ISRAEL JOURNAL OF
|
VETERINARY MEDICINE home archive journal |
VOLUME 55 (2) 2000
REPRODUCTIVE PERFORMANCE OF WEST
AFRICAN DWARF GOATS IN THE HUMID TROPICAL ENVIRONMENT OF IBADAN.
Akusu, M.O. and Ajala, O.O.
Department of Veterinary Surgery and
Reproduction, University of Ibadan, Ibadan, Nigeria
Introduction Materials and Methods Results Discussion
Abstract
|
The
mean oestrus cycle length of West African dwarf goat was 18.30±1.61 days.
Statistical analysis showed that medium length cycles (16-27 days; 63.3%) were
significantly more frequent (p<0.05) than short (² 15 days) or long (³ 28
days) cycles (30% and 6.6%, respectively). The prolificacy ratio was
significantly better in does bred during oestous that followed cycles of normal
length rather than following short cycles (2.25±0.25 vs. 1.25±0.25,
respectively), while prolificacy was superior in does bred postweaning than
preweaning (2.00±0.23 kids vs. 1.85±0.15 kids, respectively). The mean
gestation length of does was 144.9 days. It was shorter in multiple than in
single births. Female kids were carried 1.13 days longer than male kids. The
kidding rate was 191%. |
Agricultural
development in Nigeria has placed more emphasis on crop production although the
rearing of cattle, sheep and goats have always formed an integral part of the
domestic economy and source of wealth for Nigerians. The consequence of this
imbalance is that most Nigerians consume far less animal protein daily than the
minimum recommended level.
In
the livestock sector some attention has been focused on non-ruminant farm
animals, particularly poultry. Efforts have also been made to exploit the
potential of cattle, whereas the goat has remained neglected and untapped.
Various reports (1, 2) have shown that apart from poultry, the goat is the most
numerous of the domestic livestock species in Nigeria. With goats numbering over
24,500,000 (3), it is estimated that there are 245 goats to 1000 Nigerians.
There
are three main breeds of goats in Nigeria, the Red Sokoto, the Sahel and the
West African dwarf goat (4). The West African dwarf goat is most prevalent in
southern Nigeria. Its characteristics have been described earlier (4) while its
relative trypanotolerance has singled it out as the breed of choice in southern
Nigeria.
The
West African dwarf goat is early maturing, prolific and a non-seasonal breeder
(4,5). An average of 80.6% multiple births was recorded in one survey (6) and a
total of 5 kidding in 3 years in another (7).
This
present study is to investigate the effect of certain non-genetic factors on the
prolificacy of the West African dwarf goat. It is hoped that the information
generated will form part of a package required for profitable goat husbandry.
Back To Top Introduction Materials and Methods Results Discussion
Thirty
adult West African dwarf goat aged between 1 and 4 years and 10- to 30 kg in
weight were used for the study on fertility and prolificacy over a 4 year
period. Following parturition, 9 does were assigned to a study on the variation
of the post-partum period on oestrus cycle length. Another 8 does were used to
study the effect of breeding at oestrus succeeding oestrus cycle lengths of
short or long duration. The effect of the service period on the fertility and
prolificacy of does was studied in 26 does; 13 were bred while suckling their
kids (preweaning) while 13 were bred postweaning.
All
animals were housed in roofed pens with concrete flooring and low wooden
partitions. They were fed a corn-based concentrate ration (0.5 kg per day).
Clean water and fresh giant star grass and centrosema were provided ad
libitum while routine medication consisted of deworming with 10% Rintal
(Bayer, Leverkusen) suspension and an ectoparasitic bath with Gamatox (Wellcome
Coy, England).
Data
were analysed by Chi square and Student’s t-test for the establishment of
significance (8).
Back To Top Introduction Materials and Methods Results Discussion
The
fertility and prolificacy of the does were assessed from 77 services. Each doe
became pregnant following breeding at each oestrus. Placentas were usually
dropped within 10-30 minutes post partum.
The mean kid number per doe from the 77 services was 1.91±0.08. The male/female ratio of kids was 81/66 (i.e. 55.1% males). Male kids were heavier than female kids at birth (p>0.05). The mean birth-weight of the kids was 1.16±0.03 kg. Litter type had significant influence on kid birth-weight. The season of birth had no significant influence on birth-weight (Table 1).
Table 1: Effect of season, sex and litter
size on birth weight
|
Source of
Variation |
Number of
kids born |
% |
Birth-weight
(kg) |
|
Season |
|
|
|
|
Late dry
season |
50 |
34.01 |
1.14±0.03 |
|
Early
rainy season |
19 |
12.93 |
1.19±0.07 |
|
Late
rainy season |
61 |
41.50 |
1.18±0.03 |
|
Early dry
season |
17 |
11.56 |
1.15±0.05 |
|
Sex |
|
|
|
|
Male |
81 |
55.10 |
1.20±0.02 |
|
Female |
66 |
44.90 |
1.12±0.03 |
|
Litter
size |
Number of
parturitions |
|
|
|
Single |
21 |
27.27 |
1.31±0.66a* |
|
Twins |
44 |
57.14 |
1.19±0.02a |
|
Triplet |
10 |
12.99 |
1.05±0.04b |
|
Quadriplet |
2 |
2.60 |
0.92±0.05b |
Number
on the same vertical column differently superscripted differ significantly
(p<0.05)
The mean gestation length for 68 observed parturitions was 144.9 days and was not significantly affected by season of birth. Does with singles had a longer gestation than those with twins or triplets. The mean gestation length in dams giving birth to only female kids was 1.13 days longer than in does with only male kids (Table 2).
Table 2: Effect of season, sex, litter size
and parity on gestation
|
Source of
Variation |
Number of
parturitions |
Gestation
Length (days) |
|
Season |
|
|
|
Late dry
season |
20 |
144.64 |
|
Early
rainy season |
9 |
144.89 |
|
Late
rainy season |
34 |
145.06 |
|
Early dry
season |
3 |
145.00 |
|
Sex |
Number of
kids |
|
|
Male |
29 |
143.93±0.73 |
|
Female |
18 |
145.06±0.70 |
|
Litter
size |
|
|
|
Single |
17 |
146a* |
|
Twins |
41 |
144.8a |
|
Triplet |
10 |
142.8b |
|
Parity |
|
|
|
Pluripara |
34 |
144.24±0.62 |
|
Primipara |
13 |
144.69±0.95 |
Number
on the same vertical column differently superscripted differ significantly
(p<0.05)
A total of 30 oestrus cycles were observed in 9 does post partum. The first observable post-partum oestrus occurred at 55.70±4.62 days.
The period was significantly longer (p<0.05) than subsequent cycles which were not significantly different from each other. The frequency distribution of oestrus cycle length is presented in Fig. 1 and Table 3. Table 4 summarises the influence of breeding during oestrus succeeding cycles of short and medium durations on some reproductive indices. The mean cycle lengths for short and medium oestrus cycles were 5.25±0.48 and 12.25±0.95 days (p<0.05) respectively. Oestrus duration and gestation lengths were not affected. Similarly, the mean kid birth-weights were not significantly influenced. However, prolificacy of does bred during cycles of medium duration was significantly superior (p<0.05) than their counterparts.
Fig 1.: Frequency distribution of oestrus cycle length in West African dwarf goats.

Table 3:
Prevalence of oestrus cycle type
(days) in West African dwarf goats
|
Oestrus
Cycle Type |
Number
(%) |
Mean ±
SEM |
|
Short
-- 15
days or less |
9 (30) |
5.67 ± 0.5c |
|
Medium
-- 16-27 days |
19
(63.33) |
22.68 ±
0.66b |
|
Long --
28 days
and up |
2 (6.67) |
33.5
± 2.51a |
|
Total |
30 (100) |
18.4
± 1.68 |
Number on the same vertical column differently superscripted differ significantly (p<0.05)
Table 4: Effect of breeding during short
(A) and medium (B) oestrus cycle type (days) on some reproductive parameters of
WAD goats (Mean ± SEM)
|
Parameter |
A (n = 4) |
B (n = 4) |
|
OCL
(days) |
5.25 ±
0.40b |
12.25 ± 0.95a |
|
Oestrus
duration (hours) |
48 ± 4.87 |
41.00 ± 6.56 |
|
Gesstation
length (days) |
145
± 0.41 |
142.75 ±
0.25 |
|
Kids/Doe |
1.25 ±
0.25c |
2.25 ± 0.25d |