Stage-specific effects of dietary lipid sources on abdominal fat deposition and adipose tissue characteristics in...

This study investigated the effects of different dietary oil sources and phase-specific lipid substitution on growth performance, abdominal fat deposition, and adipose tissue characteristics in yellow-feathered broilers. A total of 4,000 one-day-old female chicks were assigned to eight treatments and fed diets containing soybean oil (SO), rice bran oil (RO), or cottonseed oil (CO) throughout the 78-d trial, or CO during the starter and grower phases followed by oil replacement during the finisher phase. During 1-25 d of age, broilers fed CO showed lower average daily gain and higher feed conversion ratio compared with those fed SO (P < 0.05). No significant differences were detected in overall growth performance from 1 to 78 d. At 78 d, birds fed SO throughout had lower abdominal fat weight (57.3 g) and abdominal fat percentage (3.81 %) than those fed RO or CO (P < 0.05). Late-phase lipid substitution did not significantly reduce abdominal fat deposition. Dietary lipid source markedly influenced the fatty acid profile of abdominal fat. Continuous CO feeding increased the proportion of saturated fatty acids (40.68 %) and decreased unsaturated fatty acids (P < 0.05), accompanied by a marked increase in shear force (18.45 N). Replacing oil during the finisher phase modified fatty acid composition and reduced shear force but had limited effects on total fat accumulation. Serum total cholesterol and high-density lipoprotein concentrations were higher in the RO and CO groups than in the SO group (P < 0.05). These findings indicate that the effects of dietary lipid source on abdominal fat deposition and adipose tissue characteristics are stage-dependent. Early lipid supply is associated with final fat accumulation, whereas lipid manipulation during the finishing phase primarily alters fatty acid composition and adipose firmness rather than fat mass.