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

Special Article - Pig Health

Austin J Vet Sci & Anim Husb. 2022; 9(5): 1109.

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

Vangroenweghe Frédéric1,2*

¹Elanco, BU Food Animals, Plantijn en Moretuslei 1-3rd Floor, 2018 Antwerpen, Belgium

²Ghent University, Faculty of Veterinary Medicine, Unit of Porcine Health Management, Merelbeke, Belgium

*Corresponding author: Frédéric Vangroenweghe, BU Food Animals, Elanco Benelux, Plantijn en Moretuslei 1, 2018 Antwerpen, Belgium

Received: October 03, 2022; Accepted: October 28, 2022; Published: November 04, 2022

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.

Keywords: β-mannanase; Grow-finishing pigs; Net energy reduction; Performance; Carcass quality

Introduction

Feed cost is by far the most expensive production factor in the swine industry and continues to increase due to price volatility of different crucial ingredients on the global market. Besides the concerns on protein supply and quality, energy supply and cost for swine diets remains a major issue under the current market situation. Recent calculations [September 2022] reveal an additional 100 kcal net energy have an estimated economical value of € 19.50 per tonne of formulated diet. Polysaccharides, polymers of monosaccharides linked by glycosidic bonds, are major components of feed ingredients frequently used as an energy source in the swine industry. Starch, a polymer of glucose units linked by α-(1-4) with a few α-(1-6) bonds, is digested in the small intestine of pigs through endogenous enzyme activity. Non-Starch Polysaccharides (NSPs) are fibrous materials found in plant cell wall which include celluloses, hemicelluloses, pectins and oligosaccharides. Monogastric animals such as pigs do not possess endogenous enzymes capable of cleaving and digesting β (α)-linked NSPs, such as β-mannans. β-mannans in swine diets might hinder utilization of nutrients [1].

β-Mannan is an antinutritive factor found in common feed ingredients [2], which has received increasing attention in recent years. β-Mannans are linear polysaccharides composed of repeating units of β-1,4-mannose and α-1,6-galactose and/or glucose units attached to the β-mannan backbone [3,4]. They are unsuitable in pig feed in high concentrations due to their antinutritive properties resulting in the stimulation of the innate immune response. In fact, the innate immune cells identify pathogens using distinct molecules, called Pathogen Associated Molecular Patterns (PAMP), expressed on the pathogen surface [5]. Binding of PAMPs to Pathogen Recognition Receptors (PRR) present on innate immune cells, results in the release of innate defense molecules such as reactive oxygen and nitrogen species, bacteriolytic enzymes, antimicrobial peptides and complement proteins [6]. These PAMPs include complex polysaccharides such as β-mannan [5]. Therefore, β-mannans from feed can create a false signal about the presence of pathogens in the gut, eliciting an unwarranted immune activation [7,8], which is also known as a feed-induced immune response FIIR; [9]. This recognition mistake leads to a futile immune response that causes energy and nutrients to be wasted [4]. Hydrolysis of these β-mannans through inclusion of exogenous β-mannanase enzymes can reduce and potentially eliminate their ability to induce FIIR.

In poultry, the inclusion of dietary β-mannanase has been shown to improve daily gain and feed efficiency, while decreasing digesta viscosity [10], and to upregulate a broad range of metabolic functions related to digestion, metabolism and immunity [9]. Moreover, beneficial effects of β-mannanase addition in chickens, challenged with Eimeria sp. and Clostridium perfringens, were observed with improved performance and reduced lesion scores in diseasechallenged animals [11].

Supplementation of β-mannanase to maize-soybean meal (SBM)-based diets improved growth performance, whereas nutrient digestibility remained at a similar level [12]. Moreover, supplementation of β-mannanase to low- and high-mannan diets has the potential to improve the performance of growing pigs. The improved overall pig performance following supplementation of β-mannanase to corn-SBM-PKM diets might be due to increased adjusted ileal digestibility of different amino acids [13-15]. Others concluded that β-mannanase improved growth performance in both weanling and growing-finishing pigs on corn-SBM diets [16,12,17] with minimal effects on nutrient digestibility [12].

The objective of the current study was to evaluate the effects of β-mannanase supplementation to grow-finishing diets with reduced net energy content of 65 kcal/kg on performance and slaughter data of grow-finishing pigs.

Materials and Methods

Description of Experimental Farm

The field trial was performed on a conventional fattening unit in Belgium with 2 compartments of 8 pens each, in both grow and finishing facility. Ventilation of compartments was performed mechanically with a central fan and an air inlet through the door. All pens had partially slatted concrete floors. Water was distributed through a nipple in the feeder.

Each pen was equipped with a dry feeder filled with meal. Feed intake was calculated at group level (1 feed bin per treatment group).

Experimental design

Treatment groups: Two treatment groups were enrolled during the trial. The Control group received a standard 3-phase feeding schedule, whereas the Enzyme treated group received a reformulated 3-phase diet with a reduction of 65 kcal NE per kg feed and supplementation of a β-mannanase enzyme. Both groups were blinded to the farm personnel and only distinguished by letter codes (A,B). The 2 groups were equally distributed over the 2 compartments and 16 pens, containing each 11-12 pigs. Between Phase 1 and Phase 2, pigs were moved to another building to comply with a stocking density of 0.45 m² per pig during the grow phase and 0.80 m² per pig during the finishing phase at a stocking density of 0.8 m².

Experimental diets

Pigs were fed a pelleted 3-phase diet consisting of starter (0-28 d), grower (29-63 d) and finisher (64-127 d) diet in both treatment groups. The Enzyme treated group differed predominantly from the Control group by reduction in net energy content of 65 kcal per kg feed in starter, grower, and finisher diets. This reduction in net energy was realized through reduction of soya oil percentage in the Enzyme treated group by 0.8%. Addition of a β-mannanase enzyme (Hemicell HT; Elanco, Indianapolis; IN) was performed at an inclusion level of 300 g per tonne of feed, according the manufacturer’s instructions. All other enzymes (xylanase and phytase) in the diets remained at the same levels in both treatment groups.

Experimental animals

DanBred x Belgian Piétrain piglets were obtained from a conventional commercial sow farm in Belgium operating in a 4-week batch-management system, which is known to improve overall pig health [18]. Pigs were vaccinated to protect against Mycoplasma hyopneumoniae and Porcine Circovirus type 2 (PCV-2) during the suckling period. All pigs originated from the same farrowing batch and were approximately 10 weeks of age at the start of the feed trial.

Performance data collection

Pig Body Weight (BW) at pen level was measured at 0, 28 (end of Phase 1) and 127 days (end of Phase 2) after arrival on the finisher farm. Feed provision (ad libitum) was recorded per period for the entire treatment group. For both phases (Phase 1 = start; Phase 2 = grow-finishing), average daily weight gain (ADFI; expressed as g/d), average daily feed intake (ADWG; expressed as g/d) and feed conversion rate (FCR; expressed as kg feed per kg of weight gain) were calculated.

Veterinary treatments

Individual antibiotic treatments could be performed as needed due to the critical state of the piglet and in case of a broader health issue in the barn, group treatment could performed. Both types of treatment were always performed according to the clinical criteria of the farm veterinarian. The same veterinary products, active ingredients, formulations, and dosages (ml/kg) were used throughout the entire study period. Individual antibiotic treatments or group treatments were recorded daily by date, product, dose, ID number of treated piglets, presumed cause of treatment, and number of times the treatment was repeated. For all treatment groups, the same antibiotic product and dosage was applied for the same indication.

Data management and statistical analysis

Data were hand-recorded by the farm personnel and stored in MS Excel on OneDrive at the end of each day. Following the end of the finisher phase, data were extracted from Excel into JMP 15.0 and the blinded letter-coded treatments were unblinded to reveal the respective treatment groups. Calculations, exploratory data analysis and quality review, and subsequent statistical analysis were all performed in JMP 15.0. All data are presented as means with their standard error of the mean (SEM, where available). All means were tested for significant differences (P < 0.05) using a post-hoc T-test.

Results

Pig weight and average daily weight gain

Pigs were transferred to the grow-finishing unit at 10 weeks of age and an average weight of 22.16 ± 1.61 and 22.32 ± 1.58 kg for the Control and Enzyme treated group, respectively. At the end of Phase 1 (0-28 days), Control pigs were slightly, but not-significantly (P > 0.05) heavier compared to Enzyme treated piglets (40.73 ± 2.86 kg vs. 40.01 ± 1.01 kg, respectively). After the subsequent transfer to the finishing pens, some additional pigs, that were fed the same diets in Phase 1 and had a similar weight (n = 4 and 2 in Control and Enzyme treated group, respectively), were introduced to compensate for mortality and to optimize the pen occupation. Therefore, at the start of Phase 2 (28-127 days), Control pigs were still slightly, but notsignificantly (P > 0.05) heavier as compared to the Enzyme treated pigs (41.22 ± 1.51 kg vs. 40.07 ± 0.88 kg, respectively). At loading, the Control pigs remained slightly, but not-significantly (P > 0.05) heavier as compared to the Enzyme treated pigs (134.55 ± 1.15 kg vs. 133.91 ± 2.16 kg, respectively) (Table 1).