Economic losses caused by the use of low-efficacy anthelmintic drugs in growing heifers.

The aim of this study was to compare the economic revenue related to the use of low- or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high- and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil.

Metabolism, intake, and digestibility of lambs supplemented with organic chromium.

The aim of the present study was to evaluate the metabolism of organic chromium and its effect on digestibility and intake of lambs. Four 4-month-old male lambs, each weighing 28 kg, were used. The animals were kept in metabolic cages for a period of 20 days (15 days of adaptation and 5 days of experimentation), in two experimental phases, with inverted treatments. Organic chromium was administered by intraruminal infusion of 1 mg of chromium-rich yeast (Saccharomyces cerevisiae) throughout the adaptive and experimental period. The dry material rates of the diet and feces of the animals were evaluated to estimate consumption, digestibility, and fecal production. During the experimental period, blood, feces, and urine were collected every 24 h to determine chromium levels. There was no significant difference in the excretion of chromium in the urine, and no mineral remnants were detected in the blood. Excretion was generally fecal. There was greater excretion of chromium in the feces of lambs in the treated group on day 0 and day 3, compared with the control group. The use of organic chromium promoted an increase in the consumption of dry material in the treated animals only at day 0 (P <0.05). The production of fecal dry matter was greater among the treated lambs than among the animals of the control group on day 1, day 2, day 3, and day 4 (P <0.05). The results obtained showed that organic chromium associated with live yeasts is not absorbed by the body and do not affect the intake time in the dose used.