Depression of reticulo-ruminal motor functions through the stimulation of 012-adrenoceptors

Inhibition of the cyclical contractions of the reticulum and the rumen by detomidine (10-40 micrograms/kg, i.v.), xylazine (20-80 micrograms/kg, i.v.) and clonidine (2.5-10 micrograms/kg, i.v.) were compared in sheep and cattle housed individually in box stalls. Two alpha 2-adrenergic receptor blocking agents, tolazoline and yohimbine, were administered intravenously for prevention (0.1-0.4 mg/kg) or reversal (0.4-1.2 mg/kg) of these effects. Continuous recording of the reticuloruminal contractions and measurement of the volume of ruminal gas eliminated through the upper respiratory tract indicated that the three alpha 2-agonists inhibited the primary ruminal contractions associated with the reticular contractions. The occurrence of secondary ruminal contractions was also blocked in sheep, but only suppressed in cattle. The inhibition of reticulo-ruminal contractions was prevented or reversed competitively by the two alpha 2-blocking agents, suggesting an alpha 2-adrenoceptor mediation of the inhibition of cyclical motor activity of the reticulo-rumen. In contrast with tolazoline, yohimbine was unable to alleviate the accumulation of gas resulting from inhibition of the secondary ruminal contractions.     

The course of selected bone resorption marker concentrations in response to short-term hypocalcemia experimentally induced with disodium EDTA infusions in dairy cows

The collagen metabolites hydroxyproline (HYP), deoxypyridinoline (DPD), and the carboxyterminal telopeptide of type I collagen (ICTP) are suitable markers for bone resorption in humans and several animal species. The purpose of this study was to describe the course of bone resorption markers during short-term hypocalcemia induced with disodium ethylenediaminetetraacetic acid (Na2EDTA) and to investigate whether bone resorption is increased in dairy cows under these conditions. EDTA infusions have been used as a model for periparturient paresis in dairy cows and to estimate the calcium mobilization rate from body reserves in ruminants. In this study, hypocalcemia was induced by means of a 5% Na2EDTA infusion (0.55 mg/kg/min Na2EDTA for 5 h = total dose of 100.6 g). Two experiments were conducted: (1) Six 4-11 years-old Brown Swiss cows were infused intravenously with EDTA for 5 h. Blood and urine samples were taken repeatedly from 1 day before until 10 days after infusion. (2) Towards the end of the lactation, the experiment was repeated with the same animals after a 14-day-period of feeding a low calcium diet (26 g/animal per day). The EDTA-infusion induced hypocalcemia and hypophosphatemia. The HYP-, DPD- and ICTP-concentration remained mainly unaffected during both infusions. Only DPD showed an increase during infusion and HYP an increase 2 days after the infusion. In conclusion, the EDTA infusion had little effect on the concentrations of the measured bone markers, which may be due to the fact that the serum calcium pool was refilled by increased absorption of Ca via the gastrointestinal tract. From these results, it can be concluded that bone resorption was not influenced by EDTA infusion.     

Hemodynamic and metabolic alterations associated with intravenous infusion of a combination of adenosine triphosphate and magnesium chloride in conscious horses.

OBJECTIVE: To determine hemodynamic and metabolic effects of IV infusion of ATP-MgCl2 combination and maximal safe IV infusion rate in conscious horses. ANIMALS: 6 adult female horses. PROCEDURE: All horses received an IV infusion of ATP-MgCl2 combination, beginning at a rate of 0.05 mg of ATP/kg of body weight/min, which was increased by 0.05 mg/kg/min increments at 10-minute intervals until a rate of 1.0 mg/kg/min was achieved. Data were collected prior to the start of the infusion, at the end of each infusion rate, and at 15-minute intervals for the next hour after discontinuation of the infusion. Measured or calculated hemodynamic variables included cardiac output, cardiac index, heart rate, stroke volume, systemic and pulmonary arterial pressures, and systemic and pulmonary vascular resistances. Arterial blood gas tensions, CBC, plasma biochemical profiles, urine volume and specific gravity, and selected clinical signs of disease also were evaluated. RESULTS: Intravenous infusion of ATP-MgCl2 significantly increased cardiac output, decreased systemic vascular resistance, and caused mild pulmonary hypertension. Magnitude of the hemodynamic alterations was dependent on rate of infusion. Maximal safe infusion rate for these horses was 0.3 mg/kg/min. All horses became lethargic, and their appetites diminished during the infusion; 5 horses had mild signs of abdominal discomfort. Flank sweating was observed in all horses as infusion rate increased. Urine volume and specific gravity and hematologic, biochemical, and arterial blood gas alterations were detected during and after infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous administration of ATP-MgCl2 in healthy, conscious, adult horses caused various metabolic and hemodynamic alterations that were without appreciable detrimental effects.     

Blockade of satiety factors by central injection of neuropeptide Y in sheep

The ability of neuropeptide Y (NPY) to stimulate feed intake was tested in combination with two treatments known to depress feed intake in sheep. Six ewe and three wether lambs (mean BW = 40 kg) fitted with lateral cerebral ventricular guide cannulas and ruminal cannulas had free access to a nutritionally complete, pelleted diet. Balloons placed into the rumen were filled with either 0, 30 or 60 ml of water/kg BW and left in place for 6 h; intake was measured. Based on the decline in feed intake observed with increasing balloon volume in the rumen, Exp. 2 was designed to test effects of NPY injection (0 or 3.0 nmol) into the lateral cerebral ventricle and ruminal distension (0 or 35 ml/kg BW) for 6 h. During the 6-h test period, feed intake was depressed (P less than .05) by intraruminal balloon distension, but feed intake was increased by NPY injection (P less than .05); no interaction between NPY and distension was detected. Ruminal evacuation revealed that digesta occupied only 43% of the rumen's total volume capacity. Balloons occupied 14% of capacity, whereas meal size in control sheep following a 1.5-h fast equaled 7% of capacity. In Exp. 3, intraruminal infusion of 8 mmol/min of propionate depressed (P = .11) feed intake, whereas NPY injection enhanced (P less than .05) intake. There was no interaction between NPY and propionate infusion. In none of these experiments was cumulative feed consumption at 24 h influenced. We conclude that NPY is a versatile feeding stimulant. It promotes feed intake in feed-satiated, ruminally distended and propionate-infused sheep.     

Site of 3-methylindole and indole absorption in steers after ruminal administration of L-tryptophan

To determine the site of 3-methylindole (3MI) and indole absorption in cattle after ruminal administration of L-tryptophan (TRP), 4 Holstein steers were given 0.4 g of TRP/kg of body weight directly into the rumen through ruminal cannulas. Chromium EDTA and ruthenium phenanthroline were added to feedings of orchard grass hay twice a day for measurement of fluid and particulate flow to the duodenum, respectively. Passage of 3MI and indole (products of ruminal fermentation of TRP) to the duodenum was determined by the products of digesta flow rate and concentration in duodenal contents. Ruminal fluid, duodenal contents, and jugular blood were sampled at postdosing hours (PDH) 0, 6, 12, 18, 24, 36, and 72 for analysis of 3MI, indole, and digesta flow markers. Ruminal, duodenal, and jugular plasma concentrations of 3MI and indole peaked at PDH 12 to 24 at 152.4 and 25.9; 15.5 and 1.0; and 8.7 and 2.2 mg/L, respectively. Most 3MI and indole reaching the duodenum were associated with the particulate phase of the digesta. On a molar basis, total passage of 3MI to the duodenum during 72 hours amounted to 1.0% of the TRP dose for 3MI and 0.1% of the TRP dose for indole. Absorption of 3MI and indole in these steers was almost entirely proximal to the duodenum.     

The effect of applying sodium fertilizer on the rate of digestion of perennial ryegrass and white clover incubated in rumen liquor, with implications for ruminal tympany in cattle

A high herbage K:Na ratio increases the risk of ruminal tympany in cattle, which may relate to digestion rate. Experiment 1 examined whether in vitro digestibility of ryegrass was affected by NaCl fertilizer or by Na concentration in artificial saliva. Fertilizer Na increased grass digestibility, but Na in artificial saliva decreased it, probably due to the energy cost of sodium exclusion from bacteria. Increased herbage digestibility with fertilizer Na is therefore not due to additional Na, but may relate to increased water-soluble carbohydrates.Experiment 2 examined whether NaCl fertilizer applied at 35 or 70 kg Na ha(-1)to ryegrass and white clover affected in vitro gas production. Sodium fertilizer increased maximum gas output from grass and rate of production, confirming the increase in grass digestibility recorded previously, but in clover it had the opposite effect, thereby potentially reducing ruminal tympany in cows fed a high legume diet.     

Effects of nitric oxide donor and nitric oxide synthase inhibitor on ruminal contractions in conscious sheep

The present study was planned to evaluate a role of nitric oxide (NO) in the regulation of regular ruminal contractions in conscious sheep. Intravenous infusion of S-nitroso-acetyl-DL-penicillamine (SNAP) at doses of 3-30 nmol kg(-1) min(-1)for 30 minutes inhibited both the amplitude and frequency of ruminal contractions in a dose-dependent manner. However, intravenous infusion of Nomega-nitro-L-arginine-methyl ester (L-NAME) at doses of 0.3-3.0 micromol kg(-1) min(-1)did not alter the basal tone of intraruminal pressure and the amplitude of ruminal contractions. The frequency of contractions was slightly inhibited by L-NAME infusion at 1.0 micromol kg(-1)min(-1). The effects of L-NAME were abolished by simultaneous infusion of L -arginine at 30 micromol kg(-1) min(-1). These results suggest that exogenous NO can diminish the ruminal contractions, while endogenous NO is not involved in the regulatory mechanism of basal tone and regular phasic contractions of the rumen in healthy sheep.     

Motility of the rumen and abomasum during hypocalcaemia.

The relationship between plasma calcium level and rumen motility in cows and sheep and abomasal motility in cows was investigated by inducing hypocalcaemia in seven cows and five sheep by the infusion of Na2 EDTA over a period of approximately two hours. Rates and amplitudes of rumen and abomasal contractions were markedly reduced by the reduction of plasma calcium level to approximately 50% of normal. There were significant positive linear relationships (P less than 0.05) between rate and amplitude of rumen contractions in both sheep and cows over a plasma calcium range of 1-3 mmol/L. There was also a significant linear relationship (P less than 0.05) between plasma calcium and abomasal rate of contraction over the same range in cows, but the relationship with amplitude of abomasal contraction was not quite significant (P less than 0.1 greater than 0.05).     

Electromyographic changes of motor unit activity in horses with induced hypocalcemia and hypomagnesemia

OBJECTIVE: To determine whether electromyographic abnormalities are evident in skeletal muscles in horses with induced hypocalcemia and hypomagnesemia. ANIMALS: 7 healthy adult Dutch Warmblood horses. PROCEDURES: Electromyographic examination was performed in the lateral vastus, triceps, and subclavian muscles before and after IV infusion of EDTA. An initial dose (mean +/- SD, 564+/-48 ml) of a 10% solution of sodium EDTA was administered IV during a period of 21+/-73 minutes to establish a blood concentration of ionized calcium of approximately 0.5 mmol/L. Average rate of EDTA infusion to maintain ionized calcium at this concentration was 6.6 ml/min. RESULTS: Mean blood concentrations of ionized calcium and magnesium were 1.39+/-0.06 and 0.84+/-0.09 mM, respectively before EDTA infusion; after EDTA infusion, concentrations were 0.48+/-0.05 and 0.44+/-0.20 mM, respectively. This state induced positive waves; fibrillation potentials; doublets, triplets, and multiplets; complex repetitive discharges; and neuromyotonia. Analysis of motor unit action potentials (MUAP) after EDTA infusion revealed an increase in prevalence of polyphasic and complex MUAP in all muscles. CONCLUSIONS AND CLINICAL RELEVANCE: None of the horses had classical signs of hypocalcemia and hypomagnesemia. In contrast, all horses had spontaneous activity in the measured muscles indicative of nerve hyperirritability. Calcium and magnesium deficits appear to have consequences, which may be subclinical, affecting functions of the neuromuscular system. This is of interest for equestrian sports in which hypocalcemia and hypomagnesemia are expected, such as during endurance rides.     

Study on the Effects of Increasing Production Rate of Ruminal Acetate and Butyrate on Their Absorption and Passage in Alimentary Tract of Sheep

Six Inner Mongolian semifine-wool wethers（1.5 years old,29-31 kg BW） fitted with a ruminal and a duodenum cannula were used to study the effects of increasing production rate of ruminal acetate and butyrate on their absorption and passage in alimentary tract by simulating continuous feeding and pulse-continuous infusion technology.The sheep were     

人工唾液对绵羊瘤胃液相平衡、瘤胃发酵和微生物氮合成的影响

进行两个试验,研究灌注人工唾液对绵(?)平衡,瘤胃发酵和微生物蛋白质合成的影响。用尿液嘌呤衍生物总量作为供给宿主动物微生物氮的指标。试验1内,4只绵羊每天饲喂1kg以侧短干草为基础的配合日粮,采用4×4拉丁方(?),别向瘤胃中灌注0,1.5,3和4L/d单倍浓度的人工唾液(AS)。试验2内,3(?)每天饲喂与试验1成分相同的颗粒日粮1kg,采用3×4不完全拉丁方设计,分别(?)瘤胃中灌注0,4和8L/d单倍浓度和4L/d双倍浓度的人工唾液(DAS)。试验1发现,灌注人工唾液对瘤胃液体积、瘤胃液稀释率、发酵类型及微生物氮合成没有影响试验又发现,灌注8L/d AS和4L/d DAS显著提高瘤胃液稀释率和微生物氮的今成(P<0.05):但对瘤胃液体积没有显著影响(P<0.05)。4个处理的微生物氮合(?)效率分别为8.50,11.20,13.10和13.97g/kg可消化有机物(DOM)(S.E=(?) 95)。微生物氮合成效率与瘤胃液稀释率有相关关系。     

Eructation of gas through the gastroesophageal sphincter before and after limiting distension of the gastric cardia or infusion of a beta-adrenergic amine in dogs

Gas eructation function of the gastroesophageal sphincter (GES) was investigated in 6 conscious dogs before and after a sleeve was placed around the GES and gastric cardia and during IV infusion of a beta-adrenergic amine (epinephrine). To induce eructation, nitrogen gas was insufflated (351.4 +/- 2 ml/min; mean +/- SEM) into the stomach through 1 channel of a 4-lumen catheter. After baseline studies and epinephrine infusion studies were completed in each dog, surgery was done to limit partially gastric distension by intraluminal contents by placing a silicone rubber sleeve around the GES and the first few centimeters of the cardia. Gastroesophageal sphincter pressure was 31.8 +/- 2.2 mm of Hg in baseline studies, 17.3 +/- 1.3 mm of Hg during epinephrine infusion (P. less than 0.003), and 30.3 +/- 2.2 mm of Hg after the sleeve was placed around the GES and cardia. During insufflation, gastric pressures before eructation increased to 5.74 +/- 0.41 mm of Hg before and to 15.15 +/- 1.63 mm of Hg after cardia sleeve placement (P less than 0.001). Eructation occurred at intervals of 1.83 +/- 0.41 minutes before cardia sleeve placement, and eructations were not observed with the sleeve in place. Before the sleeve was placed, administration of epinephrine resulted in an eructation interval of 0.84 +/- 0.09 minutes, which was significantly different from that in the same dogs given no drugs (P less than 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)     

Wheat pasture bloat dynamics, in vitro ruminal gas production, and potential bloat mitigation with condensed tannins

The aim of this study was to determine the effect of winter wheat (Triticum aestivum L.) forage growth stage, forage allowance, time of day, and commercial condensed tannins (CT) on steer bloat dynamics and in vitro ruminal gas production. Twenty-six crossbreed steers (Angus x Hereford x Salers; average initial BW = 194 +/- 26 kg) were used. Wheat forage allowances were either 18 kg (high forage allowance) and 6 kg (low forage allowance) of DM/(100 kg BW.d). In each bloat observation period, fresh wheat forage samples were hand-clipped to ground level in all study pastures for nutrient and in vitro ruminal gas production analyses. In vitro ruminal gas accumulation was measured at 0, 1, 2, 3, 4, 5, 6, and 12 h. Commercial CT was added at 0, 10, 15, and 20 mg of CT/g of DM. Bloat was scored once per week on two consecutive days at 0800 and 1500 during the vegetative stage and once every 2 wk during the reproductive stage of wheat development. Mean bloat score was calculated for each steer by time of day, stage of plant growth, and forage allowance. Bloat was detected in 65.8% of the observation periods. Average bloat scores were four and 2.5 times greater (P < 0.05) in cattle grazing at a high forage allowance than at a low forage allowance in the vegetative and reproductive growth phases of wheat, respectively. Rate of gas production was greater (P < 0.001) in the vegetative stage than in the reproductive stage. Steer bloat score was positively correlated with forage CP (r = 0.22; P < 0.05) and IVDMD (r = 0.32; P < 0.05). Rate of ruminal gas production was positively correlated (P < 0.01) to forage CP (r = 0.48), NPN (r = 0.40), soluble protein (r = 0.32), and IVDMD (r = 0.47). Conversely, negative correlations were found for forage DM (r = -0.20; P < 0.05), insoluble protein (r = -0.40), NDF (r = -0.69), and forage height (r = -0.49; P < 0.01) on the rate of ruminal gas production. Addition of CT at levels greater than 10 mg of CT/g of DM decreased (P < 0.05) the rate of in vitro ruminal gas and methane gas production after 5 h of incubation. Wheat pasture bloat is a complex disorder that varies across an array of forage and environmental conditions. Condensed tannins have the potential to decrease bloat by altering ruminal gas production and soluble protein digestibility from wheat forage.     

Caudal epidural analgesia induced by xylazine administration in cows

Xylazine (0.05 mg/kg of body weight diluted to a 5-ml volume, using 0.9% NaCl) or 5 ml of 0.9% NaCl was administered epidurally into the first caudal intervertebral space (Co1-Co2) in 8 cows (mean +/- SD body weight, 583 +/- 150 kg). Cows were observed for responses to deep needle pricking of the caudal dermatomes (S3 to Co), sedation, and ataxia. Heart rate, respiratory rate, body temperature, rate of ruminal contractions, coccygeal arterial blood pressure, pHa, blood gas tension (PaO2, PaCO2), base excess, total solids concentration, and PCV were determined before and after xylazine administration. Epidurally administered xylazine induced sedation and selective (S3 to Co) analgesia for at least 2 hours. Mild ataxia of hind limbs was observed in 6 cows, but all cows remained standing. Heart rate, respiratory rate, rate of ruminal contractions, arterial blood pressure, PaO2, PCV, and total solids concentration were significantly (P less than 0.05) decreased, and PaCO2, base excess, and bicarbonate concentration were significantly (P less than 0.05) increased after xylazine administration. Epidurally administered 0.9% NaCl did not alter sensory perception to needle pricking and did not affect any of the physiologic variables determined. Although epidural administration of xylazine induced analgesia and sedation in healthy cows, it should be avoided for epidural analgesia in cattle with heart disease, lung disease, and/or gastrointestinal disease because of its potent cardiopulmonary and ruminal depressant effects.     

The effect of hyoscine on dobutamine requirement in spontaneously breathing horses anaesthetized with halothane

OBJECTIVE: To determine whether hyoscine has a sparing effect on the volume of dobutamine required to maintain mean arterial pressure (MAP) at 70 mmHg in horses anaesthetized with halothane. STUDY DESIGN: Prospective, randomized, controlled clinical trial. ANIMALS: Twenty adult horses weighing 507 +/- 97 kg (mean +/- SD), aged 10 +/- 5 years. MATERIALS AND METHODS: Pre-anaesthetic medication in all horses was intramuscular (IM) acepromazine (40 mug kg(-1)) and intravenous (IV) detomidine (0.02 mg kg(-1)). Anaesthesia was induced with ketamine (2.2 mg kg(-1) IV) and diazepam (0.02 mg kg(-1) IV), and maintained with halothane in oxygen. Horses breathed spontaneously. Flunixin (1.1 mg kg(-1) IV) was given to provide analgesia. Heart rate, ECG, invasive arterial pressure, respiratory rate, percentage end-tidal carbon dioxide, percentage end-tidal halothane and partial pressure of oxygen and carbon dioxide in arterial blood and blood pH were monitored. Dobutamine was infused by an infusion pump to maintain MAP at 70 mmHg. Horses were randomly assigned to receive saline or hyoscine (0.1 mg kg(-1)) IV 30 minutes after induction. The heart rate, MAP and volume of dobutamine infused over 30-minute periods were measured and analysed statistically using a one-way anova. RESULTS: After administration of hyoscine, heart rate increased for 10 minutes (p < 0.01) and MAP for 5 minutes (p < 0.01). There was no difference in the volume of dobutamine infused over 30 minutes between horses given hyoscine or saline, although there was a wide individual variation in dobutamine requirements. No side effects of hyoscine were seen. CONCLUSIONS: The increase in heart rate and blood pressure that occurs after 0.1 mg kg(-1) hyoscine is given IV in anaesthetized horses, is of short duration and does not significantly alter the amount of dobutamine required to maintain arterial pressure over the next 30 minutes. Clinical relevance The short duration of action of 0.1 mg kg(-1) hyoscine IV may limit its usefulness for correction of hypotension in horses anaesthetized with halothane. Further work is necessary to investigate the effects of higher or repeated doses or constant rate infusions of hyoscine.     

新型脲酶抑制剂对绵羊瘤胃酶活性和细菌总数的影响

为了研究新型脲酶抑制剂对绵羊瘤胃酶活性和细菌总数的影响 ,进行了两个实验。实验一 ,采用反转设计 ,用4头装有瘤胃瘘管的绵羊 ,分别测定了瘤胃液中脲酶、纤维素酶、蛋白水解酶、总脱氢酶的活性和瘤胃细菌总数。结果表明 ,在瘤胃内灌注50mg脲酶抑制剂 (氢醌 ,HQ )可以使脲酶的活性降低65 % (P<0.01) ,使纤维素酶的活性提高28 % (P<0.05) ,对蛋白水解酶、总脱氢酶的活性和瘤胃细菌总数没有影响(P>0.05)。实验二 ,采用滤纸片法观察了氢醌在10、20、40和80mg/L浓度范围内对瘤胃微生物的抑制作用。测定结果表明 ,除了80mg/L氢醌对瘤胃微生物有微弱的抑制作用外 ,其它浓度的氢醌对瘤胃微生物的生长没有影响。上述结果表明 ,HQ是瘤胃微生物脲酶的专一性抑制剂 ,对瘤胃微生物的繁殖和代谢活性无不良影响。HQ在较低浓度范围内使用 ,就可以非常有效地减缓瘤胃中尿素的释放速度 ,对瘤胃微生物和宿主动物安全 ,无毒副作用 ,在反刍动物尿素利用方面具有非常大的开发潜力。     

Effect of intravenous infusion of proglumide on ruminal motility in conscious sheep (<Emphasis Type="Italic">Ovis aries</Emphasis>)

The effects of intravenous infusion of proglumide on regular ruminal contractions were examined in conscious sheep using doses that inhibit pancreatic exocrine secretion. After a control period of 20 min, proglumide was infused intravenously for 40 min at a dose of 15, 30 or 60 μmol/kg per min and venous blood was collected. The intravenous infusion of proglumide significantly increased the frequency of ruminal contractions at 15 μmol/kg per min without altering the amplitude, while it significantly decreased the frequency and amplitude of ruminal contractions at 30 and 60 μmol/kg per min in a dose-dependent manner. Proglumide did not increase contractile activity of the omasum, abomasum and duodenum or the plasma concentration of immunoreactive cholecystokinin (CCK). Application of proglumide at 1–30 mmol/L inhibited bethanechol-induced contraction in both longitudinal and circular muscle strips of the dorsal sac of the rumen. These results suggest that proglumide at a low dose acts indirectly on the rumen as a CCK receptor antagonist to increase the frequency of contractions, whereas at higher doses it inhibits cholinergic-induced contraction of the ruminal muscles or acts as an agonist to inhibit contractions in sheep. Hence, proglumide at high doses seems unsuitable for research or therapeutic use as a CCK receptor blockade in sheep.     

In vitro ruminal biotransformation of benzimidazole sulphoxide anthelmintics: enantioselective sulphoreduction in sheep and cattle

The comparative in vitro sulphoreduction of the (+) and (-) enantiomers of albendazole sulphoxide (ABZSO) and oxfendazole (OFZ) by ruminal fluid obtained from sheep and cattle, was investigated, under anaerobic conditions, in this study. Ruminal fluid samples were obtained from Holstein steers fitted with a permanent rumen fistula and from Corriedale lambs via an oesophageal tube. Albendazole sulphoxide, incubated as either the racemic (rac) mixture or as each individual enantiomeric form, was extensively sulphoreduced to form albendazole (ABZ) by ruminal fluid from both species. The concentrations of ABZ formed at different incubation times were between 55 and 158% greater after the incubation of cattle ruminal fluid with (+) ABZSO, compared with that produced when (-) ABZSO was the incubated substrate. Similarly, the concentrations of ABZ were 1.3--3.0-fold higher when (+) ABZSO was incubated with sheep ruminal fluid. Significantly higher rates of depletion were observed for the (+) enantiomeric form when ABZSO was incubated with ruminal fluid from both species. The rates of ABZ formation from both ABZSO enantiomeric forms were significantly higher in sheep compared with cattle ruminal fluid. Fenbendazole (FBZ) was the metabolite formed after the incubation of the racemic form of OFZ with ruminal fluid obtained from both species. The metabolic profile of both OFZ enantiomers followed a similar pattern to that observed for ABZSO enantiomers. A bi-directional chiral inversion of one enantiomer into its antipode was observed. The (+) enantiomer appeared in the incubation medium when (-) ABZSO was the incubated substrate, and also the (-) antipode was detected after (+) ABZSO incubation with ruminal fluid obtained from both species. The results reported here demonstrate an enantioselective ruminal sulphoreduction of ABZSO and OFZ (substrate enantioselectivity). These findings contribute to interpret the chiral behaviour of benzimidazole-sulphoxide anthelmintics.     

Comparative utilization of warm- and cool-season forages by cattle, sheep and goats

The quality of different classes of forage hay (C3, C4 grasses and legumes) was determined in intake and digestibility trials with mature cattle, sheep and goats. For all nine hays, DM and NDF digestibility by cattle and goats was higher (P less than .05) than by sheep, with no differences due to forage class. Cattle had a higher (P less than .01) DM intake than sheep or goats averaged across forage (92.6 vs 65.8 and 68.6 g/kg BW.75); hay intake was highest on legume, with no difference between C3 and C4 grasses. Mean NDF intake by cattle was greater than by sheep or goats (58.7 vs 39.6 and 42.6 g/kg BW.75); NDF intake for all animal species decreased in the order C4 grass greater than C3 grass greater than legume. Particle passage rates did not differ (P greater than .05) with forage class but were higher (P less than .02) for sheep and goats than for cattle. Prefeeding ruminal DM fill values, determined by emptying, were 10.6, 15.0 and 19.9 g/kg BW1.0 for alfalfa, orchardgrass and switchgrass hays fed to cattle, and 11.2, 11.3 and 16.5 g/kg BW1.0 for the same hays fed to sheep. Estimated turnover times for DM and NDF were shorter (P less than .05) for sheep than for cattle; DM turnover was longer for switchgrass than for alfalfa and orchardgrass, with no forage differences in NDF turnover between these two animal species. Results show that goats were superior to sheep in NDF digestion.     

Parenteral methods of supplementation with copper and selenium

Parenteral treatments can provide a rapid successful method of supplementing ruminants with copper and selenium, and avoid the possible interactions between an oral supplement and other dietary constituents. The copper preparations studied contained copper complexed with calcium edetate (EDTA) or copper methionate , copper oxide or copper oxyquinoline sulphonate. The recommended doses of these commercial preparations contain different amounts of copper only part of which is transferred to the liver stores from which it can be released during the following months. The recommended dose of copper oxyquinoline sulphonate contains only 12 mg copper and the duration of its protective effect is short. Only a small proportion of the copper in copper methionate and copper oxide is transferred to the liver whereas nearly all the copper in a single dose of the EDTA complex (50 mg copper for sheep) is transferred to the liver stores. Although no longer recommended for use in sheep the copper EDTA complex can be administered to cattle to provide up to 1 mg copper/kg bodyweight. Selenium deficiency in both cattle and sheep can be corrected by the subcutaneous administration of up to 0.15 mg selenium/kg bodyweight as sodium selenate. However, if a dietary deficiency persists copper and selenium treatments are effective for only a few months. To avoid the need for repeated treatments, slowly dissolving or controlled release systems have been developed. Subcutaneous depots of barium selenate have been used (1 mg selenium/kg bodyweight) but large residues remained at the site of injection for up to three months. Initial trials with controlled release glasses containing copper have shown that they maybe useful for routine parenteral therapy.