1. Importance of dairy cattle
Dairy cattle make a major contribution to both national and household economies as well as provide milk, which contains essential nutrients. Milk contributes significantly to meeting the human requirements for animal protein and is especially important in the diet of children and the sick.
Regionally, dairy cattle farming contributes to employment on the farm (production), during value addition (processing) and marketing. The farming also supports a large service sector that offers specialized services in nutrition and health.
Increase in human population has resulted in pressure on arable land leading to deterioration of soil fertility and deforestation. Manure from dairy cattle plays a major role in improving soil fertility and it is a source of energy (biogas) for the household.
2. Qualities of a good dairy cow
Though milk production may not be 100% related to the external appearance of a dairy cow, some physical features are related to milk yield and the longevity (length of time animal is productive) of the animal in the herd. These features (Figure 1.1, Table 1.1) are commonly used in judging the goodness of a dairy cow from its external appearance. These characteristics should be considered by dairy farmers while buying, selling or culling dairy animals.
Figure 1.1. Parts of the dairy cow.
Table 1.1. Characteristics used in judging dairy cattle
| Physiology | Character | Description | Desired |
| Size | Size | Stature (height in cm at rump or withers) | Jersey = 120, Guernsey = 125, Ayrshire = 130, Friesian = 135 |
| Chest width | Distance between the front legs | Should be large to give room for the heart and lungs | |
| Rump width | Distance between the pin bones | Should be big to ease calving and allow wide rear udder attachment | |
| Dairy character | Angularity Body frame Dairy type | Reflects the appearance that the cow has the will to milk | Rib structure: ribs wide apart, rib bones wide, flat, long and free from excess flesh Neck: long, lean and blending smoothly into shoulders Barrel: width tending to increase towards rear |
| Rump angle (pelvic angle) | Angle from hooks to pins | Pins should be slightly lower than hooks (about 2.5 cm). Improper angle can hinder reproductive performance and mobility | |
| Topline | Level of backbone from shoulders to pelvis | Should be strong and level | |
| Udder | Fore udder attachment | Attachment to trunk | Attachment of fore udder to trunk should be almost level |
| Udder depth | Distance between bottom of udder and ground in relation to height | Should be shallow and above the hock. Deep udder is prone to injury. Consider age and stage of lactation | |
| Rear udder height | Distance between vulva and udder fold | Should be attached high | |
| Udder suspension | Udder cleft—suspensory ligament | Should be clearly visible and continue upwards. Should be strong to keep udder firm and prevent teats from pointing outwards | |
| Teat placement | Direction of teats | Should point straight down or slightly inwards (for ease of milking) | |
| Teat length | 5 cm ideal for machine milking; slightly longer for hand milking | ||
| Legs and feet | Rear leg set | Angle at hock viewed from side should not be straight | Ideally, pin bone, hock and dew claw should be in one line. Should be straight from the rear |
| Hoof diagonal | Distance between point of toe and top of heel | Intermediate desirable |
3. Basic needs of a cow for optimum production
The aim of keeping a dairy cow is to obtain the maximum amount of milk. A cow will perform at its best only if its basic needs are met. These include:
- freedom from hunger and thirst (good feed and clean water)
- freedom from pain, injury and diseases (good health)
- freedom from discomfort (comfortable environment, e.g. temperature, clean floor)
- freedom from fear and distress (friendly, loving, gentle and caring handler)
To exploit the cow’s full genetic potential, there is need to have a good nutrition program and meet all other needs.
4. The ruminant digestive system
Ruminants are various cud-chewing hoofed mammals having a stomach divided into four compartments (rumen, reticulum, omasum and abomasum), each one with a specific role to play. The most important is the rumen. Cattle, sheep and goats are ruminants. All ruminants ‘chew the cud’. This means that the food they consumed earlier is returned to the mouth for a second thorough chewing before it is re-swallowed.
The rumen is full of tiny microorganisms (bacteria and protozoa) that digest fibrous feed, such as fresh grass and hay, foodstuffs that humans and most other animals cannot digest. After digesting the fibre, the animal makes use of the end products for growth and milk production. The microorganisms can also convert non-protein nitrogen-containing ingredients (e.g. urea) into protein that the animal can use.
These microorganisms also manufacture some vitamins, such as the vitamin B group.
5. The cow as a milk factory
A dairy cow can be thought of as a milk manufacturing factory. Into any manufacturing factory go raw materials, which are processed, and out of the factory comes a new product. The quality and quantity of the product are a combination of both the quality and the quantity of the raw materials and the efficiency of the factory.
The raw materials that go into milk manufacturing are the nutrients. The quantity and quality of these nutrients depend on the feed consumed by the cow. If the cow is fed on poor-quality feed in large quantities or high-quality feed in small quantities, little milk will be manufactured. The size of the factory can be compared to the size of the cow—where a large factory will hold more raw materials, so will a large cow have a larger rumen.
The machinery that converts raw materials into milk constitutes the digestive system (stomachs and intestines) and the udder (mammary gland). All cows can be assumed to have a similar digestive system but the capacity of the udder will vary depending on the number of milk-making units (alveolar cells), which is determined by the genetics of the cow.
These cells are housed within the cow, which provides a conducive environment for them to function (the cow must be comfortable and free from pain). In a factory, this can be equated to the workers (their number and their comfort).
The factory concept is diagrammatically illustrated in Figure 1.2:
