The Warriors ran in nine tries, with Tom Davies and Joe Burgess scoring two apiece to leave Huddersfield coach Rick Stone admitting his side are lacking belief at the moment.
The Giants, who have won just two games all season, lost McGillvary, Sam Wood and Dale Ferguson to leg injuries as they head into the busy Easter period.
Stone said: “We have a long way to go. Getting bodies will help, so will a little bit of belief at the moment because we are definitely down on confidence. We are not playing with the same spirit I know we can play with.
“It is frustrating and disappointing, but there is only one way of getting out of it and that is getting some bodies, working hard, believing in yourself and sticking together. If we do that we will give ourselves a chance.”
The injuries to McGillvary, Wood and Ferguson could see them join Oliver Roberts, Sebastine Ikahihifo, Tom Symonds, Jake Mamo and Leroy Cudjoe on their lengthy injury list.
“We will check those boys out in the next couple of days, if we need some scans we’ll get them done and hopefully a little bit more information in the next 48 to 72 hours,” said Stone, whose side played most of the second half with just one substitute available.
“It was disappointing, the second half was a bit of a different game because we had a number of injuries to key positions. We had to reshuffle the team significantly, for all the problems we had in the second half I was happy with the effort.”