Authors:Vera Faigl, Mónika Keresztes, Alíz Márton, Hedvig Fébel, Margit Kulcsár, Sándor Nagy, Sándor Cseh, László Solti and Gyula Huszenicza
Seasonal differences in the resumption of postpartum ovarian activity, milk production and periparturient metabolic status were investigated in lactating non-suckling dairy Awassi sheep in two consecutive experiments. In Experiment 1, autumn-lambing (AL, n = 27) and spring-lambing (SL, n = 37) ewes were investigated. Ovarian activity was monitored by means of individual progesterone (P4) profiles from day 5 to day 100 post partum. Most of the AL dams (89%) ovulated till day 35 after parturition and became cyclic thereafter. Incidence of persistent corpus luteum (CLP) and short luteal phases (sCL) was frequent (18% and 29%, respectively) among non-conceiving dams. In contrast, only 24% of the SL ewes ovulated before day 35. P4 levels during the luteal phase were lower in cyclic animals, and the cycle was longer in SL than in AL animals. No CLP or sCL was detected in the spring-lambing group, and 61% of SL ewes remained acyclic till the end of the trial. Lactation length was significantly longer in SL dams than in AL ewes (P = 0.008). According to the plasma metabolites (BHB, NEFA) and metabolic hormones (insulin, IGF-I, thyroxine) examined, negative energy balance did not appear in any of the animals. However, seasonal differences were seen in IGF-I and thyroxine levels, which were higher in the SL dams. In Experiment 2, influence of additional lighting was studied in autumn-lambing ewes. The long-day photoperiod (LD, n = 23) group was exposed to artificial light from sunset till midnight (approx. 16 h light/8 h dark) from some weeks before the expected date of delivery in mid-September until the end of December. The control group (n = 25) experienced only natural daylength. The first postpartum ovulation tended to occur later in the LD animals than in the controls (P = 0.047). The lactation of the LD group tended to be longer (P = 0.061). NEFA, BHB, insulin, IGF-I and thyroxine levels did not differ between the groups. Conclusions: (i) The ovarian function of the Awassi population is seasonal under temperate continental climate conditions. (ii) The first postpartum ovulation of non-suckling, autumn-lambing dams may occur very early, even before the completion of uterine involution. (iii) Additional artificial lighting may delay the time of first postpartum ovulation in AL ewes. (iv) Postpartum negative energy balance is unlikely to occur in dairy Awassi ewes even in high-producing intensive systems.
Mateus, L., da Costa, L. L., Bernardo, F. and Silva, J. R. (2002): Influence of puerperal uterine infection on uterine involution and postpartum ovarianactivity in dairy cows. Reprod. Dom. Anim. 37 , 31
Authors:László Könyves, Ottó Szenci, Viktor Jurkovich, Lászlóné Tegzes, Attila Tirián, Norbert Solymosi, Gyula Gyulay and Endre Brydl
., Bartyik, J., Lohuis, J. H. C. M., Jánosi, Sz. and Szita, G. (1999): Uterine bacteriology, resumption of cyclic ovarianactivity and fertility in postpartum cows kept in larges-cale dairy herds. Reprod. Domest. Anim.
Induction of ovulation for timed artificial insemination (TAI) with the Ovsynch protocol was evaluated in 49 anoestrous and lactating Bos taurus × Bos indicus cows. Palpation per rectum and transrectal ultrasonography were used on Days -30, -20, -10 and 0 (start of treatment) to confirm anoestrus but with the presence of follicles = 10 mm, and every other day during treatment to determine ovarian activity. Cows were randomly assigned to: (1) Ovsynch (n = 24; Day 0, 200 µg GnRH; Day 7, 150 µg PGF2a; Day 9, 200 µg GnRH + TAI 16 to 20 h later) and (2) control (n = 25; no treatment). Rates of ovulation for the first GnRH injection, detection of a corpus luteum (CL) at PGF2a injection, pregnancy and induction of cyclicity were greater (P < 0.05) with Ovsynch. There was no effect of body condition score (P ? 0.05). In conclusion, the Ovsynch protocol was not effective in obtaining acceptable pregnancy rate for TAI, but it was effective for induction of cyclicity in anoestrous and lactating Bos taurus × Bos indicus cows under tropical conditions.
Authors:Margit Kulcsár, Gabriella Dankó, H. G. I. Magdy, J. Reiczigel, T. Forgach, Angella Proháczik, Carole Delavaud, K. Magyar, Y. Chilliard, L. Solti and Gy. Huszenicza
Maternal plasma leptin is elevated in ewes during pregnancy. The authors studied whether there was any relation between maternal plasma leptin and insulin concentrations, the number of fetuses and the circulating and faecal levels of gestagens. At the end of the breeding season in January the ovarian activity of Prolific Merino ewes was induced/synchronised with gestagen + eCG treatment. Ewes were inseminated artificially (AI) by laparoscopy. Blood and faecal samples were collected before AI (day 0) and again 41, 81 and 101 days later. The plasma levels of leptin (pL), insulin and progesterone (pP4), and the faecal P4 metabolite (P4-met) content were determined. The day 0 level of pL was significantly higher in pregnant (n = 24) than in non-pregnant ewes (n = 32). By day 41 the pL of pregnant animals had doubled, it showed a further moderate increase on day 81, and decreased slightly thereafter. During pregnancy pP4 and faecal P4-met rose continuously and were positively correlated at all stages. The mean levels of pL and pP4 and the faecal content of P4-met were lower in ewes bearing single (n = 12) than in those with 2 (n = 6) or 3-5 fetuses (n = 6). Analysis of variance demonstrated significant differences according to the number of fetuses in the pL and pP4, but not in P4-met (p = 0.042, 0.044, and 0.051, respectively). Leptin showed positive correlation with insulin before the AI but not during pregnancy. On days 41 and 81 pL showed a slight positive correlation with P4 and P4-met, which decreased slightly by day 101. This study shows that although leptinaemia is affected by the number of fetuses and the level of P4, pregnancy stage is a more important regulator than these additional factors.
Authors:L. Veress, Zs. Tasi, T. Pécsi, S. Babik, Irén Horváth and K. Magyar
Cleverdon, J. M. and Hart, D. S. (1981): Oestrus and ovarianactivity of Booroola Merino crossbred ewe hoggets. Proceeding N. Z. Soc. Anim. Prod. 41, 189--192.
Oestrus and ovarianactivity of Booroola Merino crossbred ewe hoggets