Observations on the Behaviour of Cows
with Some Possible Explanations
Interruption of Milk Flow at Time of Oestrum
Certain cows almost cease production for twelve or twenty-four hours during the three-weekly heat period, either refusing to give down their milk or being incapable. Other cows show no change in the flow of milk and some even show a slight increase. The relationship between glandular secretions of hormones and milk production seems to control this. Some cows which have an inadequate hormone secretion call upon all available resources to raise the quantity of hormones required for the heat period, with the result that there is an inadequate secretion in the udder to keep the milk flowing. The cow therefore holds the milk until activity in the uterus and vagina slows down. I have found that whereas at such a time a cow of this type is unable or unwilling to give milk to the inanimate milking machine, she will respond to the human hand, thus demonstrating the stimulating effect of 'flesh to flesh' contact on the flow of hormones in the udder.
May it not be that the lack of emotional sensation which the cow feels in the mechanical milking process is one cause of increasing udder troubles, linked with the growing practice of disallowing the cow any emotional stimulus from the suckling of her calf (the practice in large herds being to take the calf away at birth)?
Cows which increase in yield at the time of oestrum do so by the over-production of hormones to all the organs that are associated with the process of reproduction. Hormones stimulate milk flow and a flush of hormones to the udder, brought on by the excitement of oestrum, causes a flush of milk.
It seems, then, that the effect of the heat period on the milk yield of a cow depends on the adequacy of glandular or endocrine secretions. If the cow has an ample functioning of the endocrines she will rise in yield; if her endocrines are not functioning properly she will draw from the udder for the effort of oestrum, and a fall in yield will result.
A cow with a balanced secretion of hormones will come on heat without affecting the milk yield.
Period of Lactation and the Strain of Fertilization
A cow which is yielding heavily will sometimes show no oestrum until she is past the peak of her production, or, if she does come on heat, she will give one of four indications that hormone activity is not adequate to the two functions of high milk yield and fertilization.
- She will fall markedly in yield for the period of the oestrum.
- She will cease production altogether and show great difficulty in regaining output.
- She will go wrong in one or more quarters, or
- A combination of the first three.
If she is effectively fertilized while showing any one of these conditions the chances are that she will either abort or go seriously wrong in the udder before pregnancy is completed. Or she will have a weakly calf which will exhibit tendencies to difficult breeding or udder trouble in later life, if indeed it survives to maturity.
High yielders are therefore best kept empty until they are declining in yield.
Seasonal Influences on the Cow's Ability to Retain Her Calf in Uterus
Sarkies Dream -- born 27th June 1937
1st calf 1st August 1939
2nd calf 17th August 1940
3rd calf September 1941
4th calf August 1942
5th calf 22nd July 1943, died at birth
6th calf 31st August 1944, aborted
7th calf February 1946, alive
Variety -- born 16th July 1940
1st calf 17th February 1943
Slipped 2nd calf 5th July 1944
Slipped 3rd calf April 1945
Slipped 4th calf March 1946
April was like midsummer in 1945 and may have had the seasonal influences of July and August.
As far as Sarkies Dream is concerned, it seems that she has some difficulty in carrying a calf through the summer months. Twice in successive summers she has been found with her udder and the lower half of her body immersed in a stream or water ditch, indicating the possible excess of heat in the udder and sexual organs. An exaggeration of this condition in thundery weather may cause the cow to reject the calf from the uterus and thus reduce the temperature in the region of the uterus.
The same explanation may easily apply to Variety, July 1944 and April 1945 being much alike in weather.
I have found that the summer months show the highest incidence of abortions. This may, of course, be explainable by the higher percentage of autumn calvers aborting at seven months (which is the most common stage), thus falling in the summer.
Clematis, who has a habit of calving twins, is one of the cows who also increases her milk yield during the heat period. She also has the habit of following almost any human that may enter the field, trailing at heel like a dog. This desire to have human contact may have a sexual significance; a strong development of the instinct which makes a herd of cows investigate any strange intrusion to the field in which they may be grazing, i.e. the advent of a calf, a bull, or a strange dog; all, no doubt, having some emotional stimulus on the sexual instincts of maternity (protection of young or desire to procreate the species, etc.).
Fertilization and its Effect on the Udder of Variety -- and Others
It has been my observation that clots in the milk, in one or more quarters, are a frequent aftermath of fertilization of a cow which is not adequate to the task of pregnancy. The system at the time of nidation is no longer able to perform satisfactorily the two functions of milk secretion and foetus nutrition simultaneously. Consequently, if nidation is successful, the udder often suffers.
Variety, previously mentioned in connection with frequent abortion, was served for her fifth calf on 15th July 1946. On 3rd August 1946 she gave clotted milk in watery substance in the near front quarter. At this time she had been allowed to diminish in yield as low as one gallon daily before being served. It is clear, then, that in the case of this cow she is not able to give milk and become pregnant at the same time without ill consequence to her health.
The above notes record typical examples of many observations bearing on my theory that diseases of cows such as mastitis, abortion, sterility, are not primarily caused by bacteria. They point to faulty endocrine functions as a more potent cause, resulting from unnatural methods of management and going right back to inadequate nutrition of soil, crops, and animals.
I am convinced that this line of action will be far more effective in the elimination of animal disease than the old-fashioned germicidal warfare.
Next: 23. The Dread Disease -- Abortion
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