The effects of anabolic agents and breed on the fibers of the longissimus muscle of male cattle

Sample of longissimus muscle were taken from carcasses of steers, steers implanted with anabolic agents and bulls of Friesian and Charolais X Friesian breeds of cattle. Percent and mean cross-sectional areas (CSA) of three myofiber types (beta R, alpha R and alpha W) were determined. The percentage of beta R myofibers did not vary significantly with treatment. The implanted steers had 26% more alpha R and 8% less alpha W myofibers than the untreated steers, while the bulls had 33% more alpha R and 20% less alpha W myofibers than the implanted steers (P less than .001). In the implanted steers the mean CSA of the beta R myofibers was significantly greater than that of the untreated steers, but did not differ from that of the bull. The mean CSA of the alpha R myofibers increased considerably with treatment, but only that of the bull was significantly greater than that of the untreated steers. The mean CSA of the alpha W myofibers in the implanted steers was identical with that of the untreated steers and significantly smaller than that of the bulls. In comparison to the untreated steers, significant hypertrophy of all three myofiber types occurred in bulls. These findings demonstrate a significant increase in the oxidative capacity of the longissimus when the levels of both endogenous and exogenous anabolic agents are increased. They are also consistent with the greater efficiency of deposition of protein obtained with implanted steers and bulls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of general anesthesia on myoelectric activity of the intestine in horses.

Myoelectric activity was monitored from the terminal ileum, cecum, and colonic pelvic flexure by use of AgpAgCl bipolar electrodes in 4 adult horses before, during, and after general anesthesia. Horses were anesthetized by way of 3 commonly used regimens, including xylazine (1.1 mg/kg of body weight) and ketamine hydrochloride (2.2 mg/kg); thiopental sodium (7.7 mg/kg), followed by halothane vaporized in oxygen; and thiopental sodium (2.5 g) in guaifenesin (100 mg/ml) solution given to effect, followed by halothane in oxygen. All 3 anesthetic regimens decreased intestinal spike-burst activity in the areas monitored. The slowest return to preanesthetic myoelectric activity was observed after xylazine and ketamine administration. After both of the barbiturate/halothane anesthetic regimens, there was a rebound increase in spike-burst frequency, without alteration in the proportion of propagative myoelectric events. All 3 anesthetic regimens appeared to reset the timing of the small and large intestinal migrating myoelectric complexes. By 9 hours after recovery from anesthesia, the effects of anesthesia, irrespective of regimen, had disappeared. Although anesthesia significantly (P less than 0.05) altered intestinal myoelectric activity, no particular anesthetic regimen had a prolonged effect. Results of our study indicate that the particular chosen regimen of general anesthesia is unimportant in development of motility disturbances in horses after anesthesia.     

Effects of repeated handling on the cortisol responses of young lambs castrated and tailed surgically

Changes in the plasma concentrations of cortisol were recorded in 5-6 weeks-old lambs during the first 480 minutes after surgical castration and tailing in order to define the full post-treatment cortisol response and to determine whether or not the handling associated with repeated blood sampling delayed the return of cortisol concentrations to pretreatment values. Four groups of six or seven lambs were studied: One group was bled regularly throughout the 480 minutes of the study, and in the other three post-treatment blood sampling began at 90, 240 or 480 minutes. Plasma cortisol concentrations increased after treatment and returned to or approached pretreatment values by 480 minutes. No significant differences in mean cortisol concentrations were observed between the groups at any stage. It is concluded that the acute distress response of these lambs to surgical castration and tailing lasted about 8 hours and that repeated handling for blood sampling did not contribute significantly to this distress.     

Cortisol responses of young lambs to castration and tailing using different methods

Lambs at 4-5 weeks of age were studied during the first 4 hours after castration and/or tailing using three methods in various commonly used combinations. The methods were cutting with a knife, application of constricting rubber rings and using a heated docking iron (tailing only). The integrated cortisol response (area under the cortisol curve) was determined for each lamb during the first 4 hours after treatment and was considered to reflect the overall magnitude of the lamb's acute distress response. On that basis, cut lambs (tailing only, castration only, castration plus tailing) experienced more distress than any other groups. Also the distress response (indicated by elevated plasma cortisol concentrations) lasted longer than 4 hours in cut lambs, unlike all other groups. The use of rings apparently caused similar distress when lambs were castrated only, were castrated plus tailed, or were short-scrotumed (testes pressed against the abdominal wall by a distally located scrotal ring) plus tailed. The magnitudes of distress apparently caused by tailing alone with a ring or a docking iron were similar and were lower than the distress caused by any other castration and/or tailing procedure. It is concluded that acute distress responses to these husbandry procedures would be minimised in lambs of this age if rings and/or a docking iron were used in preference to a knife.     

Actinobacillus capsulatus peritonitis and chyloabdomen in a Warmblood gelding

Primary peritonitis in horses attributable to Actinobacillus equuli has been reported in Australia, New Zealand and North America. Published reports describe a rapid response to treatment with appropriate antimicrobial and supportive treatment and an excellent prognosis for survival. To our knowledge, this is the first reported case of Actinobacillus capsulatus in the horse. The case was complicated by the development of an idiopathic chylous abdominal effusion. The report highlights the importance of molecular methods in the correct identification of bacterial species. Prognosis for horses diagnosed with Actinobacillus peritonitis may be guarded given the atypical response to appropriate antimicrobial treatment in this case.     

Comparative efficacy of flubendazole and a commercially available herbal wormer against natural infections of Ascaridia galli, Heterakis gallinarum and intestinal Capillaria spp. in chickens

The efficacy of a commercially available flubendazole-based product and a commercially available herbal product were compared against three species of helminth parasites of chickens: Ascaridia galli, Heterakis gallinarum and Capillaria spp. A total of 48 naturally infected chickens were used in the study with 16 birds in each of three treatment groups (untreated control; flubendazole; and a herbal product). One bird from each treatment group was necropsied on Day 0 prior to first treatment to confirm the parasite species present in the birds. Treatments were administered as labelled and the 45 remaining birds were necropsied on Day 12 and worm counts performed. Average worm counts in the two treated groups were compared to the untreated controls to calculate efficacy. Flubendazole (Group A) achieved an overall efficacy of 99.4% for the three parasite species. The herbal product (Group B) achieved efficacies ranging from less than zero to 11.6% for the three parasites, with worm counts not significantly different to the untreated controls. At present, commercially available herbal products claiming anthelmintic properties do not require licencing as veterinary medicinal products (Directive 2004/28/EC: see Article 17 and 33-38) and thus are not required to meet specific efficacy thresholds. Products which do not appear to deliver acceptable anthelmintic efficacy, are obviously a concern from many aspects but specifically from an animal welfare perspective.