This experiment was conducted in a state research farm
(APTAdAlta Mogiana Regional Center) located in Colina,
São Paulo, Brazil. All of the heifers were kept on Brachiaria
brizantha pasture and given mineralized salt and free access
to water. Data collection was performed during the 2010/
2011 (group 1) and 2011/2012 (group 2) spring-summer
(November–January) breeding seasons. A total of 57 cyclic
Nelore (Bos indicus) beef heifers ranging between 20 and 24
months of age were assigned into two groups (group 1
[n ¼ 32] and group 2 [n ¼ 25]). The heifers were examined
by transrectal ultrasonography to determine the presence
of a CL on the first day of the synchronization protocol.