Introduction to Swine
Swine or pigs are agricultural animals used mainly for meat production. A few breeds of swine include, durocs, landrace, chester white, spot, poland china, berkshire, hampshire, and yorkshire. According to the USDA, BCS of swine is from 1-5, where a score of one is too thin, a score of three is ideal, and a score of five is too fat. Female pigs are called sows and give birth to piglets. A gilt is also a female pig, but they have not given birth to a litter yet. Boars are male pigs.
Digestion
![Anatomy of the Pig Digestive System Picture](/uploads/5/6/7/3/56734417/2025133.gif?429)
Unlike the other animals discussed in this website, the pigs digestive system is considered a non-ruminant or monogastric. This type of digestive system is very simple, in that there is only one stomach that does the work of digestion. Food eaten by the pig enters the mouth to the esophagus, travels to the stomach, followed by small intestine, cecum and large intestine (Figure 1). The mouth not only grinds food into smaller particles, but saliva is produced from salivary glands to break down chemicals in the food to make digestion easier. Once chewed and mixed with saliva, food is swallowed down the esophagus. The esophagus uses muscle peristalsis to move food down to the stomach. Once in the stomach, breakdown of nutrients from ingesta (food) is initiated. Gastric glands in the stomach secrete hydrochloric acid (HCl) which has a pH of 1.5-2.5. With this acidic pH, most bacteria that was ingested with the food is killed. Digestive enzymes are also found in the stomach which aid in the breakdown of nutrients. Pepsinogen is one such digestive enzyme that is broken down by HCl to form pepsin. Pepsin in return breaks down proteins for the body to use. Mucus is secreted by the stomach to line the digestive membranes to protect the stomach from HCl eating away at the stomach. Chyme (digesta) from the stomach is passed into the small intestines in small amounts. The chyme is mostly fluid at this point and more nutrients are broken down and absorbed in the small intestine. Digesta passes through the cecum to the large intestine and is excreted in the feces of the pig. The main function of the large intestine is absorption of water from the chyme.
Nutrition
Water is the most essential nutrient and is required for pigs to survive. More water is needed for lactating sows. The energy requirements of pigs is dependent on their weight, genetics, and temperature of housing. Protein is required for maintenance, muscle growth, development of fetuses, and milk production in lactating sows. There are 22 amino acids, of which the pig can synthesize 12 from their bodies, the other 10 must must be provided in the diet. The amino acids with the greatest importance are lysine, tryptophan, threonine, and methionine. Corn, grain sorghum, barley, wheat, and soybean meal are most often fed to pigs but they are deficient in the 4 main amino acids required by pigs. Of the minerals, calcium and phosphorus are important to keep in perfect rations together. A deficiency in one will cause illness in pigs. Vitamins are essential for sight, reproduction, and growth and they come in a variety of feeds.
Reproduction
![Sow Reproductive System Picture](/uploads/5/6/7/3/56734417/9717786_orig.jpg)
- The sow reproductive tract is similar to the cow, consisting of two paired ovaries, oviducts and uterine horns. A single cervix, vagina, and vulva make up the lower portion of the reproductive system. A sow can produce 18-20 ova (eggs) to fertilize, but a gilt will only produce 12-14 ova. The estrous cycle is 21 days on average but can range from 18-24 days. Lactation of a sow with piglets will not come into heat again until the piglets have been weaned. Estrus of the gilt is 44 hour or 1.5-4 days long. Ovulation occurs roughly 40 hours after the onset of estrus. Gestation in sows is 110-114 days and piglets grow to weigh 3-3.5 lbs before parturition. Piglet presentation in the uterus of the sow does not matter, they can be born in most any position.
- The boar is similar in every way as the bull, however it does not have an ampulla to store sperm. Ejaculate from boars is huge and takes several minutes to complete ejaculation. Ejaculate volume of the boar is 150-350ml per ejaculation.
Piglet Requirements
![Ear Notching of Piglets Picture](/uploads/5/6/7/3/56734417/6123523_orig.jpg)
After birth it is important for the piglets first action to be drinking of the colostrum or first milk from the sow. The colostrum is important for pig survival and long-term health. A few hours after birth, piglets need to be processed. Processing piglets includes, clipping needle teeth, docking tails, administering iron and other medication(s), identification of piglets, and castration. Piglets are born with 8 teeth that are very sharp, called needle teeth. These teeth need to be clipped to prevent damage to the sow's teats while nursing. It is also done to prevent injury to litter mates during rough play. Tail docking is done to prevent tail biting, which can cause infection. Sow's milk contains insufficient levels of iron and thus an iron injection is necessary to prevent anemia in pigs. Ear notching, tattooing, tagging, etc. are done to identify which piglets belong to which sow. It is also a good record and management procedure. Ear notching is more widely used (Figure 3). Castration of piglets occurs at 7 days after birth. Castrating is done at a young age to avoid problems with carcass when sent to market.
References
"Baby Pig Management - Birth to Weaning." eXtension. N.p., 7 Apr 2010. Web. 21 July 2015. <http://www.extension.ord=g/pages/27050/baby-pig-management-birth-to-weaning#.VbukPvm96ec>.
- "Digestive System of the Pig: Anatomy and Function." The Pig Site. N.p., 10 June 2009. Web. 20 July 2015. <http://www.thepigsite.com/articles/2749/digestive-system-of-the-pig-anatomy-and-function/>.
- Singleton, Wayne, Dr., and Mark Diekman, Dr. "Reproductive Physiology and Anatomy of the Sow." Reproductive Physiology and Anatomy of the Sow. Purdue University Department of Animal Sciences, n.d. Web. 31 July 2015. <http://www.ansc.purdue.edu/swine/porkpage/repro/physiol/reppaper.htm>.
- "Nutritional Requirements of Pigs." The Merck Veterinary Manual. N.p., n.d. Web. 20, July 2015. <http://www.merckvetmanual.com/mvm/management_and_nutrition/nutrition_pigs/nutritional_requirements_of_pigs.html.>
- "Swine Reproduction." Illinois Livestock Trail. N.p., 5 Nov 2003. Web. 21 July 2015. <http://livestocktrail.illinois.edu/swinerepronet/paperDisplay.cfm?ContentID=6274>.
- "Baby Pig Management - Birth to Weaning." eXtension. N.p., 7 Apr 2010. Web. 21 July 2015. <http://www.extension.ord=g/pages/27050/baby-pig-management-birth-to-weaning#.VbukPvm96ec>.