Effect of Different Levels of Multienzymes on Immune Response, Blood Hematology and Biochemistry, Antioxidants Status and Organs Histology of Broiler Chicks Fed Standard and Low-Density Diets

This study was executed to investigate the effect of supplementing three multienzyme levels (0, 0. 1, and 0.2%) with two types of diet [standard diet (SD) vs. low-density diet (LDD)] on immune response, blood hematology and biochemistry, antioxidant status, and organ histology of broilers during 1–38 days of age. A total of 216 unsexed 1-day-old Arbor Acres broiler chicks were randomly distributed, on a factorial design (2 × 3), to six treatments each with six replicates. There were six chicks per replicate. Results showed that LDD significantly decreased body weight gain (BWG) of broilers, but did not affect the European Production Efficiency Index (EPEI). Addition of multienzymes at both levels (0.1 and 0.2%) significantly increased BWG and improved EPEI, compared to the control diet. Alanine aminotransferase (ALT), aspirate aminotransferase (AST), malondialdehyde (MDA), lymphocyte, lymphocyte transformation test (LTT), and phagocyte activity (PA) were significantly higher for LDD than the SD, but eosinophil was lower. Supplementation of multienzymes significantly decreased ALT, AST, and MDA, compared to the control group, but increased packed cell volume (PCV), hemoglobin (Hgb), lymphocytes, and monocytes. Immune organs, such as spleen, thymus, and the bursa of Fabricius were significantly increased with multienzyme supplementation. It could be concluded that multienzyme supplementation at either 0.1 or 0.2% to SD or LDD improved EPEI and immune status of broiler chicks.

Introduction

The cost of poultry feed ingredients represent about 60–70% of the total production cost, and hence, feed formulation is a critical approach in poultry industry. Feed utilization can be met with inclusion of enzymes, antimicrobials, probiotics, or prebiotic or natural products (1–9).

The immunomodulatory effect of supplementing poultry feed with multienzymes has been well-documented in the literature. Hosseindoust et al. (10) concluded that β-mannanase has a potential to improve the gut health of broiler chickens fed with a corn and soybean meal (SBM)–based diet. In the same study, growth performance and the total tract retention of nutrients were also improved. Liu et al. (11) investigated the effect of multienzymes containing phytase, protease, and xylanase at 1,000, 2,000, and 2,000 U/kg of broiler feed, respectively. The authors showed that multienzymes significantly improved feed intake, body weight gain, polymeric Ig receptor (pIgR), secretary IgA (sIgA), and ileal counts of Lactobacilli and Bifidobacteria and significantly reduced lesions in the intestine, serum a-toxin antibodies, mucin 2 expression, and ileal count of Clostridium perfringens. However, the strength of the multienzyme effect depends on the protein content in the diet. The authors pointed that high non-conventional protein in the diet can lead to increased occurrence of subclinical necrotic enteritis, while multienzyme supplementation can reduce this effect in broiler chickens by enhancing the gut immunity (11).

Supplementing poultry feed rations with enzymes can enhance feed utilization and eliminate the negative effect of non-starch polysaccharides (NSPs) in broiler performance (12–14). Multienzyme supplementation, such as amylase, xylanase, and protease is claimed to stimulate disintegration of starch, cell walls, and endogenous proteins, and thus improves energy utilization in corn-SBM and sorghum-SBM diets (15). Attia et al. (16) revealed that supplementing poultry diet with multienzyme enhanced the economic cost of the diets. However, the composition and the type of enzyme mixture determine the effect of the multienzyme supplementation on poultry production performance (17<