National Goat Handbook

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significantly by equal milking intervals or by 3-times milking for very
high milkers.
26 Rapid removal of milk after stimulation of letdown is essential for
complete milking. There is always some residual milk left in the udder
after milking, but it is normally less in goats than in cows. Regular
and complete milking is one of the requirements for continuance of
lactation. The stimulus of nursing prevents mammary gland regression.
The response is due to release of prolactin from the anterior pituitary.
Lack of this hormone hastens mammary involution and drying off of the
doe.
27 Stage of Lactation Effects
There is a great difference in the composition of milk during the
various stages of lactation among does. Management practices such as
the length of the dry period, feeding program and general health
practices play a significant role in the quality and quantity of milk
that is produced during lactation.
28 Colostrum appears to be a waste product from the new development of
secretory tissues; and while essential to the kid, is not used for
human consumption normally. In some does, during the first few weeks
for milk production, there can be evidence of some blood in the milk.
This is more common in the heavy producing, first-time freshner and
likely the result of rupturing some tiny blood vessels in the udder.
Milking the doe 3 or even 4 times a day may alleviate the problem. A
lack of calcium may also be involved, and should be supplemented in the
diet. Forceful milking is another possibility.
29 The production level of goat milk increases for about 20-30 days
after kidding. During this period of lactation, there is an inverse
relationship between levels of milk and fat content. The percentage of
total fat as well as the composition of milk fat varies. Towards the
end of lactation, fat and protein contents rise while milk yields
decrease.
30 Calcium and phosphorous levels in milk are high in colostrum, then
decrease constantly until near the end, when they rise again. During
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MILK SECRETION
this period, the overall salt content of milk tends to increase,
affecting the taste of milk. Somatic cell numbers are also very high
normally in late lactation as well as in colostrum.
31 Persistency of milk secretion throughout lactation can be
mathematically expressed by determining the average percentage of
decrease in milk for each month, compared to the previous month.
Goats, given proper feed and not being rebred, will continue to give
milk with a high degree of persistency for a long time. High production
on a yearly basis must combine high initial production and good
persistency, which is a heritable characteristic.
32 Age Effects
Milk volume increases with age up to the fourth or fifth year.
After that, the volume decreases with advancing age. The rate at which
production decreases is slower than the rate at which it increased to
maximum yield. The average milking life of a doe maybe about 12 years.
33 Body Size
The relationship of size to milk production provides a misleading
picture. Large does are not necessarily more efficient producers. Based
on gross energetic efficiency, there is little difference in milk
production due to species. Although a goat produces more milk per unit
of bodyweight than a cow, the actual net energy efficiency is close.
Goats have, however, a relatively high basal metabolic rate and
therefore tend to have among the single-purpose dairy breeds a
relatively high dairy merit and net efficiency.
34 Estrus
It appears that upon coming into estrus, the doe goes through a
decrease in milk production. This is only temporary, and is usually
compensated for by a brief period of higher than normal production
after the estrus cycle. There may also be an increase in the level of
fat produced during the estrus period, as is often the case when milk
production is lowered.
35 Disease Effects
Most diseases, including mastitis reduce milk yields. Fat content
will rise due to lower milk production. The solids (and minerals),
albumin, globulin and non-protein nitrogen levels will increase, while
casein and lactose contents decrease.
36 Dry Period
A dry period for the doe is necessary to rebuild her body reserves,
especially minerals and to prepare for the period of heavy production
in the next lactation. Fattening during the dry period can lead to
ketosis or pregnancy toxemia problems. A 60-day dry period is
considered normal. Goats without a dry period tend to produce less in
the next lactation.
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37 Season Effects
Temperature, humidity, management practices and feeds tend to vary
with seasons, thereby affecting milk and fat production. Does test lower
in the summer than in the winter, not necessarily due to drop in milk
production. Does which freshen later in the spring or early summer will
usually have a higher test average for the year than does freshening at
other times.
38 There are many variables that can affect quality and quantity of
goat milk. Many may be hard to control. Careful and efficient
management with a willingness to learn and try new ideas, is certain to
increase productivity of the goats and the quality of their milk.
��The National Dairy Database (1992)��
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%f TITLE;MILK SECRETION
%f COLLECTION;GOAT HANDBOOK
%f ORIGIN;United States
%f DATE_INCLUDED;June 1992
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NUTRIENT REQUIREMENTS AND FEED VALUES
NUTRIENT REQUIREMENTS AND FEED
VALUES
COLLECTION: GOAT HANDBOOK
ORIGIN: United States
DATE INCLUDED: June 1992
Extension Goat Handbook
This material was contributed from collections at the National Agricultural
Library. However, users should direct all inquires about the contents to
authors or originating agencies.
DOCN 000000022
NO C-1
TI NUTRIENT REQUIREMENTS AND FEED VALUES
AU R. S. Adams; Pennsylvania State U., University Park
B. Harris; U. of Florida, Gainesville
M. F. Hutjens; U. of Illinois, Urbana
E. T. Oleskie
F. A. Wright; Rutgers U., New Brunswick, NJ
RV D. L. Ace; Pennsylvania State U., University Park
DE Nutrition
Text
1 The Ruminant Stomach
The dairy goat belongs to the cud-chewing or ruminant group of
animals. This group, which includes cows, sheep, and deer, has the
unique ability of being able to digest roughages which contain
relatively large amounts of cellulose. Cellulose is a part of plants
and thus one of the largest potential sources of energy for animals.
The digestive system of ruminants can also manufacture many essential
nutrients. Drawings of the four compartmentalized stomachs of the
ruminant are shown in Figure 1, indicating the changes from youth to
maturity.
2 Rumen -- This is the largest of the four compartments representing
about 80 percent of the total stomach area. The rumen is often called a
fermentation vat because it contains a large number of microorganisms
bacteria and protozoa, which supply enzymes that break down fiber and
other parts of the feed. The cellulose is converted to volatile fatty
acids that are absorbed through the rumen wall and provide up to 75 [ Pobierz całość w formacie PDF ]