Effect of phytase supplementation of a plant-based diet on phosphorus and nitrogen bioavailability in sea breamSparus aurata

Abstract

To assess to what extent addition of phytase to a plant‐based diet results in spatio‐temporal changes of phytate, available P, soluble protein, total amino acids and the activity of the main digestive proteases in gilthead sea bream, fish were fed two plant‐based diets with or without phytase. Stomach, proximal intestine and distal intestine contents were monitored for these parameters at 0, 1, 2, 4 and 6 h after feeding. A reduction (P < 0.0001) of the soluble P–IP6 in the stomach when phytase was added to the diet was observed. Within stomach, most of the total P–IP6 was precipitated (86%), possibly due to the low acidification capacity of the sea bream (pH > 4), but 57% of the dietary P–IP6 was dephosphorylated, suggesting that phytase could have the capacity to dephosphorylate insoluble IP6 at such pH. An increment (60%) (P < 0.01) in total gastric protease activity was observed by phytase addition, this being the first demonstration of the in vivo effect of IP6 on the pepsin activity in fish stomach. Gastric pH and residence time of the digesta inside the stomach are critical factors for an efficient phytase action and improve P and N bioavailability in plant‐based diets used in fish aquaculture.

Effects of dietary phytase supplementation on growth performance and apparent digestibility coefficients of Pacific White ShrimpLitopenaeus vannamei

“…Phytate can non‐selectively bind with amino acids and reduce amino acids availability (Kumar et al., ). Phytate has also been shown to inhibit activities of enzymes including trypsin and pepsin (Kies, de Jonge, Kemme, & Jongbloed, ; Morales, Saenz de Rodrigañez, Marquez, Diaz, & Moyano, ; Morales et al., ). Phytase can improve protein and amino acid availability through the breakdown of phytin‐protein complexes and neutralize the negatives influence of phytate on protein and other nutrients in the feed of monogastric animals (Kornegay & Qian, ; Mitchell et al., ).…”

In vitro assays predicts mineral retention and apparent protein digestibility of different fish feed measured using a juvenileP. mesopotamicusmodel

“…In this regard, Morales et al. () reported the activity of gastric protease measured in gilthead sea bream fed on the phytase diet was around 60% higher than that of fish receiving the control diet. As it is known, It is noteworthy that the reduction in the hydrolysis of dietary protein due to the presence of phytate can be attributed not only to the formation of low digestible binary complexes with substrate proteins, but also in an indirect way to its binding to digestive proteases (Morales, Saenz de Rodrigañez, Márquez, Díaz, & Moyano, ).…”

“…Note that under the physiological conditions existing in the gut, phytate chelates positively charged ions such as Ca 2+ , Mg 2+ , Zn 2+ and Fe 2+ , thus reducing their bioavailability in fish. Moreover, most the phosphorus present in vegetable protein sources is bound to phytate and due to its low digestibility (Morales et al., ). The higher zinc and iron bioavailability of D 3 also was observed in white muscle zinc content and plasma iron concentration, which is a biomarker of iron store.…”

Comparative efficacy of phytase from fish gut bacteria and a commercially available phytase in improving the nutritive value of sesame oilseed meal in formulated diets for fingerlings of rohu, Labeo rohita (Actinopterygii: Cypriniformes: Cyprinidae)

“…It is clear that supplemental phytase can enhance the digestibility and bio-availability of phosphorus, nitrogen and other minerals, reduce the amount of inorganic-P supplement to maximize growth and bone mineralization, and markedly decrease P load to aquatic environment (Cao et al 2007, Morales et al 2014, Yoo and Bai 2014. The optimum doses of phytase to replace inorganic P have not been evaluated in fi sh diets.…”

“…Roy et al (2014) assessed the role of phytase-producing fi sh gut bacteria in enhancing the nutritive value of sesame (Sesamum indicum) seed meal incorporated diets for rohu fi ngerlings and increasing the bioavailability of nutrients and minerals. There are several reports regarding the effi cacy of phytase on growth performance, body composition and phosphorus utilization by the fi sh fed diets pretreated with microbial phytase (Sugiura et al 2001, Debnath et al 2005, Baruah et al 2007a, 2007b, Cao et al 2008, Roy et al 2014, Das and Ghosh 2015, but the report based on the comparison of the effi cacy of phytase produced by fi sh gut bacteria and commercially available phytase is lacking.It is clear that supplemental phytase can enhance the digestibility and bio-availability of phosphorus, nitrogen and other minerals, reduce the amount of inorganic-P supplement to maximize growth and bone mineralization, and markedly decrease P load to aquatic environment (Cao et al 2007, Morales et al 2014, Yoo and Bai 2014. The optimum doses of phytase to replace inorganic P have not been evaluated in fi sh diets.…”