Breeding a hot-weather chicken
You cannot leave Ghana without tasting Kyinkyinga, a popular version of khebab made with chicken. This is good news not just for diners, but for Ghana's farmers – indigenous chicken production is a major source of income for many households, particularly in poor rural areas.
Ghanaian chickens represent a precious local genetic resource, well adapted as they are to hot and humid tropical environment. However, in the last decade there has been an increase in imported exotic chicken aimed at improving the performance of the local birds. This has depressed the indigenous market in Ghana, even though the introduced birds suffer from the tropical climate and do not survive.
"Over the years, Ghanaian chickens have developed interesting features that make them well-suited to the country's climate," explained Ghanaian scientist Julius Kofi Hagan, a TWAS Young Affiliate. "Heat-tolerance is very important for their well-being, therefore there is the need to preserve them as we live in an era of climate change where temperatures can be very high, resulting in heat stress for the birds." Heat stress, as he added, generally affects the growth and reproductive performance of the animals, especially birds.
Hagan, elected a TWAS Young Affiliate in 2016, presented his research on 17 November 2016 at the 27th TWAS General Meeting in Kigali, Rwanda. He is a senior lecturer in the Department of Animal Science at the University of Cape Coast in Ghana.
His interest in improving poultry breeding has earned him some international recognition: In 2014 he was named one of the world's top 20 innovators by the Technical Centre for Agricultural and Rural Cooperation, an international non-profit organisation established under a joint agreement between African, Caribbean and Pacific countries and the European Union. In 2013, Hagan placed third in a competition for the Best Young Professional Scientist in Africa, organised by the Forum for Agricultural Research in Africa.
"I developed an interest in this topic during my PhD studies, in 2006. And since then I have been working on heat-tolerance traits in local chickens," he said.
"Conservation of local genetic resources is one of the surest ways of ensuring food security, especially in the developing world," he maintained during his lecture. "That's why we carried out a study to first describe the morphological features and how they impact on the behaviour of different populations of indigenous chickens in five ecological zones of Ghana."
A total of 1,484 indigenous chickens in five agro-ecological zones of Ghana – each with different rainfall pattern, temperature and humidity – were studied. Ten qualitative traits were studied. Among the traits were: naked-neck, frizzle feathers, dwarfism, silkiness, and polydactyly (extra toes). Two of them, naked-neck and frizzling in particular, were confirmed to be associated with heat tolerance.
Traditional improvement of chicken can be obtained in many different ways, depending on the objective of the breeder or the farmer. It can be through cross-breeding of selected chickens with the aim of selecting traits that are desirable. Or, scientists can also use molecular genetic analysis to identify genes that drive high productivity, resistance or others, and incorporate them in new individuals through genetic engineering techniques. This involves the use of genetic markers and gives faster results.
"Naked-neck chickens, for example, have reduced feathers," Hagan explained, "and as a result they are able to dissipate heat easily during periods of heat stress. Hence they are able to eat well and perform better than their counterparts which are fully-feathered." In addition, because of fewer feathers, all the proteins that could have been channelled into feather development would be re-channelled into other functions, such as muscle development and egg production.
From the morphological traits, Hagan and his colleagues moved to identify associated genes that govern heat-tolerance. They found two such genes and decided to incorporate them into exotic layers that were heat-stress susceptible, to make them as well-adapted to Ghana as the indigenous ones. In another line of investigation, they did similar experiments also to improve egg production. Both experiments are still in progress, but results so far are promising.
He is now waiting to receive funds from the Ghanaian government and other interested funding institutions, and he also has an on-going collaboration with a private farm – the biggest poultry farm in Ghana – which is trying to commercialize his technology.
Hagan has clear-cut future plans: "I want to develop commercial layers and broilers with heat-tolerant traits for the tropics, not only in Ghana but also in other African countries."
"Local chickens are unique and represent special genetic resources in Africa and the tropics," he concluded. We must do our best to preserve them and, possibly, improve them."