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1.
The influence of training on blood lactate concentrations during treadmill exercise and a 40-minute inactive recovery period was examined in seven trained and seven detrained thorough-bred horses. Lactate concentrations were measured in venous blood collected at the end of each exercise state, and at intervals for 40 minutes afterwards. Measurements were made of maximum oxygen uptake (V̇O2max, ml kg−1 min−1), VLA4 (velocity at which blood lactate concentration was 4 mmol litre−1); LA8 (lactate concentration [mmol litre−1] during exercise at 8 m sec−1), peak lactate (highest lactate concentration after exercise), LA40 (lactate concentration 40 minutes after exercise), the time of peak lactate concentration (minutes after exercise) and the rate of disappearance of blood lactate (Rtd). The trained horses had a significantly lower LA8 (2·1 ± 0·1 vs 6·5 ± 1 mmol litre−1, P<0·01), higher VLA4 (9·8 ± 0·2 vs 5·8 ± 0·6 m sec−1, P<0·01) and higher V̇02max (156·3 ± 3·8 vs 107·1 ± 3·9 ml kg−1 min−1, P<0·001). The value of Rtd and the time of peak lactate concentration were not significantly different.  相似文献   

2.
The effect of dietary chloride content (0·2, 0·4 and 1·3 per cent chloride on a dry matter basis) on the disposition of a single oral dose of bromide (14 mg kg−1 was evaluated in normal beagles. Increasing the dietary chloride content from 0·2 to 1·3 per cent resulted in a significant decrease in the mean apparent elimination half-life from 69 ± 22 days to 24 ± 7 days. The mean area under the concentration curve ( ) for dogs fed 1·3 per cent chloride was significantly smaller than the for dogs fed 0·2 per cent chloride. Dietary chloride had no effect on the maximum serum concentrations (Cmax) or on the time (Tmax) to reach the maximum concentrations. The steady-state serum bromide concentrations predicted from the single dose data for daily doses of 14 mg kg−1 of bromide were significantly lower in dogs fed 1·3 per cent chloride (310 ± 150 mg litre−1) than in dogs fed 0·2 per cent chloride (1950 ± 1140 mg litre−1). The predicted mean daily doses of bromide necessary to maintain serum levels within the therapeutic range for dogs fed 1·3 per cent chloride (43 ± 13 mg kg−1) were almost twice as high as the dose estimated for dogs fed 0·4 per cent chloride (22 ± 3 mg kg−1) and nearly three times as high as the dose estimated for dogs fed 0·2 per cent chloride (15 ± 4 mg kg−l). These differences were statistically significant (P=0·002).  相似文献   

3.
Heat shock protein (HSP) expression is an adaptive mechanism against the disruption of cell homeostasis during exercise. Several antioxidant supplementation strategies have been used to enhance tissue protection. In this study, we examined the effects of a redox modulator, α-lipoic acid (LA) on HSP responses in six standardbred trotters following intense aerobic exercise. DL–LA supplementation (25 mg kg−1 d−1) for five weeks increased the resting levels of HSP90 (1.02 ± 0.155 in control and 1.26 ± 0.090 after supplementation in arbitrary units) and the recovery levels of inducible HSP70 (0.89 ± 0.056 in control and 1.05 ± 0.089 after supplementation in arbitrary units) in skeletal muscle. Furthermore, LA increased skeletal muscle citrate synthase activity at rest and lowered the blood lactate concentration during exercise without any changes in the heart rate. LA had no effect on concentrations of HSP60, HSP25 or GRP75 in skeletal muscle. LA decreased the exercise-induced increases in plasma aspartate aminotransferase and creatine kinase concentrations during recovery. Our results suggest that LA supplementation may enhance tissue protection and increase oxidative capacity of the muscle in horse.  相似文献   

4.
Fluconazole (100 mg) was administered to six adult cats as an intravenous infusion over 30 minutes, and the same cats received 100 mg of the drug orally 16 weeks later. The cats were bled repeatedly through an indwelling jugular catheter, the plasma fluconazole concentrations were assayed by high performance liquid chromatography, and the concentration-time data were subjected to a non-compartmental pharmacokinetic analysis. The mean (SD) intravenous half-life (13·8 [2·6] hours) was similar to that observed after oral dosing (12·4 [3·0] hours). The plasma clearances (intravenous 0·9 [0·1], oral 0·9 [0·2] ml min−1 kg−1) and the volumes of distribution at steady state (intravenous 1·1 [0·1], oral 1·0 [0·1] litre kg−1) were also similar after the two routes of dosing. The peak plasma concentration was reached 2·6 hours after oral dosing and the drug was completely bioavailable (1·09 [0·05]). On the basis of this single dose study, the administration of 50 mg fluconazole every eight hours to a 4 kg cat should produce average steady state plasma fluconazole concentrations of approximately 33 mg litre−1.  相似文献   

5.
High muscle camosine and anserine contents contribute significantly to intra-cellular physico-chemical buffering. Our aim was to measure carnosine, anserine and taurine contents directly in individual type I, HA and IIB fibres from the middle gluteus muscle of the camel. Mean carnosine contents in type I, IIA and IIB were 24·6 ±9·2, 39·4 ±11·4 and 42·8 ±18·8 mmol kg−1 dry weight (dw), respectively. Mean anserine contents in type I, HA and IIB fibres were 30·0 ±8·4, 37·3 ±10·1 and 34·5 ±9·7 mmol kg−1 dw, respectively. Mean taurine contents in type I, IIA and HB fibres were 42·4 ±15-9, 203 ±12·9 and 24·7 ±15·9 mmol kg−1 dw, respectively. Higher carnosine contents in type II fibres emphasise the importance of carnosine to intra-muscular acid-base regulation. A specific role for taurine in type I fibres is unclear.  相似文献   

6.
Five days after the induction of acute systemic inflammation in greyhounds by intramuscular and subcutaneous injections of Freund's adjuvant, the hepatic concentrations of cytochromes P-450 and b5, the activities of the hepatic microsomal enzymes aniline p-hydroxylase and aminopyrine n-demethylase and the disposition and urinary excretion of phenylbutazone were determined. The mean plasma concentrations of phenylbutazone after intravenous administration were described by the bi-exponential equations: Cp = 144·2e−34·6t + 171·5e−0·104t for five normal greyhounds and Cp = 113·6e−16·13t + 163·1e−0·108t for five febrile greyhounds. The elimination half-lives, total body clearances and apparent volumes of distribution were 6·7 hours, 18·4 ml kg−1 hour−1 and 0·18 litre kg−1, for the normal greyhounds, and 6·4 hours, 19·5 ml kg−1 hour−1 and 0·18 litre kg−1, for the febrile greyhounds. There were no significant differences between the pharmacokinetic parameters describing the distribution and elimination of phenylbutazone, or between the quantities of phenylbutazone, oxyphenbutazone and hydroxyphenylbutazone excreted in the urine. In the febrile greyhounds, there were significant decreases in the hepatic microsomal concentrations of cytochromes P-450 and b5 and in the activities of aniline p-hydroxylase and aminopyrine n-demethylase.  相似文献   

7.
Ureaplasma species were isolated from semen samples collected sequentially from one Awassi and three Assaf breeding rams. Each ram was injected subcutaneously with an aqueous solution of lincomycin and spectinomycin for five consecutive days at a dose equivalent to 4·5 mg kg−1 lincomycin and 9·0 mg kg−1 spectinomycin daily. Serum and semen samples were collected at intervals during the treatment and assayed for lincomycin. No Ureaplasma species were isolated from semen samples collected during the course of the treatment and at intervals for 17 days after the last treatment. The concentration of lincomycin in semen ranged from 0·51 μg ml−1 four hours after treatment to 0·08 μg ml−1 24 hours after treatment, and these levels were three to nine times higher than the corresponding serum concentrations.  相似文献   

8.
These studies were undertaken to examine the systemic and renal effects of the pharmacological inhibition of endothelium-derived nitric oxide (EDNO) in cats. In six healthy cats, the intravenous infusion of nitro-L-arginine at a dose of 100 μg kg−1 bodyweight min−1 resulted in a marked increase (P<0·001) in mean arterial pressure from the control value of 116·7 ± 4·6 mmHg to 154·2 ± 6·8 mmHg and an increase (P<0·05) in renal vascular resistance from the control value of 3·69 ± 0·33 mmHg min ml−1 to 6·83 ± 1·15 mmHg min ml−1. The increase in renal vascular resistance was generalised, with comparable increments in preglomerular and postglomerular vascular resistance. Mean values for glomerular capillary pressure (61·1 ± 61·9 vs 1·9 ± 1·6 mmHg), calculated from the sum of arterial colloid osmotic pressure plus proximal tubule stop-flow pressure, did not change in response to the infusion of nitro-L-arginine. However, there was a marked reduction in renal blood flow (29·4 ± 3·1 to 16·9 ± 2·3 ml min−1, P<0·01) and glomerular filtration rate (5·22 ± 0·57 to 3·52 ± 0·45 ml min−1, P<0·01). These results provide evidence that EDNO plays an important role in the basal regulation of systemic arterial blood pressure and renal haemodynamics in cats.  相似文献   

9.
Six healthy horses were anaesthetised with halothane (1·2 times the horse minimal alveolar concentration) in oxygen for more than 12 hours. Serum bilirubin, aspartate aminotransferase, alkaline phosphatase and L-iditol dehydrogenase values were significantly (P<0·05) increased for up to nine days after anaesthesia. These changes suggest au anaesthesia related liver dysfunction. Creatine kinase increased to an average of more than 1400 iu litre−1 24 hours after anaesthesia and this change is indicative of muscle cell disruption. Renal-associated biochemical results, (that is serum creatinine and inorganic phosphate concentrations) were significantly increased transiently and are indicative of reduced renal function during and immediately after anaesthesia. Plasma concentrations of eicosanoids (6-keto-PGF1a, PGF2a, pge and thromboxane) following anaesthesia were not different from preanaesthetic values. The magnitude of liver and muscle cell related increases in serum enzyme activities resulting from prolonged halothane anaesthesia was in excess of that previously reported for anaesthesia of shorter duration.  相似文献   

10.
The pharmokinetic properties of amoxycillin, and its penetration into respiratory tract tissue, were determined in 18 Actinobacillus pleuropneumoniae infected pigs, after a single i.v. dose of 8·6 mg amoxycillin kg−1 bodyweight. Pleuropneumoniae was produced experimentally in pigs by an aerosol infection model. The infection created a homogenous response, characterised by depression of breathing and increased body temperature. The clinical symptoms were accompanied by increased haptoglobin levels and circulating white blood cell counts. At necropsy the findings were characterised by a bilateral fibrinous pleuropneumonia. Twenty hours after infection, the pigs were administered amoxycillin i.v. The plasma concentration-time curve was described by a three compartment open model. The mean residence time and the elimination half-life were l·5 and 3·4 hours, respectively. The steady-state volume of distribution was 0·67 litres kgl, and the clearance was 0·46 litres kg−1 hour−1. There were no significant differences between these values and those reported previously for healthy pigs. The concentration of amoxycillin in bronchial secretions, lung tissue and diseased lung tissue peaked two hours after intravenous drug administration, while amoxycillin concentration in pleural fluid, lymph nodes and tonsil tissue peaked at the first sampling point one hour after drug administration. The concentration of amoxycillin in secretions and tissue decreased by a slower rate than amoxycillin concentration in plasma, resulting in an increasing tissue-to-plasma concentration ratio. The distribution ratios (AUCtissue/JAUCplasma) was 0·53 for bronchial secretions, 0·44 for pneumonic lung tissue, 0·42 for lung tissue, 1·04 for pleural fluid, 0·58 for lymph nodes and 0·37 for tonsil tissue. The distribution of amoxycillin to secretions was increased compared with that previously reported for healthy pigs, while only minor changes were observed in lung tissue.  相似文献   

11.
In an open, controlled, multi-centre clinical field trial, seven ‘naturally occurring’ outbreaks of acutefebrile (rectal temperature ≥ 39·5°C) respiratory disease in housed calves were treated with a single antimicrobial agent, and either the non-steroidal anti-inflammatory drug (NSAID) carprofen (n=95) or flunixin meghunine (n=92) on an alternate basis. Carprofen was administered as a single subcutaneous injection at a mean dosage of 1·4 mg kg−1 (range 1·2 to 1·9 mg kg−1) body weight on the first day and flunixin meglumine by intravenous injection at a mean dosage of 2·0 mg kg−1 (range 1·2 to 2·6 mg kg−1) body weight on the first 3 consecutive days. All calves were examined clinically immediately prior to initial treatment and on three occasions up to 1 week after the end of treatment. There were no statistically significant differences between NSAID groups in reduction of clinical parameters between examinations, or in overall efficacy. This trial demonstrated that a single dose of carprofen was equally effective as three daily closes of flunixin meglumine as adjunctive therapy to antimicrobial treatment in acute respiratory disease in calves.  相似文献   

12.
Low capacity, high affinity [3H] dexamethasone binding receptors were identified in cytosolic preparations of liver (mean number 45±10·1 fmol mg−1 protein, apparent dissociation constant 0·4±0·1 nM) and skin (mean number 46·4±23·8 fmol mg−1 protein, apparent dissociation constant 1 ± 0·2 nM) of clinically normal dogs. For clinically normal cats, approximately half these numbers of receptors with a lower affinity, were detected in liver (mean number 23·1±10·4 fmol mg−1 protein, apparent dissociation constant 3·2±0·9 nM) and skin (mean number 23·90±10·9 fmol mg−1 protein, apparent dissociation constant 2·2±1·5 nM). This difference between dogs and cats in [3H] dexamethasone binding receptors may contribute to the relative glucocorticoid resistance observed in cats.  相似文献   

13.
Six veal calves were medicated with clenbuterol at 20 μg kg bodyweight−1 day−1 for 42 days before they were slaughtered, to evaluate the lesions and residues in target organs. Compared with six unmedicated calves the most noticeable changes were tracheal dilatation, decreased uterine weight, slight mucous hypersecretion in the uterus and vagina and depletion of liver glycogen. The highest concentrations of clenbuterol (62 to 128 ng/g−1) were recorded in the choroid/retina, and the aqueous humour had the lowest concentration (0·5 to 2·4 ng ml−1). The residue concentrations were higher than the maximum residue level set for clenbuterol (0·5 ng g−1)  相似文献   

14.
This study characterised the peripheral plasma concentration of PSP-60 throughout gestation, and examined the effect of stage of gestation and foetal number on this protein in Holstein cows after non-surgical embryo transfer. Cows (n=12) were divided into two groups; Group 1 contained single embryo recipient cows (n=5), Group 2 contained twin-embryo recipient cows (n=7). Blood was collected approximately every third day from day 0 (first day of standing oestrus), then daily for the last 10 days of gestation and until one day post-partum. Two of the twin-embryo recipient cows had abnormal pregnancies, consequently data from them was considered separately. In both groups PSP-60 increased progressively from about day 20 post-oestrus to 20 days pre-partum (from 0·9 ± 0·2 to 49·7 ± 8·7 ng ml−1, and from 1·3 ± 0·6 to 115 ± 34·9 ng ml−1 (mean ± SEM), in singleton and twin-bearing groups, respectively). The mean concentrations between 20 and 10 days pre-partum increased dramatically by about six-fold (P<0·001) in singleton-bearing cows (from 49·7 ± 8·7 ng ml−1 to 2838 ± 73·7 ng ml−1) to over two-fold in twin-bearing cows (from 115 ± 34·9 ng ml−1 to 284 ± 98·2 ng ml-1). The mean concentrations of the two groups were indistinguishable between 10 days pre-parturn and parturition. Cows giving birth prematurely to stillborn calves or to a schistosomus reflexus calf exhibited abnormal PSP-60 profiles. Our findings indicate that peripheral plasma PSP-60 concentrations are correlated to the stage of gestation and foetal number, and assist in predicting foeto-placental viability.  相似文献   

15.
Clenbuterol (0·8 μg kg −1 intravenously) was investigated in ponies (small horses) anaesthetised with acepromazine, detomidine and thiopentone, then halothane in oxygen alone (hyperoxic group) or with nitrous oxide (hypoxic group). Following instrumentation, ponies were placed in dorsal recumbency for 60 minutes, clenbuterol (both groups) or a saline control (hyperoxic group) given, and cardiopulmonary parameters monitored for a further 60 minutes. In the hyperoxic group, clenbuterol administration resulted in a transitory (<five minutes) 15 per cent fall in arterial blood pressure and 78 per cent rise in intramuscular blood flow. Heart rate increased from a mean of 42 (SD 4) to 54 (12) beats per minute, the rise being significant for 15 minutes. Cardiac index increased from 2·1 (0·7) to 3·-9 (0·7) litres m−2 and remained significantly elevated for the remainder of the measurement period. Cardiovascular changes in the hypoxic group were similar. 30 minutes after clenbuterol administration, PaO2 had changed non-significantly from 32·.3 (19·2) to 33·.4 (17) kPa in the hyperoxic group and from 7·9 (1·8) to 8·.6 (1·3) kPa in the hypoxic group. The study concludes that under these experimental conditions, clenbuterol does not cause significant improvement in arterial oxygenation, but its cardiovascular effects are minimal or advantageous.  相似文献   

16.
Intravenous infusions of hydrocortisone sodium succinate (HSS) were given at 0·625 mg kg−1 hour−1 and 0·312 mg kg−1 hour−1 to six dogs. Plasma cortisol concentrations were measured by radioimmunoassay at 0, 15, 30, 45 and 60 minutes and then every 30 minutes for a further five hours. Chronic hypocortisolaemia was induced and maintained with mitotane and the HSS infusions were repeated after 31 and 50 days. No statistically significant difference was observed in the plasma cortisol concentrations after either period of hypocortisolaemia, but the plasma cortisol concentrations tended to be higher in most of the dogs.  相似文献   

17.
The purpose of this, trial was to determine the effect of hyperkalemic periodic paralysis (HYPP) on exercise tolerance in Quarter Horses. Five HYPP affected and five nonaffected horses were matched for age, size, gender and reproductive status. HYPP status was diagnosed by DNA analysis and potassium chloride challenge testing. Plasma lactate concentration and heart rate were used as indicators of work intensity. Serum potassium concentrations were also monitored. Two exercise experiments were conducted, the first being forty-five minutes of slow, aerobic exercise (hacking) and the other being moderate, partially anaerobic exercise (galloping). Post-exercise the horses were cooled out by randomly assigning them to either forty minutes, of standing still or forty minutes of walking. Heart rates of HYPP affected and unaffected horses were not significantly different during exercise or recovery. Plasma lactate concentrations changed slightly following slow exercise and were significantly higher for HYPP affected horses (P=0.01).At the end of exercise, values were 1.4±0.2 mmol/L and 1.0±0.1 mmol/L for HYPP affected and unaffected horses, respectively. Following moderate exercise, plasma lactate concentrations were much greater, and the difference (P<0.001) between affected and unaffected horses was more marked: immediately following exercise concentrations were 10.6±1.8 and 6.2±1.0 mmol/L in affected and unaffected horses, respectively. The higher post-exercise plasma lactate concentrations in affected horses indicates increased anaerobic muscle metabolism. Serum potassium concentrations rose following exercise and significantly higher values were seen in horses that were walked rather than stood still post-exercise.Hyperkalemic periodic paralysis (HYPP) is a dominant autosomal genetic defect occurring in American Quarter Horses and related breeds. 1–5 The condition is widely geographically distributed and has been estimated to affect 0.4% of all Quarter Horses.6 Signs include sporadic attacks of muscle fasciculation, muscle spasm, sweating and weakness. Oral administration of potassium chloride produces a more severe hyperkalemia in HYPP affected horses and induces clinical attacks.1 Electromyography reveals widespread continuous, spontaneous, muscle contraction.2 Some people believe that HYPP affected horses are suitable for riding7; others have expressed doubts about the safety of this practice and the exercise tolerance of affected horses. HYPP affected horses have an unstable muscle membrane potential causing random muscle fiber contractions,2,8 which could antagonize purposeful movement. This, in combination with increases in extracellular potassium concentration occurring during exercise,9–11 may cause affected horses to stumble or collapse while being ridden, posing a danger to both horse and rider. In HYPP affected people, potassium concentration rises approximately one to two hours after exercise during which time HYPP attacks can occur.9,10 For these reasons, the exercise tolerance of HYPP affected horses and the effects of exercise on spontaneous HYPP attacks deserves investigation.We standardized the exercise test and chose heart rate and plasma lactate concentrations as indicatoors, of exercise tolerance and energy metabolism.12 Heart rate is the major determinant of oxygen delivery to muscle and the rate rises with exercise intensity until it reaches a plateau at high velocities.13,14 Several lines of investigation indicate that plasma lactate concentrations reflect muscle work. Lactate release from resting muscle is minimal but large amounts are released during strenuous exercise.15–17 Lactate release increases with increasing muscle work.16,18 During exercise, muscle oxygen consumption increases until eventually a plateau is reached after which no further increase in oxygen consumption in response to increased work loads is possible.18 At this point the mitochondrial electron chain transport system is operating at its maximal possible rate, energy production can only be supplemented by the use of inefficient anerobic glycolytic metabolism and the muscle starts to release lactate. If the concentrations of plasma lactate are high, the muscles are depending on anaerobic metabolism and are working closer to exhaustion16,18–21The objectives of this experiment were twofold. One was to determine if HYPP adversely affects exercise performance. The second was to study the effects of cooling out, by either standing still or walking, on serum potassium and plasma lactate concentrations.  相似文献   

18.
The activities of danofloxacin, a novel fluoroquinolone, and two other antimicrobials were determined in vitro against field isolates of seven Mycoplasma species of veterinary importance isolated from cattle, swine and poultry in five European countries. The minimum inhibitory concentrations (MIC) of danofloxacin, tylosin and oxytetracycline were determined against a total of 68 isolates. Danofloxacin showed excellent activity against isolates of all Mycoplasma species (range 0·008 to 0·5 μg ml−1), but in some isolates there was evidence of reduced sensitivity to tylosin (range 0·008 to 2·0 μg ml−1) and oxytetracycline (range 0·008 to over 16·0 μg ml−1). Danofloxacin was more active than other antimicrobials against, M hyopneumoniae, M dispar and M bovigenitalium, and showed activity similar to that of tylosin against M bovis and M gallisepticum. Tylosin was the most active against M synoviae and M hyosynoviae. Generally, oxytetracycline showed the poorest activity, but was superior to tylosin against M bovigenitalium. A second (final) MIC reading was taken for all isolates 14 or 21 days after the initial reading, and MIC values rose during that time. However, the increase seen in danofloxacin values (typically one to two dilutions) was less than that seen for tylosin and oxytetracycline. It is concluded that danofloxacin is highly active in vitro against all of the Mycoplasma species tested, and thus shows great potential for the treatment of respiratory and other infections caused by Mycoplasma species in cattle, pigs and poultry.  相似文献   

19.
The dose response relationship for the intermediateacting non-depolarising muscle relaxant, atracurium besylate in the pig was determined using evoked electromyography. An incremental dose technique was used in seven Large White/Landrace crossbred pigs anaesthetised with nitrous oxide and halothane. ED50 and ED95 were 510 ± 87 μg kg−1 and 1150 ± 270 μg kg−1, respectively. Although these values may represent an overestimate, they provide a reasonable guideline for the use of atracurium by veterinary anaesthetists.  相似文献   

20.
The study investigated rumen dry matter (DM) degradability characteristics in a completely randomized design and the effects of milk, sweet potato foliage (SPF) from three cultivars (A = TIS-87/0087; B = TIS-8164; C = TIS-2532.OP.1.13), dried brewers' grains (DBG) and cottonseed meal (CSM) as supplements to Panicum maximum (Panicum) for pre-weaned calves in randomized complete block designs. Diet 1 = milk + SPF-A foliage + Panicum, Diet 2 = milk + SPF-B foliage + Panicum, Diet 3 = milk + SPF-C foliage + Panicum, and Diet 4 = milk + DBG & CSM + Panicum (as control). Dry matter (130 ± 0.4 to 864 ± 3.9 g kg− 1), ash (54 ± 4.2 to 173 ± 2.8 g kg− 1 DM), OM (827 ± 4.2 to 946 ± 5.7 g kg− 1 DM), N (7.4 ± 0.6 to 38.6 ± 1.4 g kg− 1 DM), and NDF (439 ± 1.4 to 774 ± 8.5 g kg− 1 DM) contents were highly significant (P < 0.01). In Trial I, 16 pre-weaned calves were used over 70 d with milk intake (34.8 ± 4.4 ml kg W− 0.75 d− 1), Panicum DMI (22.3 ± 2.77 g kg W− 0.75 d− 1), total DMI (35.7 ± 2.83 g kg W− 0.75 d− 1), and LWG (198 ± 44.6 g d− 1) not significantly different (P > 0.05). Supplement DMI varied (P < 0.05) from 11.6 g kg W− 0.75 d− 1 in Diet 3 to 16.6 g kg W− 0.75 d− 1 in Diet 4. In Trial II, 16 pre-weaned local and crossbred calves were involved over 77 d with initial age of calves, Panicum intake, metabolic DMI, and LWG similar (P > 0.05) among crosses. Birthweight varied (P < 0.05) from 17.3 kg for N'Dama × Jersey crosses to 21.2 kg for White Fulani × Brown Swiss crosses. Supplement and total DMI ranged (P < 0.05) from 172 to 483 g d− 1 for N'Dama × Jersey crosses to 233 and 674 g d− 1 for non-inseminate or purebred calves, respectively. The LWG in the White Fulani × Brown Swiss and the N'Dama × Jersey calves were respectively 30% and 24% better, though not significantly, than purebred calves. In Trial III, rumen DM degradability characteristics of feeds in three N'Dama steers showed no significant differences (P > 0.05) in slowly degradable fraction (b) and rate of degradation of b (c). Soluble fraction (a), 48-h degradation, potential degradability (PD) and effective degradability (ED) varied significantly (P < 0.05) and were lowest in Panicum, but similar for foliage among the three sweet potato cultivars. Panicum fodder showed improvements in degradation characteristics with supplementation.  相似文献   

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