how can i use xcorr function to detect pitch of a speech signal

I'm facing some difficulty to detect the pitch of the signal

[y fa]=wavread('watch.wav');
Fs=1000;
t=(0:(Fs-1))*(1/Fs);
plot(y);
z=fft(y);

R = xcorr(y);
[pks,locs]=findpeaks(R);
max(Fs./diff(locs))

but by increasing Fs max the value is 5(multiples of 10) but i think it is not pitch help me wid perfect solution