Dietary guanidine acetic acid addition improved carcass quality with less back-fat thickness and remarkably increased meat protein deposition in rapid-growing lambs fed different forage types

Abstract

Background: The aim of this study was to investigate whether guanidine acetic acid (GAA) yields a response inrapid-growing lambs depending on forage type. In this study, seventy-two small tailed Han lambs (two months old; initial body weights = 12 ± 1.6 kg) were used in a 120-d feeding experiment after a 7-d adaptation period. A 2 × 3 factorial experimental feeding design was applied to the lambs, which were fed total mixed ration with two forage types (OH: oaten hay; OHWS: oaten hay plus wheat silage) and three forms of additional GAA (GAA: 0 g/kg; UGAA: Uncoated GAA, 1 g/kg; CGAA: Coated GAA, 1 g/kg). Results: The OH diet had greater dry matter intake, average daily gain, and hot carcass weight than OHWS diet. The GAA supplementation increased final body weight, hot carcass weight, dressing percentage, and ribeye area in longissimus lumborum. Meanwhile, decreased backfat thickness and serum triglycerides in GAA fed lambs may through increasing hormone sensitive triglyceride lipase (HSL). Dietary GAA decreased the pH value, elevated the water-holding capacity (by reducing drip loss and cooking loss) in mutton. In addition, the crude protein content in mutton increased with GAA addition may through regulation with PIK3C3 /Akt1/mTOR signaling pathway. Conclusions: Dietary GAA (UGAA or CGAA) might be an effective additive in lamb fed different forage types, as it has potential to improve growth performance and meat quality.