Digestibility of the diet of grazing Nellore bulls receiving concentrated supplementation with additives

Abstract Text: The objective of this study was to evaluate the effect of a commercial concentrate supplement with additives in the digestibility of the nutrients on grazing bulls, during the dry/rainy transition season in Aquidauana-MS, Brazil. Twelve Nellore bulls (initial body weight of 370±15 kg) were randomly assigned to twelve Brachiaria decumbens Stapf pastures (1.0 ha/pasture; one bull/pasture) on a completely randomized design. Treatments were: 1) concentrate supplement Lipomax^® with homeopathic additives (Convert H^®, Sodo 100^®, Figotonus^®) and Virginiamicina^® (Lipomax treatment), and 2) concentrate supplement with a similar protein content (18% CP), and without additives (Control treatment). Animals were feed daily at rate of 0.5% of the animal’s body weight. After 45 days, when the animals achieved body weight closed to 420 kg, the digestibility trial started. Digestibility was estimated using the enriched and purified lignin (LIPE^®) as marker for fecal excretion estimation, and the indigestible neutral detergent fiber as internal marker. Forage nutritive value was estimated by hand-plucked sampling, and supplement intake was measured directly for each animal. A significance level of 5% was adopted. The coefficients of digestibility (CD) of the nutrients were obtained by the intake and composition of the forage and the supplement, and by analysis of feces, which was collected for five consecutive days. A significance level of 5% was adopted. The digestibility of the ether extract differed (P<0.05), was greater in the Control treatment (Table 1) and no other differences were significant. The similarity in composition between concentrated supplements, and the fact that the concentrate represented just around 10% of the diet of the animals influenced these results. The additives appears to work just in the animal’s metabolism, without affecting the diet digestibility.

Table 1. Digestibility of the diet of grazing Nellore bulls receiving concentrated supplementation with or without additives

Item, %	Treatments		CV (%)	P-value
	Control	Lipomax®
CDEE1	79.0a	67.9b	7.19	0.004
CDCP2	77.8	75.2	7.46	0.359
CDNDF3	68.2	67.8	7.88	0.817
CDNFC4	74.7	73.8	11.4	0.949
ME5 (Mcal/Kg)	2.488	2.395	4.68	0.187

¹CDEE is the coefficient of digestibility of ether extract, ²CDCP is the coefficient of digestibility of CP. ³CDNDF is the coefficient of digestibility of NDF. ⁴CDNFC is the coefficient of digestibility of non-fiber carbohydrates. ⁵ME is the metabolizable energy of the diet.

Keywords: additives, digestibility, grazing bulls