Phases of the Swine IndustryThere are four phases of the swine production industry. These include breeding-gestation, farrowing, nursery pigs, and grow-finishing phase. Swine production begins with the sow being bred. After breeding, the sow gestates her litter for 113 to 116 days before the pigs are farrowed. Just before giving birth, called farrowing, sows are moved into a "farrowing room." Sows typically farrow from eight to twelve piglets. Piglets weigh about three pounds at birth and are weaned from the sow at anywhere from five days to four weeks. After weaning, pigs are placed in a nursery where they are kept in a temperature-controlled environment. The temperature in the nursery may be as high as 85 degrees and then dropped gradually to about 70 degrees as the pigs grow. Pigs are removed from the nursery at about six to ten weeks old and placed in a grow-finishing building. The grow-finishing phase is where pigs are fed as much as they wish to eat until they reach market weight of 250 to 275 pounds. Marketing normally occurs at five to six months of age.
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Digestive System |
The digestive system of a pig is similar to a human's digestive system. Swine are monogastrics, which means that they only have one true stomach. The monogastric digestive tract begins with the mouth and ends at that anus. The mouth serves a role for the consumption of food and reduces the initial partial size of the food though grinding. There are three main salivary glands within the mouth. These are the parotid, mandibular, and sub-lingual glands. Saliva secretion is a reflex act stimulated by the presence of food in the mouth. The amount of mucus present in saliva is regulated by the dryness or moistness of the food consumed. Once food is chewed and mixed with saliva, it passes through the mouth, down the esophagus, and into the stomach. The stomach is a muscular organ responsible for storage, initiating the breakdown of nutrients, and passing the digesta into the small intestine. The small intestine is the major site of nutrient absorption, and is divided into three sections. The first section is the duodenum. The duodenum is approximately 12 inches long and is the portion of the small intestine that ducts from the pancreas and the liver. Upon leaving the duodenum, enters the middle portion of the small intestine, the jejunum. This portion involves both the further breakdown of nutrients as well as the beginning of absorption of nutrients. Nutrient absorption continues into the final section of the small intestine, the ileum. The main function of the large intestine is the absorption of water. Digesta from the small intestine passes into the cecum. The cecum is connected to the colon, where digesta is passed to the rectum and anus where the remaining digesta is excreted.
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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 gilt is in heat for 44 hours and the length of her estrous cycle is 21 days. Her approximate time of ovulation is 30-38 hours after onset of estrus and her gestation period is 110-114 days. There are four parts that make up the male reproductive 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 epididymis of a boar is longer that 100 feet in length. 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. Boars do not have a holding area for sperm cells that are ready to ejaculate. Ejaculate from boars are huge and it takes them several minutes to complete ejaculation. A boar's ejaculate volume is 150-350 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 is longer than six hours in sows. The second stage ends with the expulsion of the fetus and associated membranes. Sows typically take approximately two hours. However, large litters can take additional time. The last stage is the expulsion of the placenta. In this stage, sows usually take between one and four hours after the last piglet.
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