第三节 发情和发情周期极其影响因素 Estrus, Estrus cycle and Factor Effecting Estrus 第四节 发情周期中机体生理变化和激素调 Physiological Change and Hormone Regulation During Estrus Cycle 第五节 乏情与异常发情 Anestrus and Abnormal Estrus 第六节 家畜发情周期特点及发情鉴定 Characteristic of Estrus cycle and Estrus testing