Caecal fermentation characteristics of commonly used feed ingredients

BACKGROUND

Commercial horse feeds use cereal grains and by-products; however, their effects on the caecal environment remain poorly characterised.

OBJECTIVE

Characterise the effect of commonly used feed ingredients on caecal pH and volatile fatty acid (VFA) concentration.

STUDY DESIGN

6 × 6 Latin square.

METHODS

Two days prior to the start of the study, 6 caecally cannulated Quarter horses were moved into individual stalls where Smooth bromegrass hay (brome) was offered at 2.0% BW/d split between 2 feedings (0600 and 1800). On day 0, caecal digesta was collected every 2 h for 12 h relative to the 0600 feeding to establish control values for horses consuming only brome (HAY). On day 1, horses began consuming their respective treatments which consisted of beet pulp (BP), maize (M), dehydrated alfalfa (A), oats (OAT), soybean hulls (SBH), or wheat middlings (WM) at 0.25% BW/d split into 2 feedings. On day 7 of each treatment period, caecal digesta was collected every 2 h for 12 h and analysed for pH and VFA. Data were analysed using mixed ANOVA with repeated measures, fixed effects of treatment and time and random effects of horse and period.

RESULTS

There was a main effect of hour (P ≤ .05) indicative of post-prandial shifts in caecal metabolites. There were no main effects of treatment on pH or VFA concentration (P ≥ .3). Effects of hour × treatment (P ≤ .04) were observed for all response variables. Regardless of treatment or hour, caecal pH remained well within normal limits. Three horses exhibited signs of lower oesophageal choke immediately after consumption of BP pellets.

LIMITATIONS

Interactions between ingredients when mixed for formulation of a concentrate warrant further research. Furthermore, a short adaptation period was chosen to mimic common management practices.

CONCLUSION

Minimal differences in caecal fermentation parameters were detected when ingredients were fed at a common inclusion level.

Effects of corn distillers dried grains with solubles in finishing diets on pig growth performance and carcass yield with two different marketing strategies

Feeding diets high in corn distillers dried grains with solubles (DDGS) before market can negatively impact carcass yield, hot carcass weight (HCW), and belly fat iodine value (IV). Two experiments were conducted to evaluate the effects of switching from DDGS-based to corn-soybean meal (CSBM)-based diets at increasing intervals (withdrawal periods) before harvest on finishing pig performance and carcass characteristics. Diets in both experiments contained either 0% or 30% DDGS and were balanced for net energy (NE). In Exp. 1, 985 pigs (initially 99.6 kg body weight [BW]) were used with 12 pens per treatment. The four treatments were increasing DDGS withdrawal periods: 28, 21, 14, or 0 d (no dietary switch) before marketing. All pens were marketed by removing the 17% heaviest pigs 21 d before slaughter and the remaining 83% all slaughtered 21 d later. Overall, there was no evidence for treatment differences on final BW, average daily feed intake, or feed efficiency (G:F;P > 0.10); however, average daily gain (ADG) increased (linear, P = 0.022) and belly fat IV decreased (linear, P = 0.001) the longer pigs were fed CSBM diets. There was no evidence for differences for HCW (P > 0.10); however, carcass yield increased (linear, P = 0.001) with increasing time following the switch to CSBM. Backfat depth decreased and percentage lean increased as CSBM feeding time increased (quadratic; P < 0.05). In Exp. 2, 1,158 pigs (initially 105 kg BW) were used in a 35-d study. There were 15 pens per treatment and four treatments of increasing DDGS withdrawal periods: 35, 28, 14, or 0 d (no dietary switch). All pens were marketed by removing the 15% heaviest pigs on day 28, the 28% heaviest pigs on day 14, and a final marketing of approximately 57% of starting barn inventory. There was no evidence that final BW, ADG, G:F, or HCW differed among dietary treatments (P > 0.10). Average daily feed intake and carcass yield increased and belly fat IV decreased (P < 0.050); the longer pigs were fed CSBM. In conclusion, growth performance was minimally impacted following dietary switch from DDGS- to CSBM-based diets, possibly due to similar dietary NE. For carcass yield and belly fat IV, the optimal time to make a dietary switch from high to low fiber appears to be linear in nature and at least 28 d before marketing.

The Use of Bioelectrical Impedance to Assess Shelf-Life of Beef Longissimus Dorsi

ObjectivesTo evaluate quality attributes of beef longissimus dorsi (LD) during 15 d of simulated retail display using surface and internal bioelectrical impedance analysis (BIA) measurement techniques.Materials and MethodsThe experiment was designed as a split-plot with loin as the whole-plot and pairekd steaks as the sub-plot. Display day (DD) was treated as the sub-plot treatment. Postmortem age time (PM) and DD were treated as fixed effects. Beef strip loins (N = 18; IMPS #180), obtained from 3 commercial processors (PM = 27, 34, or 37 d), were fabricated into 12 2.54-cm thick steaks (N = 216). Steaks were subdivided into 6 consecutively cut pairs and pairs were randomly assigned to one of 6 display days: 0, 3, 6, 9, 12, and 15. For all pairs, one steak was allocated to microbiological analysis and pH and the paired steak for BIA, objective color assessment, proximate composition, and TBARS. Surface BIA (S-BIA) and internal BIA (I-BIA) assessment were compared. Steaks were packaged on styrofoam trays with a moisture absorbent pad, overwrapped with polyvinyl chloride film, and displayed under fluorescent lighting at 0–4°C in coffin-style retail cases.ResultsThere was a PM × DD interaction (P < 0.05) for S-BIA values. From d 0 to 12 of display, steaks aged 27 d had higher (P < 0.05) S-BIA values than steaks aged 34 and 37 d; however, on d 15 of display, steaks aged 34 d had 22% higher (P < 0.05) S-BIA values than steaks aged 37 d, but had similar (P > 0.05) values compared to steaks aged 27 d. There was no PM × DD interaction (P < 0.05) for I-BIA values; however, an effect on PM and DD was found (P < 0.05). Steaks aged 27 d were 17% higher for I-BIA values (P < 0.05) than 37 d, but similar (P > 0.05) to steaks aged 34 d. For all PM aging times, d 0 had the lowest (P < 0.05) I-BIA values among all display days with 81.44. D 3 was the second lowest (P < 0.05) and 8% higher than d 0 for I-BIA values. D 6 was 16% higher (P < 0.05) than d 3 but similar (P > 0.05) to d 9 and d 12. D 12 and D 15 were similar (P > 0.05). There was a DD × BIA method interaction (P < 0.05). On d 0, 3, and 6, BIA values were different (P < 0.05); however, after d 6 onward, BIA values were similar (P > 0.05). Covariance component was smaller in I-BIA than S-BIA. There were no PM × DD interactions (P > 0.05) for a* and b* values; however, there was an interaction for L* values. Postmortem aging had no effect (P > 0.05) on L*; however, an effect on a* and b* was found (P < 0.05). For APC populations, there was a PM × DD interaction (P < 0.05). No PM × DD interaction or PM effect (P > 0.05) were found for TBARS; however, there was a DD effect (P < 0.05). There was no PM day × DD interaction (P > 0.05) or PM day (P > 0.05) for moisture content. Display day (P < 0.05) had an effect on moisture content. Moderate negative correlations occurred between S-BIA values and a*, b*, and moisture content with –0.48, –0.46, and –0.46, respectively; and –0.51, –0.48, and –0.43, respectively, for I-BIA. Conversely, moderate positive correlation was found between S-BIA values and APC and TBARS with 0.34 and 0.53, respectively; and 0.29 and 0.51, respectively, for I-BIA.ConclusionI-BIA has potential for use to assess shelf-life of retail steaks and it was more precise than S-BIA; however, I-BIA may translocate bacteria into the muscle. Protein degradation and WHC should be evaluated to better understand BIA changes over time.

An epidemiological investigation to determine the prevalence and clinical manifestations of slow-moving finished cattle presented to slaughter facilities

Cattle mobility is routinely measured at commercial slaughter facilities. However, the clinical signs and underlying causes of impaired mobility of cattle presented to slaughter facilities are poorly defined. As such, the objectives of this study were 1) to determine the prevalence of impaired mobility in finished cattle using a 4-point mobility scoring system and 2) to observe clinical signs in order to provide clinical diagnoses for this subset of affected cattle. Finished beef cattle (n = 65,600) were observed by a veterinarian during the morning shift from six commercial abattoirs dispersed across the United States; the veterinarian assigned mobility scores (MS) to all animals using a 1–4 scale from the North American Meat Institute’s Mobility Scoring System, with 1 = normal mobility and 4 = extremely limited mobility. Prevalence of MS 1, 2, 3, and 4 was 97.02%, 2.69%, 0.27%, and 0.01%, respectively. Animals with an abnormal MS (MS > 1) were then assigned to one of five clinical observation categories: 1) lameness, 2) poor conformation, 3) laminitis, 4) Fatigued Cattle Syndrome (FCS), and 5) general stiffness. Of all cattle observed, 0.23% were categorized as lame, 0.20% as having poor conformation, 0.72% as displaying signs of laminitis, 0.14% as FCS, and 1.68% as showing general stiffness. The prevalence of lameness and general stiffness was greater in steers than heifers, whereas the prevalence of laminitis was the opposite (P < 0.05). FCS prevalence was higher in dairy cattle than in beef cattle (0.31% vs. 0.22%, respectively; P ≤ 0.05). These data indicate the prevalence of cattle displaying abnormal mobility at slaughter is low and causes of abnormal mobility are multifactorial.

Sequential Femorodistal Composite Bypass with Second Generation Glutaraldehyde Stabilized Human Umbilical Vein (HUV)

OBJECTIVE

To evaluate the performance of sequential composite bypasses with second generation glutaraldehyde stabilized human umbilical vein (HUV) and autologous vein.

DESIGN

Retrospective study of consecutive patients, in a single centre.

PATIENTS

From January 1998 to December 2003, 54 femoro-distal HUV-autologous vein sequential composite bypasses were constructed in 52 patients with critical leg ischemia and absence of sufficient length of autologous vein.

METHODS

All infra-inguinal bypass operations were registered in a computerized database and prospectively followed. Bypasses using sequential HUV-composite technique were reviewed for graft patency, limb salvage and patient survival.

RESULTS

Primary patency and secondary patency rates at 1, 2, 3 and 4 years were 71, 61, 53 and 53% and 89, 80, 73 and 67%, respectively. Corresponding limb salvage rates were 96, 92, 88 and 88%. Patient survival was 56% at 4 years. After 30 days additional procedures to maintain graft patency were necessary in six bypasses. Asymptomatic occlusion of one sequential anastomosis was found in five patients.

CONCLUSION

Graft patency and limb salvage rate support the use of the sequential composite technique with second generation HUV in femorodistal bypass surgery, when autologous vein of sufficient length is not available.

["Computer- and Sensor-Assisted Surgery" Special Research Area 414--goals and concepts]

This paper presents an overview of our research in computer assisted surgery within the "Sonderforschungsbereich 414--Information Technology in Medicine: Computer and Sensor Supported Surgery". The overall goal is to achieve improved operation methods including higher quality, more safety and also more economy due to shorter operation time and less postoperative treatment. The SFB 414 is divided into three different sections focusing on projects concerning the heart, projects supporting cranio-facial interventions and interconnecting projects that serve both categories.

[Aortic dissection--when operative treatment, when endoluminal therapy?]

GOAL

To demonstrate the Heidelberg results of the previous 2 years in patients referred for acute aortic dissection.

MATERIAL AND METHODS

93 patients referred for acute aortic dissection were treated by cardiac surgery, vascular surgery and interventional radiology according to a novel therapeutic algorithm including stent-grafts and combined open and interventional procedures and conservative medical therapy when no malperfusion syndrome was present or patients were considered prohibitive for even minor surgical procedures. Stent-graft placements were done assisted by short term cardiac arrest to facilitate correct device deployment.

RESULTS

36 patients presented with type A and the other 57 with type B dissection. 32 of the A patients were operated and 20 of the B patients, respectively. 12 patients with B dissection were treated with stent-grafts. 3 required additional interventional therapy for organ malperfusion. The mortality was 0% in these 12 patients The overall mortality rate in the A group was close to 40% mainly as a result of postoperative organ malperfusion while it was 15% in the B group. In both groups mortality was highest in the respective untreated patient subgroup (3/4 and 8/37, respectively). The main mortality factor was visceral (mesenteric or liver) ischemia. Paraplegic complications occured in neither group. In 4 patients a combined approach applying cardiac surgery of the ascending aorta and endluminal stent-graft placement for the residual B dissection was successfully performed. In one patient this was done simultaneously.

DISCUSSION

Acute aortic dissection of type A with or without valve involvement, coronary artery ischemia can be treated with high technical success rates. However, remaining distal aortic dissection associated with true lumen collapse and organ malperfusion is the main causative factor for clinical failures. Successful combination of open proximal aortic surgery with endoluminal treatment of residual B dissection encourages further use of this novel approach. Acute B type dissection appears to be effectively and safely treated by endoluminal approach in selected cases. Unsolved questions of this less invasive therapeutic approach focus mainly on the design of the proximal anchoring part of the devices.

Endothelial dysfunction of coronary resistance arteries is improved by tetrahydrobiopterin in atherosclerosis

BACKGROUND

Tetrahydrobiopterin (BH4), an essential cofactor for the synthesis of NO, improves endothelial dysfunction after ischemia/reperfusion. Therefore, we hypothesized that reduction of BH4 is involved in the attenuation of endothelium-dependent vasodilation in atherosclerosis, and we investigated the effect of alterations of the BH4 level on the vasodilatory potential of coronary resistance vessels from humans and pigs with atherosclerosis.

METHODS AND RESULTS

Coronary arterioles were obtained from patients undergoing CABG (atherosclerosis group) or valve replacement (control group) and from pigs fed either a standard diet (control group) or atherogenic diet (atherosclerosis group). After isolation, vessels were cannulated, pressurized, and placed on the stage of an inverted microscope. Dose-response curves were investigated in response to the endothelium-dependent agonists histamine, serotonin, and acetylcholine (for pigs, substance P) and to the endothelium-independent agonist sodium nitroprusside (SNP) under control conditions and before and after incubation of the vessels with sepiapterin (substrate for BH4 synthesis). In vessels from patients and from animals with atherosclerosis, compared with vessels from the control groups, there was a significant (P:<0.05) reduction of vasodilation to all tested endothelium-dependent agonists but not to SNP. After application of sepiapterin, the responses to the endothelium-dependent agonists but not to SNP were significantly improved in vessels from the atherosclerosis groups. Sepiapterin did not influence vascular reactivity in the control groups.

CONCLUSIONS

Atherosclerosis severely compromises endothelial function of coronary resistance arteries. Administration of sepiapterin leads to a significant improvement of endothelium-dependent vasodilatation to different agonists in vessels from humans and pigs with atherosclerosis. Therefore, we conclude that a reduced availability of BH4 is involved in the development of endothelial dysfunction in atherosclerosis.

Aortic input impedance and ventriculoarterial coupling following cardioversion/defibrillation

Defibrillation shocks are commonly used after cardiac surgery or during defibrillator implantation. The hemodynamic consequences of countershocks on circulatory dynamics are not completely understood, and there is a lack of information concerning the effects on ventriculoarterial interaction. The study presented here was performed to assess the influence of defibrillation shocks on arterial hemodynamics and ventriculoarterial coupling. Eight mongrel dogs (weight 15-18 kg) were anesthetized and median thoracotomy was performed. Pressure in the ascending aorta and the left ventricle and flow in the ascending aorta were continuously monitored. After induction of atrial or ventricular fibrillation, termination was achieved by epicardial low energy shocks (atrium, 3J; ventricle, 51). In an additional attempt ventricular fibrillation was terminated by a high energy shock (34J). Aortic input impedance was calculated by fast-Fourier-transformation of aortic flow and pressure signals, while ventriculoarterial coupling was expressed by the ratio of aortic and ventricular end systolic elastance (Ea/Ees). Defibrillation by low energy shocks of atrial or ventricular fibrillation did not result in changes of the aortic impedance spectrum, and ventriculoarterial coupling remained unaltered compared to control conditions. High energy defibrillation, however, resulted in a marked rise in total peripheral resistance (P < 0.03). The ratio of Ea/Ees increased significantly (P < 0.005). These effects were reversible within 15 minutes. Low energy defibrillation does not alter arterial hemodynamics and ventriculoarterial coupling in this experimental setup. High energy defibrillation, however, results in a temporary increase of ventricular load. This finding may be of particular interest in patients with poor left ventricular function.

Modified surgical concept for fulminant pulmonary embolism

Surgical intervention in fulminant pulmonary embolism (PE) is still associated with an overall 30% fatal outcome which increases to about 60% when cardiopulmonary resuscitation (CPR) is necessary. Despite unfavorable conditions like hemodynamic instability, failed lysis or CPR, the surgical strategy might have a certain impact on the patient's outcome since 30-40% of the surgical mortality is related to persistent right heart failure and early thromboembolic recurrence. From 1/88 to 8/94 a total of 25 patients (15 females, 10 men, mean age 57 [25-78]) years underwent emergency pulmonary embolectomy with the use of the heart-lung machine. Seventeen patients were operated upon between 1988 and 1992. A standard approach by central pulmonary artery incision with extraction of adjacent pulmonary emboli using forceps, suction of Fogarty catheters was used. Six of these patients (35%) died, with four out of six operated upon under CPR. Since 1993 we have used a modified surgical strategy in eight patients. Five patients (63%) were operated on after or under CPR. In these cases, left and right pulmonary arteries were incised peripherally and all segmental arteries were desobliterated selectively using small suction devices. Thereafter the right atrium was opened and inspected. After removal of the inferior caval vein cannula all inferior body blood was taken with cardiotomy suction while both legs and the abdomen were massaged centripetally to mobilize additional fresh thrombotic material. In three cases up to 50 cm long thrombi could be delivered. All patients have survived to date with two patients receiving a LGM caval filter placed percutaneously after bilateral postoperative phlebography had revealed ongoing thrombotic disease. We conclude that selective desobliteration of every segmental pulmonary artery in combination with simultaneous clearance of major body veins from additional thrombotic material will probably lower surgical mortality in these critically ill patients.

Performance of dynamic cardiomyoplasty related to the functional state of the heart

Cardiomyoplasty (CMP) was performed with the left Latissimus dorsi in five beagles (group 1) with intact hearts and seven foxhounds (group 2) in whom the left ventricle was enlarged by 31 +/- 11.9% of cross-sectional area. Ventricular function curves were constructed at filling pressures ranging from 15-40 mmHg (group 2). Myocardial contraction patterns were investigated by epicardial 2-D echocardiography. Skeletal muscle contraction caused a significant increase in aortic pressure, dP/dt, stroke volume, work and performance in all animals. Function curves were shifted upward in a parallel manner. Echocardiography showed an increase of the LV cross-sectional delta area of 14.8% +/- 5.8% (group 1) and of 39.5% +/- 15.1%, and approximation of the edges of the wall defects (group 2). In conclusion, dynamic CMP as applied in this acute model, increased the performance of normal canine hearts and hence, a model of cardiac failure may not be a prerequisite for the investigation of certain technical aspects of CMP. In the failing heart, a parallel upward shift of myocardial function curves suggested increased performance of the heart/skeletal muscle complex over a wide range of filling pressures. However, the descending limb of the function curve with increasing filling pressures was observed despite skeletal muscle contraction. Hence, similar to other assist systems, the residual function of the heart may be of considerable importance in the overall performance of dynamic CMP.

Inorganic phosphate inhibits contractility and ATPase activity in skinned fibers from human myocardium

During hypoxic heart failure, inorganic phosphate (Pi) accumulates. We report the effects of Pi on force development and on myofibrillar ATPase-activity of human skinned atrial fibers, both at normal and at reduced levels of Mg-ATP. Pi (10 mM) depressed force production at maximal calcium activation (pCa 4.3) by about 40%. At higher pCa values (pCa 5.6), force inhibition was even more pronounced, but at low concentrations of Mg-ATP (10 microM), Pi was less effective. In contrast to contractile force, myofibrillar ATPase was only inhibited by about 10% at pCa 4.3, whereas it could be inhibited by 40-50% at submaximal calcium activation (pCa 5.6). As Pi inhibited contractile force more than ATPase activity, the ratio of ATPase-activity to force (tension cost) was increased by inorganic phosphate. ATPase-activity and tension cost were significantly reduced by lowering Mg-ATP concentration to 10 microM, whereas contractile force was less affected. Pi did not affect ATPase under these conditions at 10 mM Mg-ATP. Pi also shifted the calcium-force relationship towards higher Ca++ concentrations, that is, it decreased calcium sensitivity. In contrast, the calcium sensitivity of myofibrillar ATPase was less affected. These findings suggest that inorganic phosphate may affect the myocardium by altering crossbridge kinetics rather than the calcium affinity of troponin-C. Because of its inhibitory effect on myofibrillar ATPase, inorganic phosphate may be partly cardioprotective in the hypoxic myocardium. However, this "energy sparing' effect is probably offset by the greater "tension cost' that decreases the "efficiency' of tension maintenance in the presence of inorganic phosphate.