Results
3.1. Estrus onset and presentation
Estrus onset was earlier (Po0.05, Table 3) for ewes fed the CON
diet compared with the FMO diet. Expression of estrus in response
to synchronization was not different (P40.05) between
treatments.
3.2. Hormone profile
3.2.1. Progesterone (P4)
The concentration of P4 in serum was not significantly different
(P¼0.377) when ewes were fed the FMO diet compared with the
CON diet and the interaction between diet and day of feeding was
also not significant (P¼0.377), except on the day 8 (Po0.001) of
the synchronized luteum phase before sponge removal (Fig. 2).
3.2.2. Insulin (INS)
No differences were found between treatments (P¼0.109) in
average INS concentrations in serum by effect of supplementation
with fish meal and oil. However, INS concentrations, were affected
(Po0.001) by the interaction between diet and time. The interaction
occurred because INS was greater in CON ewes on d 10 of
the synchronised cycle, but was lower on d 4–6 of the subsequent
estrous cycle (Fig. 3).
3.2.3. Pregnancy and prolificacy
The percentage of pregnant ewes under the different treatments,
up to d 30, was not different (P40.05; Table 3). However,
at lambing, there were differences in the prolificacy index
(Po0.05); the highest index was found for the FMO group relative
to the CON group.