NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
TREATMENT OF FOLLICULAR MANGE IN DOGS
121
out by Marotel and Pierron [1926]. According to these authors, the best results in
ultra-violet therapy are obtained with a mercury lamp (" model 2, type c ") of 1,200
candle power, the animal concerned being " irradiated" for 50-60 minutes at a
distance of 20 cm. As pointed by them, the ultra-violet phototherapy has a three-
fold advantage: (1) Like all baths in general (liquid or gaseous) the luminous
bath most certainly touches all the affected parts, contrary to what would be
possible with any form of manual treatment (e.g., friction, puncture, scarification,
etc.); (2) ease of application; (3) absolute curative value, when the directions for
treatment are rigorously followed (the authors treated twelve animals by this
method and cure was obtained in every case). On the other hand, the authors
mention three outstanding disadvantages of the method: (1) Risk of the skin
being burnt when the patient is " irradiated " at a distance of less than 20 cm. or
when exposed to radiation for more than 60 minutes or when the animal concerned
happens to be a sensitive one (with a thin or insufficiently pigmented skin); (2) the
head, because of the eyes, does not admit of being " irradiated ", and one is there-
fore obliged to treat it apart by means of other remedies; (3) compared with
other methods, radiant therapy is somewhat expensive.
In two recent articles, Hardenbergh and Sheard [1927, 1928] have published
some observations upon the effects of ultra-violet and infra-red radiation on
Demodex folliculorum in the dog. The observations, however, were mostly made
upon the parasites in vitro and only a very small number of cases in vivo, their
main conclusions in regard to the actual efficacy of the treatment being as follows :
" The daily radiation of an animal affected with demodectic mange for from 15 to
45 minutes with an air-cooled quartz-mercury are lamp, operated at 90 volts at a
distance of 50 cm., apparently maintains the general physical tone of the whole
animal at a higher level and thereby aids in combating the untoward conditions
set up in the host by the invading parasites". The authors regard it as possible
that Demodex folliculorum is more susceptible to heat (infra-red) than to other forms
of radiant therapy and that the benefits of this method of treatment are not due to
any specific lethal effects on the parasites, imbedded as they are in the deeper layers
of the skin, but to its stimulating action which causes a general improvement in the
condition of the animal and thereby enables it to overcome the effects of the
invading parasites. On the other hand, Marotel and Pierron (l.c.) describe the
effects of ultra-violet phototherapy as follows : " After the first radiations, the
skin tumefies and sweats (" suinte ") at the level of the pustules which then become
powdered (" saupoudres") over with tannin and this latter gets dissolved in the
exudate, thus forming an acaricidal and astringent solution. At the end of the fifth
day, the pimples disappear and the sweating commences to dry up and desquamate,
and at the end of a fortnight, it attains a condition of simple dermatitis which
c2
122 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
follows its normal course. It is noteworthy that, according to Patton [1926],
the areas to be " irradiated " should be " free from scurf, excretions, dirt, grease and
so forth ", and it is therefore possible that a lack of proper attention to this detail
may have been responsible in the past for a proportion of the failures to obtain
satisfactory results with radiant therapy.
Quite recently, Bannerjee [1933] in India has claimed to have obtained " most
encouraging results " in the treatment of follicular mange in dogs by exposure to
ultra-violet rays. The apparatus used by this worker was a mercury quartz lamp
("Hanovia"), the animal concerned being "irradiated" daily for five or more
minutes on each side of the body at a distance of about 3 feet. The protocol of
only one dog, however, is given and in this case the treatment comprised three
courses, the first consisting of eighteen exposures and the second and third each of
seven exposures, but skin scrapings continued to reveal the parasites until the com-
mencement of the third course of treatment. Concurrently with the ray treatment,
the animal was periodically subjected to " Pot. sulphate baths " combined with a
skin dressing.
Removal of the affected parts, in cases of circumscribed infection, has been
recommended by Roth (cited by Hutyra and Marek, I. c), the method consisting in
cutting the epidermal layer until drops of blood appear, the animal being anaesthe-
tized.
REFERENCES.
Alston, J. J. (1933). Mange Treatment for Dogs. Vet. Med., 28, 164.
Aruch, E. (1922). Cura della Rogna demodectica del cane. La Clinica Vet., 55, 333-334
(Abstr. in Rev, App. Ent., Ser. B. 10, 211; 1922.)
Banerjee, G. S. (1933). Treatment of Follicular Mange in Dogs by Exposure to Ultraviolet
Rays. Vet. Abstr., 1, 47-49.
Barat, M. (1928). L'huile de chaulmoogra dans le traitment de la Demodecic. Rec. Med,
Vet., 102, 666-669.
Crane. D. B. (1933). Rotenone—A new Parasiticide. Cornel Veterinarian, 23, 15-31.
Hardenbergh, J. G. and Schlotthauer, C. F. (1925). Domodectic Mange of the Goat and its
Treatment. Jl. Amer. Vet. Med. Assoc., 67, 486-489.
Hardenbergh, J. G. and Sheard, C. (1927). The possible Role of Rdiant Therapy in Demo.
dectic Mange. Jl. Amer. Vet. Med. Assoc., 71, 607-617.
Holmes, R. P. (1920). A treatment of the Different Forms of Mange and other parasitic Skin
Diseases of Horses and Mules with a Combination of Calcium Sulphide and Horse Fat.
Vet. Jl, 76, 380-335.
Hutyra Franz and Marek, Josef (1926). Special Pathology and Therapeutics of the Discases
of Domestic Animals, 3, 761-776. Alexander Eger Chicago.
Kappel. A. (1925). Acariasis hos et Faar. Maanedsskrift f. Dyrlaeger, 36, 501-502.
(Abstr. in Rev. App. Ent., Ser. B, 15, 2 ; 1927.)
TREATMENT OF FOLLICULAR MANGE IN DOGS
123
Marotel and Pierron (1926). Traitment de la gale dénodécique canine par les rayons ultra-
violets. Jl. Méd. Vet. et Zootech., 72. 350-358.
Muller, Georg and Glass, A. (1926). Diseases of the Dog and their Treatment. Alexander
Eger, Chicago.
Patton, J. W. (1926). Ultraviolet Radiation as a Therapeutic Agent in Veterinary Medicine.
Jl. Amer. Vet. Med. Assoc, 69, 734-758.
Sheard, C. and Hardenbergh, J. G. (1928). The Effect of Ultraviolet and Infra-red Irradiation
on Demodex folliculorum. Jl Parasit., 14, 36-42.
Stephenson, H. G. (1933). Hints in Small Animal Practice. Vet. Med., 28, 343.
Wooldridge, G. H. (1923). Encyclopaedia of Veterinary Medicine, Surgery and Obstetries,
1, 472-474. Henry Frowde and Hodder and Stoughton, London.
A STUDY OF THE DATA OF MILK YIELDS OF VARIOUS TYPES
OF CATTLE OBTAINED FROM THE RECORDS OF THE
GOVERNMENT MILITARY DAIRY FARMS.
PART II. PERSISTENCY OF LACTATION AND ITS RELATION TO AGE
AND LEVEL OF PRODUCTION.
BY
K. P. R. KARTHA, B.A.,
Statistical Assistant, Animal Husbandry Bureau, Imperial Council of Agricultural
Research.
(Received for publication on the 6th April 1934.)
(With six text-figures.)
In part I* of this paper the milk records of herds of Indian and Cross-bred cows
and buffaloes were analysed and it was shown that the milk yield may be expressed
as a function of the two characters, namely, the initial rate of yield and the rate
at which it declines. This rate of declines was used as a measure of persistency,
(by which term is meant the degree to which the level of yield is maintained), the
animal that declines most being the least persistent and vice versa. It is commonly
known that the rate of decline varies with breed and with individuals in the same
breed ; it is affected by age, level of production, pregnancy, state of nutrition and
other environmental factors; it is also affected by heredity. The rate of decline is
thus subject to the same variations as milk yield or fat yield, and has to be studied
as a separate character. In order to do this it is necessary to evolve a value of the
rate of decline for each lactation; then alone can one find out the range within
which this value varies in the several breeds, what its standard deviation is and how
far it is influenced by the various factors enumerated above. In the following
pages a preliminary attempt is made to measure the effect of age and level of pro-
duction on the rate of decline, the study being based on a total of 812 lactations
for each of which a value of the rate of decline was found out. The influence of
pregnancy will be considered in a later section.
* Part I of the paper was published in the Ind. Jour. Vety. Sci. and Anim. Husb. Vol. IV, Pt. 1,
pp. 36-62.
( 124 )
PERSISTENCY AND ITS RELATION TO AGE AND LEVEL OF PRODUCTION
125
Data of monthly yields had already been collected for the study reported in
Part I. Some more were collected, making up a total of 344 lactations for the
cross-bred, 244 for the buffaloes, 113 for the pedigree Sahiwal and 111 for the ordi-
nary Sahiwals. The equation made use of to describe the lactation curve is of the
same form as used in Part I, but the method of determining the constants (rate of
yield and rate of decline) is slightly different, as the method employed there, though
more accurate, is too laborious to be applied when hundreds of lactations are
involved. The method is known as the method of averages, and an example of
working is given in the Appendix.
The values of rates of decline are classified and given in Table I for the four
breeds, and those for the cross-bred are represented graphically in Fig. 1. The
Fig. 1. Frequency distribution of the values of rate of decline. (Crcse-bied cows.)
126 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
TABLE I.
Distribution of persistency values.
Persistency expressed
as rate of decline per
434.3 lb. milk per month
Class mid-point
—2.5 ....
2.5 ....
7.5 ....
12.5 ....
17.5 ....
22.5 ....
27.5 ....
32.5 ....
37.5 ....
42.5 ....
47.5 ....
52.5 ....
57.5 ....
62.5 ....
67.5 ....
72.5 ....
77.5 ....
82.5 ....
87.5 ....
92.5 ....
97.5 ....
102.5 ....
107.5 ....
112.5 ....
117.5 ....
122.5 ....
127.5 ....
Total .
Mean ....
Cross-bred
cows
4
2
3
8
19
28
31
49
41
40
33
23
18
14
9
9
9
2
..
2
..
..
..
..
..
..
..
344
39.986
Frequency
Pedigree
Sahiwal
3
3
2
4
7
18
8
13
14
8
8
2
7
6
1
2
..
1
2
1
1
1
1
..
..
..
..
113
37.456
Ordinary
Sahiwal
..
l
2
..
9
5
11
4
8
7
9
8
10
8
8
3
5
4
3
..
1
1
1
..
1
1
1
111
50.92
Buffaloes
3
..
6
4
2
16
23
23
46
27
30
16
14
10
7
5
6
1
2
..
..
1
..
2
..
..
..
244
42.27
NOTE.—To save arithmetical labour the rate of decline is expressed per 434.3 lb. milk. The
percentage decline is obtained by dividing these by 4.343. These figures will be found in Table II.
PERSISTENCY AND ITS RELATION TO AGE AND LEVEL OF PRODUCTION
127
TABLE II.
Means, standard deviations and co-efficients of variations of persistency, initial rate
of yield and age in the various breeds.
Breed
Cross-bred cows .
Pedigree Sahiwal .
Ordinary Sahiwal .
Buffaloes . .
Rate of decline*
per month
per 100 lb. milk
No. of
records
averaged
344
113
111
244
Mean
9.210
8.624
11.725
9.733
Standard
devia-
tion
3.960
5.07
5.77
4.119
Co-effi-
cients of
variations
43.0
58.84
49.25
42.32
Rate of yield per month*
at maximum (i.e. at one
month after calving)
Mean
974.70
740.264
504.955
621.31
Standard
devia-
tion
357.1
232.26
148.1
165.9
Co-effi-
cients of
variations
36.63
31.4
29.3
26.7
Mean age
(in lacta-
tions.)
5.02
5.39
5.03
4.59
means and standard deviations are entered in Table II. Figure 1 shows that over
60 per cent. of the observations are scattered round the mean within the range
indicated by the standard deviation. As was already noticed in Part I the
specially bred pedigree Sahiwal at Ferozepore is the most persistent and the
ordinary Sahiwal cow is the least persistent. The cross-bred and the buffalo are
more or less on the same level. From the figures of coefficients of variation it
would appear that the pedigree Sahiwals are most variable.
Table II contains also the rates of yield per month at maximum (which is yield
per month at one month after calving). The cross-bred cow is the highest and is
above the Ferozepore herd by 4 to 5 lbs. a day at their maximum, though a good
deal of this difference is made up in the course of a lactation on account of their
higher persistency. The buffalo is seen to be a distinctly better type of dairy
animal than the ordinary Indian cow. Her rate of yield and persistency are both
higher than that of the ordinary Sahiwal.
RELATION OF PERSISTENCY TO LEVEL OF PRODUCTION.
The strength of relationship between two factors is measured by the coefficient
of correlation between them; and this coefficient can be calculated by well known
methods. The value of this coefficient would lie between the limits 0 and 1, 0
indicating absence of, and 1 indicating perfect relationship.
The lëvel of production is indicated by the initial rate of yield. Tables III to
VI show the correlation between the initial rate of yield and the rate of decline.
* The slight differences noticed between these values and those recorded on page 47 of Part I may
be accounted for by (1) the difference in the method of determination of the values and (2) the increase
in population.
128 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
TABLE III.
Correlation surface showing the relation of Rate of decline to Rate of yield. (Data : Cross-bred cows.)
Rate of decline
per month per
434.3 lb. of
milk.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Class
mid-
point.
—2.5
2.5
7.5
12.5
17.5
22.5
27.5
32.5
37.5
42.5
47.5
52.5
57.3
62.5
67.5
72.5
77.5
82.5
87.5
92.5
Total
Mean of columns .
2
2.5
2
...
...
...
...
1
...
...
...
...
...
...
...
...
...
...
...
...
...
...
3
5.9
3
3.5
..
...
...
...
2
2
...
...
...
...
...
...
...
...
...
...
...
...
...
...
4
20.0
4
4.5
1
...
1
1
2
1
3
...
5
2
1
2
...
...
...
...
...
...
...
...
19
30.6
5
5.5
.. 1
...
2
3
1
3
1
...
1
...
...
1
...
1
...
...
...
...
...
14
27.5
6
6.5
1
...
1
1
1
1
1
9
2
2
1
2
1
...
1
1
1
...
...
...
26
37.1
7
7.5
...
1
1
2
3
6
7
8
7
3
3
1
1
1
3
1
...
...
...
...
48
34.3
8
8.5
..
...
...
2
4
7
5
4
2
1
6
3
3
1
...
...
1
...
...
...
39
35.7
9
9.5
...
...
... ...
2
4
3
11
3
11
4
1
2
1
...
...
...
...
...
...
42
35.1
10
10.5
...
...
... ...
...
3
2
8
5
5
4
4
4
3
2
1
...
1
...
...
42
45.0
Yield per month at one month after calving, in 100 lb units.
Class Mid
point.
11
11.5
...
...
... ...
1
1
4
1
2
5
8
3
1
3
... 1
2
...
... 1
33
47.6
12
12.5
...
...
...
...
1
...
... 3
6
3
2
2
... 1
... 1
1
...
...
...
20
44.0
13
13.5
...
...
...
...
1 1
...
...
4
2
1
...
1
1
1
2
1
1
...
...
15
49.8
14
14.5
...
...
...
...
...
...
1
1
3
3
1
2
3
2
1
...
...
...
...
...
17
48.1
15
15.5
...
...
...
...
...
...
1
...
1
1
...
...
1
...
...
...
...
...
...
...
4
41.3
16
16.5
...
...
...
...
...
...
...
...
1
...
... 2
... 1
...
...
2
...
...
...
6
60.0
17
17.5
...
...
...
...
...
...
... 1
....
...
1
1
...
...
... 1
...
...
...
...
4
51.75
18
18.5
...
...
...
...
...
...
1
2
...
...
...
...
...
...
...
...
...
...
...
1
4
46.75
19
19.5
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
...
..
...
1
77.5
20
20.6
...
...
...
...
...
...
....
...
...
...
1
...
...
...
... 1
....
...
...
...
2
60.0
21
21.5
...
...
...
....
...
...
....
...
...
...
... ....
...
...
...
...
...
....
...
...
...
...
22
22.5
...
...
...
...
...
...
....
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
23
23.5
...
...
...
....
...
...
.....
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
24
24 .5
...
...
...
...
...
...
...
...
... l
...
...
...
...
...
...
...
...
...
...
1
42.5
Total.
4
2
3
8
19
28
31
49
41
40
33
23
18
14
9
9
9
2
... 2
344
Mean rate of yield
„
„
decline
. 9740.70 lb. per month
. 39.9885
per 434.3 15. of milk.
Co-efficient of correlation
Standard deviation of yield
....
„
„
rate of decline .
.
. .4817
357.1 lb.
17.195 lb.
PERSISTENCY AND ITS RELATION TO AGE AND LEVEL OF PRODUCTION
129
TABLE IV.
Correlation surface showing the relation of rate of decline to rate of yield . (Data-
pedigree Sahiwal cows.)
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Rate of decline
per month per
434.3 lb of milk
Class mid-point
—2.5 . .
2.5 . .
7.5 . .
12.5 . .
17.5 . .
22.5 . .
27.5 . .
32.5 . .
37.5 . .
42.5 . .
47.5 . .
52.5 . .
57.5 . .
62.5 . .
67.5 . .
72.5 . .
77.5 . .
82.5 . .
87.5 . .
92.5 . .
97.5 . .
102.5 . .
107.5 . .
Total .
Mean of columns .
1
2.5
1
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
1
—2.5
2
7.5
..
1
..
..
1
1
..
..
..
..
..
..
..
..
..
..
..
..
1
..
..
..
..
4
32.5
Yield per day in lb. at one month, after calving
Class mid-points
3
12.5
1
..
1
..
..
..
..
2
1
..
..
1
..
..
..
..
..
..
..
..
..
..
..
6
26.7
4
17.5
..
..
..
1
..
3
1
1
..
2
2
..
..
1
1
..
..
..
..
..
..
..
..
12
37.5
5
22.5
1
..
..
3
2
3
1
1
2
1
2
..
1
..
..
..
..
..
...
..
1
..
..
18
43.6
6
27.5
..
..
1
..
3
8
2
6
5
3
3
1
..
..
..
2
..
..
..
1
..
..
1
36
37.6
7
32.5
..
1
..
..
1
3
2
2
4
..
..
..
3
2
..
..
..
..
..
..
..
1
..
19
39.9
8
37.5
..
1
..
..
..
..
2
..
2
2
1
..
2
1
..
..
..
1
1
..
..
..
..
13
47.1
9
42.5
..
..
..
..
..
..
..
1
..
..
..
..
1
2
..
..
..
..
..
..
..
..
..
4
53.8
Total
3
3
2
4
7
18
8
13
14
8
8
2
7
6
1
2
..
1
2
1
1
1
1
113
..
Mean rate of yield
„
„ decline
. 26.438 lb. per day.
. 37.4555 lb. per month per
434.3 lb. milk. |
Co-efficient of correlation
Standard deviation of yield
„
„
decline
. .2598.
. 8.295 lb.
. 22.04 lb.
130 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
TABLE V.
Correlation surface showing the relation of Rate of decline to Rate of yield.
(Sahiwal cows. Ordinary).
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Rate of decline
per month per
434.3 lb. of milk
Class mid-point
2.5 . . .
7.5 . . .
12.5 . . .
17.5 . . .
22.5 . . .
27.5 . . .
32.5 . . .
37.5 . . .
42.5 . . .
47.5 . . .
52.5 . . .
57.5 . . .
62.5 . . .
67.5 . . .
72.5 . . .
77.5 . . .
82.5 . . .
87.5 . . .
92.5 . . .
97.5 . . .
102.5 . . .
107.5 . . .
112.5 . . .
117.5 . . .
122.5 . . .
127.5 . . .
Total .
Mean of each, column
Yield per month in 100 lb units at one month after
calving. Class mid-point.
1
2.5
1
..
.. 3
2
.. 2
..
..
1 ..
..
..
..
..
..
..
..
..
..
..
...
..
...
..
..
9
23.15
2
3.5
.. 2
.. 1
2
2
.. 1
1
3
1
1
2
1
..
..
..
..
..
..
..
..
..
..
..
..
17
38.7
3
4.5
..
..
.. 2
1
2
1
2
3
2
4
3
2
2
1
3
1
2
..
..
.. 1
..
..
..
..
32
54.85
4
5.5
..
..
3 ..
.. 5
1
3
1
1
1
3
1
4
1
1
..
..
..
..
..
..
..
..
.. 1
26
47.5
5
6.5
..
..
..
..
1
..
..
..
2
1
.. 2
1
1
1
1
2
1
..
..
1
..
..
..
1
..
15
68.9
6
7.5
..
..
..
..
.. 1
..
2
.. 2
1
1
1
..
..
..
1
..
..
..
..
..
..
..
..
..
9
50.3
7
8.5
..
..
..
..
..
..
..
..
..
..
..
..
1
..
..
..
..
..
.. 1
..
..
..
..
..
..
2
80.0
8
9.5
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
.. 1
..
..
1
117.5
Total
1
2
..
9
5
11
4
8
7
9
8
10
8
8
3
5
4
3
..
1
1
1
..
1
1
1
111
..
Mean rate of yield
„
„
decline ,
504.955 lb. per month.
50.92
„
per
434.3 lb. milk.
Co-efficient of correlation
Standard deviation of yield
„
„
decline
. .4153
. 14.05 lb.
. 25.065 lb.
PERSISTENCY AND ITS RELATION TO AGE AND LEVEL OF PRODUCTION
131
TABLE VI.
Correlation surface showing the relation of rate of decline to raid of yield,
(Data:—Buffaloes).
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Rate of decline
per 434.3 lb. milk.
Class
Mid- point
-2.5
+ 2.5
7.5
12.5
17.5
22.5
27.5
32.5
37.5
42.5
47.5
52.5
57.5
62.5
67.5
72.5
77.5
82.6
87.5
92.5
97.5
102.5
107.5
112.5
Total .
Mean of each column.
Rate of yield per month in 100 lb. units at one month after calving.
Class mid-point.
1
1.5
...
...
...
...
...
..
1
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
27.5
2
2.5
1
...
...
...
...
...
...
...
2
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
3
24.2
3
3.5
1
...
1
...
1
3
1
1
2
3
...
...
...
1
..
...
...
...
...
...
...
...
...
...
14
29.7
4
4.5
1
...
2
2
...
...
7
6
9
3
1
2
2
1
...
2
1
...
...
....
...
...
...
1
40
38.9
5
5.5
...
...
2
1
1
10
3
8
12
3
6
1
2
1
2
...
2
...
...
...
...
...
...
..
54
37.4
6
6.5
...
...
1
1
...
1
6
6
8
12
7
6
3
2
3
1
1
..
1
...
...
...
...
...
59
44.0
7
7.5
...
...
...
...
...
1
4
...
11
3
9
3
3
3
...
2
1
1
1
...
...
...
...
..
42
47.8
8
8.5
...
...
...
...
...
1
1
1
1
2
2
3
3
...
1
...
1
...
...
...
...
1
...
...
17
51.6
9
9.5
...
...
...
...
...
...
....
1
1
1
5
...
1
2
...
..
...
...
...
...
...
...
...
1
12
53.8
10
10.5
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
11
11.5
...
...
...
...
...
...
...
...
...
....
...
...
...
...
1
...
...
...
...
...
...
...
...
...
1
67.5
12
12.5
...
...
...
...
...
..
...
...
...
...
...
1
...
...
...
...
...
...
...
...
...
...
...
...
1
52.5
Total
3
...
6
4
2
16
23
23
46
27
30
16
14
10
7
5
6
1
2
...
...
1
...
2
244
„
Mean rate of yield per month
„
„
decline
„
. 621.31 lb.
. 42.27 lb. per 434.3 lb. milk.
Co-efficient of correlation
.
Standard deviation of yield
„
„
decline
. .3499
. 165.9 lb.
. 17.89 lb.
132 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [IV, II.
For convenience of reference the coefficient of correlation is entered below each
table, as also the means and standard deviations of the two variables. The means
of columns corresponding to each yield group are entered at the foot of the column.
These means for Table III are plotted in Figure 2. The means are a bit irregular,
Fig. 2. Relation of rate of decline to rate of yield at maximum. (Cross-bred cows.)
but they show a definite tendency to rise as the level of production rises. The
best value for the variation in the rate of decline with variation in the level of
production is calculated from the data and the thick line shows the calculated
values. It will be noticed that the line cuts through the data very well especially
between the 400 and 1,500 lb. groups (i. e. between about 15 to 50 lb. per day)
which represent the most usual range of values of yield. Beyond these points the
observations are scanty and the means are not reliable. The values of the rate of
decline for the different breeds with increase in the level of production are calculat-
ed for all breeds and are entered in Table VII. The increase in the rate of decline
PERSISTENCY AND ITS RELATION TO AGE AND LEVEL OF PRODUCTION
147
TABLE VIII.
Correlation surface slwving the relation of rale of yield to age. (Dala—Buffaloes.)
No.
1
2
3
4
5
6
7
8
9
10
11
12
Rate of
yield in
100 lb.
unit
Class Mid-
point
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
11.5
12.5
Total
Mean yield per
month lb. .
1
1
1
2
3
1
1
..
1
..
..
..
..
10
450
2
..
1
3
8
10
15
8
2
2
..
..
..
49
607
3
..
1
2
7
10
17
7
2
1
..
..
..
47
607
4
..
..
3
3
14
7
6
3
4
..
..
..
40
638
5
..
..
..
5
6
7
..
..
..
1
..
19
687
Age In lactations
6
..
..
2
5
2
3
7
1
1
..
..
..
21
621
7
..
..
..
5
4
3
4
4
..
..
..
..
20
640
8
..
..
1
4
2
3
2
3
1
..
.
..
16
639
9
..
..
1
3
1
2
1
1
1
..
..
..
10
610
10
..
..
..
1
3
..
..
..
1
..
..
..
5
610
11
..
..
..
..
1
1
..
..
..
..
..
..
2
600
12
..
..
..
1
1
1
..
..
1
..
..
..
4
650
13
..
..
..
..
..
..
..
..
..
..
..
1
1
1.250
Total
1
3
14
40
54
69
42
17
12
..
1
1
244
Mean of age
. . . . .
Mean rate of yield per month at max
4.5943
. 621.31 lb.
Coeflicient of correlation
Standard deviation .
Standard deviation .
....
. . . .
. . . .
.1518
2.601
165.9 lb.