LAUSR

BACKGROUND Beta-hydroxy-beta-methylbutyrate (HMB) is the metabolite of leucine that plays an important role in muscle protein metabolism. The objective of the present study was to determine effects of in ovo feeding (IOF) of HMB at 7 d of incubation (DOI) via air cell or 18 DOI via amnion on hatchability, muscle growth and performance in prenatal and posthatch broilers. RESULTS IOF of HMB via air cell at 7 DOI increased hatchability by 4.34% compared with the control (89.67% vs 85.33%). Birds in IOF groups exhibited higher body weight, average daily body weight gain and pectoral muscle percentage. Furthermore, IOF of HMB significantly increased the level of plasma growth hormone, insulin, insulin-like growth factor-1. Chicks hatched from IOF treatment had larger diameters of muscle fibre and higher mitotic activity of satellite cells at early posthatch age. IOF of HMB activated satellite cells by up-regulation mRNA expression of myogenic transcription factors, myogenic differentiation 1 (MyoD) and myogenin. Chicks hatched from air cell injection group had higher pectoral muscle percentage at 5 d posthatch, and increased satellite cell mitotic activity at 7 d posthatch than counterparts from amnion injection group. CONCLUSION IOF of HMB via amnion at 18 DOI or especially via air cell at 7 DOI could be used as an effective approach to enhance hatchability, productive performance and breast muscle yield in broilers. This article is protected by copyright. All rights reserved.