Evaluation of ear tags impregnated with cypermethrin for the control of sheep body lice (Damalinia ovis).

The application of polymer matrix ear tags impregnated with 8.5% w/w cypermethrin to 6 wethers following shearing reduced lice to non-detectable levels on 4 of them at 29 weeks after tagging. At the conclusion of the study at 45 weeks the mean count of lice on tagged wethers was 3 per sheep compared to 158 on untreated wethers. In a second experiment, 6 non-infected sheep were treated at shearing with cypermethrin tags, 6 with 25 g/l cypermethrin backline formulation, 6 with tags plus backline and 6 were left untreated. Each group was exposed to 6 sheep with moderate to heavy infestations of lice. Compared to controls, all treatments delayed infestation, but cypermethrin tags gave no longer protection than backline treatment. All sheep were infested by 17 weeks after commencement of the study. At 45 weeks mean counts of lice were 38, 27, 20 and 74 respectively for sheep treated with tags, backline formulation, backline plus tags and untreated. Possible reasons for the better effect observed from applying tags to infested sheep than to sheep which were not infected at application but which were subsequently exposed to infested sheep are discussed.

Effect of insecticidal ear tags on populations of lice (Damalinia ovis) infesting sheep.

Polymer matrix ear tags containing 13.7% w/w tetrachlorvinphos or 8.5% w/w cypermethrin were applied to Merino wethers infested with lice and carrying two months wool. The cypermethrin tags reduced louse numbers by a maximum of 89% in comparison to controls at 16 weeks after treatment and by 85% at the conclusion of the experiment 38 weeks after application. Lice were not eradicated from any sheep. The number of lice counted on sheep treated with tetrachlorvinphos-impregnated tags was not significantly different from controls.

Evaluation of high protein oats as a replacement for corn in diets fed to growing-finishing swine.

In a series of five trials, 680 crossbred pigs were fed isolysine diets in which high protein (13.8 to 16.0%) oats constituted 0, 20, 40 or 60% of the cereal portion. There was a linear depression in average daily gain (P less than .001) and average daily feed intake (P less than .005) with increasing level of oats, but feed/gain was unaffected (P less than .05) during the growing period from 22 to 46 kg. There were no significant differences in average daily gain during the finishing period from 46 to 102 kg; however, feed/gain increased linearly (P less than .01) with increasing level of oats in the diet. Increases in the percentage of oats in the cereal portion of the diet resulted in a linear (P less than .01) decrease in average daily gain and an increase (P less than .01) in feed/gain for the entire feeding period. We conclude that high protein-high lysine oats of the quality used in these trials can be included at up to 20% of the cereal portion of the diet without greatly affecting performance.

Effect of bambermycins and tylosin on performance of growing-finishing swine.

Five experiments (five different locations) with a total of 1,230 pigs (135 pens) were conducted in Minnesota, Missouri and Indiana to study the effects of supplementary bambermycins (2.2 ppm) and tylosin (44 or 22 ppm) in swine diets. The antibiotics were fed during the growing and finishing periods, and effects on rate of gain and efficiency of feed conversion were measured. A significant improvement in ADG and F:G over the control pigs was observed with the bambermycins treatment. A numerical but nonsignificant improvement in ADG and a significant improvement in F:G over control were observed with the tylosin treatment. The performance was divided into growing and finishing periods. In the growing period, bambermycins and tylosin numerically but nonsignificantly improved ADG and F:G over control pigs. The finishing period response to bambermycins was significantly improved for ADG and F:G. The tylosin finisher response was numerically but nonsignificantly improved for ADG and F:G over negative control. Significant location effects were observed. This result would be expected due to variation in genetic background of the experimental animals and differences in housing, environment and management.