For a bigger, better pound of meat

FARM VIEW

Even as hysteria continues to surround the controversy over genetically modified (GM) and transgenic crops and products, animal biotechnologists have quietly achieved some major successes in producing transgenics of fish and livestock like chicken, rabbit, sheep and pig.

By transferring selected genes from species unrelated to these animals, scientists have managed to raise the body weight of these animals with lower feed intake, besides making their meat healthier for human consumption by modifying protein, fat and other contents.

Significantly, unlike the GM crops where India was a late starter and, thus, lagged far behind other nations, in the case of GM and transgenic animals, the country has managed to make some headway despite being in a similar situation otherwise. Indeed, India has already developed transgenic fish that grows several times faster than its natural counterpart. Some other Asian countries are also engaged in such endeavours, making Asia the world leader in producing transgenic fish.

Gene manipulation has been the basic approach for implanting the desired and commercially-important traits in plants and livestock ever since organised work on their performance enhancement began. A transgenic animal is essentially one whose genome has been artificially altered by introducing foreign DNA. The science of biotechnology has only provided the means for refining and hastening the gene-transfer process.

The most significant advantage of transgenic technology is that it helps prevent the transfer of unwanted traits during the gene-transfer process. This is because the specific portion, and not the whole of the genome, is inducted into the recipient species.

The fact that scientists at the Madurai Kamraj University had evolved the country's first transgenic fish way back in 1991 was a little-known fact until it was revealed in a paper presented at the national conference on transgenics in Indian agriculture, held recently at New Delhi. Until then it was mentioned only in scientific literature.

Dr T J Pandian reported in his paper that the transgenics of a popular fish, rohu, grew four to eight times faster than the ordinary rohu. Significantly, the transgenics also consumed feed at reduced rate but converted it more efficiently into body weight. This implies enhanced commercial potential.

Elsewhere, experiments with fish species, such as salmon and mud loach, have indicated that evolution of their transgenics can result in 11- to 30-fold growth acceleration.

Transgenics of carp, which are commercially the most important fish species of Asia, have also been successfully produced. Notably, transgenic carp is deemed as healthier human food because it has been observed to contain more protein and less fat.

Considering the criticality of the use of animals in research in various bio-fields, including pharmaceuticals, the achievement of Indian scientists in developing indigenous technology for transgenic fish production assumes great significance. So far, mostly rats have been used in pharmaceutical research. But they have their own limitations. For instance, rats are normally not affected by polio and thus cannot be used in research for developing the polio vaccine. From that point of view, Indian scientists feel that fish may prove more advantageous than mammals as experiment models.

As reported in another paper, the production of transgenic ornamental fish (glow fish) carrying fluorescent genes borrowed from jellyfish, has paved the way for producing new multi-coloured fluorescent fish. This development is significant from the Indian perspective because the Western Ghats and the north-eastern region are known to be rich in high-value freshwater ornamental fish varieties. The diversity in such types of fish can be vastly enhanced for commercial exploitation.

Indeed, there are countless possibilities for modifying the livestock produce to suit human needs through the use of transgenic technology. Theoretically, it should be possible to evolve breeds of cattle or buffaloes yielding milk that has low or even zero fat content. Besides, even the processing-related traits of milk could be changed by modifying the enzymatic configurations to produce better dahi (yogurt), paneer (cheese) and other products. Similarly, the cholesterol content of eggs could be altered according to the requirement of the consumers.

Of course, the most significant use would remain in increasing the reproduction capacity of economically-important animals, as also their potential to yield the desired product. All this is in addition to the all-important use of transgenics in pharmaceutical research and production.

But this is unlikely to start happening straightaway. Animal transgenic technology is still in its preliminary state and, thus, has a long way to go before its commercial potential can actually be realised.

Moreover, the issues relating to ethics, as also to ecology, will have to be addressed before this highly-potent technology is put to any gainful use.