Dietary Calcium and Protein Levels Influence Growth Performance, Intestinal Development, and Nutrient Utilization in Goslings

This study evaluated the effects of dietary calcium (Ca) and crude protein (CP) levels on growth performance, nutrient utilization, intestinal morphology, and digestive enzyme activities in goslings during the brooding period. A total of 972 one-day-old Jiangnan White goslings were assigned to a 3 × 3 factorial design with three levels of Ca (0.32%, 0.96%, and 2.88%) and three levels of CP (14.5%, 18.5%, and 22.5%). Results showed that moderate Ca (0.96%) and CP (14.5-18.5%) levels optimized growth performance, with higher body weight (BW), average daily gain (ADG), and average daily feed intake (ADFI), while excessive Ca (2.88%) impaired growth and the feed conversion ratio (FCR). Intestinal morphology was enhanced by 0.96% Ca and moderate CP levels, as reflected by greater villus height and crypt depth. Digestive enzyme activities in the duodenum, jejunum, and ileum were significantly influenced by dietary treatments, with moderate nutrient levels supporting optimal enzymatic efficiency. Nutrient utilization analyses revealed that Ca and CP levels interacted to optimize calcium, phosphorus, and protein metabolism, with the highest utilization rates observed at 0.96% Ca and 14.5% CP. These findings emphasize the importance of balanced dietary formulations to enhance growth performance, nutrient absorption, and metabolic efficiency in goslings, providing practical insights for improving poultry production.