Effects of high ambient temperature on urea‐nitrogen recycling in lactating dairy cows

Effects of exposure to hot environment on urea metabolism were studied in lactating Holstein cows. Four cows were fed ad libitum a total mixed ration and housed in a temperature‐controlled chamber at constant moderate (18°C) or high (28°C) ambient temperatures in a cross‐over design. Urea nitrogen (N) kinetics was measured by determining urea isotopomer in urine after single injection of [¹⁵N₂]urea into the jugular vein. Both dry matter intake and milk yield were decreased under high ambient temperature. Intakes of total N and digestible N were decreased under high ambient temperature but urinary urea‐N excretion was increased. The ratio of urea‐N production to digestible N was increased, whereas the proportion of gut urea‐N entry to urea‐N production tended to be decreased under high ambient temperature. Neither return to the ornithine cycle, anabolic use nor fecal excretion of urea‐N recycled to the gut was affected by ambient temperature. Under high ambient temperature, renal clearance of plasma urea was not affected but the gut clearance was decreased. Increase of urea‐N production and reduction of gut urea‐N entry, in relative terms, were associated with increased urinary urea‐N excretion of lactating dairy cows in higher thermal environments.     

Effect of nitrogen supplementation and zilpaterol-HCl on urea kinetics in steers consuming corn-based diets

We studied effects of zilpaterol-HCl on steers consuming corn-based diets with nitrogen (N) supplementation provided by dried distillers grains with solubles (DDGS) or urea. Two sets of six steers (approximately 350 kg) were used in two replicates of similarly designed trials. Within each replicate, three steers were fed 60 mg/day of zilpaterol-HCl throughout the trial and three steers received no zilpaterol-HCl. Within zilpaterol treatment, three corn-based dietary N treatments were offered in Latin square designs: control (9.6% crude protein), urea (UREA; 12.4% crude protein) or DDGS (13.7% crude protein). Total feed intake was unexpectedly greater (p < 0.01) with zilpaterol feeding but was not affected by dietary N (p = 0.76). Nitrogen intake was greater (p < 0.01) when zilpaterol was fed and was greater (p < 0.05) for DDGS and UREA than for control. Despite greater N intake, zilpaterol did not affect urea entry rate (p = 0.80) or urea-N recycled to the gastrointestinal tract (GER; p = 0.94). As a percentage of N intake, urea entry rate (p = 0.19) tended to be less when zilpaterol was fed (91 vs. 123% of N intake), and GER was numerically (p = 0.34) less (72 vs. 92% of N intake). Microbial N flow was greater (p = 0.02) for zilpaterol than for control but did not differ (p = 0.78) among dietary N treatments. As a percentage of N intake, microbial N flow was unaffected by zilpaterol (p = 0.97), but was greater (p < 0.05) for control than DDGS or UREA. The lack of change in urea entry and GER in response to zilpaterol, despite greater N intake, as well as lower urea entry and GER when expressed as proportions of N intake provide some evidence that the amount of N available for urea production and recycling was reduced by zilpaterol.     

Effects of protein sources and inclusion levels on nitrogen metabolism and urea kinetics of Nellore feedlot steers fed concentrate-based diets

Urea recycling occurs in all mammalian species and represents an important source of ruminal nitrogen (N) for ruminants fed protein-restricted diets. However, its importance for cattle fed adequate amounts of protein and energy remains unclear. Six Nellore feedlot steers fed concentrate-based diets were used in a 6 × 6 Latin square design with a 3 × 2 factorial arrangement of treatments to evaluate ruminal fermentation, urea kinetics, and N excretion. Treatments consisted of 3 protein sources (PS: soybean meal plus urea [SU], corn gluten meal [CGM], and dry distillers grains [DDG]) and 2 inclusion levels (PL; 11% and 14%). Steers were adapted to the diets for 14 d followed by 8 d of sample collection. Feed intake, fecal output, and urine production were measured from day 18 to day 22 of each period. Blood samples were collected every 6 h on day 18. [¹⁵N-¹⁵N]-urea was infused into the jugular vein for 82 h over day 19 to day 22, and measurement of ¹⁵N in background (day 18) and enriched feces and urine (day 21) were used to evaluate urea kinetics. To evaluate the incorporation of recycled urea N into microbial protein (MICP), ruminal and duodenal fluid were collected on day 22. Steers fed SU diets had lower (P < 0.05) nitrogen use efficiency (NUE), greater (P < 0.05) urea-N entry rate (UER), and tended (P < 0.10) to have greater gastrointestinal entry rate of urea-N (GER) compared with those fed CGM or DDG. In addition, steers fed SU had greater (P < 0.05) urea-N returned to ornithine cycle (ROC) compared with those fed CGM or DDG. Increasing PL tended (P < 0.10) to increase UER. The proportion of total microbial N from recycled urea-N was greater (P < 0.05) for steers fed CGM compared with those fed SU and also greater for steers fed diets with 11% CP than for those fed with 14% CP. Diets with 11% CP can be used for Nellore feedlot cattle fed concentrate-based diets without negatively affecting intake, digestibility, and ruminal fermentation. Moreover, diets containing rumen undegradable protein (RUP) feed sources (CGM or DDG) compared with diets with SU markedly increased NUE, while maintaining microbial protein (MICP) synthesis. Results from this study suggest that the equation adopted by NASEM (NASEM. 2016. Nutrient requirements of beef cattle. 8th revised ed. Washington, DC: The National Academies Press) was not accurate in estimating the urea-N used for anabolism (UUA) in Nellore feedlot cattle fed concentrate-based diets.     

Fiber digestion in various segments of the hindgut of horses fed grass hay or silage

We studied in vivo fiber digestibility and fermentation parameters such as volatile fatty acid concentration and in vitro degradation in each segment of hindgut of horses fed timothy hay or silage made from the same sward. Six Thoroughbred horses were fed timothy hay or silage in equal amounts (1.6% of bodyweight per day, bodyweight mean 572 kg) every 3 h per day, then slaughtered. There were no differences between hay and silage in the concentration of the total volatile fatty acids, the apparent digestibility of dry matter, organic matter, and fiber, and in vitro neutral detergent fiber (NDF) disappearance rate in each segment. The total volatile fatty acid concentration and the apparent digestibility of dry and organic matter and fiber differed ( P  < 0.01) depending on the digestive segments. Both for hay and silage, the concentration of total volatile fatty acids in the digesta liquid phase largely increased ( P  < 0.01) from the cecum to the right ventral colon, and kept a constant value from the right ventral colon to the right dorsal colon, and then decreased from the right dorsal colon to the small colon. For dry and organic matter and fiber components, the apparent digestibility changed in the same manner from former to hinder segments of the hindgut. Regardless of diet, dry and organic matter and fiber components showed lower values in the cecum and the right ventral colon and increased ( P  < 0.01) largely from the right ventral colon to the left dorsal colon, then kept constant values in segments to the rear of left dorsal colon. There were no differences in in vitro NDF disappearance among cecum, ventral colon and dorsal colon.     

提高反刍动物氮利用率的研究进展

提高反刍动物氮利用率是应对全球饲料资源短缺、环境污染和畜牧业可持续发展的有效措施。论文从当前对反刍动物氮代谢规律的最新认识、日粮和瘤胃因素对反刍动物氮利用率的影响以及经济与环境友好型集成技术等方面,综合阐述了国内外在提高反刍动物氮利用率方面的研究进展。     

Phylogenetic analysis of hindgut microbiota in Hokkaido native horses compared to light horses

The analysis of 16S rDNA sequence of bacteria in feces of Hokkaido native horses and light horses were performed to compare the hindgut microbiota between the two breeds. One hundred and four bacterial 16S rDNA clones (57 clones from four native horses and 47 clones from two light horses) were obtained. Only four sequences (3.8% of total sequences) showed 97% or more similarity to known species. The sequences were mainly affiliated with Cytophaga–Flavobacter–Bacteroides and low GC Gram‐positive bacteria (LGCGP). Proportion of LGCGP was higher in light horses. Other phyla including Verrucomicrobia, Spirochaetes and Archaea were detected only for native horses, suggesting high diversity of microbiota in native horses. In LGCGP, clusters related to known cellulolytic species were found only for native horses, while a cluster related to soluble sugar‐utilizing species was detected only for light horses. The library composition‐comparing software LIBSHUFF showed significant (P < 0.05) difference of fecal microbiota between the horse breeds. The number of Fibrobacter succinogenes‐related sequence and the frequency of detection of novel groups were found to be higher in native horses by selective amplification analysis. The results suggest that genetic diversity and population size of the F. succinogenes group are higher in the hindgut of native horses.     

Changes in faecal bacteria associated with concentrate and forage‐only diets fed to horses in training

Reasons for performing study: Diets rich in readily fermentable carbohydrates, fed traditionally to meet the increased energy requirements of the performance horse, are associated with a number of gastrointestinal disorders that involve disturbances in the intestinal microbiota, however, these changes are poorly understood. Objectives: With the long‐term objective of improving intestinal health and to increase understanding of the relationship between diet and microbiota, the effect of feeding Standardbred horses a high‐energy forage‐only (F) diet was studied compared to a more traditional forage‐concentrate (C) diet on faecal microbiota. Methods: Diets were fed in a cross‐over design to 6 mature geldings on a scheduled training regime, both periods consisting of 29 days. DNA was extracted from faecal samples collected at 4 time points from each period, bacterial 16S rRNA genes were amplified and community composition assessed by terminal‐restriction fragment length polymorphism, cloning and sequencing. Faecal pH and cultivable lactic acid bacteria (LAB) and enterobacteria were also assessed on the final collection day of each period. Results: Diet F resulted in a microbial composition that was more stable between sampling periods and had lower counts (P<0.05) of cultivable LAB and specifically members of the Streptococcus bovis/equinus complex. Motile and swarming Lactobacillus ruminis was present in all horses on diet C and not in horses on diet F. Diet C also resulted in the increase (P<0.05) in members of Clostridiaceae cluster III and a concomitant reduction (P<0.05) in an unknown group of Bacteroidales. Conclusions and potential relevance: The greater microbial stability and reduction in LAB and members of the Streptococcus bovis/equinus complex on diet F indicate an opportunity to develop feeding strategies that support equine health and welfare. Novel changes identified in the faecal microbiota that resulted from carbohydrate inclusion merit further investigation.     

周期性变动饲粮蛋白质水平对内蒙古白绒山羊内源尿素氮循环和微生物蛋白质合成的影响

本试验旨在探讨周期性变动饲粮蛋白质水平对内蒙古白绒山羊内源尿素氮循环和微生物蛋白质合成的影响。饲粮分为低(7.5%)、中(10.5%)和高(13.5%)3个蛋白质水平。选用9只体况良好,体重为(45.63±3.15)kg,装有瘤胃瘘管的内蒙古白绒山羊,采用单因子随机区组试验设计分为3组,即中蛋白质饲粮组(对照组)、变动低蛋白质饲粮组(2 d低蛋白质饲粮—2 d高蛋白质饲粮,循环饲喂)、变动高蛋白质饲粮组(2 d高蛋白质饲粮—2 d低蛋白质饲粮,循环饲喂)。预试期16 d,正试期12 d。通过全收粪尿法、嘌呤衍生物法和同位素灌注法测定山羊氮代谢、内源尿素氮循环以及微生物蛋白质合成的变化。结果表明:1)中蛋白质饲粮组与变动蛋白质饲粮组比较,瘤胃液氨氮(NH3-N)浓度显著增加(P<0.05),粪氮、尿氮排出量显著增加(P<0.05),沉积氮/摄入氮显著降低(P<0.05),尿中嘌呤衍生物排出量和微生物蛋白质合成的量显著降低(P<0.05);2)变动低蛋白质饲粮组与变动高蛋白质饲粮组比较,瘤胃液NH3-N浓度显著降低(P<0.05);3)周期性变动饲粮蛋白质水平后,进入胃肠道的尿素氮/肝脏合成的内源尿素氮显著增加(P<0.05),进入尿中的尿素氮/肝脏合成的内源尿素氮显著减少(P<0.05),返回鸟氨酸循环的尿素氮/进入胃肠道的尿素氮显著减少(P<0.05),用于再合成的尿素氮/进入胃肠道的尿素氮显著增加(P<0.05)。综上所述,周期性变动饲粮蛋白质水平有利于提高内蒙古白绒山羊氮利用率和微生物蛋白质合成量。     

Utilization of dietary urea nitrogen is stimulated by D‐mannitol feeding in rabbits

The effect of D‐mannitol as an indigestible sugar on apparent digestibility of nutrients, nitrogen (N) utilization and growth performance, have been investigated in growing rabbits fed a urea‐containing diet. In experiment 1, 40‐day‐old male rabbits were fed a commercial diet with urea 10 g/kg with added glucose or D‐mannitol 60 g/kg each. Thereafter, in experiment 2 the rabbits aged 55 days were fed a commercial diet with or without urea 10 g/kg. Feed restriction at 55 g/kg^0.75/day was carried out in both experiments. Addition of D‐mannitol to the urea‐containing diet decreased urinary N excretion, which consequently increased N retention and ratios of retained N to consumed N or apparently absorbed N. Addition of urea alone to the diet increased daily N intake and urinary N excretion but did not affect N retention. Weight gain and feed efficiency were improved by D‐mannitol feeding, whereas feeding with urea alone did not affect these parameters. Utilization of dietary urea was enhanced in growing rabbits fed the urea‐containing diet with D‐mannitol, resulting in improvement of N retention and growth performance.     

Substitution of corn and soybean with green banana fruits and Gliricidia sepium forage in sheep fed hay‐based diets: effects on intake,digestion and growth

This study aimed to evaluate the substitution of imported corn and soybean by local feed resources from tropical production settings such as entire green banana and Gliricidia sepium forage as energy and protein sources, respectively, in sheep diets. Two experiments were conducted: first, a ‘growth trial’ and second, an in vivo digestion study. In the ‘growth trial’, 40 Martinik lambs [body weight (BW): 29.4 ± 3.6 kg; 6 months old) were used and distributed into four groups of 10 lambs each according to treatment: HBGl (banana + gliricidia at low level; 1500 g/day; 119 g/kg BW^0.75), HBGh (banana + gliricidia at high level; 3000 g/day; 238 g/kg BW^0.75), HBS (banana + soybean cake) and Control (corn + soybean cake). In digestion trial, four Martinik rams (BW: 57.2 ± 3.45 kg) fitted with ruminal and duodenal cannulae were used; treatments (HBG, HBS and Control) were similar but adjusted to metabolic body weight (MW) and just one level of gliricidia was used. Intake, average daily gain (ADG), feed intake to gain index (F:G), apparent total and ruminal digestibilities as well as nitrogen balance, microbial efficiency and volatile fatty acid (VFA) profile were monitored. Lambs fed HBGh had greater dry matter (DM) intake based on MW and ADG (173 g/day vs. 141 g/day; p < 0.001), whereas HBGl lambs showed the lowest ADG (71.5 g/day) and the worst F:G (14.4; p < 0.001). The DM, organic matter (OM), neutral detergent fibre and acid detergent fibre digestibilities were not influenced by treatment, whereas crude protein digestibility was higher (p = 0.024) in diets offered banana or corn + soybean cake (687 g/kg DM and 658 g/kg DM, respectively). Ruminal DM and OM digestibilities did not differ among treatments. Total or individual VFA concentrations were also not influenced by the diet. Higher (p = 0.006) ruminal fluid pH values were recorded for diets combining banana and gliricidia (6.54) or banana and soybean (6.39) until 3 h after a meal. As all animals on gliricidia‐ and banana‐supplemented diets gained weight and maintained a positive N balance, it is concluded that green banana and gliricidia forage may be a viable alternative to replace conventional energy and protein supplements in sheep diets.     

Tear urea nitrogen and creatinine levels in horse and their correlation with serum values

The objective of this paper was to determine the physiological values of urea nitrogen and creatinine in tears, and to compare the results with those obtained from serum. Thirty healthy thoroughbred horses were included in the study. Tear fluid samples were obtained using a glass capillary tube placed in lower conjunctival cul-de-sac. Blood samples were taken from the jugular vein. Tear and serum urea nitrogen and creatinine levels were quantitatively analyzed by an enzymatic colorimetric method. Urea nitrogen values were 4.22+/-1.84 mmol/l in tears and 4.44+/-1.78 mmol/l in serum, whereas creatinine values in tears were 14.14+/-7.74 micromol/l and in serum 147.63+/-12.17 micromol/l. Statistical analysis confirmed a significant correlation between serum and tear urea levels (P<0001). However, there was no significant correlation between blood and tear creatinine values. Mean value of creatinine obtained from tears was 9.6% of the mean value from serum. Urea nitrogen and creatinine levels can be measured in tears. A significant correlation was found between serum and tears urea levels. This finding may permit development of a new alternative laboratory diagnosis of uremia based on the content of urea in tears.     

不同蛋白质水平日粮对中国荷斯坦奶牛生产性能、氮消化和血液生化指标的影响

旨在研究饲粮不同粗蛋白质(CP)水平对中国荷斯坦奶牛乳尿素氮(MUN)、氮(N)消化及血液尿素氮(BUN)的影响。采用4×4拉丁方设计,16头经产中国荷斯坦奶牛随机分为4个处理。4个处理的饲粮能量相近,CP水平分别为12. 72%、13. 52%、14. 43%和15. 37%。试验分为4个周期,每个周期15 d,后5 d为样品收集期。奶样收集3 d,同时收集粪便,每期最后1 d晨饲前空腹采集血样。每天测量产奶量和干物质摄入量。结果:不同蛋白水平日粮奶牛干物质采食量(DMI)和产奶量组间差异不明显(P>0. 05),除了MUN随着饲粮CP水平的增加呈现增加趋势以外,其他乳成分影响不显著(P>0. 05),高蛋白质水平组MUN明显高于低蛋白组(P<0. 05)。随着饲粮CP水平的提高,氮的摄入量明显增加(P<0. 05),同时N的排泄量和消化率也不断增加,但组间无显著差异(P>0. 05)。BUN和MUN变化趋势基本一致,高蛋白质组的BUN明显高于低蛋白质组(P<0. 05),而对其他血液指标的影响不显著(P>0. 05)。在本试验条件下,不同蛋白质水平日粮能够影响中国荷斯坦奶牛MUN、BUN的变化,且两者变化趋势一致,而对产奶量、N消化率影响不明显,MUN可以代替BUN成为检测奶牛蛋白质营养状况的指标之一。     

Transfer of blood urea nitrogen to cecal microbial nitrogen is increased by fructo‐oligosaccharide feeding in guinea pigs

The present study was conducted to determine the mechanism by which nitrogen (N) availability is improved by fructo‐oligosaccharide (FOS) in guinea pigs. Adult male guinea pigs were fed a commercial pellet diet (50 g/day) with either 5% glucose or 5% FOS for 7 days in individual metabolism cages. After 7 days of feeding the diet, ¹⁵N‐urea was administered intravenously 1 h before slaughter under anesthesia. The amount and concentration of total, protein, bacterial, ammonia and urea N and the ¹⁵N atom % excess were measured in blood, liver, gut contents and urine. The ¹⁵N atom % excess of total and protein N, and the amount of total, protein and bacteria N and ¹⁵N in the cecum were significantly increased by the consumption of FOS. Furthermore, the concentration and amount of short‐chain fatty acids were significantly increased by the consumption of FOS. In contrast, the amount of urinary ¹⁵N was significantly decreased by the consumption of FOS. These results suggest that consumption of FOS increases transfer of blood urea N into the large intestine for bacterial N synthesis, which is subsequently re‐absorbed by cecotrophy, and contributes to the increase of N utilization in guinea pigs.     

Method for estimating maximum permissible load weight for Japanese native horses using accelerometer‐based gait analysis

The aim of this study was to establish a method for estimating loading capacity for Japanese native horses by gait analysis using an accelerometer. Six mares of Japanese native horses were used. The acceleration of each horse was recorded during walking and trotting along a straight course at a sampling frequency of 200 Hz. Each horse performed 12 tests: one test with a loaded weight of 80 kg (First 80 kg) followed by 10 tests with random loaded weights between 85 kg and 130 kg and a final test with a loaded weight of 80 kg again. The time series of acceleration was subjected to fast Fourier transformation, and the autocorrelation coefficient was calculated. The first two peaks of the autocorrelation were defined as symmetry and regularity of the gait. At trot, symmetries in the 100, 110, and 125 kg tests were significantly lower than that in First 80 kg (P < 0.05, by analysis of covariance and Sidak's test). These results imply that the maximum permissible load weight is less than 100 kg, which is 29% of the body weight of Japanese native horses. Our method is a widely applicable and welfare‐friendly method for estimating maximum permissible load weights of horses.     

Pentosan polysulfate regulates hepcidin expression in native Mongolian horses

The aim of this study was to investigate the anti-hepcidin effect of pentosan polysulfate (PPS) in Mongolian horses. Twenty-six healthy horses were randomly allocated in to two-groups; one group was treated with a PPS once a week for 4-weeks while another group keeping as placebo. Blood samples at day 0 (D0), before race (BR; day 28) and after race (AR; day 28) were analyzed for serum biochemistry, hepcidin and iron concentrations. Significant reduction of hepcidin was observed at AR in PPS group when compared with BR placebo (P<0.05) and AR placebo (P<0.01). Mean hepcidin concentration difference of D0-BR and BR-AR in PPS was greater than the placebo whereas the iron concentration difference is reduced compared to placebo. Results indicate a novel therapeutic application of PPS as an anti-hepcidin compound to control hepcidin in horses while emphasizing further molecular studies.     

基于牦牛氨态氮和尿素氮分布特征构建粗蛋白质进食量估测模型

本试验旨在探讨饲粮氮水平对牦牛体内不同部位氨态氮和尿素氮浓度的影响,以期了解牦牛机体对氮胁迫的适应性响应,并构建粗蛋白质进食量估测模型。采用4×4拉丁方设计,选取4头体重[(192±12)kg]相近的3岁去势健康牦牛。分4个试验期,每期21 d;4头牦牛分成4组,每组1头,分别饲喂4个氮水平的饲粮[以粗蛋白质水平(干物质基础)计,分别为6.45%、12.18%、17.81%和23.49%]。结果表明,1)瘤胃液氨态氮(RNN)、血浆尿素氮(PUN)、唾液尿素氮浓度以及尿中尿素氮(UUN)、尿中氨态氮日排泄量均随着饲粮氮水平的升高而极显著增加(P<0.01);瘤胃液尿素氮(RUN)浓度有随着饲粮氮水平升高而增加的趋势(P<0.10)。2)RNN、RUN和PUN浓度(mg/d L)以及UUN日排泄量(g/d)与牦牛饲粮蛋白质摄入水平密切相关,可建立以下估测牦牛粗蛋白质进食量(CPI,g/d)和可消化粗蛋白质进食量(DCPI,g/d)的模型:CPI=174.102+840.096RNN-3.068RNN2,CPI=185.818+47.744RNN+22.258RUN;DCPI=36.037UUN0.712,DCPI=-0.789+8.375UUN+101.275PUN。综上,饲粮氮水平对牦牛体内氨态氮和尿素氮浓度具有广泛的影响,由此建立的估测模型可为牦牛的放牧和管理提供参考。     

单宁酸对绵羊日粮养分消化利用及氮代谢的影响

通过在饲料中添加不同比例的分析纯单宁酸(鞣酸),对绵羊营养物质消化利用及氮代谢参数的影响进行了研究,并探讨分析纯单宁酸在饲粮中的适宜添加量。试验选用4只安装永久性瘤胃瘘管的羯绵羊(2岁,平均体重为35±2.15 kg)作试畜,采用4×4拉丁方设计进行试验,研究了饲粮单宁酸水平(A、B、C、D分别为0、10、15、20 g/kg DM)对绵羊养分消化利用与氮代谢参数的影响,16 d(预试期10 d,正试期6 d)为一个饲粮循环,全期共64 d。结果表明,高浓度单宁酸(20 g/kg DM)影响绵羊的采食量,进而影响绵羊对干物质(DM)、有机物(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)的食入量(P<0.01);但随着单宁酸浓度的增加,绵羊对DM、OM、NDF、ADF、Ca、P的消化率并无显著影响(P>0.05);处理组A、B、C的N食入量与N消化量极显著高于D(P<0.01),N存留率随单宁酸比例的增大而升高,仅C处理组显著高于A(P<0.01);N消化率、pH、总N浓度差异不显著(P>0.05);而瘤胃液NH₃-N浓度和尿素氮(BUN)呈线性下降,A的NH₃-N显著高于D(P<0.05),而其血浆尿素氮(BUN)高于C、D(P<0.01)。可见,单宁酸具有提高蛋白质在绵羊体内消化吸收的功效;饲粮中单宁酸含量小于15 g/kg DM时,能够显著提高氮存留率,对蛋白质保护的效果较好;故单宁酸在饲粮中的添加量不应该超过15 g/kg DM。     

Post‐anesthetic pulmonary edema in two horses

Case 1 A two‐year old, 462 kg Standard bred horse was anesthetized for arthroscopy and castration. During anesthesia, hyperemia of the mucosal membranes and urticaria were noticed. During 5 hours of anesthesia subcutaneous edema of the eyelids and neck region developed. In the recovery box, the orotracheal (OT) tube was left in situ and secured in place with tape. Following initial attempts to stand, the horse became highly agitated and signs consistent with pulmonary edema developed subsequently. Arterial hypoxemia (PaO₂: 3.7 kPa [28 mmHg]) and hypocapnia (PaCO₂: 3.1 kPa [23 mmHg]) were confirmed. Oxygen and furosemide were administered. The horse was assisted to standing with a sling. Therapy continued with bilateral intra‐nasal oxygen insufflation. Ancillary medical therapy included flunixin meglumine, penicillin, gentamycin and dimethylsulfoxide. Following 7 hours of treatment the arterial oxygen tensions began to increase towards normal values. Case 2 An 11‐year old, 528 kg Paint horse was anesthetized for surgery of a submandibular mass. The 4‐hour anesthetic period was unremarkable. The OT tube was left in situ for the recovery. During recovery, the horse was slightly agitated and stood after three attempts. Clinical signs consistent with pulmonary edema and arterial hypoxemia (PaO₂: 5 kPa [37.5 mmHg]) subsequently developed following extubation. Respiratory signs resolved with medical therapy, including unilateral nasal oxygen insufflation, furosemide, flunixin meglumine and dimethylsulfoxide. The diagnosis of pulmonary edema in these horses was made by clinical signs and arterial blood‐gas analysis. While pulmonary radiographs were not taken to confirm the diagnosis, the clinical signs following anesthesia support the diagnosis in both cases. The etiology of pulmonary edema was most likely multifactorial.     

Effect of super dosing of phytase on growth performance,ileal digestibility and bone characteristics in broilers fed corn–soya‐based diets

A feeding trial was designed to assess the effect of super dosing of phytase in corn–soya‐based diets of broiler chicken. One hundred and sixty‐eight day‐old broilers were selected and randomly allocated to four dietary treatment groups, with 6 replicates having 7 chicks per treatment group. Two‐phased diets were used. The starter and finisher diet was fed from 0 to 3 weeks and 4 to 5 weeks of age respectively. The dietary treatments were consisted of normal phosphorus (NP) group without any phytase enzyme (4.5 g/kg available/non‐phytin phosphorus (P) during starter and 4.0 g/kg during finisher phase), three low‐phosphorus (LP) groups (3.2 g/kg available/non‐phytin P during starter and 2.8 g/kg during finisher phase) supplemented with phytase at 500, 2500, 5000 FTU/kg diet, respectively, to full fill their phosphorus requirements. The results showed that super doses of phytase (at 2500 FTU and 5000 FTU/kg) on low‐phosphorus diet improved feed intake, body weight gain, ileal digestibility (serine, aspartic acid, calcium, phosphorus), blood P levels and bone minerals such as calcium (Ca), P, magnesium (Mg) and zinc (Zn) content. It could be concluded that super doses of phytase in low‐phosphorus diet were beneficial than the normal standard dose (at 500 FTU/kg) of phytase in diet of broiler chicken.