Effects of artificial photoperiod on reproductive performance of seasonally anestrous ewes
2010
Sadeghipanah , Hassan | Gharadaghi, A. | Aghashahi, A. R | Asadzadeh, N. | Papi, N | Javaheri Barfouroosh , H
In order to investigate the effect of artificial photoperiod on reproductive performance in seasonally anestrous ewes, 40 non-pregnant Chios ewes in spring were allocated into two groups on the basis of photoperiodic patterns: 1- natural long day photoperiod group (LD) 2- artificial short day photoperiod group (SD). On April 12, ewes In SD group were firstly exposed to 10 long days (15 h and 35 min lightness and 8 h and 25 min darkness; equal to local summer solstice) then in next 60 days, were gradually followed by exposure to short days (8L:16D) using light-sealed rooms; this treatment is referred to as LD_¨SD. Ten days after the 8L:16D program was fixed for the SD group, rams were introduced to both groups suddenly and simultaneously. Interval from ram introduction to first oestrus was shorter and estrus rate was greater in the SD group than in the LD group (P0.05). Conception rate, parturition rate, prolificacy and fecundity in the SD group were nonsignificantly (P0.05) better than in the LD group. The lamb crop at both lambing and weaning times, in SD group (respectively, 3.15 and 15.63 kg) was greater than the in LD group (respectively, 2.27 and 9.83 kg). Totally, these results indicated that artificial short day photoperiod used in this experiment, can improve reproductive performance in seasonally anestrous Chios ewes.
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