Evaluation of organic salts on the performance of dairy crossbred milking cows and growing animals on pasture

The use of additives in ruminant diets has occurred more intensely in recent years to increase animalperformance, through changes in the ruminal microbiota. Thus, this study aimed to evaluate: 1) the use of Isomix (Iso)and virginiamycin (Vir) in concentrate, in a 2x2 factorial (without and with 30 g of Isomix/cow/day; without and with 210mg of virginiamycin/cow/day), on the productive performance of mixed cows on pasture; 2) the use Isomix in multiplesupplement (without and with 30 g of Isomix/animal/day), on the productive performance of pasture growing dairy mixedanimals; and 3) the use Isomix in concentrate, at an increasing level (without and with 30, 60 or 90 g of Isomix/cow/day),on the productive performance of crossbred cows on pasture in the wet season. The work was conducted at Fazenda BoaVista, district of Cachoeira de Santa Cruz, Viçosa, MG, and belonging to the Federal University of Viçosa. In experiment 1,there was no significant effect of the additives in the concentrate on milk production in cows producing 13.4 kg of milk/dayin tropical pasture during the wet season, and more production research and nutritional parameters were required underthese conditions. In experiment 2, there was an effect of Isomix on body weight gain, and therefore, the use of this additivein multiple supplements is recommended to improve the performance of growing cattle in the wet season, depending on thecost-benefit ratio with supplementation. In experiment 3, there was no significant effect of Isomix on the concentrate onmilk production in cows producing 6.8 kg of milk/day, with presence of calves during milking, in tropical pasture of the wetseason, but there was a tendency to increase fat, protein and lactose contents with the use of Isomix, being a possible benefitfrom the use of that additive.