Factors Affecting yield & Composition of Milk (Part 1) Flashcards
A cow yielding ….. per day
40 kg milk
Some factors-are under the control of the farmer
frequency of milking
They can alter them to increase improve its composition
Some factors-are outside the farmer’s control, e.g.
Stage of lactation , pregnancy and estrus
Genetics :
Large among breed differences due to differences in …
gene frequencies
Differences among …. are greater than differences among breeds
individuals within a breed
……… are heritable traits
Milk yield and milk components
Milk yield is … correlated with fat and protein percentage.
Negatively
Most variable in milk
Fat
Least variable in milk
Ash , lactose
The diameter of the fat globule as example of differences
Guernseys have the largest and Holsteins and Ayrshires the smallest fat globules
….. and ….. cow convert much less carotene to vitamin A than other breeds
Guernsey and Jersey
Why Guernsey cows “Golden Guernsey” are becoming less
popular ?
convert much less carotene to vitamin A than other breeds
Yellow milk
fast (easy) milking cows
Less RM (more milk will be removed before the myoepithelial is relax)
Higher fat content (more of the last milk is obtained)
Slow (hard) milking cows are
incompletely milked
Rate of milking is a …. trait
heritable
….. have the highest milking speed among the major dairy breeds.
Holsteins
Milking speed is related to
- The strength of the sphincter muscle
- surrounding the streak canal
- The diameter of the teat opening
- Vacuum level , pulsation rate and pulsation ratio
Why easy milking cows with wider teat opening are more susceptible to mastitis
One function of the streak canal is to prevent bacteria from gaining entrance into the teat
Mature cow reach peak yield in …
40 - 60 day
………. and ……… define the shape of the lactation curve
Peak milk
Persistency
PY Is the highest daily milk production in the cow’s first ..
150 days in milking
First lactation animals reach peak yield in …
70 DIM
The timing and level depend on
1) the cow’s genetic potential
2) BC at calving (Most important)
3) Feeding level
Higher producing cow tend to peak … than low producing ones
later
305 day yeild
Daily yield at peak X (200 to 250)
Peaky yield has a direct effect on ….
Total yield of the year
