Manipulation of lactation and suckling on the resumption of postpartum reproductive activity in Damascus goats

The reproductive activity of Damascus goats was studied in does that were not allowed to mate (non-lactating does) (Group C) and lactating does with different suckling treatments (Groups A and B). Time resumption of sexual activity was not significantly different between lactating and non-lactating does or between does’ groups of different suckling treatments. All does started to demonstrate estrous behavior during autumn (September). In Groups A, B and C the mean length of the estrous cycle was 19.0±0.6, 19.5±0.3 and 22.0±2.0 days, duration of the estrous period 29.6±3.0, 31.0±5.3 and 25.3±5.8 h, mean corpus luteum (CL) counts 1.6 ± 0.2, 1.8 ± 0.2 and 1.8 ± 0.3, while mean litter size was 1.1 ± 0.1, 1.2 ± 0.2 and 1.3 ± 0.5, respectively. In the three groups an increase in the plasma progesterone concentrations started from summer (mid-June), indicating the occurrence of one or more ovulatory anestrus (silent ovulation). Plasma prolactin levels were higher (P < 0.01) in lactating does than in non-lactating does and at 4 weeks postpartum. Moreover, prolactin levels were significantly higher (P < 0.01) in does suckling their kids than in does being machine milked. Plasma progesterone levels during postpartum were negatively significantly correlated with prolactin levels. The study demonstrated that lactation and suckling lengths have no effect on the resumption of postpartum sexual activity in Damascus goats and that season is the major factor controlling the ovarian activity. © 2003 Elsevier Science B.V. All rights reserved