Item

The efficiency of wool growth in merino, Corriedale and Romney : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science with Honours in the University of Canterbury [Lincoln College]

South, A. C.
Date
1965
Type
Thesis
Fields of Research
ANZSRC::070202 Animal Growth and Development , ANZSRC::070204 Animal Nutrition
Abstract
In determining the profitability of a system the producer is vitally concerned with the amount offered for sale. So it is with sheep farmers when marketing wool. However, also determining net returns is the quality of the wool offered and this, in fact, can have greater influence on income than fluctuations in the quantitative seasonal production. However, most farmers aim to keep the “count” of their fleeces at a fixed level and any variation is incidental or a major change in farm policy. Therefore quantitative wool production takes precedence over qualitative wool production. This in turn leads us to the cost of producing the wool and the efficiency with which feed is converted to wool. Obviously, sheep which produce a maximum of wool for a minimum of feed consumed are preferable to perhaps equally high producing sheep, but with a greater intake. Wool production among sheep in a flock is known to be highly variable (Schinckel 1960) and that this should be paralleled by a similar variation in efficiency is not surprising (Weston 1959; Ferguson 1959). This coupled with a probable moderate heritability of efficiency (Turner 1958) enables considerable scope for a substantial gain from the material economy of wool production. Enthusiasm for such a selection policy is dimmed at the first obstacle – the measurement of feed intake. At the farm level a practical solution is difficult and with present techniques any scheme would be very ambitious. On a smaller scale faecal marker dyes both natural and artificial can be used but not all alternative methods are accurate. A number of important assumptions in ill-controlled experiments may increase errors further. The only suitable method of measuring intake is to pen the sheep and feed accurately measured quantities. This places the sheep in an artificial environment which must then be related to natural grazing conditions. This disadvantage is not serious and is more than compensated for by ease of handling and measurement of intake. Using pen fed sheep this experiment set out to find variations in efficiency with breed and nutrition. Three breeds of sheep were chosen (Merinos, Corriendales and Romneys) on two planes of nutrition (sub-maintenance and supra-maintenance). Because all sheep were changing in weight the efficiency measured is the gross efficiency, but for the purposes of the experiment the relative efficiency was deemed sufficient to detect differences due to breed, or nutrition, or both.
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