Effect of stocking density on performance, diet selection, total-tract digestion, and nitrogen balance among heifers grazing cool-season annual forages.

Grazing annual cool-season forages after oat grain harvest in South Dakota may allow an opportunity to increase efficient use of tillable land. However, data are limited regarding effects of stocking density on diet selection, nutrient digestion, performance, and N retention by cattle grazing annual cool-season forage. Heifers were blocked by initial BW (261 ± 11.7 kg) and randomly assigned to 1 of 12 paddocks (1.1 ha) to graze a mixture of grass and brassica for 48 d. Each paddock contained 3, 4, or 5 heifers to achieve 4 replicates of each stocking density treatment. Ruminally cannulated heifers were used to measure diet and nutrient intake. Effects of stocking density on diet and nutrient selection were measured after 2, 24, and 46 d of grazing, and BW was measured at the beginning, middle, and end of the experiment as the average of d 1 and 2, d 22 and 23, and d 47 and 48 BW, respectively. Measures of DMI and DM, OM, NDF, and ADF digestion were collected from d 18 to 23. Increased stocking density increased intake of brassica relative to grass on d 24 (quadratic, = 0.02), but increased stocking density decreased (linear, ≤ 0.01) intake of brassica compared with grass on d 48 (stocking density × time, < 0.01). Increased stocking density increased DM (quadratic, < 0.01), OM (quadratic, = 0.01), and NDF (quadratic, = 0.05) digestion, and stocking density tended to increase DMI (quadratic, = 0.07). Additionally, increased stocking density quadratically increased ( = 0.05) N retention but did not affect overall BW gains. Increased stocking density did, however, contribute to linearly decreased ( = 0.05) BW gains from d 1 to 22 of grazing, but BW gains during the latter half of the experiment were greater than BW gains from d 1 to 22. Ruminal concentration of acetate:propionate was least on d 24 of grazing, and ruminal nitrate concentration tended to linearly decrease ( = 0.06) with greater amounts of time on pasture. Ruminal liquid and particulate fill and amounts of VFA were less (quadratic, ≤ 0.01) with greater amounts of time on pasture. Apparently, binary mixtures of brassica and grass planted after oat grain harvest can provide an opportunity to increase efficient use of land by providing forage resources. Increased stocking density may facilitate a more rapid adaptation to and intake of brassica among cattle grazing brassica-grass-based pastures.

Molecular survey of trichostrongyle nematodes in a Bison bison herd experiencing clinical parasitism, and effects of avermectin treatment.

North American bison (Bison bison) producers face many challenges, including the potential clinical and economics problems caused by trichostrongyle nematodes within their herds. Little is known about the prevalence, intensity, geographical distribution and clinical significance of these parasites in commercial bison herds, even from regions where bison production has become popular. This study involved a large herd of bison from eastern South Dakota that was experiencing clinical parasitism due to a temporary over-stocking problem. After documenting fecal egg counts (FECs) and trichostrongyle genera present among the 3 main age-categories (i.e. adults, yearlings, calves) of bison during this heavily infected grazing season, the effects of doramectin treatment on the different age groups was also evaluated. This is the first bison study using PCR to identify genera of trichostrongyles in fecal samples. Virtually all 103 bison fecal samples from all 3 age classes were shedding trichostrongyle eggs by the end of the season, and the mean FECs were 34 eggs/g (EPG) among the cows, 125 EPG in the yearlings, and 186 EGP among calves. Based upon this heavily-infected herd, there is evidence that the susceptibility of bison to trichostrongyles is more similar to beef cattle than to sheep. Other parasites such as Moniezia, Nematodirus, Trichuris, and coccidians were also identified in these samples. All but 3 of the 51 samples analyzed with PCR shown at least 1 trichostrongyle genera. Ostertagia was detected in 68.6% of the samples, Cooperia in 80.39%, Haemonchus in at least 73% and Trichostrongylus in 16% of the herd. Most commonly, bison were infected with combinations of Haemonchus/Ostertagia/Cooperia. After treatment with doramectin, the mean FECs dropped by 99.9% for all of the bison age classes.

Influence of feeding various quantities of wet and dry distillers grains to finishing steers on carcass characteristics, meat quality, retail-case life of ground beef, and fatty acid profile of longissimus muscle.

Two hundred forty Angus crossbred steers were used to determine the influence of feeding various quantities of wet and dry distillers grains to finishing steers on carcass characteristics, meat quality, retail-case life of ground beef, and fatty acid profile of LM. Three replications of 5 dietary treatments were randomly applied to 15 pens in each of 2 yr. A finishing diet containing dry-rolled corn, soybean meal, and alfalfa hay was fed as the control diet. Wet distillers grains with solubles (DGS) or dry DGS was added to the finishing diets at either 20.0 or 40.0% of the dietary DM to replace all soybean meal and part of the cracked corn in treatment diets. Carcasses of steers fed DGS had greater (P < 0.05) fat thickness (1.47 vs. 1.28 cm), greater (P < 0.05) USDA yield grades (3.23 vs. 2.94), and smaller (P < 0.05) percentage of yield grades 1 and 2 (41.1 vs. 60.4%) than carcasses of steers fed the control diet. Longissimus muscle from steers fed dry DGS had greater (P < 0.05) ultimate pH values (5.52 vs. 5.49) than LM from steers fed wet DGS. Ground beef from steers fed DGS had greater (P < 0.05) concentrations of α-tocopherol (1.77 vs. 1.43 µg/g) than ground beef from steers fed the control diet. Ground beef from steers fed 40% DGS had greater (P < 0.05) thiobarbituric acid-reactive substances (2.84 vs. 2.13 mg/kg) on d 2 of retail display than ground beef from steers fed 20% DGS. Longissimus muscle of steers fed DGS had less (P < 0.05) C17:0 and more (P < 0.05) C18:0, C18:1t, C16:1c9, C18:2c9c12 (where t is trans and c is cis), and total PUFA than LM of steers fed the control diet. Feedlot steers fed DGS may need to be marketed earlier than normal to avoid excess external fat and carcasses with a greater numerical yield grade. These data suggest feeding DGS to finishing steers will have no adverse or beneficial effects on glycolytic variables (dark cutters), retail display life of ground beef, or meat tenderness. However, beef from cattle finished on diets containing DGS will likely have a greater proportion of PUFA and therefore may be more susceptible to oxidative rancidity.

Circulating ghrelin concentrations fluctuate relative to nutritional status and influence feeding behavior in cattle.

The objective of these experiments was to establish the relationship of plasma ghrelin concentrations with feed intake and hormones indicative of nutritional state of cattle. In Exp.1, 4 steers (BW 450 +/- 14.3 kg) were used in a crossover design to compare plasma ghrelin concentrations of feed-deprived steers with those of steers allowed to consume feed and to establish the relationship of plasma ghrelin concentrations with those of GH, insulin (INS), glucose (GLU), and NEFA. After adaptation to a once-daily feed offering (0800), 2 steers continued the once-daily feeding schedule (FED), whereas feed was withheld from the other 2 steers (FAST). Serial blood samples were collected via indwelling jugular catheter from times equivalent to 22 h through 48 h of feed deprivation. Average plasma ghrelin concentrations were greater (P < 0.001) in FAST compared with FED (690 and 123 +/- 6.5 pg/mL) steers. Average plasma ghrelin concentrations for FED steers prefeeding were elevated (P < 0.001) when compared with those postfeeding (174 and 102 +/- 4.2 pg/mL, respectively). Average plasma GH concentration was elevated (P < 0.05) for FAST steers compared with FED steers. Plasma GLU concentrations were not different; however, for FAST steers, NEFA concentrations were elevated (P < 0.001) and INS concentrations were decreased (P < 0.001). In Exp. 2, 4 steers (BW 416 +/- 17.2 kg) were used in a crossover design to determine the effects of i.v. injection of bovine ghrelin (bGR) on plasma GH, INS, GLU, and NEFA concentrations; length of time spent eating; and DMI. Steers were offered feed once daily (0800). Serial blood samples were collected from steers via indwelling jugular catheter. Saline or bGR was injected via jugular catheter at 1200 and 1400. A dosage of 0.08 microg/kg of BW bGR was used to achieve a plasma ghrelin concentration similar to the physiological concentration measured in a FAST steer in Exp. 1 (1,000 pg/mL). Injection of bGR resulted in elevated (P < 0.005) plasma GH concentrations after the 1200 but not the 1400 injection. Plasma INS, GLU, and NEFA concentrations were not affected by bGR injection. For the combined 1-h periods postinjection, length of time spent eating was greater (P = 0.02) and DMI tended to be increased (P = 0.06) for bGR steers. These data are consistent with the hypothesis that ghrelin serves as a metabolic signal for feed intake or energy balance in ruminants.

Clinical experience with Repotin, a locally produced recombinant human erythropoietin, in the treatment of anaemia of chronic renal failure in South Africa.

OBJECTIVE: To evaluate the efficacy and safety of Repotin, a locally produced recombinant human erythropoietin (rHuEPO), in the treatment of the anaemia of chronic renal failure (ACRF). DESIGN: The study consisted of two multicentre non-randomised open stages. SETTING: Renal units at several teaching hospitals in South Africa. PARTICIPANTS: Haemodialysis patients with haemoglobin (Hb) levels less than 8.0 g/dl were recruited. The first stage examined 26 patients during a 12-week period in which the dose of intravenous rHuEPO was adjusted according to haematological response. In the second stage 27 patients were stabilised with intravenous rHuEPO and then maintained at a Hb level above 8.0 g/dl by subcutaneous administration for up to 1 year. OUTCOME MEASURES: In both stages, outcome was measured by clinical examination, blood pressure, full haematological parameters and blood chemistry. RESULTS: In stage 1, all patients responded to therapy with a statistically significant increase in Hb from geometric means of 6.28 g/dl to 8.50 g/dl (geometric SDs of 1.17 and 1.20 respectively). The doses used ranged from 25 IU to 125 IU/kg (average 47.1). In the second stage, Hb levels reached a mean of 8.06 g/dl (SD 0.9) and were maintained at target range with an average dose of 55.5 IU/kg three times a week. Apart from changes in serum iron, ferritin (associated with increased haematopoiesis) and potassium, there were no significant alterations in blood chemistry. The incidence of adverse events reported during the 12-month second stage was no greater than that reported for other forms of rHuEPO therapy. CONCLUSION: Repotin is a safe and effective rHuEPO preparation for the treatment of ACRF.

Pharmaco-economic assessment of the HMG-CoA reductase inhibitors.

OBJECTIVE: To perform a comparative pharmaco-economic assessment of two HMG-CoA reductase inhibitors. DESIGN: A cost-effectiveness analysis was employed using comparative efficacy data from selected clinical trials. A comprehensive international literature search formed the basis for this selection. Criteria for inclusion of clinical trial results in the analysis were set a priori. Acquisition costs used were the recommended reimbursement prices as at September 1994. MAIN OUTCOME MEASURES: Two outcome measures are reported: (i) the comparative cost-effectiveness in lowering blood lipid concentrations; and (ii) the comparative cost-effectiveness of the medicines when used to achieve a predetermined therapeutic goal. RESULTS: The average cost per 1% decrease in total cholesterol is 21.9% higher on 10 mg pravastatin daily than on 10 mg simvastatin daily. Similarly the average cost per 1% decrease in low-density lipoprotein (LDL) cholesterol is 23.1% higher on 10 mg pravastatin than on 10 mg simvastatin daily. This difference is consistent throughout the dosage range. The use of incremental doses of simvastatin monotherapy in order to reach a predetermined therapeutic goal (LDL < or = 4.14 mmol/l) is more cost-effective than an equivalent pravastatin dosage regimen. Total treatment costs for simvastatin-treated patients are 3.5% less than for pravastatin-treated patients. More patients on simvastatin are successfully treated; the difference in overall treatment costs per successfully treated patient is 27.9% in favour of simvastatin. Sensitivity analysis shows these results to be stable under extreme scenarios. CONCLUSIONS: This analysis employed objective comparative efficacy data obtained from peer-reviewed sources to compare the economic and clinical outcomes of simvastatin and pravastatin in the treatment of hypercholesterolaemia. The acquisition cost of simvastatin is 10.3-22.8% higher than an equivalent milligram dose of pravastatin, depending on the dosage used. However, because of the greater milligram potency of simvastatin, it is a more cost-effective alternative. Simvastatin therefore provides better value for money than pravastatin in lowering lipid levels in clinical practice.

Aspects of roaccutane prescription in South Africa.

A nationwide postmarketing surveillance study on the use and outcomes of use of isotretinoin has been conducted in South Africa. A representative sample of prescribers of the drug was identified from drug utilisation data and the overall doctor response rate was 90.1%. A total of 766 patients was enrolled in the study, of which 728 were analysable for safety and efficacy. More than half the patients prescribed isotretinoin were women, of whom only 48.25% were practising some form of contraception. The mean overall dosage prescribed was 0.64 mg/kg/day and the mean overall duration of therapy prescribed was 15.5 weeks. The mean dose and duration of therapy prescribed by dermatologists was significantly higher than that prescribed by general practitioners. Potentially dangerous drug interactions involving the concomitant use of isotretinoin with tetracyclines, vitamin A and oral contraceptives together with antibiotics were noted. Mucocutaneous drying effects were the most common adverse events and the incidence of these effects decreased with continuation of therapy. The known effectiveness of the drug was confirmed by the results of the study.

Zocor, the postmarketing experience.

The aim of this study was to develop and test a descriptive, intensive drug surveillance methodology in order to examine the effectiveness and safety of new drugs in the immediate postmarketing period. The HMG-CoA reductase inhibitor, simvastatin (Zocor), was chosen as the test drug. Data were collected from 100 randomly chosen cardiologists, specialist physicians and general practitioners practising in the six main centres of South Africa. A 66% doctor response rate was achieved and 438 patients were enrolled in the study. The overall effectiveness expressed as a percentage decrease (from baseline) in total cholesterol levels was 20.5% for the 251 patients who started on a 10 mg daily dose of the drug and 27.6% for the 42 patients who started on 10 mg but changed to 20 mg/d. The safety profile of simvastatin was comparable with the premarketing clinical trial data, and patient non-compliance appeared to be dose-related. The methodology employed was found to be suitable for the collection of safety and effectiveness data in the postmarketing period and simvastatin was shown to be effective with few adverse events reported.