Engineer In the Garden by Colin Tudge

Author:Colin Tudge
Language: eng
Format: epub
ISBN: 9781446466988
Publisher: Random House

‘EFFICIENCY’

‘Efficiency’ means in livestock farming precisely what it means in engineering: work (or energy) got out, divided by work (or energy) put in. What the farmer puts in can be measured in food energy, area of land, farm labour, or straight cash. What he gets out is measured in kilos of flesh, number of eggs, or litres of milk of appropriate quality.

Suppose, for example, a farmer is raising young pigs, lambs, or calves for beef, which we will henceforth refer to collectively as ‘offspring’. ‘Energy in’ equals the amount of feed given to these offspring by the time they reach slaughter, plus the amount given to each animal’s mother during the whole period of her pregnancy and lactation, plus a proportion of the amount given to her when she herself was a youngster, and in the intervals between pregnancies. After all, the only cash the farmer receives is from sale of the offspring, so the cost of keeping the mother has to be ascribed to those offspring.

We can increase efficiency by raising ‘energy out’, and/or reducing ‘energy in’. ‘Energy out’ in this context can in practice be gauged as ‘weight of the offspring at slaughter’; we can clearly increase this by (a) raising the weight of individual offspring at slaughter and (b) increasing the number of offspring.

We can reduce ‘energy in’ in three ways: (a) by ensuring that the offspring reach their slaughter weight in the minimum possible time; (b) by increasing the number of offspring produced in a given time, and (c) by reducing the amount of feed given to the mother. Pertinent to this last requirement is that small mothers eat less than big mothers.

It follows, then, that the ideal mother – whatever the species – would be tiny, and eat very little, but she would give birth to huge litters of offspring that grow enormously fast. A cow the size of a collie dog that gave birth to half a dozen calves that grew to half a tonne in about three months would be ideal – from the farmer’s point of view.

In practice, such a cow with such an output is probably a biological impossibility. But breeders and farmers, working together, none the less strive to move as closely as possible to the ideals of efficiency. Thus lambs in Britain are traditionally born on the uplands, where their mothers live permanently, and they are fattened for slaughter on the lush grass of the lowlands. The mothers are small, agile mountain sheep, such as Welsh Mountain ewes, while their fathers are big meaty rams, such as Border Leicesters or Suffolks. (In fact, traditional sheep breeding is far more complicated than this, involving cross-bred ewes and pure-bred rams. But this is the essence.) The lambs then grow faster than would a pure-bred Welsh Mountain lamb. If the ewe can be persuaded to have twins, then this is two for the price of one, a definite bonus. One development in sheep breeding is, therefore, to cross ewes such as Welsh

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