Application of a β -Mannanase Enzyme in Diets with a Reduced Net Energy Content Results in Reduced Production Costs Per Kg of Carcass Weight

Abstract

β-Mannans are strongly anti-nutritive polysaccharide fibres found in most vegetable feed ingredients. They belong to the hemicellulose fraction and have a backbone composed entirely of mannose, as in mannans and galactomannans, or of mannose and glucose, as in glucomannans and galacto-glucomannans. The estimated content of soluble β-mannans in common fattening diets is only 0.20-0.35%, and in vitro studies have demonstrated that as little as 0.05% soluble β-mannan in feed can elicit a strong innate immune response. This innate response is often referred to as a feed induced immune response or FIIR, which suppresses growth to protect the liver and reserve energy and nutrients for high priority immune functions. Hemicell HT (Elanco Animal Health) is a β-mannanase enzyme for animal feed that breaks down β-mannans and thereby prevents economic losses from the wasteful immune response to β-mannans. The aim of the present study was to compare pig performance and carcass parameters on a control diet and a reformulated diet with lower energy content - a 65 kcal reduction in net energy per kg – and inclusion of a β-mannanase enzyme. An eighteen-week feeding trial was conducted on a commercial fattening unit with DanBred x Belgian Piétrain pigs starting at 10 weeks of age. Standard two-phase control diets (Control group) were compared to reformulated diets with an energy reduction of 65 kcal NE/kg and inclusion of a β-mannanase enzyme (Hemicell HT; Elanco) at 300 g/tonne (Enzyme treated group). Standard production and health data were collected including days in fattening, bodyweight at start, at 28 days and at 127 days (prior to slaughter), feed intake, mortality and antibiotic use. Additionally, Average Daily Weight Gain (ADWG), Average Daily Feed Intake (ADFI) and Feed Conversion Rate (FCR) were calculated from the collected data. Furthermore, pigs were slaughtered on separate slaughter days to reliably collect relevant carcass parameters at slaughterhouse level. The data were analysed using JMP 15.0 statistical program. Overall, performance data did not differ significantly between trial groups in both Phase 1 and Phase 2, except for mortality that was significantly higher during Phase 1 in the Control group (3.19% vs. 0.00% in the Enzyme treated group). Carcass quality did only significantly (P < 0.05) differ for muscle depth (73.58 ± 0.66 mm vs. 75.33 ± 0.59 mm in the Control and Enzyme treated group, respectively). Following calculation of feed costs per kg carcass weight and considering the cost of enzyme inclusion, Enzyme treated pigs had € 0.033 lower feed costs per kg carcass weight as compared to Control pigs. The trial demonstrated that inclusion of Hemicell HT in reformulated diets with a lower energy content (65 kcal NE/kg) was able to degrade β-mannans in diets and therefore maintain production performance and overall carcass quality. Reduction in mortality may indicate an improved overall immunity due to decreased FIIR by the breakdown of β-mannans in the feed. Inclusion of a β-mannanase enzyme resulted in an overall reduction in production costs of € 0.033 per kg of carcass weight, which is an additional advantage considering the current feed prices globally.