to 12th right intercostal spaces and associated succussion. Biochemical changes were a severe hypokalemic (mean ± SD, 2.9 ± 0.5 mmol/L; median, 3.1 mmol/L; range, 2.08 to 3.92 mmol/L), hypochloremic (mean, 69.7 ± 11.1 mmol/L; median, 71.7 mmol/L; range, 49.1 to 94.1 mmol/L) metabolic alkalosis (mean total CO(2), 44.5 ± 7.4 mmol/L; median, 45.3 mmol/L; range, 31.5 to 59.6 mmol/L) and hyperbilirubinemia (mean, 32.4 ± 29.0 μmol/L; median, 20.5 μmol/L; range, 7.8 to 107 μmol/L). Surgical findings for DSFV included an empty descending duodenum adjacent to a dorsally displaced and dilated cranial segment of the duodenum, distended abomasum and gallbladder, and a tight volvulus at the base of the duodenal sigmoid flexure. Manual reduction was considered successful if the descending duodenum filled after cranial duodenal massage. Twenty-two patients were successfully treated; the remaining 7 died or were euthanized within 4 days after surgery. Conclusions and Clinical Relevance-A condition clinically resembling abomasal volvulus but affecting the duodenal sigmoid flexure has been recognized in dairy cattle. When a focal, dorsal right-sided ping and succussion are present combined with severe hypokalemic, hypochloremic metabolic alkalosis and high bilirubin concentration, DSFV should be suspected, especially when there is a history of prior abomasal fixation. After surgical correction, the prognosis is fair to good.     

Anatomical,histological and biochemical studies of desert rodent Gerbillus tarabuli (Thomas, 1902) kidney

The present work aimed to study the anatomy, histology, cytology and some biochemical parameters (urea, osmolality, haematocrit, serum natrium, serum kalium) of the kidney of Gerbillus tarabuli. The investigated animals (n = 16) were collected from the desert, weighed and transferred alive to the laboratory in separate cages. A blood sample was taken by puncture at the retro-orbital sinus of each animal using a Pasteur-type capillary pipette capillary. They were anaesthetized with urethane injection (25%), after which they were carefully dissected; their organs were taken out and prepared for the histological and cytological studies. Pasteur pipette capillary type the kidney of the Gerbillus tarabuli is subdivided into three regions: Cortex (1193.625±60μm), Outer Medulla (1316.72±73μm), Inner Medulla (2525.08±85 μm). Pasteur pipette capillary type the kidney of the Gerbillus tarabuli is subdivided into three regions: Cortex (1193.625±60μm), Outer Medulla (1316.72±73μm), Inner Medulla (2525.08±85 μm). The concentration of the biochemical parameters of urea (0.41 ± 0.02 g/L), osmolality (300.75 ± 3.33 mOs/kg), haematocrit (34.18 ± 1.3%), serum natrium (141.37 ± 2.31 mmol/L) and serum kalium (7.69 ± 0.39 mmol/L) is in the interval of the norm compared with several studies on desert and semi-desert rodents and also on the Wistar rat. These findings revealed the adaptive morphology and physiological function in the kidney of G. tarabuli to the desert environment.     

Determinants and Utility of the Anion Gap in Predicting Hyperlactatemia in Cattle

The objectives of this study were to investigate the determinants of the anion gap (AG) in cattle and to evaluate the utility of AG in detecting hyperlactatemia in sick neonatal calves and adult cattle. The AG was calculated as AG = ([Na+] + [K+]) - ([Cl^-] + [HCO₃]), with all values in mEq/L. The AG of healthy neonatal calves (n = 16) was 29.6 ± 6.2 mEq/L (mean ± SD), and the blood L-lactate concentration ranged from 0.5 to 1.2 mM/L. The AG was significantly (P > .05) correlated with serum phosphate (r = .66) and creatinine (r = .51) concentrations. The AG of neonatal calves with experimentally induced diarrhea (n = 16) was 28.6 ± 5.6 mEq/L, and the blood L-lactate concentration ranged from 1.1 to 2.9 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .67), serum phosphate concentration (r = .63), creatinine concentration (r = .76), and blood pH (r = -.61). The AG of adult cattle with abomasal volvulus (n = 41) was 20.5 ± 7.8 mEq/L, and the blood L-lactate concentration ranged from 0.6 to 15.6 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .60), serum phosphate concentration (r = .71), creatinine concentration (r = .65), albumin concentration (r = .47), total protein concentration (r = .54), blood pyruvate concentration (r = .67), and blood pH (r = -.41) but not plasma β-OH butyrate concentration. The results indicate that the AG in cattle is only moderately correlated with blood L-lactate concentration and is similarly correlated with serum phosphate and creatinine concentrations in neonatal calves and adult cattle, as well as with serum albumin and total protein concentrations in adult cattle. Anion gap determination is of limited usefulness in predicting blood L-lactate concentration in sick cattle, whereas the correlation between AG and serum creatinine concentration in sick cattle suggests that an increased AG should alert the clinician to the potential presence of uremic anions.     

Effect of supplementation of rice bran and fumarate alone or in combination on in vitro rumen fermentation,methanogenesis and methanogens

This study investigated the effect of fumarate (FUM) and rice bran (RB), alone and together, on in vitro rumen fermentation, methanogenesis and methanogens. In vitro incubation was performed with six media that were either unsupplemented (control) or supplemented with 10% RB, 5 mmol/L FUM, 10% RB + 5 mmol/L FUM, 10 mmol/L FUM, or 10% RB + 10 mmol/L FUM. Methane (CH₄) production, dry matter digestibility, CH₄ per digested dry matter, total short‐chain fatty acid (SCFA) production, proportion of SCFA, acetate : proprionate ratio, production of NH₃‐N, and population density of rumen microbes were determined. Supplementation with 10% RB + 10 mmol/L FUM yielded a 36% decrease in CH₄ production compared to the control. Supplementation of FUM, in the presence or absence of RB, provided increases in total SCFA production and propionate proportion up to 61% and 31%, respectively. Total bacteria, methanogens and protozoa populations were significantly (P < 0.05) decreased with the 10% RB + 10 mmol/L FUM supplementation. The effect of anti‐methanogenesis of FUM was enhanced by the addition of RB. Notably, the CH₄ production attenuation was achieved by 10% RB + 10 mmol/L FUM without reduction of digestibility or of ruminal fermentation.     

Effect of animal age,postmortem chilling rate,and aging time on meat quality attributes of water buffalo and humped cattle bulls

The study was aimed to investigate the influence of animal age, post‐slaughter chilling rate, and aging time on meat quality of M. longissimus dorsi (LD) of water buffalo (Bubalus bubalis) and humped cattle (Bos taurus indicus) bulls. After slaughtering, one side of carcasses was subjected to rapid chilling (RC) (0 ± 2°C) and other side was hanged in controlled room temperature (25 ± 2°C) for 3 hr, then allowed to the chiller (0 ± 2°C). The meat quality traits were analyzed at 1, 7, and 14 days of storage. It was noted that rapidly chilled carcasses from the younger animals of both species missed the ideal pH/temperature window, which affects the toughness of the meat. Buffalo meat presented higher shear force, color L* values, and lower b* value as compared to the cattle meat. Moreover, meat shear force values decreased while all color coordinates and cooking loss values increased with lengthening the storage time in both age groups of cattle and buffalo. In conclusion, the tenderness of cattle meat was superior to that of buffalo and RC adversely affect the shear force values of young cattle and both age groups of buffalo bulls.     

Selection and characterization of broad‐spectrum antibacterial substance‐producing Lactobacillus curvatus PA40 as a potential probiotic for feed additives

Lactic acid bacteria were screened for potential probiotics for use as feed additives. We obtained 3,000 isolates from feces of: cattle, dogs, goats, and infants; milk; yogurt; cheese; fermented sausages; Kimchi; and Cheonggukjang and tested their antibacterial activity toward indicator pathogens, including Bacillus cereus, Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica Enteritidis. We further tested their tolerance to artificial gastric juice (1% [w/v] pepsin, pH 2.5) and bile acid (0.1% [w/v] oxgall, pH 6.8). Six isolates exhibited strong antibacterial activity against indicator pathogens. The PA40 isolate from Kimchi exhibited marked resistance to artificial gastric juice and bile acid. The antibacterial substances produced by PA40 were stable to heat, pH, and enzymes. Strain PA40 was identified as a Lactobacillus curvatus strain using chemical tests and 16S rDNA sequencing and produced 248.4 mmol/L lactic acid after 48 hr of fermentative growth. The L. curvatus PA40 strain was also highly tolerant of the artificial gastrointestinal model system. Our results indicate that L. curvatus PA40 could be used as a potential probiotic feed additive.     

Serum pharmacokinetics of oxytetracycline in sheep and calves and tissue residues in sheep following a single intramuscular injection of a long-acting preparation

The pharmacokinetics of a long‐acting oxytetracycline (OTC) formulation (Liquamycin® LA‐200®) injected intramuscularly (i.m.) at a dose of 20 mg/kg were determined in four calves and 24 sheep to determine if the approved label dose for cattle provided a similar serum time/concentration profile in sheep. The AUC for the calves was 168±14.6 (μg ? h/mL) and was significantly less than the AUC for sheep (209±43 μg ? h/mL). Using the standard two‐stage approach and a one‐compartment model, the mean Cmax for the calves was 5.2±0.8 μg/mL, and for the sheep was 6.1±1.3 μg/mL. The mean terminal phase rate constants were 0.031 and 0.033 h, and the Vdss were 3.3 and 3.08 L/kg for the calves and sheep respectively. Analysis of the data using the standard two‐stage approach, the naive pooled‐data approach and a population model gave very similar results for both the cattle and sheep data. Sheep tissue residues of OTC in serum, liver, kidney, fat, muscle and injection site were measured at 1, 2, 3, 5, 7 and 14 days after a single i.m. injection of 20 mg/kg OTC. Half‐lives of OTC residues in the tissues were 38.6, 33.4, 28.6, 25.4, 21.3, and 19.9 h for injection site, kidney, muscle, liver, mesenteric fat and renal fat, respectively. The ratio of tissue to serum concentration was fairly consistent at all slaughter times, except for the fat and injection sites. The mean ratios were 1.72, 4.19, 0.11, 0.061, 0.84 and 827 for the liver, kidney, renal fat, mesenteric fat, muscle and injection sites, respectively. The tissue concentrations of OTC residues were below the established cattle tolerances for OTC in liver (6 p.p.m.), muscle (2 p.p.m.) and kidney (12 p.p.m.) by 48 h, and in injection site muscle by 14 days after the single i.m. injection of 20 mg/kg.     

Correction of Hyperkalemia in Dogs with Chronic Kidney Disease Consuming Commercial Renal Therapeutic Diets by a Potassium‐Reduced Home‐Prepared Diet

Background: Hyperkalemia occurs in dogs with chronic kidney disease (CKD). Objectives: (1) To determine the incidence of hyperkalemia in dogs with CKD, (2) to determine the proportion of hyperkalemic dogs that required modification of dietary potassium intake, (3) to evaluate the response to dietary modification. Methods: The hospital database was reviewed retrospectively to identify dogs with CKD and persistent (>5.3 mmol/L on at least 3 occasions) or severe (K ≥ 6.5 mmol/L) hyperkalemia while consuming a therapeutic renal diet. Records of dogs with hyperkalemia that were prescribed a home‐prepared, potassium‐reduced diet were evaluated further. Response was evaluated by changes in body weight, BCS, and serum potassium concentration. Results: One hundred and fifty‐two dogs were diagnosed with CKD, of which 47% had ≥1 documented episode of hyperkalemia, 25% had ≥3 episodes of hyperkalemia, and 16% had ≥1 episodes of severe hyperkalemia (K > 6.5 mmol/L). Twenty‐six dogs (17.2%) with CKD and hyperkalemia were prescribed a potassium‐reduced, home‐prepared diet. The potassium concentration of all hyperkalemic dogs on therapeutic diets (potassium content, 1.6 ± 0.23 g/1,000 kcal of metabolizable energy [ME]) was 6.5 ± 0.5 mmol/L but decreased significantly to 5.1 ± 0.5 mmol/L in 18 dogs available for follow‐up in response to the dietary modification (0.91 ± 0.14 g/1,000 kcal of ME, P < .001). Potassium concentration normalized in all but 1 dog. Conclusions and Clinical Importance: Hyperkalemia is a potential complication of CKD. In a subset of CKD dogs, hyperkalemia can be associated with commercial renal diets and could restrict use of these diets. Appropriately formulated, potassium‐reduced, diets are an effective alternative to correct hyperkalemia.     

In ovo L‐arginine supplementation stimulates myoblast differentiation but negatively affects muscle development of broiler chicken after hatching

In this study, we tested the hypothesis that in ovo feeding (IOF) of L‐arginine (L‐Arg) enhances nitric oxide (NO) production, stimulates the process of myogenesis, and regulates post‐hatching muscle growth. Different doses of L‐Arg were injected into the amnion of chicken embryos at embryonic day (ED) 16. After hatching, the body weight of individual male chickens was recorded weekly for 3 weeks. During in vitro experiments, myoblasts of the pectoralis major (PM) were extracted at ED16 and were incubated in medium containing 0.01 mm L‐Arg, 0.05 mm L‐Arg, and (or) 0.05 mm L‐nitro‐arginine‐methyl‐ester (L‐NAME), an inhibitor of nitric oxide synthase (NOS). When 25 mg/kg L‐Arg/initial egg weight was injected, no difference was observed in body weight at hatch, but a significant decrease was found during the following 3 weeks compared to that of the non‐injected and saline‐injected control, and this also affected the growth of muscle mass. L‐NAME inhibited gene expression of myogenic differentiation antigen (MyoD), myogenin, NOS, and follistatin, decreased the cell viability, and increased myostatin (MSTN) gene expression. 0.05 mm L‐Arg stimulated myogenin gene expression but also depressed muscle cell viability. L‐NAME blocked the effect of 0.05 mm L‐Arg on myogenin mRNA levels when co‐incubated with 0.05 mm L‐Arg. L‐Arg treatments had no significant influence on NOS mRNA gene expression, but had inhibiting effect on follistatin gene expression, while L‐NAME treatments had effects on both. These results suggested that L‐Arg stimulated myoblast differentiation, but the limited number of myoblasts would form less myotubes and then less myofibers, while the latter limited the growth of muscle mass.     

植物角质降解菌的种属鉴定、发酵条件优化及酶学性质研究

本试验旨在通过角质降解菌株X8P的种属鉴定、发酵条件优化和酶学性质研究,探讨降解植物表面角质层,进一步改善动物对植物纤维利用的可能新方案。试验通过形态观察和16 S r DNA测序鉴定菌株X8 P种属,并对其产酶所需碳源、氮源、发酵温度与时间进行优化,其发酵液经硫酸铵盐析沉淀获得其胞外蛋白粗酶,并对其粗酶催化的适宜p H和p H稳定性、温度和温度稳定性,以及有机溶剂、表面活性剂和金属离子对其活性的影响进行研究。结果表明:1)菌株X8P经形态观察和分子鉴定为东方醋杆菌(Acetobacter orientalis)。2)菌株X8P适宜产酶发酵条件为溶菌肉汤(LB)培养基中37℃发酵4 d,1%橄榄油和1%葡萄糖明显促进菌株产酶,而1%可溶性淀粉明显抑制菌株产酶。3)该菌株胞外粗酶催化适宜p H和温度分别为6.5和45℃,且表现出一定p H稳定性,但在有机溶剂中不稳定,仅甘油中可保留全部活性,在二甲基亚砜(50%)中活性可保留66%。吐温(Tween)-20(1 mmol/L)、Tween-80(1 mmol/L)和聚乙二醇辛基苯基醚(1和10 mmol/L)可使菌株X8P粗酶活性提高3%~35%。金属离子钾离子(K+)、锰离子(Mn2+)(1和10 mmol/L)可使菌株X8P粗酶活性提高2%~20%。由此可见,菌株X8P具有一定的产角质酶潜力和应用前景,可进一步深入研究。