Abstract :
Goat production in North Morocco represents a livelihood base for resource-poor producers
in need of technological change. Considering that reproduction aspects of these animals
have not been assessed yet, this study characterized their main reproduction characteristics
under the prevailing photoperiod at latitude 35◦N: seasonal variation in females (n = 18) and
bucks (n = 6), female puberty attainment (n = 18) and gestation (n = 22). Nutritional effects
on female seasonality and age at puberty of female kids were tested under two levels of
nutrition: L (low) and H (high), respectively. The L does (n = 9) were fed at maintenance
requirements for adult goats whereas the H does (n = 9) at twice the maintenance requirements.
The H female kids (n = 9) and the L female kids (n = 9) were fed with diets to support
fast and slow average daily gains, respectively. Blood samples were regularly collected from
does and female kids for progesterone assay to assess ovulation occurrence; from bucks to
assess seasonal testosterone changes; from pregnant does to assess progesterone profiles
during pregnancy. Does displayed a marked reproductive seasonality influenced by the
photoperiod. Their ovulation and estrus occurrence diminished progressively starting at
the winter solstice, was completely halted from April to June and progressively resumed
at the summer solstice. The seasonal pattern was uninfluenced by the feeding level. In
bucks, significant seasonal changes were observed in testis measurements (scrotal circumference,
testicular diameter and length), sperm characteristics (volume of the ejaculate and
sperm concentration) and plasmatic testosterone, with low values in winter that increased
during the spring and peaked in the summer. Puberty in females was attained at an average
body weight of 17.6 kg, regardless of the feeding level provided (P > 0.05) and with
high incidence of abnormal estrus cycles (60%). However, improved feeding reduced significantly
puberty age by 19 days (278±8 vs. 297±2 days, P < 0.05). Average pregnancy
length was 149.7 days and slightly longer in does kidding singles than those kidding twins
(151.0±1.4 days vs. 148.3±1.7 days; P < 0.05). Litter size did not affect progesterone plasma
concentrations. The results obtained, offer important information to consider managerial
changes to improve the productivity of the prevailing production systems under extensive
and intensive production plans.
