Lysine Depletion during Different Feeding Phases: Effects on Growth Performances and Meat Quality of Broiler Chickens

Abstract

The present study aimed at assessing the impact of lysine restriction performed during different feeding phases on growth performances, meat quality traits and technological properties as well as on the incidence and severity of breast muscle abnormalities. For this purpose, a total of 945 one-day-old Ross 308 male chicks was randomly divided into three experimental groups: CONT, fed a four feeding phases commercial diet, GRW I, and GRW I + II fed CONT diet with the depletion of synthetic lysine during grower I and grower I and II feeding phases, respectively. Productive performances were recorded throughout the whole rearing cycle and the incidence of breast muscle growth-related abnormalities assessed at slaughter (49 d) on 280 breasts/group. Quality traits and technological properties of breast meat were measured on a total of 54 Pectoralis major muscles. Lysine restriction only marginally affected the productive performances and the quality parameters of breast meat. The increased (p < 0.05) solubility of the protein fraction along with the remarkably higher (p < 0.05) anserine content found in GRW I + II suggests an increased energy requirement in the pectoral muscles belonging to lysine-restricted birds and supports the hypothesis of a reduced protein synthesis taking place within these muscles.

Estimating In Vitro Protein Digestion and Protein Digestibility Corrected Amino Acid Score of Chicken Breasts Affected by White Striping and Wooden Breast Abnormalities

“…Amino acid compositions in cooked breast samples was assessed using gas chromatography–mass spectrometry (GC-MS) [ 45 ]. In brief, 40 mg of the sample were hydrolyzed using 5 mL of 6 N HCl at 110 °C for 18 h. The hydrolysates were neutralized using sodium bicarbonate solution and mixed with internal standard (50 µL of norleucine).…”

“…The supernatant collected at the end of the intestinal phase was profiled for free amino acids using GC-MS following a method described elsewhere [ 45 ]. Prior to the analysis, 400 mg of the supernatant were mixed with 4 mL of 25% acetonitrile in 0.1N HCl and sonicated at room temperature for 20 min.…”