Effect of phytase dose on productive performance and bone status of layers fed with graded levels of digestible lysine

• Published in: Veterinaria México OA Vol. 5; no. 3
• Main Authors: Martinez Rojas, Ingrid Yolani, López Coello, Carlos, Ávila González, Ernesto, Arce Menocal, J., Gomes, G. A.
• Format: Journal Article
• Language: English; Portuguese
• Published: Universidad Nacional Autónoma de México, Facultad de Medicina Veterinaria y Zootecnia 01.09.2018
• Subjects: Veterinary Sciences; productive performance; laying hens; bone parameters; phytase dose; digestible lysine
• ISSN: 2448-6760; 2448-6760
• DOI: 10.22201/fmvz.24486760e.2018.3.564

Exogenous phytase could influence dietary protein availability by variation in using dose. The objective of the present study was to determine if incremental dosing of an evolved E.coli 6-phytase would lead to improvements in lysine availability through evaluating performance and bone status in Bovans White layers. A total of 182 layers were placed in individual cages and distributed to 13 treatments: a 3×4 factorial arrangement with three levels of digestible lysine (dLys - 0.67, 0.77, and 0.87 %) and four doses of phytase (0, 300, 1 200, and 4 800 FTU/kg) in 0.12 % available P (avP) diets. Additionally, one phytase-free control treatment was included with 0.25 % avP and 0.87 % dLys. Productive parameters were recorded for 25 weeks, from 39 week-old. At the end, abdominal fat deposition and the tibia were sampled; in bone was determined breaking strength and bone ash. Layers fed 1 200 FTU/kg phytase increased egg production percentage (F3,169 = 2.01, p = 0.019), abdominal fat deposition (F3,169 = 2.52, p = 0.059), bone breaking strength (F3,169 = 4.29, p = 0.006) and bone ash weight (F3,169 = 3.62, p = 0.015) compared with non-phytase inclusion. Furthermore, 1 200 FTU/kg phytase decreased incidence of broken eggs and soft-shell eggs (F3,169 = 2.9, p = 0.037). Phytase and dLys levels influenced egg mass and bone ash concentration (F12,169 = 1.86, p = 0.043). FCR and body weight loss was reduced with phytase inclusion (respectively: F12,169 = 2.43, p = 0.045, and F12,169 = 2.24, p = 0.001). Phytase-free control diet increased egg weight (F12,169 = 3.70, p < 0.068), but gave greater BW loss (F12,169 = 17.79, p < 0.001), less abdominal fat content (F12,169 = 5.85, p < 0.017), and no effect on other variables (p > 0.07). In conclusion, 1 200 FTU/kg of phytase improved productive performance and preserved body weight and bone status, without equivalence of phytase inclusion for dLys level, even with higher doses.Figure A. Response of egg marketable mass