Abstract: Provided are an altrenogest injection and a preparation method and use thereof. The altrenogest injection includes 0.1-35 g altrenogest, 0.01-70 mL of polyethylene glycol, and a balance of an alcohol solvent per 100 mL of the altrenogest injection. The altrenogest injection can effectively inhibit estrus of sows, synchronize the estrus cycle of sows, and is more convenient and efficient to use, and the dosage is more precisely controllable. A single injection can effectively inhibit the estrus of sows for 6 to 12 days, which significantly reduces the labor costs for large-scale farms.

Abstract: The present invention provides a crane boom with multi main chord consisting of an underpart boom sections, an insert jib section and a boom head connected in turn. Said underpart boom sections and insert jib section are multi-main-chord boom sections, there is a main-chord on each of the angle part of the cross-section of the multi-main-chord boom section. Said main-chords are connected one another by several belly bars. Add at least one main-chord on the angle part of the cross section along the width or the height of said multi-main-chord boom, and the added main-chord parallels to the original main-chord. The crane boom with multi main chord of the present invention, without changing the size of the boom sections during transporting, the cross-sectional area of the main-chord is increased and the integral stiffness of the boom is strengthened by increasing main-chord number of boom, thus fold increasing the structural carrying capacity of the boom which is suitable for large crane.