Serum progesterone concentrations in cows receiving embryo transfers

Abstract

Summary. Progesterone concentrations in systemic blood were determined by radioimmunoassay in crossbred cattle used as recipients in an embryo transfer programme. An embryo was transferred surgically to the uterine horn of 528 females which were in oestrus within one half-day of the donor. Jugular blood was obtained at the time embryos were transferred (3\p=n-\7days after oestrus) and again from most females between Days 9 and 14. Pregnancy was determined by rectal palpation 45\p=n-\ 65 days after oestrus. There were no significant differences between serum progesterone levels of females which remained pregnant and those which did not. Out of 177 pregnant recipients, none had serum progesterone levels <0\m=.\5ng/ml on Days 10, 11, or 12 but in 8, values were <1\m=.\0 ng/ml. Blood samples were also taken on Days 20, 21, or 22 from 113 of these recipients. The mean \ m=+-\ s.e.m. concentration of progesterone in the pregnant females (5\m=.\14\ m=+-\0\m=.\34 ng/ml) was significantly higher (P < 0\m=.\001)than in the non-pregnant females (1\m=.\17\ m=+-\ 0\m=.\25ng/ml). The correlation coefficients between progesterone levels on Days 3, 4, 5 or 6 and 10\p=n-\12 ranged from 0\m=.\18to 0\m=.\37 (all P < 0\m=.\02).Progesterone levels were not related to length of the previous cycle, the time of day an animal was first noticed in oestrus or the side of the corpus luteum. However, cows with a short oestrus had higher progesterone levels on Days 3\p=n-\7(P < 0\m=.\01) than those in oestrus for a longer time.

Reproductive Response of Crossbred Heifers (Bos indicus * Bos taurus) Used as Embryo Recipients in Venezuela.

“…As a rule of thumb, the cyclical standard of the P4 concentrations found in this trial agrees with the changes that occur during the estrous cycle due to the functioning corpus luteum (CL), not only for pregnant recipients but also for open ones. Also, the results of the present and other studies can account for the luteal function by P4 concentration at the peripheral level [1,3,11,12].…”

Improving pregnancy rates in problem breeder cattle by administration of 15 mg of progesterone on days 3–5 post-mating

“…Additionally, there has been no correlation found between circulating P 4 concentrations and normal embryo morphology in cattle (Linares et al 1982), however, P 4 concentrations may still be the primary factor involved in the development of a successful pregnancy (Hasler et al 1980). Using reciprocal embryo transfers among virgin (fertile) heifers and PB cows (transfer embryos from virgin heifers to PB cows and vice versa), it was discovered that PB cows had significantly higher pregnancy rates than virgin heifers (Gustafsson and Larrson 1983).…”

eCG e densidade vascular em úteros bovinos

“…Essas alterações ocorrem devido ao requerimento biológico para estabelecer um ambiente intra-uterino capaz de sustentar o concepto bovino (SREENAN, 1978). Alguns trabalhos associam o aumento da concentração plasmática de progesterona (P 4 ) com o desenvolvimento embrionário e o estabelecimento da gestação (HASLER et al, 1980;SREENAN, DISKIN 1983;MANN, LAMMING 1999;BINELLI et al, 2001;MANN, LAMMING 2001;MANN et al, 2006;LONERGAN et al, 2007; (BLOECHLE et al, 1997;ENGMANN et al, 1999;CHIANG et al, 2000;KUPESIC et al, 2001;SCHILD et al, 2001;CHIEN et al, 2002;WU et al, 2003;HICKEY et al, 2003;CHIEN et al, 2004;YU et al, 2006;MERC et al, 2008;WEN et al, 2009). Em bovinos alguns trabalhos mostraram a influência da administração de gonadotrofina (eCG ou FSH) na formação e vascularização do CL, produção de progesterona e fluxo sanguíneo uterino tanto em receptoras como em doadoras bovinas (FUCK et al, 2002;BARUSELLI et al, 2004;PAPA et al, 2007;HONNENS et al, 2008 Algumas estratégias vêm sendo estudadas para estabelecer o período ideal para iniciar a hiperestimulação com uma maior eficiência do tratamento.…”

“…Diversos autores sugerem que a produção de substâncias vasoativas pelo embrião e / ou endométrio seja responsável pela estimulação local da perfusão uterina observada em bovinos , ovinos REYNOLDS, 1984), suínos ANDERSON et al, 1994) (HASLER et al, 1980;SREENAN;DISKIN, 1983;MANN, LAMMING 1999;MANN, LAMMING 2001;BINELLI et al, 2001;MANN et al, 2006;LONERGAN et al, 2007;.…”

“…A expressão do mRNA do VEGF em células da granulosa luteinizadas de humanos demonstrou ser dose e tempo dependente sob influência do hCG in vitro (NEULEN et al, 1995). Na verdade, exposição crônica ou aguda ao hCG estimula diretamente a produção e secreção de VEGF em células da granulosa luteinizadas em macacas (CHRISTENSON; STOUFFER, 1997) e em mulheres (LAITINEN et al, 1997;LEE et al, 1997;NEULEN et al, 1998;WULFF et al, 2001a A melhora na receptividade uterina com o tratamento estimulatório e superovulatório também é associada ao aumento na taxa de concepção (HASLER et al, 1980;SREENAN;DISKIN 1983;LAMMING 1999;LAMMING 2001;BINELLI et al, 2001;BARUSELLI et al, 2004a;MANN et al, 2006;LONERGAN et al, 2007;BARUSELLI et al, 2008;. Estes efeitos acontecem provavelmente devido à presença do embrião, como relatado por Spencer et al (2007).…”