Resumption of postpartum ovarian activity in Malin, Dorset Horn-Malin and Long Tail ewes

K. Musaddin, H. S. Tan, M. Y. Mohd. Khusahry and I. Jasni

Abstract

The postpartum ovarian activity of 15 Malin, 15 Dorset Horn-Malin (DHM) and 10 Long Tail (LT) ewes was studied based on the progesterone profiles and oestrus detection by rams. Selected ewes had good body condition and healthy lambs. They were kept in separate pens according to breedtype from day 3 through day 90 after lambing. Three vasectomized rams were used for oestrus detection of the ewes and were rotated at weekly intervals. Jugular blood samples were collected twice weekly from all ewes for 3 months to determine the postpartum progesterone profiles. The mean progesterone concentration during the follicular phase was 0.19 ng/mL in DHM and LT while 0.26 ng/mL in Malin. The mean progesterone concentration during the luteal phase was 2.94 ng/mL in Malin, 2.54 ng/mL in DHM and 2.33 ng/mL in LT ewes. Based on the progesterone profiles, the first postpartum ovulation in Malin, DHM and LT ewes occurred 24.5 ± 2.7, 30.0 ± 2.2 and 35.7 ± 4.3 days after lambing respectively. The oestrus cycle of the ewes varied from 16.3 ± 0.33 days in Malin to 17.6 ± 0.25 days in LT. It was observed that oestrus detection, based on crayon markings made by the vasectomized rams, was inaccurate as reflected by the progesterone profiles. The first oestrus detected by the rams in Malin, DHM and LT ewes was 36.5, 49.5 and 66.7 days postpartum respectively. Based on the progesterone profiles, the vasectomized rams failed to detect 80–90% of the first ovulation in the ewes. This study indicates that the plasma progesterone profiles can be used to determine the resumption of postpartum ovarian activity of the ewes better than using vasectomized rams.

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