But there is exciting talent to step up in their place, with the likes of fly-half Sam Davies leading the next generation at the Liberty Stadium.
And, allied to the arrivals of seasoned veterans Paul James, Gareth Delve and Brendon Leonard, Hore is certain the Ospreys, who returned to the GUINNESS PRO12 play-offs this year, can cope with their early-season absentees.
"There is a huge number of quality young players coming through in all the sides, but some are not quite ready," Hore told the South Wales Evening Post. "That is why we have brought the players in that we have.
"At the start of the season we will have De Kock Steenkamp, who missed all of last season because of an Achilles injury, alongside the likes of Lloyd Peers, Adam Beard and Rory Thornton in the second row.
"In the back row, we have Gareth Delve and Joe Bearman as well as a lot of exciting young talent.
"We have two young nines and Brendon Leonard, plus a young 10 (Sam Davies) with the likes of Jonathan Spratt and Ben John outside him.
"It is all about getting the balance right. We have got a great development pathway here at the Ospreys, it is about supporting that with the right mix in the side."
Follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channelfor extensive match highlights and sign up for our newsletter for regular updates on the GUINNESS PRO12
63x46.png){kind=logo}