Milk contributes to subsistence food supplies and provides food in areas where   other foods are often not available. Milk is produce and can be trades for foods such as sorghun, millet, pulses and vegetables. In contrast to this milk has played only a small parts in diets of people in some wetter areas where  tsetse  flies are found and which have largely excluded cattle, milk is used for daily home consumption and cash income.

Milk  animal help  to utilized spare labour in  off peak seasons and increase the efficiency of  use of land, crop residues, by  products and fodder form  fallow land.  
The mammary gland will continue  to secrete milk  at  the maximum daily level if milk is removed regularly and as fully as possible at each milking if milk is not removed, the rate of secretion will be reduced because as milk is secreted into the alveolus  the  epithelial cells secrete against an increasing pressure.
Milk is produced in the udder. Some animals like   ewe and goats have two teats  whereas cows have four udders  . see the diagram at page 4. Milk is produced after parturition of animal .  Secretion of milk is a continuous process, and milk is stored inside  the udder  until it is removed by suckling or milking . If milk is not removed, secretion soon stops or when this pressure become too great, the rate of secretion reduce secretion slow down and stops about 35 hours after the last milking.

The best time to milk is every 9 –10 hours, but this would require more than twice a day milking. Milking three times a day produces 15-25%  more milk  than twice a day milking but the labour cost and management inputs required  are usually to great. In intensive systems an 11-13 hours split between milking is adopted. While in pastoral system cattle are often only milked in the morning, but the young suckles for parts of the rest of the 24 hours period, thus maintaining milk secretion.
Milk let down is controlled by the hormone oxytoxcin   which is reduced as reflex to natural stimuli: Milk let down by the udder can be stimulated physically by pressure applied to the teats or suckling by the young animals or by washing of the treats with damp cloth.
Beside the contraction of the myoepithelial cell oxytocin also causes a  dilatation of sphincter muscle closing the  teat canal.  See the diagram iii at pg 4.

Since the secretion of milk is a continuous process, although its does not occur at a constant rate immediately following milking pressure in the duct and alveoli is at its lowest and secretion occurs at a constant rate. In hours following the pressure increases owing accumulation of milk in the gland and the mammary gland reaches approximately 40  - mmHg, secretion ceases due to the closure of the capillaries and fall in the blood flow.
If milking is inefficient and slow, all the milk will not be let down and milked out.
Normally, there is usually 15% of the total volume remaining in the udder  after let down.
Incomplete milking   reduces the long- term yield performance
The method of milking (by machine or hand) also affects the amount of milk produces.  Restricted suckled animal have been observed to produce more milk than animal which  are not  sucked.
Short –term stress due to  noise, excitement painful treatment and other disturbance can affect milk let down since the adrenalin secretion inhibits milk let down. High environmental temperature causes stress.
At ambient temperature over 24oc, milk yields may be affected due to lower food intake, temperature control activity and behavioral responses, such as shade seeking
These can be compensated for by adjusting   feeding to a low dry matter concentrate, time of feeding, night feeding and by the provision of shade and the orientation of housing.
Under this condition, whether this is due to decreased oxytocin out put or to reduced mammary blood flow as a result of activation of  the  sympathetic nervous  system by adrenlin.
Failure to get   adequate milk ejection due to constriction of the teat canal occurs in animals.  Because of excessive retention of milk in the udder, the lactation period of such animals may be shortened. Since the condition is genetic such animal should be excluded from breeding.

Share on Google Plus


The publications and/or documents on this website are provided for general information purposes only. Your use of any of these sample documents is subjected to your own decision NB: Join our Social Media Network on Google Plus | Facebook | Twitter | Linkedin