Muramidase: Enhancing broiler performance and meat yield

Muramidase has a positive effect on gut functionality, leading to higher nutrient digestibility and absorption and in the end shows to contribute to highly efficient birds with optimal body weight and higher meat yields. These highly efficient broilers contribute to reduction of two major global issues the poultry industry is facing…

Optimizing performance and maintaining gastrointestinal functionality are crucial for success in broiler production. Optimal performing, healthy broilers contribute most to the global growing protein demand and a reduction of antimicrobial resistance. The use of muramidase in broiler feed is a new promising solution to support gut functionality, thereby improving broiler performance and meat yield. In this article we will explain the benefits and mode of action of muramidase and its impact on broiler growth, feed conversion ratio (FCR) and meat yield.

THE ROLE OF MURAMIDASE IN GUT FUNCTIONALITY
As defined by Pietro Celi in Animal Feed Science and Technology, 2017, an optimal gastrointestinal functionality is ‘a steady state where the microbiome and the intestinal tract (host) exist in symbiotic equilibrium and where the welfare and performance of the animal is not constrained by intestinal dysfunction’. Muramidase contributes to an optimal gastrointestinal functionality by breaking down bacterial cell debris. Peptidoglycans (PGNs) form the structural base of bacterial cell walls. After cell death or division, PGNs are left behind in the lumen of the intestinal tract and can hinder nutrient absorption and optimal gut function. By breaking down PGNs, muramidase contributes to better nutrient digestion, -absorption and -partitioning in the body. This can be seen by birds having a higher body weight gain, a better FCR and higher meat yield.

MURAMIDASE IMPROVES NUTRIENT DIGESTIBILITY, MEAT YIELD AND WELFARE IN BROILERS
Several studies have shown that broilers supplemented with muramidase have a higher nutrient digestibility and absorption. Sais et al., 2019 showed 7% higher apparent ileal energy digestibility (P<0.05) and 4% higher apparent ileal crude protein digestibility (P=0.09) at day 35 of age. The improvement of crude protein digestibility was confirmed by Goodarzi et al., 2019 who saw 6.5% higher apparent ileal crude protein digestibility (P=0.001) and a higher apparent ileal fat digestibility (ether extract) of 2% (P=0.002) at day 35 of age. Goes et al., 2022 also saw a higher fat apparent ileal digestibility of 16% (P=0.01). Sais et al, also found a higher nutrient absorption on day 9 of broiler age. The birds fed with muramidase had 18% higher amounts of vitamin A in their plasma (P=0.04). At the same age, the birds also had a significantly higher amount of total fatty acid apparent ileal digestibility of 2% (P<0.05). Knowing vitamin A is absorbed via fat, these two findings can be linked to each other. Goes et al, confirmed the improvement of nutrient absorption by measuring blood carotenoids levels. The muramidase supplemented birds had 23% higher total carotenoid concentrations in their blood (P=0.007). In all studies, the nutrient digestibility and absorption improvement lead to an improved performance of 57g BW (2%; NS) and 7 points FCR (5%; P=0.45) in Sais et al., 2019, 45g BW (2%; NS) and 4 points FCR (3%; P=0.001) in Goodarzi et al., 2019 and 80g BW (3%; NS) and 6 points FCR (4%; P=0.004) in Goes et al., 2022.

Footpad lesions are a visual sign of reduced gut functionality. Muramidase supplementation decreased litter moisture and footpad lesion scores (Pirgozliev., 2020), which was confirmed in several trials. When evaluating meat yield data from the slaughterhouse, Brugaletta et al., 2002 showed that muramidase supplementation improved breast yield% with 2.3% (>750 observations/group; 3 groups total), without increasing myopathies (wooden breast, white striping and spaghetti meat). Other trials also showed breast meat yield improvement, with an average of 3%, including higher carcass and thigh weights (data unpublished). Table 1 shows a summary of the performance, digestibility and absorption improvements described above.

THE LINK BETWEEN GUT FUNCTIONALITY, BIRD PERFORMANCE AND MEAT YIELD
How can we explain the improved meat yield when muramidase was fed to the birds? Ni et al., 2022 found that geese with higher villus height/crypt depth ratio had improved muscle fiber density and breast muscle/body weight ratio. Savaris et al., 2021 investigated the effects of vitamin A on meat yield and quality in broilers and found that vitamin A supplementation significantly improved breast and leg yield. There was also an interaction between vit. A levels and duration of supplementation and the occurrence of wooden breast and white striping, with an optimum level described at 29.000 IU/kg. Cavani et al., 2009 describes the importance of oxidative stability for meat quality. Lipid oxidation can cause toxic compound formation and the loss of nutritional values. Several nutrients such as carotenoids, vitamin E and C and selenium act as antioxidant and prevent lipid oxidation. Increasing the absorption of these nutrients can improve oxidative stability and decrease lipid oxidation, leading to meat with higher nutritional value and less toxic compounds. An increased absorption of vit. A due to muramidase supplementation can be an indication for improved breast meat yield described above. Muramidase supplementation improves gastrointestinal functionality by removing PGNs as an irritant in the gut lumen and the effects of better gut functionality described by Ni et al. is a potential explanation of the higher breast meat yields found in muramidase supplemented birds.

CONCLUSIONS
Nutrient partitioning to protein deposition is influenced by several factors. Nutrients like carotenoids and vitamins contribute to oxidative stability and reduce lipid oxidation, ensuring better meat quality. Nutrients like vitamin A contribute to meat yield. A better gut functionality (measured by villus/crypt ratios) improves muscle fiber densities. Muramidase has a positive effect on gut functionality, leading to higher nutrient digestibility and absorption and in the end shows to contribute to highly efficient birds with optimal body weight and higher meat yields. These highly efficient broilers contribute to reduction of two major global issues the poultry industry is facing: meeting the growing protein demand and reducing the reliance on antibiotics (reducing antimicrobial resistance).

About Irene Eising
Irene Eising works as Product Manager Balancius® in the EMEA performance solutions team at dsm-firmenich Nutritional Products. She has 11 years’ experience in the animal feed industry, specializing in monogastrics and gut health solutions. Prior, Eising obtained experience in both the feed mill and animal additive industry. She studied at Wageningen University and Research where she obtained both her BSc and MSc in Animal Science, specializing in animal nutrition.