In his final BBC Sport column at the Davis Cup in Madrid, Jamie Murray discusses Great Britain's semi-final exit against a Spain side inspired by Rafael Nadal, the lessons that need to be learned from the inaugural finals and trying veganism.

Overall the Great Britain team had a very good week at the Davis Cup finals, reaching the semi-finals and with all of us enjoying being part of the new-look tournament.

Although the manner of the semi-final defeat by Spain is going to hurt Neal Skupski and me for a little while, it was a great match against Rafael Nadal and Feliciano Lopez in the deciding doubles.

It was exciting and the crowd were right into it - that's what the Davis Cup is for me.

It is just a shame Rafa and Feli were so inspired!

I couldn't touch Rafa's serve; everything was 195kph on the lines.

On one of the set points we had, I had a volley I could have maybe done a bit better with but it was a good return close to the net, it wasn't easy to deal with it.

Then Rafa had that amazing lob from full stretch forwards on another, which is pretty tough to do.

It is unfortunate, but you've got to give Rafa and Feli massive credit.

The match helped show again what a great sport doubles is, that it is so fun and exciting.

In this case, it was a contrast of styles, with singles players going against specialist doubles players with different skill sets.

It was a good platform for doubles to show itself in its best light.

To see Rafa fighting so hard for his country in the decisive doubles rubber was cool. Obviously those top singles players aren't playing every week - but when they do, it is exciting and it elevates our discipline.

'Pique would be silly not to talk to the players'

For the players, the tournament was a positive experience. I particularly enjoyed seeing all the players and fans from 18 different nations being in the same place and wearing their national colours - and I thought organisers Kosmos did a good job from our perspective.

With this new 'World Cup of tennis' event being such a radical change from the old home-and-away format, there were always likely to be some issues and there are obviously a couple of major things that need to be addressed going ahead.

One is the scheduling because some matches weren't finishing until the early morning, including one at 4:04am between the United States and Italy.

A solution could be to have a second venue in Madrid, somewhere that's got two or three courts like the Caja Magica.

That would mean matches could be split across both venues and played in one day-to-evening session, instead of a day session followed by a night session like this year.

If they had six courts, the three at the Caja Magica and three somewhere else, then they can have one tie on each court and start at midday or early afternoon.

That would see play go through to the evening or until about 10pm and stop the late finishes we have seen this week.

The second issue is getting the stadiums fuller for all of the matches, because only the Spain matches were sold out.

We were fortunate we had a lot of British fans who travelled to the event and made it a good atmosphere for all the matches we played. It wasn't like that for all the other matches.

I do think the organisers missed an opportunity there by not giving the unsold tickets to schoolchildren and getting them in to watch the matches.

That would have been a good idea and would have exposed young kids - the future of the sport as potential players and fans - to tennis.

Once the tournament finishes, I would hope that Kosmos president Gerard Pique and the International Tennis Federation speak to the players to get our views on the week. I think it would be silly not to.

I'm sure they are already aware of the good and the bad things from this week and they need to address the things that didn't work.

With them investing so much money into the event, they will want it perfect.

I think there were positives this week and they will want to build on them to make next year even better.

'I've tried eating vegan and would consider becoming fully vegan after tennis'

When we were playing in Basel last month, I posted a picture of a few of the British guys - me, Neal Skupski, Dan Evans, his coach Mark Hilton and our Davis Cup captain Leon Smith - with a caption 'Back the (vegan) Brits'.

Evo is vegan and Hilts is doing it, so we were all eating vegan that week, going to a Thai restaurant every night for vegan food.

I've tried veganism before. I'm not fully vegan but I think as a base diet, the staple of your diet, it is really good.

But I find it too hard to maintain when I'm travelling and also it is about making sure you get enough content to eat. If I'm at home, I can control it but sometimes when I'm travelling it is out of your control, in terms of what food they provide at tournaments.

I did it for a couple of weeks after the French Open and I lost about two and a half to three kilos.

That tells you I probably needed to lose it, or I could afford to lose it, but I wasn't eating as much as I needed to - that's why I was losing the weight because I wasn't getting the calories in.

It's tough to say if that weight loss affected my training levels or performance, positively or negatively. I couldn't honestly say if it was beneficial or not, I don't know.

I think if I was eating enough food, then going vegan full-time would be fine, but at the time I was training a lot and not getting enough calories.

That was because I was getting food delivered each day, which had a certain amount of calories that I wasn't used to and I wasn't topping up loads.

I like the ethics of veganism and for me the biggest thing was for my own health.

Post-career, I would maybe think about becoming fully vegan. You have less appetite because you are not working out as much and need to be more aware and careful - as you need to keep the weight off otherwise you would balloon!

Jamie Murray was talking to BBC Sport's Jonathan Jurejko in Madrid.