AY Honors/Dairying/Answer Key

2. What considerations are made when selecting a calf?

The best approach is a holistic one, by taking a close look at the genetics of the calf and the environment. Both of these factors have an effect on the final phenotype. Maternal and paternal characteristics are important as well as the heritability of these traits. When selecting a calf don't always select on appearance. Know that the calf is going to be used for before selection. Characteristics differ between dairy and beef calves.

5. Know how milk is produced in the cow.

Cows make milk with their mammory tissues just like all mammals (including humans). To start a cow milking first she must get pregnant (around age 2) and give birth. The farmer then continues to milk the cow and the continued demand for milk causes the cow to continue to produce milk. It is not necessary for the cow to get pregnant or give birth again.

Over the years improved dairy science has lead to a linear growth in milk production per cow over decades with no end in sight for the increases. Factors leading to higher milk production include:

• Better control over breeding
• Culling of lower producing cows
• Emphasis on cow happiness - soft music, sand beds, lots of rest, heated and air conditioned barns.
• Better quality and engineered feed

Cows are Incredible Article: http://m.washingtonpost.com/blogs/wonkblog/wp/2014/02/17/cows-are-incredible-they-might-just-keep-producing-more-milk-forever/

USDA Chart showing historic and projected milk production per cow and the size of the US dairy herd

6. Know the steps in milking a cow either by hand or machine.

Hand Milking

Adventist Youth Honors Answer Book/Milk a cow

Machine Milking

The milking machine extracts milk from all teats

Milking machines are used to extract milk from cows when the herd is larger than about 4 cows. The milking unit is the portion of a milking machine for removing milk from an udder. It is made up of a claw, four teatcups, long milk tube, long pulsator tube, and pulsator. The claw is a manifold which connects the short pulse tubes and short milk tubes from the teatcups to the long pulse tubes and long milk tubes. Claws are commonly made of stainless steel or plastic. Teatcups are composed of a rigid outer shell (stainless steel or plastic), which holds a soft inner liner or inflation. Transparent sections in the shell may allow viewing of liner collapse and milk flow. The annular space between the shell and liner is called the pulsation chamber.

Milking machines work in a way that is different from hand milking or calf suckling. Continuous vacuum is applied inside the soft liner to withdraw milk from the teat by creating a pressure difference across the teat canal (or opening at the end of the teat). Vacuum also helps keep the machine attached to the cow. The vacuum applied to the teat causes congestion of teat tissues (accumulation of blood and other fluids). Atmospheric air is admitted into the pulsation chamber about once per second (the pulsation rate), to allow the liner to collapse around the end of teat and relieve congestion in the teat tissue. The ratio of the time that the liner is open (milking) and closed (massaging or resting) is called the pulsation ratio.

The four streams of milk from the teatcups are usually combined in the claw and transported to the milkline or collection bucket (usually sized to the output of one cow) in a single milk hose. Milk is then transported (manually in buckets) or with a mechanical pump to a central storage vat or bulk tank. Milk is refrigerated on the farm in most countries either by passing through a heat-exchanger or in the bulk tank.

In the photo above is a bucket milking system with the stainless steel bucket visible on the far side of the cow. The two rigid, stainless steel teatcup shells applied to the front two quarters of the cow are visible. The top of the flexible liner is visible at the top of the shells as are the short milk tubes and short pulsation tubes extending from the bottom of the shells to the claw. The bottom of the claw is transparent to allow observation of milk flow. When milking is completed the vacuum to the milking unit is shut off, and the teatcups are removed.

Milking machines keep the milk enclosed and safe from external contamination. The interior 'milk contact' surfaces of the machine are kept clean by a manual or automated washing procedure implemented after milking is completed. Milk contact surfaces must comply with regulations requiring food grade materials (typically stainless steel and special plastics and rubber compounds) and are easily cleaned.

Most milking machines are powered by electricity but, in case of electrical failure, there can be an alternative means of motive power, often an internal combustion engine, for the vacuum and milk pumps. Milk cows cannot tolerate delays in scheduled milking without serious milk production reductions.

7. Know eight parts of a milking machine.

The descriptions of these parts can be found in requirement 6 above.

1. Claw
2. Teatcups
3. Short milk tubes
4. Long milk tube
5. Short pulse tubes
6. Long pulsator tube
7. Pulsator
8. Collection bucket

8. What is mastitis? What steps can be taken to prevent mastitis?

Mastitis is the inflammation of the mammary gland. It is usually caused by a bacterial infection from Staphylococcus, Streptococcus, E. coli, or Mycoplasma. It can have many causes, including by poor milking practices, poorly fitting teatcups, faulty milking equipment, and freezing. It can be spread to other cows when bedding is shared between an afflicted cow and a healthy cow. It can be prevented by vaccination.

9. Know five herd health problems, their symptoms, and how to prevent and/or treat them.

Mastitis

Mastitis is an inflammation of the mammary glands. It has been covered in the previous requirement.

Bovine Spongiform Encephalopathy

Bovine Spongiform Encephalopathy (BSE) is more commonly known as mad cow disease. The infectious agent in BSE is believed to be a specific type of misfolded protein called prion. Misfolded prion proteins carry the disease between individuals and cause deterioration of the brain. Different theories exist for the origin of prion proteins in cattle. Two leading theories suggest that it may have jumped species from the disease scrapie in sheep, or that it evolved from a spontaneous form of "mad cow disease" which has been seen occasionally in cattle for many centuries.

Cattle, like most other food animals, are normally herbivores. In nature, cattle eat grass or grains. In modern industrial cattle-farming, various commercial feeds are used, which may contain ingredients including antibiotics, hormones, pesticides, fertilizers, and protein supplements. The use of meat and bone meal as a protein supplement in cattle feed was widespread in Europe prior to about 1987. Worldwide, soybean meal is the primary plant-based protein supplement fed to cattle. However, soybeans do not grow well in Europe, so cattle raisers throughout Europe turned to the less expensive animal byproduct feeds as an alternative. A change to the rendering process in the early 1980s may have resulted in a large increase of the infectious agents in the cattle feed. A contributing factor seems to have been a change in British laws that allowed a lower temperature sterilization of the protein meal.

Soybean meal is cheap and plentiful in the United States. As a result, the use of animal byproduct feeds was never common, as it was in Europe. However, U.S. regulations only partially prohibit the use of animal byproducts in feed. In 1997, regulations prohibited the feeding of mammalian byproducts to ruminants such as cows and goats. However, the byproducts of ruminants can still be legally fed to pets or other livestock such as pigs and poultry such as chickens. In addition, it is legal for ruminants to be fed byproducts from some of these animals. A proposal to end the use of cow blood, restaurant scraps, and poultry litter (fecal matter, feathers) in January 2004 has yet to be implemented, despite the efforts of some advocates of such a policy, who cite the fact that cows are herbivores, and that blood and fecal matter could potentially carry BSE.

Foot and Mouth Disease

Foot-and-mouth disease (FMD), sometimes called hoof-and-mouth disease, is a highly contagious and sometimes fatal viral disease of cattle and pigs. It can also infect deer, goats, sheep, and other bovids with cloven hooves, as well as elephants, rats, and hedgehogs. Humans are affected only very rarely.

Foot-and-mouth disease is characterized by high fever that declines rapidly after two or three days; blisters inside the mouth that lead to excessive secretion of stringy or foamy saliva and to drooling; and blisters on the feet that may rupture and cause lameness. Adult animals may suffer weight loss from which they do not recover for several months as well as swelling in the testicles of mature males, and in cows, milk production can decline significantly.

One of the difficulties in vaccinating against FMD is the huge variation between viral strains. There is no cross-protection between strains (meaning that a vaccine for one strain won't protect against any others) and in addition, two strains within a given strain may have nucleotide sequences that differ by as much as 30% for a given gene. This means that FMD vaccines must be highly specific to the strain involved. Vaccination only provides temporary immunity that lasts from months to years.

Rinderpest

Rinderpest (RP) is an infectious viral disease of cattle, domestic buffalo, and some species of wildlife, it is commonly referred to as cattle plague. It is characterized by fever, oral erosions, diarrhea, lymphoid necrosis, and high mortality. In German, Rinderpest means cattle-plague. It can be prevented by vaccination. Effective control of rinderpest has been established and by the end of 2010, the FAO plan to have eradicated it completely.

Blackleg

Blackleg is an infectious bacterial disease of sheep and cattle, caused by Clostridium chauvoei bacteria. It is found all over the world. A symptom of blackleg is characteristic swellings which make a cracking sound under pressure. Blackleg vaccine gives immunity against it. Burning the upper layer of soil to eradicate left-over spores is the best way to stop the spread of blackleg from diseased cattle.

Foot Rot

Foot rot, or infectious pododermatitisis, is a hoof infection that is commonly found in sheep and cattle. As the name suggests, it rots away the foot of the animal, more specifically the area between the two toes of the infected animal. It is extremely painful and contagious. It can be treated with a series of medications but if not treated the whole herd can become infected. The cause of the infection in cattle is two anaerobic bacteria (grow without oxygen), Fusobacterium Necrophorum and Bacteroides Melaninogenicus. Both bacteria are common to the environment in which cattle live and the Fusobacterium is present in the rumen and fecal matter of the cattle themselves. Usually there is an injury to the skin between the hooves that allows the bacteria to infect the animal. Another cause of foot rot may high temperatures or humidity causing the skin between the hooves to crack and let the bacteria infect the foot. This is one of the reasons that foot rot is such a major problem in the summer. Foot rot is easily identifiable by its appearance and foul odor. Treatment is usually with an antibiotic medication, and preventing injury to the feet is the best way to prevent foot rot.

10. Know the meaning of the following terms:

a. Concentrates

b. Crude protein

c. Cull

d. Dry period

e. Lactating

f. Lactation cycle or period

g. Oxytocin

Oxytocin is a hormone which causes the smooth muscle layer of band-like cells surrounding the alveoli to squeeze the newly-produced milk into the duct system. Oxytocin is necessary for the milk ejection reflex, or let-down to occur.

12. Assist with the care and milking of a dairy herd of cows for at least three months.

This is going to be the hardest part of the honor to arrange if you do not live on a dairy farm.