Physiology of the oestrus cycle Prof Ch Hanzen

Physiology of the oestrus cycle Prof. Ch. Hanzen Université de Liège Faculté de Médecine Vétérinaire Service de Thériogenologie des animaux de production Courriel : Christian. hanzen@ulg. ac. be Site : http: //www. therioruminant. ulg. ac. be/index. html Publications : http: //orbi. ulg. ac. be/ Facebook : https: //www. facebook. com/Theriogenologie

Hypothalamus Hypophysis

The hypothalamohypophysis complex

Hormonal relationships between hypothlamus, hypophysis and ovary US HYPOTHALAM Gn. RH Negative feedback control of oestradiol on FSH HYPOPHYSE ANTERIEURE FSH LH OVAIRE Oestrogens Follicular growth Negative feedback control of P 4 on LH Progestero ne Ovulation Oocyte maturation Follicular growth (DF)

Progesterone effects 1 2 3 4

FSH and LH effects on follicular growth

The ostrus cucle of the cow : 21 days (18 to 24) MP Oestrus Metoestrus 6 d 15 h Dioestrus 12 d Prooestrus. Oestrus 3 d 15 h Progesteronic phase 0 6 Oestrogenic phase 18 21 jours

Hormonal regulation during the estrous cycle in the cow mm Oestrus. Metoestrus Dioestrus Prooestrus/Oestr 20 19 18 17 16 15 14 12 12 11 10 9 8 7 6 5 4 3 2 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 1112 13 14 15 16 17 18 19 20 21 0 FSH Oestrogens Inhibine LH Progesterone PGF 2 a

The luteolysis Progestero ne < 12 J Luteal ischemia Apoptosis CJ Synthesis stimulati on Ocytoci ne Oestrogens Phospholipi ds Arachidonic acid R oxytocin Phospholipa se Prostaglandine synthetase Contractio ns PGF 2 a

Timing oestrus – IA ovulation Delay of the peak if less oestradiol (see milk production effect) beginning of oestrus. LH Increase of oestradiol Decrease of P 4 2 2, 8 h to 9, 1 h % de pregnancy / ovulation 6 % if 48 to 32 h End of before oestrus 22 % if 32 to 16 before Capacity of fertilization of spz 35 % if 16 to 0 h : 24 h Fertilization of oocyte : before 16 to 18 h Migration of spz : 6 to 8 h Moment of AI : Ovulation 24 to 4 h before ovulation 3 27 h 22, 0 to 34, 9 h 1 Depend more 30 h (24, 0 to 38, 5 h) on 3 than 2 25 % of cows > 30 h 10 % of cows > 36 h

Detection of the moment of Palpation/US : no CL or < 1 cm ovulation Dosage Elisa P 4 Herd-navigator and lutéolysis Palpation : tonicity of uterine horns Vaginoscopy : vaginal mucus US : uterine mucus US : thickness of uterine wall (+ 4 mm) Vaginal conductivity : min 18 h before Increase of Vaginal T° vaginale : max when LH peak oestradiol Decrease Of P 4 FOL L Oestrus Ovulation Induction with Gn. RH Detection in 40 min LH peak Ovulation > 30 h With Predibov test AI > 10 à 20 h (under construction) Palpation : firm vs soft US : diameter 11 to 19 mm US : deformation < 4 h before ovulation Doppler : hypervascularisation of theca

Periods of cyclicity in the heifer Birth Puberty 12 mths C 1 : 24 mth 1ère AI : 14 mths Beginning of pregnancy Physiological anoestrus Waiting Reproduction period Physiological anoestrus

Periods of cyclicity in the cow Calving Waiting period 1ére AI: 50 - 60 j Beginning of Pregnancy : 90 j Calv : 12 mths 15 d : dairy cows 30 d : beef cows Physiological Functionnal anoestrus Reproduction period Physiological anoestrus