Digestive System |
Goats and sheep are true ruminants, which means they have a stomach with four compartments. Their digestive system is very similar to the digestive system of a cow. The Rumen, Reticulum, Omasum, and Abomasum make up the compartments of the stomach. The rumen is a huge fermentation vat. When we feed sheep, we are actually feeding the bacteria and protozoa that live in the rumen. These microorganisms then feed the animal with "by products" of fermentation. Also, they digest cellulose, synthesize amino acids from non-protein nitrogen, synthesize B-complex vitamins, and provide some protein. The reticulum receives feed stuffs from the esophagus and sends these to the rumen. The reticulum also receives partially digested feeds from the rumen and sends these to the omasum. The omasum is characterized by its "many folds" or "pages of a book". This structure serves to absorb the water from rumen contents. It also produces a grinding action that helps break feed stuffs down into small particle sizes. After feed leaves the omasum, it travels to the abomasum. This is the true gastric pit, which is similar to the stomach of a human or a swine. There are four steps to rumination. The first step is regurgitation. This is when reverse peristalsis carries food to the mouth. The next step is remastication. In this step, bolus is rechewed in a more slower and deliberate mechanism. The third step is reinsalivation. This step adds more saliva to the digesta. The last step of rumination is redeglutition. This is when reswallowing bolus and liquids occurs. After reswallowing, the rumen contracts to move swallowed bolus into the rumen. The digestion process then continues, like it would for a human, through the small intestine, large intestine, and end at the anus.
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Reproductive System |
There are five parts that make up the female reproduction tract; ovaries, oviduct, uterus, cervix, and vagina. There are two ovaries that produce eggs and the female sex hormones, estrogen and progesterone. The infundibulum directs the egg into the oviduct, also known as the Fallopian tube. This is where fertilization occurs. After leaving the oviduct, the egg travels into the uterus. The uterus is the site of implantation and development of the embryo. At the posterior end of the uterus is the cervix. The cervix is a "gate keeper" for the uterus. Last is the vagina. It is the female organ of copulation at mating, birth canal during parturition, and serves as an exit passage for urine. When the female is in heat, the vagina becomes very moist to accept the semen. During the rest of the cycle, the vagina tends to be sticky or dry. On average, a female sheep is in heat for 30 hours and the length of her estrous cycle is 17 days. Her approximate time of ovulation is 26 hours after onset of estrus and her gestation period is 147-150 days. There are four parts that make up the male reproduction tract; testicles, epididymis, vas deferens, and penis. The testicles are responsible for the production of sperm cells and the hormone testosterone. A sperm cells unites with the eggs to make the fertilized embryo. Sperm cells mature in the epididymis. The vas deferens is responsible for delivering sperm from the epididymis to the urethra. The urethra is a muscular canal extending from the bladder through the penis and is responsible for final delivery of the semen. Rams have an enlargement in the vas deferens called the ampulla. The ampulla is a holding area for sperm cells that are ready to ejaculate. A ram's ejaculate volume is 0.8-2 milliliters. Lastly, the penis is the male organ of copulation and provides a passage way for both urine and semen. Parturition starts with softening and dilation of the cervix and the start of uterine contractions. This stage usually lasts from two to six hours in ewes. The second stage ends with the expulsion of the fetus and associated membranes. Ewes very typically spend two hours in this stage. The last stage is the expulsion of the placenta. In this stage, ewes can require as little as 30 minutes, but more typically require three to five hours.
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