Effect of Multienzyme on Late-Phase Hens Fed with Corn-Soy-Based Diet

With the recent COVID-19 pandemic disrupting the regular supply chain in agriculture and threatening food security, it is imperative to look for innovative ideas to meet the population's food demand (FAO, 2021). The agriculture sector is pressured to offer sustainable, economical, and ethically-produced animal protein. Egg, a cheap and relatively easy-to-produce commodity, is one of the best candidates for such protein. Thus, there is a surging increase in layer population, especially in developing countries where food security is still an issue. The Philippine Statistics Authority (2021) reported that a record high of 605,786.16 metric tons or 12.721 billion pieces of eggs were produced in 2020, a 4% higher compared to 2019.

To sustain the egg production requirement and to lower the cost of farming, the current tactic in the Philippines is to extend the flock age beyond breed recommendations. However, due to physiological limitations, aged birds produce low-quality eggs and have bone problems like osteoporosis (Alfonso-Carrillo et al., 2021). With this premise, it is not economical for the farmers to use expensive raw materials for the feeds since expectations of performance at this stage of the hen are different from when it is at peak production.

In nutrition, various approaches can be implemented to decrease cost, which includes using cheaper alternative feed sources and altering nutrient specifications to reduce expensive inputs. With cheaper source materials, higher ANFs are expected while alteration of specs needs formulation adjustment that will still meet nutrient standards. Both can be addressed via the addition of feed additives. Feed additives are a well-studied aspect of nutrition for improving hens' production (Świątkiewicz et al., 2018). Enzymes, and enzyme cocktails, are among the most prevalent nutritional feed additives in poultry for the last decades. It is widely accepted that the enzymes’ nutrient-liberating ability can help birds enhance performances and lower production costs. Indirectly, it can be one of the actions to support our growing population’s food demand by assisting the farmers in producing eggs efficiently and economically. This study investigates the effect of multienzyme supplementation on reduced energy diets on late-phase hens’ egg production, quality, gut morphology, and bone strength.

Three hundred and twenty-four (n = 324) Dekalb hens 96 weeks of age were randomly allotted to one of the 3 dietary treatments in a completely randomized design (CRD). Each treatment had 27 replicates with 4 hens/cage. The trial was 16 weeks, with feed and water provided ad libitum. The cage specifications were: 46 cm x 47 cm x 33 cm (L x W x H). All cages were in a well-shaded and naturally-ventilated facility experiencing a temperature of 25.3-26.6º C and humidity of 85-86% (Philippine Atmospheric, Geophysical and Astronomical Services Administration, no date). The 3 dietary treatments were a. Treatment 1(T1), positive control b. Treatment 2 (T2), 90 kcal ME reduction, and c. Treatment 3 (T3), T2 plus multienzyme (350g/tonne). Formulations among the treatments were isonitrogenous with the same level of EE, CF, and Ca, and P. The diets were based on the Dekalb guide manual and in mash form (0.5 to 3.0mm). Nutrient specs standards are as follows: ME 2750 kcal/kg, CP 17.5 g/kg, EE 3.8 g/kg, CF 2.8g/kg, Ca 4.3 g/kg, and P 0.6 g/kg. The multienzyme product Natuzyme® (BIOPROTON) contains the following at varying concentrations and activities: phytase (1,876,000 u/kg), xylanase (11,539,000 u/kg), alpha-amylase (760,000 u/kg), beta-glucanase (742,000 u/kg), cellulase (6,924,000 u/kg), protease (271,000 u/kg) and pectinase (74,000 u/kg). Initial and final body weight (BW) and average daily feed intake (ADFI) were recorded. All eggs produced were also recorded for Hen Day egg production (HDEP), Hen-housed egg production (HHEP), Average Egg Weight (Ave. EW), egg mass (EM), and FCR. Twenty-seven (27) eggs per treatment were randomly selected to be measured for Shell width (SWd) and Shell length (SL) and eventually Eggshell Shape Index (SWt/SL x 100). The eggs were broken and subjected to Egg Analyzer (ORKA Food Technology LLC, Utah, USA) to determine the Haugh unit (HU) and albumen height (AH). At the end, twelve (12) hens from each treatment were sacrificed for gut morphology and bone-breaking strength assessment (BBS). Cross sections (4um) of the gut’s ileum were stained by H&E (villi and crypt measurements) and Periodic-Acid Schiff (goblet cell counting) The left tibia was excised and subjected to strength determination using the Universal Testing Machine (4411 Instron Co., Canton, MA, USA). All data were analyzed using the General Linear Model (GLM) procedure of Statistical Analysis System software version 9.2 (SAS Inst. Inc. Cary, NC). The model assigned cages as a random effect, while dietary treatments were the fixed effect.

In this study, there were no changes in body weight gain between treatments (P = 0.9313). The current research aligns with the previous study in multienzymesthat body weight is not affected regardless of decreased ME kcal (Lee et al., 2014). In this study (16 weeks) and that of Lee et al (2014), the trial period may be too short to elucidate the long-term effect of reduced energy on BW. Feed intake showed a different pattern as the T1 gave the best results among the 3 diets (P = 0.0102), which may be related to lower dietary crude fat and crude fiber as per proximate analysis (not shown). This translates to lower heat increment; thus, T1’s hens would eat more to compensate for the heat needed. Also, the results did not conform to the theoretical idea that hens with reduced ME (T2) would tend to eat higher amounts of feed to compensate for energy requirements. The HDEP, HHED, egg weight, egg mass, and eventually, the FCR (T3) were all at par with the standard diet (T1) (P > 0.05), even with decreased energy. T2, as expected, was reduced in all parameters except higher FCR.

In egg quality, T3’s Haugh unit (P = 0.0464) and albumen height (P = 0.0033) were of superior results. Factors affecting albumen height were not fully understood, but Scott et al. (2001) suggested that it may be due to the involvement of the multienzyme’s phytase-releasing P. This could be the reason why T3 showed better results than T1 and T2 as there were no reduction in P inclusion rate in the formulation of the diets. Thus, multienzyme’s phytase in T3 diet would further increase P availability. In eggshell width (SWd) (P = < 0.0001) and eggshell length (SL) (P = < .0001), all gave good results for multienzyme-supplemented (T3) as it was consistent with the T1. The T2's egg sizes decreased, and so did the width and length. Nevertheless, the eggshell shape index (ESI), a ratio of SWd and SL, was uniform among the groups (P = 0.6406). The result implies that even if width and length is reduced in T2, the hens produced an egg shape as proportioned as possible regardless of treatment conditions.

In gut morphology, the villi mean (553.90um) of T3 was not statistically different from T1 (566.34um), and both were superior over T2 (419.87um) at P = 0.0134. In opposition, both crypt depth and VH/CD ratio were not significantly different among diets (P > 0.05). The enzyme’s action of enhancing nutrient availability in the gut lumen causes the response of increased villi length. A longer villus result is good indicator of a healthy and well-absorbing gut. Previous studies showed similar results regarding ileal crypt depth (Madigan-Stretton et al., 2021, de Souza et al., 2014), where there was no change. In contrast, a high crypt depth value is unwanted as crypts are ‘villi factory’ where an increase in length indicates a faster turnover rate of cells to produce new villi. Thus, this translates to more unhealthy cells needed of immediate replacement and is pathologic in nature. In goblet cell counting (GCC), the T3 result was at par with T1, and both were statistically significant over the T2 (P = 0.0093). The consistent result of T3 with T1 is the ideal and implies that there were no gut problems. A high density of goblet cells is unwanted as it also suggests an increase in goblet cell proliferation and consequently decreases rate of enterocyte formation, thus, lower absorptive capability.

In bone breaking strength (BBS), T3 showed superior results compared to T1 and T2 at P = 0.01. As mentioned, all diets followed Ca and P standard, but when egg production varies, the bone reserves utilization will also vary among treatments thereby affecting BBS. In T2, it was statistically higher than T1 at P = 0.021 because T2 hens did not need reserves as production also decreased in frequency. Thus, more Ca and P are still present in the bones of T2, making it ‘harder’. Meanwhile, in T1, the group is still in good production and giving decent egg sizes which still demands high Ca and P. Thus, T3 needs bone reserves as the standard Ca and P feed inclusion rate may be inadequate. This explains better BBS for the enzyme-supplemented diet (T3), even if T1 and T3 had the same egg production and sizes. Minerals liberated by multienzyme’s phytase are adequate or even excess in T3 that it did not need the bone reservesthereby addressing production demand while maintaining bone strength. Thus, supplementing late phase hen’s diet with a multienzyme at 350g/tonne and a 90 ME reduction was able to maintain or outperform the positive control in terms of hen performance, egg quality, gut morphology, and bone health. Furthermore, no adverse effects on feed intake and body weight gain occurred. Therefore, the product is advantageous for farmers planning to extend flock age without sacrificing egg production and quality and promoting animal welfare through improved bone strength.