Fig. 6. The effect of dietary polyunsaturated fatty acids (PUFAs) on
the 13,14,dihydryo-15 keto PGF2a (PGFM) response to the administration
of oxytocin. The cows were maintained on three different
diets: (i) control (n = 5) (j), high linolenic acid (LNA) (n-3) (n = 5)
(h) or high linoleic acid (LA) (n-6) ( ) (n = 6). On days 15, 16 and
17 of cycle 2 (see Fig. 1) they were challenged with 50 iu oxytocin
and blood samples were collected every 15 min from 1 h before
until 3 h after oxytocin administration. Values are presented as the
mean 6 SEM area under the curve (AUC) for PGFM measured in
pg.min ml–1 in the 2 h after the administration of oxytocin. The
response in the LA (n-6) fed cows increased between day 16 and
day 17 (b > a, P < 0.05). For the control and LNA (n-3) groups the
smaller increase occurred earlier, between day 15 and day 16. In
these cows there was an overall effect of time (P < 0.05) but no 2
days were significantly different.