EAST RUTHERFORD, N.J. -- Tuesday was Day 1 of the New York Giants 2014 training camp practice schedule, and already Tom Coughlin is not happy. And with good reason. Coughlin’s players kept dropping like flies during the two-hour afternoon workout, and at least one of them -- veteran linebacker Jameel McClain -- was taken off in a cart with a potential left foot injury.

Several other Giants reportedly suffered dehydration issues in the humidity and 85-degree heat, Coughlin said, forcing them from the field, including potential starting right guard Brandon Mosley, who is thought to have the inside track on filling the void in the lineup created by veteran Chris Snee’s retirement on Monday.

A head coach like Coughlin champs at the bit for months to get his new team out on the field and practicing (the team was not working in full pads Tuesday), and then the big day finally arrives and the departures commence. So does the aggravation.

Offseason Report Card: Giants

“Sure it does,’’ Coughlin said, when I asked if seeing so many players fail to finish a first-day practice takes the air out of a coach. “It pisses me off. After all this [meaning the long off-season program]. Then all of a sudden we’re going to have guys that can’t stay on the field for more than an hour and a half?

“But you know what, I’ve been on teams that I walked in the door [after practice] and they were all on IVs, or 50 percent of them were on IVs. But that’s something that did take place today, and a lot of them were these big offensive linemen. There were a few others, too, but the one I’m worried about was McClain. That’s the one I’ve got to find out about.’’

Coughlin said McClain, who is manning the key middle linebacker slot while Jon Beason tries to work his way off the team’s Physically Unable to Perform list following a spring foot injury, had an issue with a metatarsal. McClain was a strong candidate to start at strongside linebacker before shifting over to the middle in Beason’s absence.

“He thought it was a shoe, part of it,’’ Coughlin said. “That it was an irritation in his foot. But it was over the metatarsals so they took him in to look at that. He’s the one guy right now that, other than heat, I’d be interested to see what the discussion is inside [from the medical staff]. I’m hoping this is just a matter of a sore foot, that’s it.’’

Beason is likely to miss all of training camp but is thought to be on target to return in time for the regular-season opener. If McClain has any significant injury that forces him to the sidelines, the Giants’ depth at inside linebacker will immediately be tested. Veteran reserve Mark Herzlich and rookie fifth-round pick Devon Kennard would be among the team’s few options to handle the middle linebacker slot.

Mosley didn’t last very long at all into the Giants’ first practice before getting his cart ride off the field, and in his absence, rookie center/guard Weston Richburg, New York’s second-round pick, saw a considerable amount of first-team work. According to NJ.com, it was later learned that Mosley left the field with an upset stomach.

"Some of the [practice] was disappointing in terms of the conditioning part," Coughlin said. "Two or three guys I think relatively early in practice came up with cramps and had to be taken inside.''

Rookie first-round receiver Odell Beckham Jr. was one of those players, as he appeared to pull up short on one deep pass play, and took only a limited role in practice afterward. The pass by Eli Manning was intercepted by Dominique Rodgers-Cromartie, and Beckham was not seen in 11-on-11 team drills after that. Beckham nursed a sore hamstring through offseason workouts and may still be dealing with the aftermath of that injury.

“He’s got some work to do,’’ Coughlin said, of Beckham’s less-than-impressive practice showing. “He stopped on the ball. I know that.’’

Linebacker Spencer Adkins and tight end Xavier Gamble also left the field early, with both thought to be suffering from heat-related issues.