The 18-year-old centre, who is in the Wales U19 squad and is set to line up against Italy next Wednesday, racked up 21 points through a try, five conversions and two penalties as they put the west Wales battle to bed during an opening 40 minutes of scintillating rugby to lead 34-3.
Although Ammanford mounted a brave fightback in the second half it was a mere consolation for failing to shackle Burry Port’s strike runners and explosive forwards before the break.
“It was a brilliant team performance. We worked on everything in training and it came out in the game,” said McDonald.
“It was our 12th win in a row. We haven’t lost since Newcastle Emlyn beat us on October 8 last year.
“Everything came together against Ammanford and we will enjoy the celebrations. We had watched a video of Ammanford and saw they came up in ones in defence so the tip-off pass was on.”
McDonald praised the scoring exploits of two-try prop Jac Gaines, saying: “He was good, he does that all the time.”
Gaines and McDonald were joined on the scoresheet by centre Will Thomas and lock forward Rhys Reed.
Prop Osian Jones touched down twice for Ammanford, substitute Noah Potter getting their third try, with Sam Potter succeeding with two conversion and a penalty.
