For generations, breeding cows in the rural highlands of Kenya has hinged on knowledge and experience passed down from parents to children. But Mercy Wanjiku is unlike most farmers. Her most powerful tool is her cellphone, and a text messaging service called iCow.

The service informs her when her cows are in heat, which feed might boost their milk output and what their fair market price is. And when she needed a veterinarian recently, she relied on the service’s extensive database. “Otherwise, it would have been hard to find someone qualified in my area,” said Wanjiku, a 29-year-old farmer in Mweru, a village about 150 km north of the Kenyan capital, Nairobi.

Across sub-Saharan Africa, technology, particularly mobile technology, has transformed the lives of digital-savvy entrepreneurs. While many are forging successful high-tech businesses in urban centers, others are finding ways to help people such as Wanjiku prosper in more traditional, low-tech professions such as farming and fishing. Digital tools are also being used to overcome the continent’s obstacles to growth, such as corruption and weak health care, social services and education. In recent months, text messaging was a crucial tool in monitoring elections in Kenya and Ghana.

“In Africa, we have too many problems, which provide (so) many opportunities for technology,” said Bitange Ndemo, permanent secretary in Kenya’s Ministry of Information and Communications. “Today, there are multiple options to address these problems. If plan A doesn’t work, there’s plan B and plan C.”

Sub-Saharan Africa is the fastest-growing mobile market in the world, where it has increased an average of 44 percent annually since 2000, according to the GSMA, a global body representing cellphone operators, as competition among providers has lowered costs, creating tens of millions of users. With the advent of cheaper smartphones, many predict a surge in mobile apps in the years ahead.

In Kenya, a well-known example of how mobile technology has altered the economic and social landscape is M-Pesa, a cellphone-based money transfer service used by millions that has become the biggest such service in the world. Its success has inspired thousands of software developers across the continent, including Su Kahumbu, the founder of iCow.

“M-Pesa has done amazing things for this country. It has taught farmers the value of cellphones and SMSs,” said Kahumbu, an organic farmer, referring to text messaging. “Our system is piggybacking on this.”

In a nation where 80 percent of the population farm their land, iCow started off with a simple premise: The creation of a gestation calendar would increase the productivity of the cows and, hence, food production and the wealth of individuals and communities.

Farmers can register their cows by sending a text message to iCow. That allows them to receive cellphone messages tailored to their needs. They get alerts, for example, on feeding schedules, on when to expect their cows to be in heat or on disease outbreaks. The service also functions as a Craigslist of sorts for farmers looking to connect with their peers to buy and sell cattle.

Kahumbu said 42,000 farmers have signed up for iCow, a tiny percentage of Kenya’s farming millions. The potential, though, is enormous.

Mobile connections have risen to 475 million across the continent. Among African nations, Zimbabwe and Nigeria have some of the highest levels of mobile Internet usage globally, accounting for more than half of both countries’ Web traffic, compared with a global average of 10 percent. Across the continent, GSMA reported, more than 50 “innovation” centers have been started, including Hive Colab in Uganda, Limbe Labs in Cameroon and iHub in Nairobi. American and European firms such as Google and Nokia are encouraging African app developers to invent through contests and financial incentives.

Kahumbu said she has received requests to launch iCow in nearby countries such as Uganda, Tanzania and Rwanda, as well as from Malaysia, Russia and China. Common to all the requests is the desire to find ways to create sustainable supplies of food — in particular, milk and other dairy products.

“It’s becoming a problem in developing nations because the food chain is under pressure,” she said. “Every time we have a drought, our food resources dry up. We are driving toward disaster if we don’t do anything about it.”

The desire to solve the developing world’s problems is a thread running through many of the new digital tools. Many are funded by nonprofit or social development organizations. For example, there’s Maisha, an app that helps pregnant women and first-time mothers with the health of their children. There’s also Get H2O, a game that educates players on chronic water shortage.

Mobile technology is improving the lives of some of Africa’s poorest people, in some of the continent’s most remote areas. Ndemo said Kenyan fishermen are using text messages to set up markets along the shores of Lake Victoria and negotiate prices with buyers, which helps them sell more fish.

The technology has also reduced opportunities for abuse, especially among farmers. “We can generally say that it has improved efficiency, in some cases productivity,” Ndemo said. “Middlemen used to exploit the farmer. Now, the farmer has more information about retail and wholesale prices. They know precisely what things cost.”