Cheddar cheese was made from milk collected from two groups of cows mi
lked either two or three times daily during early, mid, and late lacta
tion. Milk from cows in late lactation had lower casein as a percentag
e of true protein and a higher acid degree value than did milk from co
ws in early lactation. Milk from cows milked three times daily had low
er concentrations of milk fat and casein and higher acid degree values
than did milk from cows milked twice daily, and thus this milk would
be expected to result in decreased cheese yield. Cheese composition wa
s not affected by milking frequency. Stage of lactation effects on che
ese composition were confined to differences in salt content and a tre
nd for higher moisture in cheese made from milk of cows in late lactat
ion. Stage of lactation influenced the pH and degradation of alpha(s),
-casein, in cheese during aging. Fat and protein losses in whey at dra
ining were higher for milk from cows in late lactation than from milk
from cows in early lactation. The typical differences in fatty acid co
mposition of milk from cows in early lactation that cause lower meltin
g point may have caused higher fat loss in press whey. Fat loss in whe
y at draining was higher in cheese made from milk from cows milked thr
ee times daily than in cheese made from milk from cows milked twice da
ily, but the protein loss was not influenced. The ADV of milk was posi
tively correlated to the fat loss in whey. Lower recoveries of fat and
protein in cheese from milk of cows in late lactation were observed a
nd may cause small but economically important decreases in cheese yiel
d. Low SCC of milk from cows in late lactation may have minimized the
changes in cheese composition and yield from stage of lactation.