Caracterização da digestibilidade aparente de rações contento níveis crescentes de proteína bruta na alimentação de juvenis de Matrinxã Brycon Amazonicus

Abstract

The objective of this study was to characterize the apparent digestibility of feeds containing increasing levels of crude protein in the feed of matrinxã. The experimental units consisted of groups with 10 matrinxã juveniles, totaling 120 fish, with three replicates per treatment. The collected data were submitted to polynomial regression analysis at 5% significance. They were observed in the dry matter digestibility, with an increase in nutrient utilization from the increase of the protein level in the rations. This behavior was directly reflected in the digestibility of the other nutrients by matrinxã juveniles, such as ash, crude protein, apparent digestible energy, apparent digestible energy digestibility and energy: protein ratio. However, this behavior was not observed in the digestibility of the ethereal extract. The digestibility of nitrogen, phosphorus, calcium, magnesium, copper and zinc showed positive linear behavior, increasing its utilization from the increase of the protein level in the rations. However, the digestibility of potassium, iron and manganese reduced from the increase of the level of protein in the rations. The present study indicated that the increase of the protein level in feeds for juveniles of matrinxã improved nutrient digestibility. Our results indicated that 40% crude protein in the diets presented better results. However, the exacerbated increase in protein levels, and consequently nitrogen, in rations can cause metabolic imbalances, weakening the absorption and utilization of some nutrients, such as microminerals.