AS-433
animal sciences sheep
OPERATIVE EXTENSION SERVICE PURDUE UNIVERSITY, WEST LAFAYETTE, INDIANA 47907
REPRODUCTION IN SHEEP
R. E. Hudgens, Animal Sciences Department
Reproductive efficiency of sheep is affected by a number of different factors. To obtain the highest possible degree of reproductive performance from your flock, you should have a general understanding about the anatomy and physiology of sheep reproduction. In addition, it’s important to know how the environment can influence the reproductive performance of sheep. Therefore, the purpose of this publication is to provide an overview of sheep reproduction so the sheep producer can make knowledgeable reproductive management decisions.
Reproductive Anatomy of the Ewe
The female reproductive organs of all breeds of sheep are the same (Fig. 1). The ovaries (two) are almond-shaped organs and are about 11/2 inches long by 1/2 inch wide. The ovaries release the ova (eggs) at 17-day intervals during the breeding season or until the ewe becomes pregnant. The ovaries also produce female hormones, progestogens and estrogens. These hormones are compounds that are involved in the control of the reproductive cycle of the ewe.
Fertilization, the union of the sperm from the ram and the egg from the ewe, takes place in the oviduct. After about four days in the oviduct, the fertilized egg(s) enters the uterus, and fetal membranes begin to grow and attach to the uterus at approximately 75 sites. These attachment sites are cup-like projections called caruncles. Nutrient and waste products are exchanged at these sites.
The cervix is a tough, tubular, gristle-like organ between the uterus and the vagina. The cervix is closed during pregnancy and does not allow foreign materials to enterthe uterus. The cervix of the ewe has approximately seven folds or interlocking
ridges and is about 3 inches long. These folds make it difficult to (insert) a catheter when artificially inseminating a ewe.
The vagina is posterior to the cervix, extending to the external opening. It receives the penis in copulation, and is the passageway for the fetus at