References of "Hanzen, Christian"
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See detailComparison of Reproductive Performance in Belgian Dairy and Beef Cattle
Hanzen, Christian ULg; Laurent, Y.; Ward, W. R.

in Theriogenology (1994), 41(5), 1099-114

A computerized program was written to collect, evaluate and compare reproductive performance data of 2004 beef (Belgian Blue breed) and 1649 dairy (Friesian Holstein and German Red) cattle in 35 Belgian ... [more ▼]

A computerized program was written to collect, evaluate and compare reproductive performance data of 2004 beef (Belgian Blue breed) and 1649 dairy (Friesian Holstein and German Red) cattle in 35 Belgian herds (6 suckler beef herds, 9 milked beef herds and 20 dairy herds). Reproduction data were collected at monthly herd health visits. No difference in age at first calving was observed. Significant differences were observed among the 3 kinds of herds, and the best results were obtained in dairy herds for the calving interval, interval from calving to the first estrus, interval from calving to the first service and average number of days open. Concerning these parameters, first calvers had lower results than multiparous cows, mainly in suckler and milked beef herds. Significant differences were noted in the number of services per pregnancy. Heifers that had never calved presented the highest fertility. Primiparous beef cows had higher fertility than pluriparous cows. In dairy herds, pluriparous cows had higher fertility than primiparous cows. Estrus detection was better in milked beef herds than in suckled beef and dairy herds. Suckled beef herds had the lowest incidence of metritis and ovarian cysts of the three types of herds. Rates of abortion, overall culling and retained fetal membranes were similar in all the herds. The percentage of animals removed for infertility was highest in milked beef herds and lowest in dairy herds. Because 90% of the 1159 calvings recorded in the beef herds required a caesarean section, the reproductive performance of beef cattle represent results after caesarean section. [less ▲]

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See detailApplications de l'échographie en reproduction bovine. 2. L'utérus gestant et non-gestant.
Hanzen, Christian ULg; Laurent, Yves; Jakovljevic, Samy

in Annales de Médecine Vétérinaire (1993)

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See detailApplications de l'échographie en reproduction bovine. 1. L'examen des ovaires.
Hanzen, Christian ULg; Laurent, Yves; Jakovljevic, Samy

in Annales de Médecine Vétérinaire (1992), 137

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See detailApplications des progestagènes au traitement de l'anoestrus fonctionnel dans l'espèce bovine.
Hanzen, Christian ULg; Laurent, Yves

in Annales de Médecine Vétérinaire (1991), 135

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See detailEtude épidémiologique de l'infécondité bovine. 1. Mise au point d'un programme informatisé de gestion de la reproduction.
Hanzen, Christian ULg; Laurent, Yves; Lambert, Eric et al

in Annales de Médecine Vétérinaire (1990), 134

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See detailEtude épidémiologique de l'infécondité bovine. 2. L'évaluation des performances de reproduction.
Hanzen, Christian ULg; Laurent, Yves; Ectors, Francis

in Annales de Médecine Vétérinaire (1990), 134

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See detailMéthodologie et applications de l'échographie bidimensionnelle à la physiopathologie de la reproduction équine. 2. La gestation
Hanzen, Christian ULg; Laurent, Yves; Jakovljevic, Samy

in Annales de Médecine Vétérinaire (1989), 133

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See detailApplications de l'échographie bidimensionnelle à la physiopathologie de la reproduction équine. 1. L'ovaire et l'utérus non-gestant.
Hanzen, Christian ULg; Laurent, Yves; Jakovljevic, Samy

in Annales de Médecine Vétérinaire (1989), 133

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See detailPropriétés physiologiques de la gonadolibérine (GnRH)
Hanzen, Christian ULg

in Annales de Médecine Vétérinaire (1988), 132

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See detailEffect of trenbolone acetate associated with 17á-oestradiol on reproductive performances of young growing fattening bulls
Istasse, Louis ULg; Evrard, Pierre; Hanzen, Christian ULg et al

in Journal of Animal Physiology & Animal Nutrition (1988), 59

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See detailUse of Transrectal B-Mode Ultrasound Imaging in Bovine Pregnancy Diagnosis
Hanzen, Christian ULg; Delsaux, B.

in Veterinary Record : Journal of the British Veterinary Association (1987), 121(9), 200-2

A 3 MHz ultrasonic transducer was used to make pregnancy diagnoses in 320 milk and beef cows and heifers, on average 41 days after the last insemination. The ultrasound diagnostic findings were ... [more ▼]

A 3 MHz ultrasonic transducer was used to make pregnancy diagnoses in 320 milk and beef cows and heifers, on average 41 days after the last insemination. The ultrasound diagnostic findings were systematically confirmed by rectal palpation. Signs of pregnancy were detected as early as the 25th day after insemination. Discounting 16 doubtful results, the accuracy of positive diagnosis (94 per cent) was better than negative diagnosis (89.7 per cent). Ultrasound scanning could be used for the study of embryo mortality or for the determination of fetal age. [less ▲]

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See detailEndocrine regulation of postpartum ovarian activity in cattle: a review
Hanzen, Christian ULg

in Reproduction Nutrition Development (1986), 26(6), 1219-1239

The problem of postpartum anoestrus is a real one because it results in prolongation of the time between calvings. The interval between the calving and resumption of cyclic ovarian activity depends on ... [more ▼]

The problem of postpartum anoestrus is a real one because it results in prolongation of the time between calvings. The interval between the calving and resumption of cyclic ovarian activity depends on several factors, i.e., amount of feeding before and after parturition, level of milk yield, age of the animal, calving difficulty, presence of a bull in the herd, season and its photoperiodism and particularly the suckling or lactating status of the cow. The anoestrus period is longer in suckled cows (30 to 110 days) than in milked cattle (20 to 70 days). The physiology of the hypothalamic-pituitary-ovarian axis is still far from clear. Nevertheless, some events are very well demonstrated. The pulsatile release of LH and GnRH and the pituitary sensitivity to GnRH increase gradually after calving. They are inhibited by suckling, which acts more on LH and GnRH release than on their synthesis. Suckling or the presence of a calf can exercise its action via oestrogens. Suckling inhibits oestrogen synthesis by follicular cells and diminishes their feed-back positive effect on the hypothalamic-pituitary axis. The suckling effect depends on oestrogen concentrations and on time after calving. The progressive LH release induces the synthesis of progesterone. After calving, the first luteal phase is shorter and the progesterone plasma concentrations are lower than what is observed during a normal cycle. Amongst some hypotheses proposed, premature luteolysis induced by uterine prostaglandins offers a new and very interesting field of research related to the utero-ovarian relationship after calving. The effects of FSH, prolactin and glucocorticoids hormones are much less understood. [less ▲]

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See detailEtude clinique comparative de l'effet de la prostaglandine F2alpha sur la rétention placentaire chez la vache
Hanzen, Christian ULg; Baudoux, Ch

in Annales de Médecine Vétérinaire (1985), 129

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See detailProstaglandines et physiologie de la reproduction humaine et animale.
Hanzen, Christian ULg

in Journal de Gynécologie, Obstétrique et Biologie de la Reproduction (1984), 13(4), 351-61

This review of 417 publications in the literature covers various aspects of the role of prostaglandins in human and animal reproductive physiology. The author points out that there are a variety of ... [more ▼]

This review of 417 publications in the literature covers various aspects of the role of prostaglandins in human and animal reproductive physiology. The author points out that there are a variety of prostaglandins all belonging to a family of substances that derive from arachadonic acid. They are present in many human and animal tissues, are extremely labile and are involved in reproduction in the ovary in follicular development and release of the follicle, in the tube in migration of the gametes, and in the uterus in implantation and delivery. The author says that the role of prostaglandins is not an exclusive one but they are linked with the hypothalamo-pituitary hormones, as well as with progesterone and oestrogens. It may be possible that PGE helps to initiate follicular development by stimulating the appearance of LH and FSH receptors. PGE is also luteotrophic. Indomethacin which is a prostaglandin inhibitor however does not modify the ability of LH to stimulate luteinization and maturation of the oocyte. The author postulates on the origin and the identification of the luteolytic factor and gives schematic illustration of the arterio-venous blood supply between the uterus and the ovary which is so important for the good function of the prostaglandins. It is possible that PGF type prostaglandins which are vasoconstrictor may reduce the flow of blood around the ovary, perhaps even specifically to luteal tissue. He postulates that PGF2 alpha in its relationship to its receptors is necessary but insufficient to explain the full luteolytic effect. Turning to the semen he shows that the nature and concentration of prostaglandins in semen varies from one species to another. He thinks that there is a triple role for prostaglandins with semen, which is: a participation in the events of ejaculation, an effect on the female genital tract, and an effect on the mobility of spermatozoa. He speaks of the role of prostaglandins on the Fallopian tubes and believes that they do have an effect on determining the movement of the tubes but cannot explain exactly what. [less ▲]

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See detailLes prostaglandines : biosynthèse et pharmacologie
Hanzen, Christian ULg

in Annales de Médecine Vétérinaire (1983), 127

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See detailElectrical and mechanical activity of the cervix in the ewe during pregnancy and parturition.
Toutain, P. L.; Garcia-Villar, R.; Hanzen, Christian ULg et al

in Journal of Reproduction and Fertility (1983), 68

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See detailEvolution de la motricité utérine chez la brebis au cours de l'oestrus induit.
Hanzen, Christian ULg

in Annales de Médecine Vétérinaire (1982), 126

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