"D.N.S." simply stands for "Did not survive" and pertains to animals born/hatched at the collection which failed to live longer than 30 days; you'll notice entries under this column tend to tally with corresponding entries in the "
Births" column.
For instance:
View attachment 485857
This entry shows that 1,0,1 Goeldi's Monkey were born in 2020, but none survived 30 days - the fact only one individual has a sex listed would tend to suggest the other was either stillborn or died very soon after birth, before a sex could be recorded.
"
Dispose" merely means animals which left the collection but did not die - in other words, were sent elsewhere.