The time for the reproductive system of postpartum cows to recover is that the inter-horn groove of the uterine horn is obvious after 8 days after delivery. On the 18th day after delivery (the day of delivery is counted as Od), the complete uterine horn with obvious inter-horn groove can be directly detected. The shape of the uterus has basically recovered, which can also be clearly shown on the cattle B-ultrasound.

The ovarian morphology of postpartum cows in the recovery stage, observed by cattle B-ultrasound, the ovaries of cows before the first estrus after delivery are particularly small, the size of a broad bean. Most of them are flat, soft, uneven on the surface, and feel firm. Observed by cattle B-ultrasound, the ovaries become smoother and rounder before and after the first estrus, with depressions on the surface of the ovaries and small protrusions on them.

The area of the cow's ovaries is mostly 15mm*20mm, 20mm*20mm, 25mm*20mm, 25mm*15mm in length and width on the cattle B-ultrasound image, and the thickness is 10-15mm. The area of the ovaries before and after estrus is mostly 30mm*30mm in length and width on the B-ultrasound images for cattle, and the ovaries are 20-35mm.

BXL-DZ20 for cattle B-ultrasound

The growth and development process of follicles and corpora lutea on the ovaries of postpartum cows. The ovaries of postpartum cows are observed on B-ultrasound for cattle. Follicles and corpora lutea exist before the first estrus and in the first estrus cycle. However, before the first estrus, there are more small follicles on the ovaries, fewer medium follicles, and fewer large follicles. Although there are large follicles, the large follicles last for a long time and do not disappear, but they do not ovulate. The corpora lutea are all white spots, and the number of small corpora lutea (the number of corpora lutea of 2mm, 3mm and 5mm) is large, and there is no large corpora lutea (greater than 10mm). B-ultrasound observation of cattle shows that a few cows have corpora lutea with cavities after the first estrus after calving, but the cavities of the corpora lutea with cavities are small. In the first estrus cycle after delivery, a corpus luteum with a cavity appears. The corpus luteum is large, sometimes reaching 30 mm, but the cavity of the corpus luteum with a cavity is generally larger.

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