Influence of continuous breeding goats on return to cyclicity in seasonal breeding goats

The boer goats which originated from the South African
Republic are continous breeding animals when kept in the
northern hemisphere and they kidd three times in 2 years. In this
study, a mixed herd was monitored to determine whether boer
goats could induce return to cyclicity in sesonal breeding goats.
All goats (n = 20) were pluriparous and kidded during January
and February. During January a mixed group was formed (10
boer goats kept together with 10 domestic breed goats). At the
same time a group of domestic breed goats (n = 12), kept in the
same manner, 40 km away from the experimental group was
used as controls. Blood samples were collected every 72 h to
determine level of progesterone in both herds. Goats were
monitored at the same time to observe for signs of oestrus.
Progesterone concentrations in sera samples were determined
using a RIA method. Data were analysed by ANOVA using
Statistica software. We observed visual oestrus in all boer goats
and in eight domestic breed goats from the mixed group during
March and April. Progesterone concentrations confirmed the
presence of functional corpora lutea between two visual cycles in
these animals. No visual oestrus or increases in progesterone
were observed in the control group of goats. In conclusion,
continuous breeding boer goats induced oestrus in 80% (n = 8)
of seasonal breeding goats when kept in a mixed herd.