* TSX ends down 0.6% at 21,873.72

* Posts first decline in six sessions

* Industrial shares lead declines

* 10-year yield climbs to a 5-month high

April 24 (Reuters) - Canada's main stock index fell on Wednesday, including declines for railroad shares, as long-term borrowing costs climbed and retail sales data added to evidence of a slowdown in the domestic economy.

The Toronto Stock Exchange's S&P/TSX composite index ended down 138 points, or 0.6%, at 21,873.72, its first decline in six sessions.

"Markets looks pretty good right now, but the big backdrop that everyone's still concerned about is bond yields", said Greg Taylor, chief investment officer at Purpose Investments.

The Canadian 10-year yield touched its highest level since Nov. 14 at 3.834%. Still, the Bank of Canada is expected to begin cutting interest rate ahead of the Federal Reserve as a slowdown in the domestic economy helps cool inflation.

Canadian retail sales fell 0.1% in February, the second straight month of declines, led by a drop in sales at gasoline stations and fuel vendors.

Shares of Canadian National Railway fell 4.8% after the company's first-quarter revenue missed analysts' estimates. Canadian Pacific Kansas City also missed estimates. Its shares were down 6.3%.

The industrials sector, which includes railroad stocks, lost 2.9% and the communication services sector ended 1.4% lower.

Rogers Communications topped estimates for first-quarter wireless subscriber additions. Still, its shares fell 3.3%. Heavily-weighted financials also lost ground, falling 0.6%. (Reporting by Fergal Smith in Toronto and Purvi Agarwal in Bengaluru; Editing by Ravi Prakash Kumar and Marguerita Choy)