(?<!w.w.)(?<![A-Z][a-z].)(?<=.|?)s

sl<-unlist(strsplit(txt1,"(?<!w.w.)(?<![A-Z][a-z].)(?<=.|?)s"))

As of Feb. 9, the Ministry of Agriculture, Fisheries and Food
said that 9,998 cattle have been destroyed after being diagnosed
with BSE. The government has paid $6.1 million in compensation, and is
budgeting $16 million for 1990.

As of Feb. 9, the Ministry of Agriculture, Fisheries and Food
said that 9,998 cattle have been destroyed after being diagnosed
with BSE.
The government has paid $6.1 million in compensation, and is
budgeting $16 million for 1990.

As of Feb.
9, the Ministry of Agriculture, Fisheries and Food said that 9,998 cattle have been destroyed after being diagnosed
with BSE.
The government has paid $6.1 million in compensation, and is
budgeting $16 million for 1990.