Feeding value of field beans (Vicia faba L. var. minor) with and without enzyme containing tannase, pectinase and xylanase activities for broilers

ABSTRACT

Effects of field beans with various tannin content and exogenous enzyme mixture containing tannase, pectinase and xylanase activities on N-corrected dietary apparent metabolisable energy (AMEn), coefficients of dry matter (DMR) and nitrogen retention (NR), fat digestibility, gastrointestinal tract (GIT) development, jejunal villus morphometry, ileal digesta viscosity and sialic acid were examined. Birds’ growth performance and energy conversion ratio (ECR) were also measured. Birds were fed one of eight mash diets. The Control diet contained as major ingredients wheat (400 g/kg) and soybean meal (SBM) (127 g/kg and 221 g crude protein/kg and 12.83 MJ AMEn/kg. To reduce nutrient density, the Control diet also contained washed sand at 119 g/kg. Another three diets containing 300 g/kg of each of three experimental field bean cultivar samples in replacement for SBM and sand were also mixed. Each diet was fed to nine pens with two male Ross 308 broilers. Diets high in tannin had low AMEn, ECR, DMR and NR (p < 0.001). Feeding field beans increased (p < 0.001) the weights of the pancreas and the proventriculus and gizzard (PG) of the birds. Supplementing diets with the enzyme mixture improved (p < 0.001) feed conversion efficiency, AMEn and all nutrient utilisation coefficients despite the tannins in diets. The enzyme mixture reduced ileal digesta viscosity (p < 0.001) and the weight of pancreas, total GIT and PG (p < 0.05) of the birds. It can be concluded that the feeding value of field beans with different tannin contents may vary when fed to broilers. The supplementation of the enzyme mixture improved the feeding value of diets for broilers. The beneficial effect of the addition of the enzyme mixture seems to be mediated through reduced ileal digesta viscosity and improved nutrient availability.

KEYWORDS:

• Broilers
• digestibility
• field bean (Vicia)
• metabolizable energy
• morphometrics
• performance
• tannase

Acknowledgements

We thank Richard James, Rose Crocker, Amjad Ali, Kevin Jones and Waseem Mirza for their technical support. We also thank Kerry Ingredients and Flavours (Ireland) for providing us with the enzyme and Askew & Barrett (Pulses) Ltd. which donated the field bean samples for this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This experiment is a part of a PhD project funded by the Ministry of Higher Education and Scientific Research – Kurdistan Regional Government – Iraq.