Effect of growing regions on morphological characteristics, protein nutrition, rumen degradation and molecular structures of various whole-plant silage corn cultivars

Little information exists on the variation of morphological characteristics, nutritional value, ruminal degradability, and molecular structural makeup of diverse whole-plant silage corn (WPSC) cultivars among different growing regions. This study investigated the between-regions discrepancies in five widely used WPSC cultivars in China (FKBN, YQ889, YQ23, DK301 and ZD958) in terms of 1) morphological characteristics; 2) crude protein (CP) chemical profile; 3) Cornell Net Carbohydrate and Protein System (CNCPS) CP subfractions; 4) in situ CP degradation kinetics; and 5) CP molecular structures. Our results revealed that significant difference were observed on growing region and WPSC cultivar interaction for all estimated morphological characteristics ( P < 0.001), CP chemical profile ( P < 0.001), CNCPS subfractions ( P < 0.001) and CP molecular structural features ( P < 0.05). Except ear weight ( P = 0.18), all measured morphological characteristics varied among different growing regions ( P < 0.001). Besides, WPSC cultivars planted in different areas had remarkably different ( P < 0.01) CP chemical profiles and CNCPS subfractions. All spectral parameters of protein primary structure of WPSC differed ( P < 0.05) due to the various growing regions, except amide II area ( P = 0.28). Finally, the area ratio of amide I to II was negatively correlated with the contents of soluble CP ( δ = -0.66; P = 0.002), CP ( δ = - 0.61; P = 0.006), non-protein N ( δ = -0.56; P = 0.004) and acid detergent insoluble CP ( δ = - 0.43; P = 0.008), in conjunction with positively correlated with moderately degradable CP (PB1; δ = 0.58; P = 0.01). In conclusion, the current study suggested that even for the same WPSC cultivar, the morphological characteristics, protein nutritional values and rumen degradability significantly varied among different grown regions due to distinguished molecular structures. Author summary As the major roughage source, whole plant silage corn plays an essential role in ruminant feed industry. The quality and quantity of it largely influenced by environmental and climate conditions except genetic factors. However, there was limited information to systematically analyze whole plant silage corn from morphological characteristics, nutritional components, rumen degradation to its inherent molecular structures. Thus, this study was conducted to investigate the discrepancies of various silage-corn cultivars grown in different regions from internal structure to phenotype based novel technology - fourier transform infrared spectroscopy. ### Competing Interest Statement The authors have declared no competing interest.