Abstract
Growth, pre-weaning kid survivability, reproduction and fertility, biomass production,
carcass value and milch potential of different genetic groups in Black Bengal (BB) goats;
Jamnapari x BB (JBB1), selected BB (SBB1) and randombred BB (RBB1) in first and
JBB2 (JBB1 X JBB1), SBB2 (SBB1 XSBB1) and RBB2 (RBB1 X RBB1) in second
generations were compared separately in each generation. A total of 363, 323, 270, 67,
67 and 66 kids respectively constituted the population of JBB1, SBB1, RBB1, JBB2, SBB2
and RBB2 at birth. Selection was performed for live weight (Lwt) at 6-month or onward in
both parents of BB. Birth weight and 12-month Lwt of JBB1, SBB1 and RBB1 were 1.44,
0.90 and 0.83 and 14.49, 14.07 and 11.34 kg respectively. Birth weight significantly
differed among genetic groups. RBB1 was lighter and JBB2 was heavier than their
counterparts at 12-month. Average daily gain (ADG, g/d) from birth to 3, 3 to 6, 6 to 9 and
9 to 12-month in JBB1, SBB1 and RBB1 were 46.61, 34.06, 32.32 and 33.56; 42.66;
35.48; 33.35 and 40.94; and 37.24, 28.19, 26.13 and 27.71 respectively.. The
corresponding values for JBB2, SBB2 and RBB2 were 44.05, 31.16, 34.88 and 35.81;
39.87, 31.51, 32.42 and 32.78; and 37.51, 31.21, 26.88 and 33.09. ADG was highest in
JBB1 and lowest in RBB1 from birth to 3-month, while it was highest in SBB1 and lowest
in RBB1 from 9 to 12-month. ADG differed among groups in second generation from birth
to 3 and 6 to 9-month. Growth velocity was highest in SBB1 followed by RBB1 and JBB1
with corresponding figures of 4.45 and 0.67; 4.15 and 0.60; and 2.86 and 0.50 for birth to
3 and 3. to 6-month respectively. Except from birth to 1-month, genetic group did not
influence kid survival in first generation. Crossbred, selected and random does reached
first estrus at 319, 250 and 241, and 362, 242 and 259 days of age in first and second
generation respectively at Lwts of 12.90, 10.81 and 9.19 and 12.71, 9.73 and 9.07 kg.
Litter size was larger in selected does than in crossbreds. Post partum heat period (d) was
longer in JBB2 (107) than in RBB2 (84) and SBB2 (70). Biomass production was higher in
SBB1and JBB1 does than in RBB1 at birth and then at day 60 it was higher in SBB1 than
JBB1 and RBB1 with values 2.19, 2.02 and 1.49, and 4.92, 6.04 and 4.62kg for JBB1,
SBB1, and RBB1 at birth and at day 60 respectively. The dressing (%) in JBB1, SBB1 and
RBB1 were 41.95, 40.11 and 38.85 respectively (P<0.05). Crossbreds gave highest total
saleable portion in carcass. Lactation yield (LY), per day yield and lactation length
ordered to be crossbred > selected > randombred. Corresponding LY were 23.74, 14.24
and 10.59 and 20.29, 16.91 and 10.02 kg for first and second generation. Genetic
parameters such as h² and re for some traits were also estimated from RBB. Selection
responses in Lwt were significant at 3, 6, 9 and 12-month in first and only at birth
second generation. It was inferred that corssbreds were superior in chevon and milk
production but inferior in growth efficiency, reproduction, fertility and total biomass yield to
selected goats.