High Egg Production in Runners: Without Selection?
By Prof. Dr. Wolfgang Rudolph, Germany
Julian Burrell’s article called “Producing Layers from Show Strains” (IRDA Newsletter, Spring 2001) hits, as I see it, the nail on the head. Nowadays hardly a subject concerning Indian Runners is worthier of notice. He stated: “Many people each year buy Indian Runners, expecting them to lay a large number of eggs only to be disappointed.” And he rightly continued: “The problem is over breeding for exhibition”. Admittedly, some Runner-enthusiasts could be taken aback by such an assessment of their ducks’ reputation. However, let me show you that J. Burrell had a point.
In 1972, G. A. Clayton (J. Reprod. Fert., Suppl. 15, pp.1-31) expressed his view on effects of selection on reproduction in avian species. As for the domestic duck he singled out the Indian Runners, and the Campbell ducks as well, for their exceptionally high fecundity. He mentioned some authors who – in his opinion – put a similar interpretation as he did on the reasons for high prolificacy. He came to the conclusion that the Runners’ pronounced performance was concomitant “with a long history of domestication but lacking, so far as can be discovered, any history of artificial selection for egg production.” And he added: “The evidence seems clear that domestication and the habits of the peasants of South-East Asia have made a far greater contribution to prolificacy than has ever been acknowledged.” Even though these remarks seem to be cogent arguments I cannot take them without raising some objections, and with reason.
Clayton claims that much of the high egg production of domesticated ducks is an expression of natural fecundity given appropriate opportunity and owes little to artificial selection. However, domestication is defined as a long course of some selective breeding accompanied by considerable modification of natural ecosystems. Therefore, one should not underestimate breeders’ efforts made in the past centuries to improve reproduction traits, even though they knew nothing about genetics and animal-breeding theory. It is true, the early history of the Indian Runner is obscure. But one thing is for certain: ducks of that type have been bred in South-East Asia for many centuries (J.A. Coutts, 1927, The Indian Runner Duck, London). Nowadays, those populations of ducks, with distinctive characteristics, are known under the name of Tegal, Medan , Tangerang, Tasikmalaya, Cirebon , Magelang, Mojosari, Bali (Mengwi) etc. (Y. Tanabe et al. 1983, Rep. Soc. Res. Native Livestock, No. 10, pp. 207-224).
The variation (phenotypical variance) in egg number of different strains of ducks can be explained by genetic and environmental diversity (variance). A measurement called heritability (h2) was introduced. It is defined as the proportion of phenotypic variance that can be ascribed to additive genetic variance. Therefore, its value varies between 0 and 1. Estimates of h2 are used to predict the likely effects of selection for one or several traits. Regrettably, h2 for the trait ‘egg number’ is relatively low (in general 0,1-0,2). Even so, under a given environment a noticeable increase in egg number can be obtained by artificial selection. But in this case one should also take into consideration the performances of the birds’ parents and siblings.
Clayton (1972; 1984 in: I.L.Mason, Evolution of Domesticated Animals, New York, pp. 334-339), assessing the prolificacy of Penguin ducks imported into Britain in the 1830s, maintained that artificial selection can be left out of consideration. Referring to Campbell ducks he even insists on the view that ”it is reasonably certain that no effective artificial selection for egg number had been applied to ducks before 1923”. Nothing heard of laying tests that were staged in the first half of the 1920s (e.g. Bentley Test)? Had he forgotten that Mrs Campbell and her followers laid particular stress on the trait ‘egg number’? Said Mrs Campbell in 1912 (The Poultry World, p. 629): “I originated the two varieties of ducks now known as “Campbells” and “Khaki Campbells”. These are ducks for egg-production firstly, with fair table qualities.”
Clayton’s opinion is incompatible with our knowledge of quantitative genetics in ducks (H. Pingel in: R.D. Crawford, 1990, Poultry Breeding and Genetics, Amsterdam et.al., pp. 771-780). Such high egg numbers in indigenous breeds of South-East Asia must have been produced by some kind of artificial selection, in addition to natural selection. Clayton refers to the so-called droving method that had been applied to ducks in those countries for hundreds of years. He had read about this in E. Brown (1929, Poultry Breeding and Production, Vol. III, London ): “…A man goes walking with this flock along the roads in the direction of Batavia . Every day they walk a small distance, the ducks foraging on the rice fields. The trip takes about 6 months. During this period the ducks start laying; therefore, the man bears upon his back a kind of rope fencing. At night he puts the flock in this fence and sleeps himself in the same place. In the morning he first collects the eggs, and then they continue on their way. In the villages he passes, he sells the eggs and also the birds which are too weak to run further; so that at the end of the run he only brings into Batavia market the strongest ducks, the best long-distance layers and the best layers.” However, Clayton seems to be labouring under a misapprehension. It is simply the question: what kind of flock produces the ducklings at the farmers’ homes? Without any care for the next generation (breeding, selection, incubation, rearing) no flock would have been available for walking into Batavia . Admittedly, those ducks owed nothing to modern western genetics and technology, as Clayton emphasized. However, developing efficient breeds of ducks was in any event accompanied with some kind of artificial selection, even if we nowadays know nothing about it.
According to Clayton the droving method “would account for the shortening of the femur (W.B. Tegetmeier, 1867, The Poultry Book, London) giving this breed its extraordinary upright posture and great running ability”. Indeed, Tegetmeier had written, at that time with a rather limited knowledge of Penguin ducks (Indian Runners): “This very extraordinary-looking duck is characterized by an extreme shortness of the femora, the thigh or upper bones of the legs …” Clayton forgot to consult Tegetmeier’s book in its second edition (1873) where one finds exactly the opposite: “This … duck is characterized by greater length of the femora, or upper bones of the legs. . . .”. Obviously, Tegetmeier by then had a look at C. Darwin's book (1868) called The Variation of Animals and Plants under Domestication, London. Darwin had stated: “. . . the femur and metatarsus (but not the tibia) are considerably lengthened, relatively to the same bones in the wild duck. . . This elongation of the leg-bones could be seen whilst the bird was alive, and is no doubt connected with its peculiar upright manner of walking.” Moreover, this renowned author had coined the noteworthy sentence: “This is the most remarkable of all the breeds, and seems to have originated in the Malayan archipelago.” Curiously, Clayton missed Darwin’s statement on the Runner’s femur although referring to his book elsewhere.
In his article cited above J.Burrell made some very helpful suggestions that I recommend to follow up. Without artificial selection no higher egg numbers per bird can be expected. And selection pays over years, if it is done systematically. Try to avoid inbreeding. Start with enough ducks and have reasonable cooperation with some experienced breeders. “Breeding closer to the standard would benefit the birds and their productivity” (Burrell). And Coutts gave the following sound advice: “As it is important to retain the laying powers, Runners should not be bred too small. Very big, heavy birds, on the other hand, would fail in activity and foraging power, another property that it is important to maintain.”
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