I agree wholeheartedly with what's been said.
I once lent out, to a neighbour a young Hereford bull. He was pedigree and one of the best bulls I've ever had. the neighbour just had a few continental cows he wanted in calf. The arrangement was he kept the bull over winter and had free use of him. When he came back he was thin and, as the neighbour remarked, had no backend on him. I was mortified as he'd been a well rounded, fantastic shaped animal when he left me. Turned out, that the neighbour had given all the animals some rolled barley, (in addition to hay) each day, but the young bull was pushed out by the large cows so didn't get any. I suspect there wasn't that much to get anyway and that they were fed poor quality hay that he couldn't sell. I never said anything and i'm sure the farmer hadn't realised that my bull was still growing and needed something better than a scarcely maintenance diet. You don't realise that, without meaning any harm, a lot of people don't treat other people's animals as well as they should. In spite of that, all the cows were in calf and produced fantastic calves.
In the early days of my sheep keeping (in the last century!) I lent someone a ram lamb for a few weeks. He came back in January. I'd no complaints about the way he'd been treated but he gave the rest of my flock scab.

The chap had bought some more ewes from market which developed scab. So he injected them all, returned my ram, and never thought to mention it. By the time the scab developed in my flock I was in the middle of lambing.
So, in my experience, I would never again lend out/hire anything I cared about as however well you know someone you cannot guarantee your animal will be returned in a suitable condition to ever be of use to you again.
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