Introduction

Mankind has been attempting genetic improvement in agriculture probably since the domestication of livestock. First reports of this are in Genesis 30, 37-40, where Jacob began a flock improvement program which resulted ultimately in the colour of sheep being changed from a dingy black to white. Some time later Solomon describes the teeth of his mistress as resembling a flock of sheep just come up from the washing (Solomon’s Song 4, 2).

Genetic change can be viewed from two broad perspectives. The first focuses on plant and animal improvement to increase production and/or productivity and often

product quality. The other view is to reflect on how nature’s forces have responded to mankind’s agricultural activities, as outlined by Pratley (1996). An appreciation of this view is becoming increasingly necessary as agriculture intensifies and the benefits of genetic improvement result in higher producing, usually monospecific, production systems.

Much has been said and written about the technologies and success of genetic

improvement. The areas of plant technologies and genetic engineering were highlighted by Luckett (1996) and Evans (1996) who considered traditional breeding through to DNA manipulation involving new inter-specific germplasm. The ability to directly manipulate DNA has huge ramifications. The entire biological world is effectively available as a source of genetically-controlled characteristics which can be used to mould and exploit plants for human needs (Luckett, 1996). Animals, too, can be manipulated through genetic engineering technology. This can be either directly as part of animal improvement programs, or indirectly via the use of products used to enhance animal performance which is produced as a result of genetic engineering. Davidge (1996) and Sillence (1996) discuss how some of these new technologies have been applied to produce better livestock by enabling animals to use their feed more efficiently, to excrete less waste into the environment and to produce carcases that are large and lean.

The ethical considerations which the use of such methods create, have been emphasised by Phelps (1996) who is concerned that gene technologies are racing ahead of the capacity to control them. He argues that biotechnology cannot be a sustainable process unless it is embedded in a sustainable system. He says it is only one tool of many, not a universal panacea as is often claimed.

How successful has genetic improvement been?

This is an interesting question and one which is difficult to evaluate objectively across the gamet of agriculture. An insight into the question can be attempted by assessment and comparison of performance in a number of diverse industries. Here, some perspective of success over time is attempted using dairy, wool, wheat and horse racing. However, as with all macro assessment, there is a difficulty in separating genetic improvement from that of other technologies which benefit productivity. In addition, in agriculture, seasonal variation and changes in the quality of the output can sometimes cloud any assessment.

To provide an independent measure of technological change free of genetic shifts, a comparison is made with times recorded for swimming (400m men’s freestyle). It is argued that the improvement in the swimming times has been totally due to improvements in training technologies, rather than genetic selection, to produce better swimmers. While it is true there is a greater population now swimming and therefore a greater choice from which to pick swimmers, there has been no conscious effort to enhance human athletic performance through genetic improvement. These comparisons are outlined in Table 1.

Table 1. Annual changes in performance for selected agricultural industries, horse racing and swimming from long-term data. (Figures in parenthesis represent the number of years data).

* In all cases analysis of time trends showed linear relationships.
G = genetic
OT = other technologies
PT = change in production types

It can be seen that improvement in the different industries has met with varying degrees of success. By far the most successful industry has been the dairy industry, which has shown enormous improvement in production through careful herd selection. The increase in milk production per cow has been exceptional (Figure 1). Such improvement in the Australian dairy herd has resulted in increased production despite a drop in herd numbers overall.

Figure 1. Dairy cattle numbers and production in Australia 1950 - 1991

From Table 1, it can be seen that changes in swimming times (where there is no improvement attributable to genetic improvement) are second behind dairy as the big improvers. This brings into question whether genetic improvement is having as big an impact as is thought. In comparison with other industries, especially horse racing which prides itself on the selection of bloodlines and pedigrees, the development of other technologies (e.g. improved training technique in swimming) is resulting in more rapid changes far ahead of those obtained through genetic selection. Improvement in race times using the Caulfield Cup over 100 years has been small and highly inconsistent (Figure 2).

A similar scenario to that with thoroughbred racing times occurs with changes in wool cut. Increases have again been small and inconsistent (Figure 4) with much of the increase and fluctuation probably due to seasonal effects and the influence of other technologies such as pasture improvement. One could contend that the dairy industry also had the benefit of this technology but gains in the industry have been consistent, especially in comparison with wool.

Nature fights back

While breeders, geneticists and agronomists have been manipulating plant and animal species to improve production and quality, many of the factors which limit growth have also changed to ensure their survival. Arthropods, mainly insects and arachnids, pathogens, fungi, nematodes and bacteria, and weeds have all rapidly adapted to their changed circumstances. The rapidity and extent of these changes are highlighted in Table 2.

Figure 4. Wool yield per head 1915-1996

Table 2. The development of resistances by plant pests and weeds.

Nature has been able to do, unaided, what thousands of scientists achieve with millions of dollars and high-tech laboratories. It could be argued that nature is actually doing it better. Through natural selection, nature is able to keep at least one step ahead of the scientists in the battle for survival. This is quite noticeable in herbicides.Where herbicides have been very effective against weeds, nature has fought back by having a proportion of the population able to resist the effects of the herbicide. The more effective the chemical, the more often it is used and the greater is the chance that herbicide resistance will build up to economic proportions (Pratley, 1996). This is particularly important when considering the impact of glyphosate-resistance crops. Glyphosate is an essential part of the conservation farming system and its role needs to be preserved. Resistance build up by weeds to this herbicide threatens modern, soil-conserving practices of reduced tillage (Pratley, 1996).

What the future holds

Sillence (1996) indicates that to meet concurrently an increasing world demand for meat, reduce animal feed use, limit environmental waste and to minimise land degradation, it is difficult to see how such aims can be achieved without further research to improve the efficacy of animal growth and hence to develop new technologies for the production of better livestock.

With respect to new plant technologies, there are exciting prospects for plant breeders but they will complement, rather than replace, the current range of techniques. In particular, there is no doubt that the arrival of transgenic plants offer many potentially novel solutions for farmers. However, it is a reductionist, rather than an holistic approach and brings with it serious ecological and ethical concerns (Luckett, 1996).

While all approaches to improvement are useful (technology in the development of better ways to do things, and breeding - using both traditional and genetic engineering techniques - to enhance potential) there is a need in the long term for an integrated approach if the gains are to be sustainable. Reliance on one aspect is unlikely to be successful over time.

References

Davidge, M.R. (1996). Biotechnology Product Development. Proceedings 25th Riverina Outlook Conference, Charles Sturt University, Wagga Wagga. NSW.

Evans, P. (1996). Pasture Varieties for the Future. Proceedings 25th Riverina Outlook Conference, Charles Sturt University, Wagga Wagga. NSW.

Luckett, D. (1996). Plant Technologies for Improved Varieties. Proceedings 25th Riverina Outlook Conference, Charles Sturt University, Wagga Wagga. NSW.

Pratley, J.E. (1996). Herbicide Resistant Crops. Proceedings 25th Riverina Outlook Conference, Charles Sturt University, Wagga Wagga. NSW.

Sillence, M.N. (1996). Animal Technologies for Better Livestock. Proceedings 25th Riverina Outlook Conference, Charles Sturt University, Wagga Wagga. NSW.