Oestrous and ovarian activities of Finn-cross ewes during the post-partum and the seasonal anoestrous periods

Amir, D.; Rosenberg, Miriam; Schindler, H

doi:10.1017/s0021859600043410

Cited by 7 publications

(5 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the results of the present study it appears that after January-February lambings the Finncross ewes of both the control and the light-treated groups resumed normal cycle activity and did not enter seasonal anoestrus, in contrast to previous reports on the same breed (Amir et al 1980;Amir, 1984;Amir, Rosenberg & Schindler, 1984). Still, the mean intervals from lambing to first ovulation and oestrus were considerably longer than those reported after October lambings in the same breed (Amir et al 1984).…”

Section: Discussioncontrasting

confidence: 72%

The effect of artificial light, hormones, and rams on the reproductive performance of Finn-cross ewes during the seasonal anoestrus in Israel

Amir

Gacitua

1985

J. Agric. Sci.

Self Cite

View full text Add to dashboard Cite

SUMMARYAdult Finn-cross ewes, pregnant from September matings, were kept under natural (control) or artificial photoperiod (experimental). The artificial photoperiod consisted of an abrupt increase in daylength to 18 h for 30 days in November, followed by a step wise decrease of 30 min every 10 days until May.The ewes of the two groups were either exposed daily to rams after lambing in January-February or after weaning in March, or were kept isolated from the males until mating in April. Time of mating in the latter animals was determined by measuring the intra-vaginal electrical impedance. Hormone treatment for oestrus induction was given after weaning to a portion of the control and experimental ewes. The ovarian activity of the animals was determined by examining their plasma progesterone changes.Daily teasing of the ewes from lambing to weaning and/or treatment with artificially decreasing daylength did not influence the ovarian activity during this period. All the ewes which were examined for ovulation, from both the control and experimental groups, ovulated 40–60 days after lambing, and 96% of the animals of the two groups which were not treated with hormones for oestrus induction exhibited spontaneous oestrus in March–May.The lambing–first ovulation and the lambing–first spontaneous oestrus intervals were longer in the light-treated than in the control ewes, and in the animals kept isolated from the rams until mating than in those exposed to the males after lambing or weaning.A conception rate of 70–100% and a high rate of cycle activity were obtained during the two consecutive years of the experiment in both control and experimental animals, treated or not with hormones and exposed or not to rams. In view of these results, no conclusions could be drawn about the effectiveness of the artificial photoperiod, ram effect and hormone treatment, alone or in combination, in inducing cycling activity and to increase the fertility of Finn-cross ewes during the seasonal anoestrus in Israel.

show abstract

Section: Discussioncontrasting

confidence: 72%

The effect of artificial light, hormones, and rams on the reproductive performance of Finn-cross ewes during the seasonal anoestrus in Israel

Amir

Gacitua

1985

J. Agric. Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…All the ewes of the present work ovulated and the majority of them came into oestrus after lambing. The mean intervals from lambing to first ovulation and oestrus were very similar to those found in ewes of the same breed after October lambing (Amir, Rosenberg & Schindler, 1984), but shorter than the intervals reported after January lambing (Amir & Gacitua, 1985), and do not conform with the absence of oestrous ewes and the occurrence of occasional ovulations only, during this period of the year (Amir et al 1984). It appears, therefore, that in the present study the ewes did not enter seasonal anoestrus after lambing in January-February.…”

Section: Discussionsupporting

confidence: 70%

“…1986), induced an autumn oestrus behaviour in the ewes. The question of the full potential effectiveness of the light and melatonin treatments, alone or in combination, to induce cyclic activity in Finn-cross ewes showing a distinct anoestrous season (Amir et al 1984), remains open.…”

Section: Discussionmentioning

confidence: 99%

The effect of a light pulse and melatonin, alone or in combination, on the reproductive performance of Finn-cross ewes in spring in Israel

1987

Self Cite

View full text Add to dashboard Cite

Adult Finn-cross ewes, pregnant from September matings, were kept under natural photoperiod (control, 30 animals) or with an additional exposure to a I h long. 300 lux light pulse, 16-17 h after an artificial dawn (light-pulse treatment, 32 ewes) for 2-5 months. After lambing, the supplementary light was discontinued and half of the ewes from each group were injected daily with 2 mg melatonin for an additional 2-5 months.The light-pulse ewes produced heavier lambs and more milk, as can be deduced from the higher rate of growth of their lambs during the first 10 days of life, than the control animals. The light-pulse and/or melatonin treatments delayed the occurrence of the first post-partum ovulation and oestrus (which occurred in the untreated animals about 4 and 6 weeks, respectively, after lambing), by 1-3 weeks. However, more ewes exhibited oestrus and cyclic activity in the light-treated than in the other groups. The fertility in the lighttreated group was, consequently, superior to that in the group kept under natural photoperiod, in spite of the similar lambing rate of the mated ewes of the different groups.It is concluded that the light-pulse, but not the melatonin treatment, had a beneficial effect on the reproductive performance of the ewes, as measured by the weight of the newborn lambs, the milk production of the dams during the first 10 days post-partum, and the cyclic activity of the ewes after February lambing in Israel.opened the way to the administration of exogenous TNTK.ODUCTION melatonin to induce the stimulatory effect of short days. In order to increase the reproductive efficiency of T h e exposure of ewes to increasing daylength is sheep it is necessary, among other ways, to increase apparently necessary before the stimulatory effect of the lambing frequency of the ewes, i.e., to obtain s h o r t d a y s ( E n g i i s h el aL i 9 8 6 ) Karsch el al. (1986), fertile matings during the anoestrous season. Since however, stated that the 'reproductive onset' in the the photoperiod was identified as the cue to the e w e s w a s l i n k e d t o cessa tion of the long day signal annual reproductive cycle of the animals (Marshall, a n d d i d n o t r e q u j r e exposure to short-day cues. In 1932), many attempts have been made to induce t h e pre sent study the possibility of inducing cyclic cyclic activity in ewes during the sexually quiescent activity in ewes after February lambings was period by exposing them to artificial light changes examined by exposing the animals to a light pulse which mimic those of the natural photoperiod a n d/or melatonin administration. In view of preprevailing before and during the breeding season v i o u s r e p o r t s o n t h e p o s s i b | e act ion of the photo-(review: Hansen, 1985). This strategy, however, p e r i o d t o w h i c h t h e d a m s a r e exposed before and necessitates light-proof buildings, which are imprac-a f t e r partU rition on their milk production and on the tical under field conditions. The existence of a g r o w t h of the litter (Pet...

show abstract

“…Silent ovulation seems to be a mediatory step which starts about 1 month before the cessation of ovarian activity. In other studies, silent ovulation was reported to occur before the period of ovarian inactivity (Amir, Rosenberg & Schindler, 1984) or before the ewes entered the breeding season (Mauleon & Dauzier, 1965;Amir et al 1984). Based on the present findings, Rahmani sheep could be considered as a breed with a very long breeding season.…”

Section: Discussionsupporting

confidence: 61%

Oestrous and ovarian activity of subtropical fat-tailed Rahmani sheep and their response to light treatment

et al. 1987

View full text Add to dashboard Cite

Oestrous and ovarian activity were studied throughout the year in 29 subtropical Rahmani ewes using both vasectomized rams and intravaginal electrical resistance measurements. Percentages of ewes in oestrus and of ewes ovulating were consistently high throughout the year with a detectable drop in spring months. The drop was more pronounced and lasted longer in oestrous activity than in ovarian activity. About 33% of the ewes showed continuous ovarian activity throughout the year while almost all ewes had periods of behavioural anoestrus.Effects of artificial light regimen on oestrous and ovarian activity were investigated in 21 Rahmani ewes over a 6-month period from January to June. Oestrous and ovarian activity were slightly lower in the light-treated (L) group than the control (C) group during the period of abrupt increase in daylength. With gradual decrease in daylength, the percentage of ewes showing oestrus was markedly higher in the L than in the C group (84-6 v. 37-5% during May).It was concluded that daylength change, although limited in this region, is a main factor controlling the seasonal changes in oestrous and ovarian activity in subtropical Rahmani sheep.

show abstract

Oestrous and ovarian activities of Finn-cross ewes during the post-partum and the seasonal anoestrous periods

Cited by 7 publications

References 14 publications

The effect of artificial light, hormones, and rams on the reproductive performance of Finn-cross ewes during the seasonal anoestrus in Israel

The effect of artificial light, hormones, and rams on the reproductive performance of Finn-cross ewes during the seasonal anoestrus in Israel

The effect of a light pulse and melatonin, alone or in combination, on the reproductive performance of Finn-cross ewes in spring in Israel

Oestrous and ovarian activity of subtropical fat-tailed Rahmani sheep and their response to light treatment

Contact Info

Product

Resources

About