Every morning, Austin Knowles pulls on his rubber boots, dodges the manure in his farmyard, and opens the creaky wooden door of his 200-year-old barn on a hilltop in Worcestershire, 130 miles northwest of London. Inside, his dairy cows are busy uploading data to the cloud. Each animal has a half-pound sensor in her stomach, which is linked via Wi-Fi to a service that helps Knowles analyze the health and well-being of his herd. If an animal falls ill, the system e-mails the vet days before the cow is visibly sick. When one is about to go into heat, Knowles and his staff get a text message. “Cows are a lot of work,” the third-generation farmer says over tea at the rough-hewn wooden table in his kitchen. “The technology takes the edge off a bit.” Knowles’s Hollings Hill is one of 350 farms in almost two dozen countries using technology from Austrian startup SmaXtec to monitor their livestock. It works like this: A weighted sensor about the size of a hot dog is inserted into a cow’s throat with a metal rod and lodges in the rumen, the first of a cow’s four stomachs.