Utilização de glicerina bruta na alimentação de cabras em lactação: concentração de metais essenciais e tóxicos em soro sanguíneo, urina, leite e queijo tipo coalho

Abstract

Goat farming is concentrated in semi-arid and tropical regions in Brazil. In 2006 to 2017 the number of goats sold in the country increased by 65.7%. The dairy products of these animals have a higher digestibility, high content of vitamin A and B, hypoallergenicity and less lactose compared to cow, in addition to the higher sales value. Since corn and soy meal generate an expense for food handling, crude glycerin, which originates from the manufacture of biodiesel, is studied as an energy substitute, but contains heavy metals, which can portray risks to animal and human health. There are few data regarding trace elements in biological samples and products derived from milk in goats with a dietary introduction of glycerin. The objective was to quantify metals in blood serum, urine, milk and rennet cheese in dairy goats fed with varying levels of crude glycerin in food handling. 16 Saanen goats were selected, lactating females that were distributed in four Latin squares and randomly treated with different levels of crude glycerin 0, 5, 10 and 15%. After the completion of each cycle of the experiment, blood, urine, milk and rennet cheese samples were collected at the four moments. The samples were submitted to digestion by microwave radiation. The multielemental analysis was carried out by means of optical emission spectrometry with inductively coupled plasma (ICP-OES). There was no influence of the levels of crude glycerin, replacing corn in whey, milk, urine and rennet cheese. The serum concentration of the metals Cu, Fe, Zn and Mn; Cu, Zn, Mn, Mo and Cr urine; milk and rennet cheese referring to Cu, Zn and Mn, remained within the standards found in the literature. The inclusion of 5 to 15% of crude glycerin, derived from cotton oil in the diets of dairy goats in partial replacement to corn, does not alter the concentration of essential and toxic metals in blood serum, urine, milk and rennet cheese, not establishing therefore, a risk factor for intoxication.