Meanwhile, the company's traditional, lower-end cellphone business, a steady cash cow in high-growth emerging markets, is under growing threat from less-expensive Asian handsets.

WSJ: Nokia Considers Adopting Microsoft Phone Platforms

But it would not likely have spread the disease, since USDA regulations prohibit high-risk parts of the cow, such as brains and spinal cords, from entering the food chain.

CNN: Mad cow case confirmed in California

Another consequence: more access to the high-priced market for bulls and cow eggs, which can be better evaluated by the new test.

FORBES: Technology

"Not only does Tencent have a cash cow in its strong gaming business, but the company is also best-positioned in high-potential markets like social media and mobile Internet services, " said Jefferies analyst Cynthia Meng, who has a buy rating on Tencent's stock.

WSJ: China's Tencent Outperforms Its Western Peers