125
118
Giving "m" the value of 2.8 years, as in Dr. Wright's paper, the following table may be constructed:-
Average herd age, and rate of wastage.
8 years.
9 years.
Maximum
life in herd (n).
7 years.
Chance of survival at end of a year. (A.)
Per cent. Average wastage herd age annually.
Per cent. wastage
in years.
annually.
Average herd age in years.
Per cent. | Average wastage herd age annually. in years.
.65
45.3
4.77
44.5
4.86
44.0
4.93
.70
38.9
4.98
37.8
5-11
37.2
5.22
+75
33-2
5.20
32-0
5.39
31.1
5.54
-80
28.2
5.42
26-8
5.67
25.8
5.89
.85
23.9
5.65
22.3
5.96
21.1
6.25
APPENDIX 3.
The estimated loss to the farming industry from cattle diseases. MONETARY loss attributable to disease among cattle occurs under three headings:
(a) the increased cost of maintaining milking herds at their full strength
consequent upon the higher death rate due to disease;
(b) the loss of meat due to condemnation on account of disease of carcases
of cows drafted out of herds;
(c) the reduction of the yield of milk among unhealthy cattle.
(i) Losses under heading (a2).
It is possible to make a rough estimate of the amount of the loss under the first of these heads upon the following lines: -
Reasons have been given in a previous note (appendix 2) for supposing that the average milking life of a dairy cow under present conditions extends over 4 years. It is assumed for the purpose of this estimate that if it were not for the occurrence of accident and disease, cows would yield milk on the average for nine years, i.e., would die at the age of 12 years. It appears from figures given in the Cambridge and Reading* inquiries into the length of life of dairy cattle that about one-sixth of the cattle lost to milking herds die or are sent to kennels, &c. The prices paid and received for animals drafted into and out of herds are naturally subject to considerable variation. It seems, however, to be generally accepted that heifers drafted into herds are worth approximately £25, and that the price received for cattle drafted out is about £15. There is, of course, no figure for the average price which would be received for cows if they were kept in the herd until 12 years of age. It would undoubtedly be lower than the price received to-day. The following passage is quoted from the Ministry of
* See appendix 2.
119
Agriculture and Fisheries report on the marketing of cattle and beef (economic series, no. 20, p. 23) : —*
"In addition to meat from steers and heifers reared and grown for beef production, a large percentage of home-produced beef comes from COWS. The quality range of this supply is very wide, extending from palatable beef of good quality to the roughest and coarsest meat marketed. The upper range is drawn from well-finished cows that have had one or, at most, two calves. After the third lactation, there is a rather rapid decline in quality in the meat yielded by cows, until, in the case of old cows, a time is reached when, on account of age and long service, the meat is not marketable in the form of joints. Meat from these old cows is sometimes boned and made up in various forms, or it may be used for animal food such as dog biscuits."
It is here assumed that if cows are kept till the age of 12 years, they will not produce more than £10.
On the basis of these figures, the loss on herd maintenance may be calculated as follows:-
TABLE 1-Cost of herd maintenance.
A.-Loss under present conditions.
Number of cows drafted into herds annually (approximately),
22 per cent. of 2,763,000 cows, or heifers in milk, is 600,000; at £25 a head these cost Number of cows sold annually is therefore 500,000 at £15,
making a receipt of
The net annual loss is consequently
£
15,000,000
7,500,000
7,500,000
B-Loss if cows attain, on the average, the age of 12 years. Number of cows drafted into herds annually would be 300,000,
costing at £25 a head
£
7,500,000
Numbers of cows sold annually would be 250,000 at £10 a
head, making
2,500,000
The net annual loss is consequently
5,000,000
2,500,000
Reduction of the annual cost of herd maintenance (A-B) is
It is obvious that the above figure has no claim to precision, It is suggested, however, that the prices assumed (which are the most doubtful factor) are likely to exaggerate rather than understate the amount of the loss under this heading.
(ii) Losses under heading (b).
The losses on account of the condemnation of carcases may be estimated on the basis of figures supplied by the Chief Veterinary Inspector, Edinburgh, according to whom, of animals showing tuberculous lesions on slaughter 10 per cent. are condemned totally, 20 per cent. are condemned in part, the salvage amounting to one-half to three-quarters of the carcase. The remaining 70 per cent. are not affected. He further estimates that between 80 and 90 per cent. of meat condemned is condemned on account of tuberculosis. If it is assumed that 40 per cent. of the carcases show signs of tuberculosis on slaughter (see paragraph 29 of the main report), then the following losses on account of condemnation may be estimated.
* H.M. Stationery Office, 24-40-20 (1929).
126
Page 70Page 71
127
120
TABLE 2.-Cow meat condemned on account of disease.
Per cent.
Condemned totally on account of tuberculosis, 10 per cent. of
40 per cent,, i.e.
4-0
Condemned on account of other diseases, say of 7 per
cent., i.e.
Condemned partially on account of tuberculosis, say of
20 per cent. of 40 per cent., i.c.
3-0
1-2
8.2
Total percentage of cow carcases condemned
The number of carcases condemned is 8-2 per cent. of 500,000, i.e., 41,000, and their value at £15 per head is £615,000.
The risk of this loss should be reflected in the price at present paid for cows drafted out of herds. If this sum of £615,000 is added to the previous sum of £2,500,000, the assumption made is that the price of £15 per cow, assumed in table 1, is not, in fact, at present realised, there being, for example, an insurance premium of £1 4s. 6d. per head payable in respect of each beast. The actual premium paid is generally less than this. The report of the Ministry of Agriculture and Fisheries, already referred to, quotes premiums for cows varying from 48. to 10s.
(iii) Losses under heading (c).
There does not appear to be sufficient information available to support an estimate of the amount of milk lost through the reduction of milk yields on account of disease. It may, however, be pointed out that some part of this loss is already accounted for in the sum of £2,500,000 already given as the loss on account of herd maintenance. Low milk yield is one of the main reasons for drafting animals out of herds to-day. The assumption made in calculating the loss on herd maintenance is that this ceases to be a cause of drafting animals out of herds as soon as disease disappears. It is obviously illegitimate to include both losses on drafting out such animals under one head, and losses on account of their diminished milk yield (if they had not been drafted out) under another, when estimating the total monetary loss from disease.
One assumption made in the above estimates of the loss due to disease is that the selling prices of similar goods are not affected by any change in methods of production. The sums quoted may more accurately be looked upon as the monetary value at to-day's prices of goods which might be produced without any addition to present expenses of production if losses from disease and accident were to be completely eliminated.