Abstract: Foxtail millet ( Setaria italica Beauv． ) is on its way developing as a new type of forage crops for hayproduction in northern China including Inner Mongolia and other cold high land regions． But the lack of knowledgeabout its growth and nutritive changing dynamics and optimum harvest stage hinds its development for hay production． Using Sicaoguzi 1 as sample， this paper reports our study on growth dynamics and nutritive component dynamics of foxtail millet forage， including crude protein， crude fat， crude fiber， neutral detergent fiber and acid detergentfiber． Results indicated that fresh and dry matter accumulation mainly occurred during a period from the beginningof stem elongation stage to the starting stage of seed filling． The crude protein content was as high as 22% at theshooting stage 50 days after sowing， and it declined combining with the progress of plant development and a 7． 3 %of crude protein content was detected at the seed middle filling stage． Crude fat content of foxtail millet hay was about 1 ． 6% to 2． 2% before heading stage and it reaches 3 ． 3 % at the heading stage and then declined to 2． 7% atthe seed middle filling stage． Both crude protein and crude fat reaches its highest yield at the starting stage of seedfilling 92 days after sowing， which is about 7 days after flowering． The yielding of crude fiber， neutral detergent fiberand acid detergent fiber were also reaching their highest point at the starting stage of seed filling． So it is reasonableto suggest that the starting stage of seed filling， which is about 7 days after flowering begins， is the optimum harvesting stage for foxtail millet hay production．

Key words: Foxtail millet, Forage, Nutritive dynamics, Harvesting time

CLC Number: 

• S54