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The Feeding Value of Mangels

Published online by Cambridge University Press:  27 March 2009

T. B. Wood
T. B. Wood
Affiliation:
Drapers Professor of Agriculture, Cambridge.
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Extract

The paper describes attempts to test the following points—the comparative feeding value of Yellow Globe and Long Red mangels as constituents of a liberal fattening diet, the comparative feeding value of Golden Tankard and Long Red mangels, also as constituents of a fattening diet, and the comparative feeding value of Yellow Globe and Long Red mangels for store cattle.

The results point to the following conclusions:

The rates of fattening of individual animals vary so greatly that little reliance can be placed on the results of single experiments with the small numbers of animals commonly employed in feeding tests.

The feeding values of Long Reds and Yellow Globes were compared on seven occasions, and the results discussed according to the ordinary methods used in the theory of probabilities.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 3 , Issue 3 , September 1910 , pp. 225 - 232
Copyright
Copyright © Cambridge University Press 1910

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References

Page 225 note 1 Wood, and Berry, , Vol. I. Part 2, page 176.Google Scholar

Page 228 note 1 Guide to Experiments, 1907.

Page 229 note 1 The following formulae were used in calculating the figures of this and succeeding tables. If d=the deviation of an observed quantity (e.g. increase per 1000 lbs. live-weight), from the mean of n such quantities, then the probable error of the mean of the n quantities =0·67

Thus the probable error of the mean daily gain per 1000 lbs. live-wt. (1·9 lbs.) of the four animals included in Table IV. =0·67

The mean daily gain per 1000 lbs. live-weight would then be written 1·9±0·1 lbs. which means that the true daily gain per 1000 lbs. live-weight of animals fed under the conditions of this experiment would be equally likely to fall outside the limits of 1·9+0·l lbs. and 1·9–0·1 lbs. as inside those limits. For calculating the probable error of the ratio of the increase due to Yellow Globe to that due to Long Bed, the formula used was probable error of ratio

where pa and pb are the probable errors of a and b.

I am indebted to Mr F. J. M. Stratton and Mr A. B. Bruce for the above and other similar paragraphs.

Page 230 note 1 Thus, if γ is the probable error of each experiment, and consequently the weight given to that experiment in calculating the weighted mean, and if d is the deviation from the weighted mean, then the probable error of the weighted mean is

Calculated in this manner the ratio of the increase produced by Yellow Globe mangel as a constituent of a liberal fattening ration to that produced by an equal quantity of Long Bed = 100: 116±4.