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UBC Theses and Dissertations

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UBC Theses and Dissertations

The establishment of a dietary interaction between molybdenum and selenium based on weight gain and feed consumption in broilers Weisstock, Silvia Rita


A series of three experiments were carried out in order to demonstrate an interaction between molybdenum and selenium in broilers. Trail I investigated the interaction of selenium (0, 0.2, 0.4, and 0.8 ppm) with various toxic and subtoxic dietary levels of molybdenum (0, 0.5, 100, and 330 ppm), supplemented to a wheat based diet to broilers from one to four weeks of age. Results indicated that at 300 ppm molybdenum, increasing selenium levels resulted in progressive decline in weight gain, compared to a non-significant decline across these selenium levels when no molybdenum was supplemented. At these levels of molybdenum, selenium appeared to be acting antagonistically with molybdenum. At lower molybdenum levels, selenium exerted no apparent effects on weight gain. Selenium at toxic levels responded different from selenium at subtoxic dietary levels over molybdenum levels. Trial II, used 480 broiler chicks, assigned in a randomized block (RB) experimental design and 12 treatment combinations of selenium and molybdenum. Although the overall interaction effect was non-significant for weeks 1 to 4 inclusive, there were some definite interaction trends. Results indicated that at either basal or 3 ppm Se over basal 100, 200, or 300 ppm Mo, a non-significant difference in weight gain and feed consumption occurred. Selenium and molybdenum appeared to be interacting reciprocally. At 6 ppm dietary supplementation of selenium, however, combining increasing levels of molybdenum appeared to result in an independent toxic effect on weight gain which was additive for the two mineral toxicities, and not interactive. Using 480 broilers chicks assigned to a 3 x 4x3x3 multifactorial arrangement of 12 treatments an experiment was performed to investigate the effect on weight gain and feed consumption upon feeding toxic levels of molybdenum and selenium. Selenium levies ranged from basal, to 6, 12, and 18 ppm and molybdenum levels from basal, 400, and 800 ppm. Treatments were arranged in a RB experimental design. Results indicated that combining toxic dietary levels of selenium and molybdenum resulted in a measurable interaction in birds based on weight gain to feed consumption from one to four weeks of the experimental period. As the toxic dietary levels of selenium increased from basal to 6, 12, and 18 ppm the adverse effect of molybdenum at basal, 400 and 800 ppm became progressively reduced. At 18 ppm selenium, weight gain and feed consumption were the same irrespective of whether basal, 400, 800 ppm Mo was supplemented to the diet. The presence of toxic levels of selenium appeared to either reduce toxicity of molybdenum, or induce an increased tolerance for increasingly toxic levels of molybdenum. The nature of the interaction between selenium and molybdenum is discussed.

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