Accepted practice. This is far from being my area of expertise, but there's a chapter in James Herriot's The Lord God Made Them All about this. Herriot's books are primarily about veterinary practice in the Yorkshire Dales of the U.K. in the 1930s through the 1950s, and he saw work on rural farms frequently. From his perspective, the many POWs who worked on farms in this period were a huge help, because country vets didn't yet have the sedatives or crushes (restraints) that make large animal work more manageable and less dangerous today.

Herriot (whose real name was Alfred Wight) comments on it in chapter 6:

There were hundreds of (POWs) employed on the land at the end of the war and it was a happy arrangement all round. The farmers had a windfall in the shape of abundant labour, and the prisoners were content to spend their pre-repatriation time in the open air with ample farm meals to sustain them in a world of food rationing. I personally had a respite from one of my constant problems—the lack of help in my job. I found now that there were always willing hands to assist me in the rough-and-tumble of large-animal practice ... I know of farming families who to this day (NB: The Lord God Made Them All was published in 1981) spend their holidays at the homes of the Germans and Italians whom they befriended at this time.

Herriot goes on to recount three stories in which he encountered POWs on the job:

• He reset the dislocated hip of a large heifer with the help of four German prisoners. He was very lucky that they were on the farm that day; the amount of force needed to reset the joint of such a large animal required several men, but the farmer's neighbors were far away. Many farmers would elect to slaughter the cow in those circumstances because quality of life with a dislocated joint was so poor, and that could deal a severe economic blow to a Dales farmer who rarely had many heifers to begin with. However, Herriot was able to chloroform the cow and pull the joint back into place with the help of all four men. The cow ambled off none the worse for the experience, and Herriot gave the prisoners cigarettes in thanks for a successful operation.
• An Italian POW named Luigi was able to keep a large Red Poll bull restrained by the ear while Herriot and his partner removed a large growth on its belly. Herriot comments: "Now, more than thirty years later, (my partner) and I still talk about him. We have both tried to catch large cattle by the ears without the slightest success; so was Luigi just an amateur with wrists of steel or was he a farmer, and do they do it that way in Italy after a lifetime of practice? We still don’t know."
• Herriot recounts hearing the singing of hundreds of Russian prisoners billeted on a large manor on a beautiful summer evening, and he was so impressed by the impromptu choir that he stopped the car and listened until it began to grow dark and he had to go home. The final part of the chapter reads: "Years later I read that these Russians went home to death or captivity, and whenever I thought of their fate, I remembered that summer evening and the beautiful music they made in the peace of the Yorkshire hills."

I do not know whether Herriot's comment there is accurate, although Stalin did reportedly regard Soviet POWs with great suspicion. However, I definitely don't have the background to go into that further; hopefully we have someone around who might know.

Fort Robinson Nebraska was home to a POW camp where Italians and Germans were held. They were sent out to work on local farms and ranches. All the local men were fighting the war, so the POWs were sent to work on local farms. Nebraska received many POWs who worked on farms. They worked voluntarily and were paid fair wages for their labor. After the war, many of the POWs returned to the Midwest to live.