WHOLE COTTONSEED AND CRUDE GLYCERIN FOR NELORE CATTLE ON PASTURE : INTAKE AND DIGESTIBILITY OF NUTRIENTS

Abstract Text: Use of by-products in the beef cattle diets have important function to reduce production costs and needs to be evaluate in different production systems. The aim of this experiment was to evaluate intake and digestibility of nutrients in beef cattle diet with associations of whole cottonseed and crude glycerin in multiple supplements for  Nelore cattle in the fattening phase at Brachiaria brizantha pastures in the rainy season. Animals were supplemented with 4 kg/d (21% of crude protein). The experiment was performed in a 5x5 (5 supplements and 5 periods) Latin square design and structured in a factorial design 2x2+1 (2 levels of crude glycerin (0 and 15%), 2 levels of cottonseed (0 and 25%) and supply of mineral mix (control)). Orthogonal contrasts were used to evaluate effect of crude glycerine, whole cottonseed and interaction, adopting 0.05 to the critical level of probability. The supplementation increased dry matter intake at 2.25 kg/day (p= 0.037), due largest apparent digestibility of dry matter in function of fed supplements (65.83%) in relation to the control treatment (55.69%) (p< 0.05). Multiple supplements increased intake of ether extract  (0.370 vs. 0.170 kg/d)(p< 0.05), crude protein (1.380 vs. 0.720 kg/d)(p< 0.001), and no fiber carbohydrates (3.715 vs. 2.07 kg/d)(p< 0.001), due to higher content of these nutrients in supplements when compared with only forage/mineral mix. Ether extract intake was still affected by the inclusion of whole cottonseed in supplement (p< 0.05) due high concentration of oil in this ingredient. Apparent digestibility of ether extract in the diets evaluated was affected by supplementation (p< 0.05) and whole cottonseed inclusion (p< 0.05) and assigning it lower contribution of endogenous excretion of ether extract when their content is high in diet. Intake and digestibility of neutral detergent fiber were not affected (p> 0.05), evidencing that extra supply of nutrients did not affect the cellulolytic microbiota, with appropriate digestibility of most abundant energy unit in grazing production system. By-products that reduce diets costs and improve voluntary dry matter intake are important in nutritional formulations because are responsible for most of the variations in productive performance.

Keywords: by products, Nelore, pastures