Abstract :
The application of photoperiod treatments to bucks of seasonal breeds could alleviate the
problem of seasonality in sperm production. As substantial differences in reproductive
activity have been recorded between Mediterranean goat breeds originating in the low
latitudes, compared to those originating from higher latitudes, a different response may
be expected after the application of photoperiod treatment. Murciano-Granadina bucks,
maintained at a latitude 38◦N, were exposed to a 1-year controlled light regime treatment
in which 2 months of long days (16L:8D) were alternated with 2 months of short days
(8L:16D). Under natural photoperiod, bucks displayed a seasonal effect regarding reaction
time (P < 0.01), sperm concentration (P < 0.01), and number of sperm per ejaculate
(P < 0.001). Photoperiod treatment eliminated seasonality in sexual behaviour (P < 0.05),
sperm concentration (P < 0.01), and overall sperm production (P < 0.001). Loss of seasonality
also induced a lowersemenvolume in spring (P < 0.01) andsummer(P < 0.05), a lower sperm
concentration in spring (P < 0.001), but an increase in sperm concentration during winter
(P < 0.01). No significant difference was recorded in the annual mean number of sperm per
ejaculate between the photoperiod intervals tested. Although the results showed the photoperiod
treatment to allow adequate sperm production in winter, it may also prompt a
decline in sperm production at other times of the year, thus limiting the overall advantage
of this method of reproduction control—at least in this Mediterranean breed of goat.
