Effect of Days Postpartum and Endogenous Reproductive Hormones on GNRH-Induced LH Release in Dairy Cows

Kesler, D.J.; Garverick, H.A.; Youngquist, R.S.; Elmore, R.G.; Bierschwal, C.J.

doi:10.2527/jas1977.454797x

Cited by 135 publications

(49 citation statements)

References 24 publications

(32 reference statements)

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“…The same holds true for GnRH pulsatile release which increases from 0-0,25 pulse an hour to 0,25-1,25 pulse an hour (Echterkamp and Hansel, 1973 ;Kesler et al, 1977 ;Webb et al, 1980 ; Peters er al., 1981 ; Britt, 1979 ;Rawlings et al, 1980 ;Webb et al, 1980 ;Foster et al, 1980 ;Peters et al, 1981 ; Ramirez-Godinez et al, 1982 ; Azzazi et al, 19831.…”

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“…In dairy cows, the pulsatile release of LH and the sensitivity of the pituitary to hypothalamic GnRH appears 10 days after calving and is greater between 12 and 15 days after calving (Echterkamp and Hansel, 1973 ;Kesler et al, 1977Kesler et al, , 1979Peters et al, 1981 Suckling may have an effect at three levels. It reduces the frequency Walters et al, 1982a ;Edwards, 1985) and amplitude of LH release (Radford et al, 1978 ;Troxel et al, 1980 ;Webb et al, 1980, pituitary sensitivity to GnRH (Carruthers et al, 1978 ;Smith et al, 1981) and pulsatile release of GnRH by the hypothalamus Walters et al, 1982c ;Schallenberger and Peterson, 1982 (Schams et al, 1973 ;Kesler et al, 1977 ;Webb et al, 1977 ;Schallenberger et al, 1978 ;Smith et al, 1981 ;Walters et al, 1982c).At last, as well as a diminution in the interval between injection of oestradiol or GnRH and the LH peak, there is also an increase in the amplitude of this peak during the first 4 weeks after calving (Stevenson et al, 1983 ;Azzazi et al, 1983). The magnitude of the GnRH-induced release of LH was directly proportionnal to follicular diameter (Smith et al, 1983 ;Lishman et al, 1979) and oestrogen concentrations in postpartum cattle (Fernandes et al, 1978 Manns et al, 1983) but tend to increase during the first few days after calving (Webb et al, 1980 ; Peters et al, 19811.…”

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Endocrine regulation of postpartum ovarian activity in cattle : a review

Hanzen

1986

Reprod. Nutr. Dévelop.

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Summary. The Clinically, the postpartum period is characterized by a period of behavioural anoestrus, the duration of which differs in different breeds.If the detection of oestrus is optimal, anoestrus lasts for 20 to 70 days in dairy cows Callahan et al., 1971 ;Schams et al., 1978 ;Pirchner et al., 1983 ;Richardson et al., 1983 ;Etherington et al., 1984). This period is highly variable in suckled cows and lasts from 30 to 110 days (Wiltbank and Cook 1958 ;Oxenreider 1968 ;Graves et al., 1968 ;Casida et al., 1968 ; Nancarrow et al., 1977 ;Holness et al., 1978 ;Wettemann et a/., 1978 ;Short et al., 1979 ;Dunn and Kaltenbach, 1980 ;Kesler et al., 1980 ;Randel, 1981 ;Montgomery, 1982 ;Peters and Riley, 1982 . Jainudeen et al., 1982Bastidas et al., 1984 ;King and Mc Leod, 1983Leod, /1984Hansen and Hauser, 1984 ;Montgomery et al., 1985).Assay of progesterone in plasma or milk has shown that 88 % of animals of dairy breeds have an luteal activity present by 35 days after calving (Ball and Lamming, 1983) and 95 % within 50 days (Bulman and Lamming, 1978). According to different authors, the first rise of progesterone appears between 16 and 69 days after calving in dairy cows (Webb et al., 1977(Webb et al., , 1980Pirchner et al., 1983) and between 56 and 96 days in suckled cows (Fonseca et al., 1980 ;Peters and Riley 1982 ; Jainudeen et al., 1982 Jainudeen et al., /1983Montgomery et al., 1985).It is possible to detect ovarian follicles by rectal palpation in both milked and suckled cow from the second week after calving (Saiduddin et al., 1968 ;Callahan et al., 1971 ;Kesler et al., 1979 ;Webb et al., 1980 ;Kesler et al., 1980 ;Stevenson et al., 1983 (Wiltbank et al., 1962(Wiltbank et al., , 1964Dunn et al., 1969 ; Lammond, 1970 ;Corah et al., 1975 ;Whitman et a/., 1975 ;Duffour, 1975 ;Holness et al., 1978 ;Carstairs et al., 1980 ;Dunn and Kaltenbach, 1980 ; Gauthier and Thimonnier, 1982 ;Peters and Riley, 1982 ; Mc Leod, 1983/1984 ;Rutter and Randel, 1984). Some authors have found that overfeeding improves ovarian (Wiltbank et al., 1962(Wiltbank et al., , 1964Hansen et al., 1982) or pituitary (Beal et al., 1978 ;Jordan and Swanson, 1979 ;Lishman et al., 1979 ;Moss et al., 1982) function. Others have found no relation between feeding and the ovarian (Lishman et al., 1979 ;Carstairs et al., 1980) or pituitary (Hill et a/., 1970 ;Dunn et al., 1974 ;Spitzer et al., 1978 ;Haresign, 1981 ;Rutter and Randel, 1984) activity.Little is known about the mechanism under which diet exerts its effect. It is conceivable that feeding influences the ovarian response to gonadotropins (Gombe and Hansel, 1973). There was a positive correlation between the degree of fatness of an animal and the plasma concentration of 17 !3-oestradiol, 7 weeks after calving (Lishman et al., 1979).Feeding affects the release of luteinizing hormone (LHI and subsequent luteal function Spitzer et al., 1975 ;Apgar et al., 1975 ;Beal et al., 1978). It has been observed that the release of LH induced by gonadotropin releasing hormone (GnRH) injection was grea...

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Endocrine regulation of postpartum ovarian activity in cattle : a review

Hanzen

1986

Reprod. Nutr. Dévelop.

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“…16 O aumento na pulsatilidade de LH é necessário para que os folículos adquiram dominância e capacidade de secretarem grandes quantidades de E 2 , evento fisiológico determinante do "feedback" positivo no hipotálamo. 9,17 Vacas de corte, com boa condição corporal, possuem um intervalo de 27 a 37 dias entre o parto e a primeira ovulação. Tal inter valo é prolongado, para 60 a 120 dias, em vacas com condição corporal ruim.…”

Section: Introductionunclassified

Efeito do eCG ou benzoato de estradiol associado ao norgestomet na taxa de concepção de vacas de corte submetidas à IATF no pós-parto

Rossa

Bertan

Almeida

et al. 2009

Braz. J. Vet. Res. Anim. Sci.

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Este estudo objetivou comparar as taxas de concepção, em vacas de corte no período pós-parto (PPP), tratadas com Gonadotrofina Coriônica Eqüina (eCG) ou Benzoato de Estradiol (BE), após o uso de Norgestomet submetidas à inseminação artificial em tempo fixo (IATF). A hipótese é que a administração de eCG ou BE aumenta as taxas de concepção. Vacas Nelore (n=138) e Brangus (n=63), lactantes, entre 26 e 118 dias do PPP, foram divididas em três grupos homogêneos e dentro de cada grupo subdivididas em dois blocos, um com um PPP < 45 dias (PPP1; n=107) e outro >; 45 dias (PPP2; n=94). Todas as fêmeas receberam um implante auricular contendo 3mg de Norgestomet (Crestar®), seguido pela administração de 5mg de Valerato de Estradiol. Os implantes auriculares foram mantidos durante 10 dias. Na retirada dos implantes, as fêmeas receberam 1mL de solução fisiológica (n=68; Grupo Controle) ou 500UI de eCG (Folligon®; n=67; Grupo eCG) ou 1mg de Benzoato de Estradiol (Index; n=66; Grupo BE) 24 horas após a retirada do implante. A IATF foi realizada 54 horas após a retirada do implante. O diagnóstico de gestação foi realizado por ultra-sonografia 30 dias após a IATF. Houve interação entre os tratamentos e o PPP. No PPP1, a taxa de concepção foi maior no grupo eCG comparado ao BE (47,22% vs. 15,38%; P<0,01). No PPP2, as taxas de concepção dos grupos eCG e BE foram maiores que no grupo controle (41,93%, 44,44% vs. 22,22%; P<0,01). Conclui-se que vacas, com até 45 dias do PPP, o eCG associado ao Norgestomet aumenta as taxas de concepção.

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“…2) plasma LH and FSH levels and LH pulsatility then increase concomitantly with mean LH hypophyseal sensitivity to LRH (Fernandes et al, 1978 ;Kesler et al, 1978) ; 3) thereafter, plasma LH and FSH levels continue to increase in spite of a decrease in LH pulsatility ; 4) when the cows have ovulated, the increased progesterone levels could cause the gonadotrophin levels to decrease (Pelletier and Thimonier, 1975).…”

Section: Introductionmentioning

confidence: 99%

FSH and LH variations in beef cows during the postpartum period

Gauthier¹,

Blanc²,

Petit³

et al. 1982

Reprod. Nutr. Dévelop.

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Summary. To study the plasma gonadotrophin profiles of 9 cows after parturition, blood samples were obtained every 20 min for 12 hrs on three occasions between 5 and 50 days postpartum and analysed by RIA techniques.The time of the first ovulation, as judged by plasma progesterone levels, varied from 30 to more than 60 days postpartum. Variations in mean levels of FSH and LH were not significantly correlated with the postpartum interval. However, the mean levels of plasma FSH and number of LH pulses were lower in females which had not ovulated than in those which had. The cows could be classified into four groups : group 1 with less than 4 LH pulses in 12 hrs and a mean plasma FSH level < 138 ng/ml ; group 2 with more than 4 LH pulses in 12 hrs and varying plasma FSH levels ; group 3 with less than 4 LH pulses in 12 hrs and a mean plasma FSH level > 138 ng/ml ; group 4 which had ovulated. This classification indicated that the LH and FSH levels progressed significantly (2.46 to 3.56 ng/ml, P < 0.05 ; 120 to 159 ng/ml, P < 0.01, respectively) from groups 1 to 3, and that they decreased in the females which had ovulated (group 4).Since the time of the first ovulation after parturition varied, it was not possible to demonstrate any relationship between that interval and the mean plasma gonadotrophin profiles. However, when ovulation was considered as time zero there was a clear increase in plasma gonadotrophin before ovulation.Introduction.

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Effect of Days Postpartum and Endogenous Reproductive Hormones on GNRH-Induced LH Release in Dairy Cows

Cited by 135 publications

References 24 publications

Endocrine regulation of postpartum ovarian activity in cattle : a review

Endocrine regulation of postpartum ovarian activity in cattle : a review

Efeito do eCG ou benzoato de estradiol associado ao norgestomet na taxa de concepção de vacas de corte submetidas à IATF no pós-parto

FSH and LH variations in beef cows during the postpartum period

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