Menu
Soybean meal (SBM) is the most commonly fed protein ingredient in poultry diets worldwide, but relative high cost and long distance transportation imply consideration of local alternative protein sources. Faba bean (FB) is relatively high in both starch (39.7–43.8%) and protein (24.7–37.2%) and is locally grown in Canada. Faba bean is gaining popularity, however, the presence of anti-nutritional factors such as vicine (6.0 g/kg), convicine (1.6 g/kg), and tannins (6.6 g/kg condensed tannins) limits FB inclusion in poultry diets. The objective of this experiment was to investigate the effects of feeding zero-tannin or high-tannin FB cultivars and dehulling on broiler growth performance, carcass traits, and yield of saleable cuts. This experiment directly addresses the lack of information feeding FB to broiler chickens.
For half of each FB cultivar (zero-tannin FB cultivars: Snowbird and Snowdrop, and high-tannin FB cultivars: Fabelle and Malik), hulls were then removed using a combination of blowing air and mesh sieving. Male broiler chicks (Ross 708; n = 585) were individually weighed (42.0 ± 0.2 g) and randomly allocated to 63 cages. At 25 d of age, 1 or 2 broilers per cage with the lowest BW were removed to reduce stocking density to 8 broilers per cage. Broilers were fed 1 of 9 regimens from 0 to 41 d of age. The control regimen was a SBM-wheat grain-based diet, whereas the treatment regimens included 1 of 4 FB cultivars (Snowbird, Snowdrop, Fabelle, or Malik), either non-dehulled or dehulled replacing part of the SBM and wheat grain. In the starter (0–12 d), grower (13–25 d), and finisher phase (26–41 d), treatment diets included 12, 24, and 36% FB, respectively. Individual broiler BW, and feed disappearance were weighed on days 12, 25, and 41. Broilers were slaughtered early the following morning and processed following commercial conditions (day 42 to 43 of age). Broilers were euthanized and carcasses and saleable cuts were weighed.
For all growth performance variables analyzed, there was no cultivar × dehulling interaction. For the overall trial and finisher phase, broilers fed Snowbird and Fabelle had the greatest ADFI and Malik the lowest; Snowdrop was intermediate (P < 0.05). Broilers fed dehulled FB had greater ADFI but lower G:F than those fed non-dehulled FB for the grower phase only (P < 0.01). Because of this dehulling effect limited to the grower phase only, reduced overall broiler ADFI was not likely due to hull tannin content. For the overall trial, broilers fed Fabelle diets had greater ADG compared with broilers fed other FB cultivars (P < 0.01). Overall G:F was greatest for Fabelle and lowest for broilers fed Snowbird (P < 0.01); Broilers fed FB had decreased carcass weight and dressing percentage compared with controls (P < 0.05). For all variables analyzed, there was no cultivar × dehulling interaction on carcass traits and yield of saleable cuts. Broilers fed Snowbird had the greatest BMY and pectoralis major yield, and Fabelle had the lowest (P < 0.01). Feeding non-dehulled FB increased total BMY and pectoralis major compared with dehulled FB (P < 0.05).
Broilers fed FB Fabelle had the greatest ADG and feed efficiency (G:F) possibly because this feeding regimen had the lowest vicine and convicine content. Hence, vicine and convicine content should be of greater consideration than tannin content when formulating poultry diets with modern FB cultivars. Other than slightly increasing (3%) breast yield (pectoralis major), dehulling FB and therefore hull tannin and(or) fiber content had no effect on broiler growth performance, chilled carcass weight, dressing percentage, and yield of other saleable cuts. Therefore, FB can be readily fed to broiler chickens without the need for dehulling. Feeding FB diets slightly reduced ADG, G:F, chilled carcass weight, and dressing percentage compared with the SBM-wheat control regimen. These results indicate that the 4 FB cultivars tested (Snowbird, Snowdrop, Fabelle, and Malik) can be fed to broilers up to 12, 24, and 36% in the starter (0–12 d), grower (13–25 d), and finisher phase (26–41 d) when diets are formulated to the same SID lysine to AMEn ratio.