Energy intake and nutrient digestibility in heavy finishing swine fed varying levels of soluble fiber

Abstract Text: Depending on its characteristics, dietary fiber may depress daily energy intake and utilization of dietary nutrients in growing pigs. These effects are likely lower in finishing pigs. This study was conducted to determine the effect of increasing dietary levels of soluble fiber on daily feed and energy intake, as well as apparent fecal nutrient and energy digestibility in finishing pigs. In total 36 individually housed barrows (commercial crossbred; initial BW 78.38 ± 0.32 kg), were assigned to 4 dietary treatments in a randomized block design: control (corn and soybean meal based; 3229 kcal/kg calculated ME, 13.9% CP, 1.5% soluble fiber) and three isonitrogenous diets with increasing levels of soluble fibers (4, 8 and 12%; from added pectin, containing 63% of soluble fiber), and consequently decreased levels of calculated ME (3095, 3017 and 2946 kcal/kg). Pigs were fed ad libitum. At a BW of 105 kg, feces were collected twice daily, during three days. Insoluble ash was used as marker for determining digestibility. Statistical analyses were performed using the PROC MIXED procedure of SAS. The results showed a linear decrease for both daily feed intake (P =0.0157) and daily DE intake (P = 0.0005) between 100.86 and 126.19 kg BW. Quadratic effects (P <0.0001) were observed for the digestibility of DM, GE and CP; the maximum digestibility values were obtained at 0.74, 1.33 and 1.60% additional soluble fiber in diet, respectively. There was linear decrease (P <0.0001) for the digestibility of ash. These results confirm that feedstuffs containing soluble fiber can be used to reduce daily energy intake in heavy finishing pigs through qualitative feed restriction, but its negative effect on the nutrient digestibility must be considered.

Table 1. Daily feed (kg/d) and DE intake (kcal/d), as well as apparent fecal digestibility (AFD, %) of energy and nutrients in finishing pigs fed diets containing different levels of soluble fiber (SF).

	Experimental diets (% SF)
	1.5	4	8	12	SE	Effect of diet SF
Daily feed intake	1.64	1.56	1.61	1.34	0.18	Linear
Daily DE intake	6822	5792	5937	4925	317.32	Linear
AFD
DM	89.75	89.26	87.54	85.35	0.32	Quadratic
GE	89.92	90.19	88.21	86.29	0.33	Quadratic
Ash	51.91	45.38	34.94	28.05	1.09	Linear
CP	86.64	87.63	84.99	82.90	0.69	Quadratic

Keywords: daily energy intake, feed restriction, soluble fiber