Effect of crude glycerin and soybean oil on intake and digestibility of Nellore bulls

Abstract Text: Crude glycerin is byproduct in the production of biodiesel, and because of its availability and nutritional properties, it has become an attractive choice for use as a feed supplement for ruminant animals. The objective was to evaluate the DM and NDF intake, and digestibility of Nellore bulls fed feedlot diets containing crude glycerin or soybean oil. We utilized 28 Nellore bulls (408 ± 28 kg and 18 ± 2 mo) in a completely randomized design with 4 treatments arranged as a 2 × 2 factorial with two levels of glycerin (0 or 10% on DMB) and two levels of soybean oil (0 or 6% on DMB). All treatments contained 60% corn silage and 40% concentrate. The experimental period was 105 d, with 21 d of adaptation and three periods of 28 d. Fecal samples were collected during three days, in 3 different times for each period, for each animal and values averaged used for digestibility. For estimate the excretion of fecal matter was used indigestible neutral detergent fiber. Data were analyzed using the MIXED procedure (SAS Inst. Inc., Cary, NC). There were no interactions between glycerin and soybean oil for DM and NDF intake (P > 0.05). Feeding oil or glycerin decreased DM intake (P < 0.01 and P = 0.04, respectively). Intake of NDF was not altered (P = 0.13) by inclusion of glycerin in the diets; however, inclusion of oil in the diet decreased NDF intake by 8.9%. For digestibility, there were interactions between the factors for DM, OM, and EE (P < 0.05). Digestibility of DM and OM was decreased by soybean oil and by a greater amount with glycerin included as well. Adding glycerin alone without oil increased DM and OM digestibility, due to increased fiber digestibility. Adding oil in diet increased EE digestibility. Thus, crude glycerin can be an alternative source of energy for Nellore bulls fed feedlot without depressing fiber digestibility.

Table 1. Simple effects of crude glycerin and soybean oil on intake and digestibility of Nellore bulls in feedlot

	Gly			No Gly			P-values
	Oil	No Oil		Oil	No Oil		Gly	Oil	Gly × Oil
Intake, kg/d
DM	8.45	9.72		8.87	10.30		0.04	< .01	0.73
NDF	2.56	2.70		2.56	2.92		0.13	< .01	0.13
Digestibility, g/kg
DM	693.7c	771.8a		698.8c	737.4b		0.02	< .01	< .01
OM	700.5c	777.9a		706.4c	743.5b		0.04	< .01	< .01
NDF	429.5	563.6		403.9	517.9		< .01	< .01	0.37
EE	884.8a	789.6b		886.6a	741.9c		0.02	< .01	0.01

Keywords: digestibility, glycerol, oil