Dairy Cow Introduction
Many breeds of cow are used for the main production of milk. Some of the breeds of dairy cattle include Ayrshire, Dairy shorthorn, Friesian, Guernsey, Holstein, Jersey, Norwegian Red, and Randall. Dairy cows are evaluated on a body condition score (BCS) scale of 1-5, with 1 being too thin, 3 preferred, and 5 too fat. Reproduction of dairy cattle can be found on beef cattle page, as they have the same reproductive system.
Digestive System
![Digestive system of cow Picture](/uploads/5/6/7/3/56734417/5657072.jpg?314)
Being a ruminant, the digestive system of the dairy cow works in the same manner as beef cattle.
Four steps to Rumination
Rumination is an important factor for all ruminants, as it allows the animal to forage and eat rapidly, and then store for later digestion. Rumination time average for grazing animals consist of eating for 8 hours, ruminating for 8 hours, and resting for 8 hours. Feed is more readily digested by rumen microbes when particle size is reduced, thus the four R's of ruminant digestion are important processes for every ruminant. The four R's of ruminant digestion include:
Four steps to Rumination
- Rumen: Located on the left side of cattle, the rumen is also known as the fermentation vat. This vat holds a large number of microorganisms (bacteria and protozoa) which do the majority of digestion in the rumen. The inside of the rumen is covered with papilli (imagine a deep pile carpet) which create more surface area and allow more room for absorption of nutrients. The average cow can hold 40-50 gallons in there rumen.
- Reticulum: Has a two part job in the stomach, known as the "traffic cop." It is located in the more cranial area of the body cavity and looks like honeycomb. The reticulum receives feed stuffs from the esophagus and sends it to the rumen. It also receives partially digested feeds from the rumen and sends these down to the omasum. A cow with "hardware disease" will have a problem here in the reticulum. This disease occurs when a cow eats metal like nails or other sharp objects, and they end up in the reticulum. Using a magnet or surgery are the only ways to extract the objects. If not removed, infection and/or death of the animal will occur. About 2 gallons is all that a cow can hold in the reticulum.
- Omasum: Known as "many plies" or "pages of a book," the omasum absorbs water and other substances from the digestive contents. Feed material (ingesta) is drier within the folds of the omasum than other compartments. Ingesta here is also grinded up to smaller particles that then passes to the abomasum. The omasum can hold about 4 gallons of ingesta.
- Abomasum: The true stomach of cattle, the abomasum works similarly to that of non-ruminants. Like humans, the abomasum contains hydrochloric acid and other digestive enzymes to help break down ingesta. It is the only compartment of the stomach that has a glandular lining. Like the omasum, the abomasum can hold about 4 gallons of ingesta at any one time.
Rumination is an important factor for all ruminants, as it allows the animal to forage and eat rapidly, and then store for later digestion. Rumination time average for grazing animals consist of eating for 8 hours, ruminating for 8 hours, and resting for 8 hours. Feed is more readily digested by rumen microbes when particle size is reduced, thus the four R's of ruminant digestion are important processes for every ruminant. The four R's of ruminant digestion include:
- Regurgitation: The process of reverse peristalsis, where food is carried back to the mouth. Stimulus for this process occurs when digesta in fiber mat scratches the surface near the cardiac sphincter of esophagus. Contraction of the reticulum forces digesta to the sphincter and the animal inhales with the epiglottis closed to produce a vacuum. This vacuum causes the cardiac sphincter to open and esophagus dilates allowing rapid reverse peristalsis of digesta to the mouth. Once at the mouth, remastication begins.
- Remastication: Digesta that has just been regurgitated is now rechewed during this process. The digesta, known as a bolus, is chewed slower in order to reduce particle size.
- Reinsalivation: During remastication, digesta is reinsalivated to break down particles easier. Parotid glands secrete more saliva during this time than when eating initially. Saliva provides liquid for the microbial population and a buffer for the rumen. This buffer helps maintain a rumen pH between 6.2 and 6.8 for optimum digestion of forages and feedstuffs.
- Redeglutition: Swallowing the bolus this time includes smaller particles and more liquids. The rumen contracts to move the bolus into the rumen.
Nutritional Needs
In order to increase productivity of a milking cow, an enhanced nutritional management technique is by using totally mixed rations (TMR). All components of the diet are mixed together making it a balanced diet. Another reason for using TMR is it masks unpalatable feeds that are important for cattle. Meeting the nutritional needs of the high producer includes a number of requirements:
- Dairy cows are producing milk an average 305 days a year. Because of this, they require a higher amount of water than most agricultural animals because milk is made up of approximately 88% water. A 1400 pound cow should be drinking between 12 and 45 gallons of water per day, depending on temperature and amount of milk production made by that cow in pounds.
- Energy from a high quality forage or increased grain is essential. Alfalfa is one such forage. Corn silage typically makes up 40-50% of the diet with a high starch content. Processed corn silage is better utilized in dairy cows. By-products like distiller grains are high in energy and protein.
- Protein sources include distillers, gluten, cottonseed, and blood meal. Though blood meal is not recommended due to diseases spread through the herds.
- Fiber sources are found in alfalfa hay, grass hay, straw, and cottonseed.
- Minerals are important for the dairy cow, in order for their milk production to be of high quality. Calcium should be 0.8-1% of the diet and phosphorus at 0.35-0.5%. Selenium, zinc, and potassium are also important in the diet.
- Vitamins A, D, and E are all essential.
Lactation
![Anatomy of the cow udder Picture](/uploads/5/6/7/3/56734417/4031257.gif?382)
Production of milk via the mammary gland is unique to mammals. The mammary gland serves two purposes for the young, nutrition and a source of passive immunity to newborns. In dairy cows, the mammary gland also serves the purpose of milk production for human consumption. The cow has four separate mammary glands that terminate into four teats. Milk production is under hormonal control. Some of the hormones include estrogen to stimulate the development of milk ducts and cisterns, progesterone which stimulates growth of alveoli, and oxytocin for milk let down. The most important milk for young calves is the "first milk," or colostrum. Colostrum contains immunoglobulins which provide the passive immunity to newborns.
References
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- "Importance of Fresh and Frequent Feeding." Lely. N.p., n.d. Web. 15 July 2015. <http://www.lelylife.com/2012/04/importance-of-fresh-and-frequent-feeding/>.
- "Total Mixed Rations for Dairy Cows: Advantages, Disadvantages, and Feeding Management." Penn State Extension. Penn State College of Agricultural Sciences. N.p., n.d. Web. 15 July 2015. <http://extension.psu.edu/animals/dairy/nutrition/nutrition-and-feeding/diet-formulation-and-evaluation/total-mixed-rations-for-dairy-cows-advantages-disadvantages-and-feeding-management>.
- "Feed nutrients." Dairy Extension. University of Minnesota. N.p., n.d. Web. 15 July 2015.<http://www.extension.umn.edu/agriculture/dairy/feed-and-nutrition/feeding-the-dairy-herd/feed-nutrients.html>.
- "Structure of mammary glands." Chapter 10 Lactation. N.p., n.d. Web. 15 July 2015. <http://nongae.gsnu.ac.kr/~cspark/teaching/chap10.html>.
- "Feeding the Dairy Herd." Dairy Extension. University of Minnesota. N.p., n.d. Web. 15 July 2015. <http://www.extension.umn.edu/agriculture/dairy/feed-and-nutrition/feeding-the-dairy-herd/nutrition.html>.