Optimization of processing parameters of 50 % aged paddy rice replace of corn in feed formula: effects of grinding sieve opening, conditioning temperature and time on the growth performance, meat quality and serum biochemical parameters in broilers.

This study aimed to evaluate the effects of different grinding sieve openings (SO), conditioning temperatures (CTP), and conditioning times (CTM) on feed processing performance, growth performance, meat quality, and serum biochemical indices of broiler chickens fed a diet in which 50 % of corn was replaced with aged paddy rice. A total of 960 white-feathered broiler chickens were randomly divided into 8 groups, with the experiment designed to test 2 SO sizes (2.0 mm and 2.5 mm), 2 CTPs (75 °C and 85 °C), and 2 CTMs (90 s and 180 s). The results showed that the 2.0 mm SO and 180 s CTM significantly improved pellet hardness and the pellet durability index (PDI) (P < 0.05). During the early stages of the experiment, when the broilers digestive systems were not fully developed, a 2.5 mm SO significantly reduced the feed conversion ratio (FCR) (P < 0.001), while 75 °C CTP significantly increased average daily gain (ADG) and body weight (BW) at day 21 (P < 0.05). Additionally, 75 °C CTP significantly reduced the cecum organ weight ratio (P < 0.05). In terms of meat quality, a 2.5 mm SO significantly reduced drip loss and cooking loss at 48 h and 72 h (P < 0.01, P < 0.01, P < 0.05), while a 90 s CTM significantly reduced drip loss and cooking loss at 24 h (P < 0.05, P < 0.01). Furthermore, the combination of 2.5 mm SO and 90 s CTM significantly increased serum urea nitrogen (BUN) levels (P < 0.05). Considering the optimization of both growth performance and meat quality, the combination of 2.5 mm SO, 75 °C CTP, and 90 s CTM is recommended for optimizing aged paddy rice feed processing and enhancing broiler growth performance and meat quality.