Efficacy of the urea dilution technique in estimating empty body composition of pigs weighing 50 kilograms

The efficacy of the urea dilution technique in estimating the empty body composition of pigs weighing 50 kg was evaluated in three trials using 17 contemporary (Large White X Landrace X Hampshire X Duroc) and 8 Nebraska Gene Pool X contemporary pigs. Blood samples were collected via ear catheter before infusion (-60, -30 and 0 min) and at various times (3 to 90 min) after urea infusion (2.16 mmol/kg live BW), and analyzed for plasma urea. Backfat thickness of live pigs from the contemporary line was measured ultrasonically. Pigs then were killed by euthanasic injection, and total bodies (with gastrointestinal contents removed) were analyzed for water, protein and fat. In Trials 1 and 2, there were linear relationships (P less than .001) between chemically determined body water and fat and between body water and protein. Urea space was related (P less than .05) to empty body components with few exceptions, but regression coefficients for urea space in Trial 3 were different from those of Trials 1 and 2. Inclusion of additional independent variables with urea space improved estimation of empty body components. Although backfat alone did not estimate empty body components (except fat) as well as urea space alone, the addition of other common independent variables resulted in better estimates using backfat than urea space. The results of this experiment indicate that the urea dilution technique can be used to estimate the body composition of growing pigs. However, the accuracy obtained depended on the population of pigs being investigated and was no greater than the accuracy with appropriate equations based on backfat.     

Prediction of empty body components in steers by urea dilution

Empty body composition of 68 mixed-breed and 50 Angus steers was determined by chemical analysis of the right half-carcass and entire noncarcass fraction of each steer. Chemical composition was used to develop prediction equations for empty body protein (EBPRO) and fat (EBFAT) in steers using urea space (US) and body weight measurements. Previous research showed a significant positive correlation between empty body water (EBH2O) and urea space in these steers. For all steers studied, the percentage of EBH2O ranged from 44.8 to 69.2 (mean = 56.0), the percentage of EBPRO ranged from 14.1 to 19.8 (mean = 17.0) and the percentage of EBFAT ranged from 6.1 to 38.1 (mean = 22.1). The best predictions obtained were multiple regression equations with actual weight of body components as dependent variables and US and empty body weight (EB) as independent variables. Urea space alone was a poor predictor of EBFAT, but US improved predictions based on live weight (LW) or EB alone. Coefficients of determination for the best predictions of percentage of composition were not as high as coefficients of determination for the best predictions of actual weight of body components. These data suggest that US measurements can be used to predict empty body composition of live steers, but this may require repeated measurements and an independent estimate of EB from LW for greatest accuracy.     

Evaluation of urea dilution as a technique for estimating body composition of beef steers in vivo: validation of published equations and comparison with chemical composition

Urea dilution equations for prediction of empty body water in live cattle, developed by three separate groups of investigators, were evaluated by comparing empty body water calculated by these equations with that measured chemically in 6-, 12- and 18-mo-old crossbred beef steers (n = 10, 9 and 9, respectively). Of four equations for prediction of percent empty body water, one derived from mixed-breeds of steers overestimated empty body water in the 6-mo-old steers by 7.59% (P less than .05). For the 12- and 18-mo-old steers, calculated and measured percent empty body water did not differ (P greater than .05). Of seven equations for calculation of empty body water volume, two derived from Angus steers with an without live weight in the equation, and one derived from a combination of Angus and mixed-breeds of steers overestimated empty body water (P less than .05) in the 6-mo-old steers. No differences (P greater than .05) between calculated and measured empty body water volume were observed for either the 12- or 18-mo-old steers. When calculated empty body water values were regressed against that measured directly, all regression slopes were not different from 1 (P greater than .05). Intercepts from regressions involving percent empty body water (four equations) were not different from 0. Three of the seven equations for calculation of empty body water volume, one derived from bulls and the others from Angus steers had intercept estimates not different (P greater than .05) from 0. Validity required that these regressions have slopes not different from 1 and intercepts not different from 0. Empty body water calculated from equations that combined live weight and urea space were more highly correlated with directly measured empty body water than that calculated from equations derived only from urea space. Urea space correlations with body composition of our steers also were improved when live weight was included with urea space in multiple regression models. Results of this study suggest that before using any prediction equation for calculating body composition of cattle in vivo, equations should be tested with a sub-sample of cattle from the population for which its use is intended.     

Evaluation of the use of deuterium oxide dilution techniques for determination of body composition of beef steers

Body composition as estimated by a one- or two-compartment deuterium oxide dilution technique was compared with directly measured body composition of 15 large- and 15 small-frame steers. Body composition of the steers was measured at 219, 412 and 603 kg live weight. Empty body protein was overestimated (P less than .05) 3.6% from a one-compartment model (1 CM, using the slope, intercept method), while empty body protein was underestimated (P less than .05) 5.4% from a two-compartment kinetic model (2CM). Empty body ether extract estimated by 1 CM was not significantly different from the direct method, although 4.7% larger. Empty body ether extract was overestimated (P less than .001) 32.2% by the 2CM. Empty body water was accurately estimated from the 1CM when a 3.2% correction factor was used for the overestimation of total body water by the 1CM, but water in gastrointestinal tract contents was overestimated (P less than .001) 13.4% by the 1CM. Empty body water was underestimated (P less than .001) 7.8% by the 2CM, and water in gastrointestinal tract contents was overestimated (P less than .001) 41.8% by the 2CM due to its dependence on regression equations that differ between groups of cattle. The 2CM offered no advantage over the 1CM. A three-compartment model was not better than the 2CM in estimating body water compartments. Assuming the amount of empty body water associated with either empty body protein or ash to be constant seemed to be valid. Suggested values calculated from data presented in the literature for growing cattle with an empty body weight greater than 175 kg are .302 and .0668, respectively, for the ratios of protein and ash to water. The relationship between empty body fat and water was, percentage empty body fat = 94.27--(1.267)(percentage empty body water), which had a 1.25 residual standard deviation and a .98 coefficient of determination.     

The composition of rumen fluid of cattle collected from fistulas using ultrasound]

Concentrations of rumen fluid characteristics were compared between rumen fluid which was taken by standardized conditions via stomach tube and via rumen fistula respectively depending on time after feeding (2.5 or 9 hours ppr.). The results were as follows: Differences (%) of the characteristics of rumen fluid taken via stomach tube to that by rumen fistula: [table: see text] Other investigations showed that the admixture of saliva to rumen fluid resulted in a degradation of the concentrations especially of VFA. The pH was not appreciable changed. The consequences for veterinary practitioners are discussed.     

Fistulization of the rumen in cattle

Various surgical techniques and two types of fistulas were tested when they were installed (Firm and PVC rumen cannulas were applied in 35 and 12 animals). We consider that the simplest process of installing the fixed rumen fistula is the total resection of abdominal wall together with peritoneum and following fixation of rumen to the abdominal wall with knot stitches and with removal of rumen wall between the stitches in the shape of circle. This process can be mastered by two people without particular equipment in approx. 30. minutes. When installing the PVC fistulas we prefer their fixation in rumen with help of seromuscular circular stitches followed by leading out the fistula off the main cut.     

尿素及其缓释产品在反刍动物上的应用

本文综述了尿素和尿素缓释产品的营养特性及其在反刍动物上的应用。     

Development of a method for determination of cyanide concentrations in serum and rumen fluid of cattle

OBJECTIVES: To develop a reliable method for measurement of cyanide concentrations in cattle, using gas chromatography-mass spectrometry (GC-MS), and establish reference ranges of cyanide concentrations in cattle. ANIMALS: 52 Fleckvieh cattle. PROCEDURE: Cattle were allocated to 3 groups; 12 were fed leguminous grass and hay, 36 were fed whole-maize and corn-cob silages, and 4 were fed other feedstuffs. Samples of blood, rumen fluid, and liver were collected at time of slaughter. Serum, rumen fluid, and liver homogenate were assayed for cyanide content, using a derivatization procedure. A technique for analysis by GC-MS that used selected ion monitoring was developed. RESULTS: Compared with a spectrophotometric method, detection of cyanide in serum and rumen fluid by use of GC-MS was selective and sensitive, with a limit of detection of 0.7 microM. Spectrophotometric analysis yielded false-negative and false-positive results. Thus, the GC-MS method was used for subsequent analysis. In all cattle except 1, cyanide concentration ranged from < 0.7 to 35 microM in serum and from < 0.7 to 28 microM in rumen fluid; cyanide concentration in that 1 animal was 206 microM. Cattle fed clover, grass, grass hay, and clover hay had 8.3- to 8.6-fold higher mean cyanide concentrations in rumen fluid and serum than cattle fed whole-maize and corn-cob silages. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study suggest a reference range that should be useful for aiding in the diagnosis of cyanide poisoning. Also, cattle can apparently accommodate a serum cyanide concentration of 206 microM without adverse effects.     

牛瘤胃臌气的诊治

瘤胃臌气,中兽医叫“气胀”,俗称“肚子胀”,临床上较为常见．笔者在多年的临床实践中,用简单易行的自拟消胀汤治疗牛瘤胃臌气病20多例,疗效佳,花钱少,均获得满意效果。现报道如下,供同行参考。     

一例牛瘤胃酸中毒的诊治

瘤胃酸中毒多发生于牛,特别是奶牛.主要是精饲料喂量过多,精粗饲料比例不当所造成.以1～3胎的奶牛发病最多,7胎后的发病较少.一年四季均可发生,但以冬春季较多.临产牛和产后3 d内的发病较多.产奶量愈多,发病率愈高.笔者于2005年夏季带学生在临夏市某兽医站实习时遇到一病例,现将诊治情况总结如下.     

精料与稀释率对瘤胃发酵与微生物蛋白的影响

采用单外流连续培养系统研究低和高2种精料水平（20％，80％）与不同稀释率（稀释率为（D）），0．06、0．12和0．18h）对瘤胃发酵和微生物生长效率的影响。每种精料水平设3个稀释率（0．06、0．12和0．18h），每个处理设2个重复。试验结果表明，随着D的增加，日粮营养物质的消化率呈二次曲线趋势（P=0．001—0．006）增加；提高精料水平导致日粮干物质（DM）和有机物质（OM）消化率增加（P=0．001），而中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）消化率下降（P=0．001）。提高D导致发酵液pH显著升高（P=0．001），NH3浓度显著降低（P=0．001）。总挥发性脂肪酸（VFA）浓度随D的增加显著下降（P=0．001），但VFA日产生量随D的增加没有显著变化（P〉0．05）。在各种VFA摩尔比例中，乙酸和丁酸的摩尔比例呈二次曲线趋势增加（P=0．001），丙酸的摩尔比例呈二次曲线趋势下降（P：0．001）。随着日粮精料水平的提高，发酵液pH和NH，浓度下降，总VFA浓度及VFA日产生量增加。在各种VFA摩尔比例中，乙酸摩尔比例随精料水平的提高而（P=0．001）下降，但丙酸与丁酸的摩尔比例下降（P=0．001）。随着日粮精料水平的提高，每日微生物氮（N）产量（DMNP）与微生物生长效率（MOEFF）增加；DMNP与MOEFF在D提高时也增加（P=0．001），在D为0．18h时达到最大值（每日微生物氮为1．088g和每千克真可消化有机物产生微生物氮为31．01g）。     

牛尿素中毒的治疗体会

尿素中毒在兽医临床上较多见。笔者曾治疗6例病牛,皆因误食多量尿素后发病,经及时抢救均痊愈,现将解毒方法总结如下。     

体外法研究硫、磷、钴及尿素对瘤胃发酵的影响

本试验采用体外法研究硫、磷、钴、尿素4种物质对人工模拟瘤胃发酵的影响及其动态变化规律.试验采用L9(34)正交设计,设4个因素3个水平.结果表明:当硫、磷、钴、尿素的含量分别为0.4%、0.0%、1.0 ms/ks、1.0%时,对瘤胃液pH值、氨氮(NH3-N)浓度、瘤胃液蛋白质(MCP)、总挥发性脂肪酸(TVFA)有显著影响,有利于瘤胃微生物活动,增加氮沉积.