Follicle deviation and ovulatory capacity in Bos indicus heifers.
The objectives of Experiment 1 were to determine the interval from ovulation to deviation, and diameter of the dominant follicle (DF) and largest subordinate follicle (SF) at deviation in Nelore (Bos indicus) heifers by two methods (observed and calculated). Heifers (n = 12) were examined ultrasonographically every 12 h from ovulation (Day 0) to Day 5. The time of deviation and diameter of the DF and largest SF at deviation did not differ (P>0.05) between observed and calculated methods. Overall, deviation occurred 2.5+/-0.2 d (mean +/- S.E.M.) after ovulation, and diameters for DF and largest SF at deviation were 6.2+/-0.2 and 5.9 +/- 0.2 mm, respectively. Experiment 2 was designed to determine the size at which the DF acquires ovulatory capacity in B. indicus heifers. Twenty-nine heifers were monitored every 24 h by ultrasonography, from ovulation until the DF reached diameters of 7.0-8.4 mm (n=9), 8.5-10.0 mm (n=10), or >10.0 mm (n=10). At that time, heifers were treated with 25 mg of pLH and monitored by ultrasonography every 12 h for 48 h. Ovulation occurred in 3 of 9, 8 of 10, and 9 of 10 heifers, respectively (P<0.05). In summary, there was no significant difference between observed and calculated methods of determining the beginning of follicle deviation. Deviation occurred 2.5 d after ovulation when the DF reached 6.2 mm, and ovulatory capacity was acquired by DF as small as 7.0 mm.
Gimenes
L U
LU
Departamento de Reprodução Animal, FMVZ, USP, Rua Prof. Orlando Marques de Paiva 87, CEP 05508-000, São Paulo, SP, Brazil. ligimenes@usp.br
Sá Filho
M F
MF
Carvalho
N A T
NA
Torres-Júnior
J R S
JR
Souza
A H
AH
Madureira
E H
EH
Trinca
L A
LA
Sartorelli
E S
ES
Barros
C M
CM
Carvalho
J B P
JB
Mapletoft
R J
RJ
Baruselli
P S
PS
D000818:Animals; D002417:Cattle / Q000502:physiology*; D048429:Cell Size / Q000187:drug effects; D004334:Drug Administration Schedule; D004343:Drug Implants / Q000627:therapeutic use; D004526:Efficiency; D004973:Estrus Synchronization / Q000379:methods / Q000502:physiology; D005260:Female; D007986:Luteinizing Hormone / Q000008:administration & dosage; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D010060:Ovulation / Q000187:drug effects / Q000502:physiology*; D010062:Ovulation Induction / Q000662:veterinary*; D011282:Pregnenediones / Q000008:administration & dosage; D045167:Progesterone Congeners / Q000008:administration & dosage; D013997:Time Factors
D004343:Drug Implants; D011282:Pregnenediones; D045167:Progesterone Congeners; C100284:norgestomet; D007986:Luteinizing Hormone