Directory UMM :Data Elmu:jurnal:S:Small Ruminant Research:Vol36.Issue2.May2000:
Small Ruminant Research 36 (2000) 171±177
Reproduction traits in the Boer goat doe
J.P.C. Greyling*
Department of Animal Science, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
Abstract
The aim of this review is to give insight into the reproduction potential of the Boer goat doe. Assessment of the
reproduction traits in the Boer goat doe demonstrates a mean body weight at puberty of between 30.6 and 27.5 kg, depending
on the dietary energy level. Kids weaned during the natural breeding season (April/May) exhibit oestrus or puberty earlier than
those weaned outside the natural breeding season. The mean age at the onset of puberty in the Boer goat doe is 191.1 and
157.2 days for kids born in August (late winter) and January (mid-summer). Although periods of complete anoestrus was not
observed, the peak of sexual activity occurred during autumn and the period of lowest sexual activity from late spring to midsummer. The duration of the oestrous cycle was recorded as being 20.70.7 days, with the mean duration of the oestrous
period being 37.48.6 h and the position of the LH peak (indicative of ovulation) being 8.01.5 h following the onset of
oestrus. The time of ovulation was recorded as occurring 36.8 h after the onset of oestrus, with a mean ovulation rate of
1.720.9 ovulations per doe. The mean gestation period is quoted as being 148.23.7 days, with multiple births having no
signi®cant effect on gestation length. Involution of the Boer goat uterus is macroscopically complete by day 28 post-partum
with the duration of the post-partum anoestrous period in the Boer goat being 55.524.9 days. The mean interval from partus
to conception recorded, was 62.020.2 days. To optimise the reproductive ef®ciency in the Boer goat doe, it is essential that
its reproductive potential be known and exploited. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Boer goat doe; Puberty; Cyclic activity; Gestation; Post-partum period; Reproduction
1. Introduction
The level of reproductive performance is dependant
on the interaction of genetic and environmental factors, but this performance is particularly susceptible to
the latter, for example, the seasonal availability of
nutrients can affect reproduction considerably (Riera,
1982). Although Indigenous goat breeds have an
excellent ability to accommodate and adapt to ¯uctuation in environment, this often involves some degree
of reproductive failure (Devendra and Burns, 1983).
*
Tel.: 27-51-401-2210; fax: 27-51-448-0692.
E-mail address: hester@landbou.uovs.ac.za (J.P.C. Greyling)
Reproduction ef®ciency in female goats is determined by many different processes. These processes
include, for example, the length of the breeding
season, cyclic activity, ovulation rate, fertilisation rate,
the post-partum anoestrous period and the growth and
viability of the offspring. Reproductive ef®ciency as
such can be measured and expressed as the kidding
rate, weaning rate, kidding interval, liveweight of kids
born or weaned and the length of the reproductive
cycle (Greyling, 1988). The goat is the most proli®c of
all domestic ruminants under tropical and sub-tropical
conditions and certain breeds are able to breed
throughout the year (Hofmeyr et al., 1965; Devendra
and Burns, 1983), while other breeds like, for exam-
0921-4488/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 1 6 1 - 3
172
J.P.C. Greyling / Small Ruminant Research 36 (2000) 171±177
ple, the Angora have a restricted breeding season
(Shelton, 1978; Van der Westhuysen, 1980). One of
the most favourable attributes of the Boer goat as a
meat producing animal, is its high rate of reproduction
and the fact that it has an extended breeding, especially as reproduction is a major contributing factor to
the ef®ciency of meat production (Naude and Hofmeyr, 1981). The Boer goat is also an above-average
milk producer, which not only holds promise for the
raising of their offspring, but also possibly in providing milk for human consumption (Raats et al., 1983;
Raats, 1988). However, in order to determine the
reproductive and productive potential of the Boer goat,
a thorough knowledge of the reproduction physiology
is essential. This review thus concentrates on reproductive aspects relevant to the Boer goat.
2. Puberty
Puberty can be de®ned in several ways. For the
purposes of the present text, it is considered as the age
of the female at which oestrus is ®rst detected and is
followed by characteristic cyclic ovarian activity in
the non-pregnant animal. In the male, puberty is
expressed as the stage when spermatogenesis is
initiated (Louw and Joubert, 1964). The direct cause
of sexual maturation at puberty is given as a rise in the
output of the pituitary hormones, leading to an
increase in size and activity of the gonads. Underlying
this process is some form of maturation of the
hypothalamo-pituitary axis, permitting changes in
neurosecretion and thereby secretion of the gonadotrophic hormones (Hunter, 1980; Cupps, 1991).
In sheep the ability of the ewe lamb to respond to
the oestradiol positive feedback becomes established
within a few weeks following birth (Foster and
Karsch, 1975). At the onset of puberty, there is a rise
in plasma LH due to an increase in the rate of pulsatile
LH discharges, which result in one or more of the
follicles developing towards the pre-ovulatory stage
and in a steady increase in oestradiol production Ð
which eventually activates the LH surge mechanism.
This is seen as a change in frequency, rather than
amplitude of pulsatile LH releases (Foster and Ryan,
1979). In the young, bodyweight is of great signi®cance in the attainment of puberty, as the occurrence
of puberty is dependant on the animal attaining a
certain critical bodyweight (Gordon, 1975). Generally
breeding in goats should be delayed until the animal
has attained 60±75% of its mature bodyweight (Smith,
1980).
There are several factors that could play a role in the
attainment of puberty in the female goat. These factors
include season of weaning, nutritional status and the
male-effect. The mean body weight at puberty of Boer
goat does has been set at 30.67.2 kg for animals on a
high energy diet (9.613 MJ/kg DM) and 27.54.3 kg
on a lower energy diet (7.688 MJ/kg DM) (Greyling,
1988). These body weights compare well to those for
Saanen goats and are heavier than that reported for
Creole goats (24 kg) in Venezuela and 25±30 kg in
northern Mexico (Delgadillo and Malpaux, 1996).
Boer goat kids weaned during the normal breeding
season (April/May) exhibit oestrus signi®cantly
(P
Reproduction traits in the Boer goat doe
J.P.C. Greyling*
Department of Animal Science, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
Abstract
The aim of this review is to give insight into the reproduction potential of the Boer goat doe. Assessment of the
reproduction traits in the Boer goat doe demonstrates a mean body weight at puberty of between 30.6 and 27.5 kg, depending
on the dietary energy level. Kids weaned during the natural breeding season (April/May) exhibit oestrus or puberty earlier than
those weaned outside the natural breeding season. The mean age at the onset of puberty in the Boer goat doe is 191.1 and
157.2 days for kids born in August (late winter) and January (mid-summer). Although periods of complete anoestrus was not
observed, the peak of sexual activity occurred during autumn and the period of lowest sexual activity from late spring to midsummer. The duration of the oestrous cycle was recorded as being 20.70.7 days, with the mean duration of the oestrous
period being 37.48.6 h and the position of the LH peak (indicative of ovulation) being 8.01.5 h following the onset of
oestrus. The time of ovulation was recorded as occurring 36.8 h after the onset of oestrus, with a mean ovulation rate of
1.720.9 ovulations per doe. The mean gestation period is quoted as being 148.23.7 days, with multiple births having no
signi®cant effect on gestation length. Involution of the Boer goat uterus is macroscopically complete by day 28 post-partum
with the duration of the post-partum anoestrous period in the Boer goat being 55.524.9 days. The mean interval from partus
to conception recorded, was 62.020.2 days. To optimise the reproductive ef®ciency in the Boer goat doe, it is essential that
its reproductive potential be known and exploited. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Boer goat doe; Puberty; Cyclic activity; Gestation; Post-partum period; Reproduction
1. Introduction
The level of reproductive performance is dependant
on the interaction of genetic and environmental factors, but this performance is particularly susceptible to
the latter, for example, the seasonal availability of
nutrients can affect reproduction considerably (Riera,
1982). Although Indigenous goat breeds have an
excellent ability to accommodate and adapt to ¯uctuation in environment, this often involves some degree
of reproductive failure (Devendra and Burns, 1983).
*
Tel.: 27-51-401-2210; fax: 27-51-448-0692.
E-mail address: hester@landbou.uovs.ac.za (J.P.C. Greyling)
Reproduction ef®ciency in female goats is determined by many different processes. These processes
include, for example, the length of the breeding
season, cyclic activity, ovulation rate, fertilisation rate,
the post-partum anoestrous period and the growth and
viability of the offspring. Reproductive ef®ciency as
such can be measured and expressed as the kidding
rate, weaning rate, kidding interval, liveweight of kids
born or weaned and the length of the reproductive
cycle (Greyling, 1988). The goat is the most proli®c of
all domestic ruminants under tropical and sub-tropical
conditions and certain breeds are able to breed
throughout the year (Hofmeyr et al., 1965; Devendra
and Burns, 1983), while other breeds like, for exam-
0921-4488/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 1 6 1 - 3
172
J.P.C. Greyling / Small Ruminant Research 36 (2000) 171±177
ple, the Angora have a restricted breeding season
(Shelton, 1978; Van der Westhuysen, 1980). One of
the most favourable attributes of the Boer goat as a
meat producing animal, is its high rate of reproduction
and the fact that it has an extended breeding, especially as reproduction is a major contributing factor to
the ef®ciency of meat production (Naude and Hofmeyr, 1981). The Boer goat is also an above-average
milk producer, which not only holds promise for the
raising of their offspring, but also possibly in providing milk for human consumption (Raats et al., 1983;
Raats, 1988). However, in order to determine the
reproductive and productive potential of the Boer goat,
a thorough knowledge of the reproduction physiology
is essential. This review thus concentrates on reproductive aspects relevant to the Boer goat.
2. Puberty
Puberty can be de®ned in several ways. For the
purposes of the present text, it is considered as the age
of the female at which oestrus is ®rst detected and is
followed by characteristic cyclic ovarian activity in
the non-pregnant animal. In the male, puberty is
expressed as the stage when spermatogenesis is
initiated (Louw and Joubert, 1964). The direct cause
of sexual maturation at puberty is given as a rise in the
output of the pituitary hormones, leading to an
increase in size and activity of the gonads. Underlying
this process is some form of maturation of the
hypothalamo-pituitary axis, permitting changes in
neurosecretion and thereby secretion of the gonadotrophic hormones (Hunter, 1980; Cupps, 1991).
In sheep the ability of the ewe lamb to respond to
the oestradiol positive feedback becomes established
within a few weeks following birth (Foster and
Karsch, 1975). At the onset of puberty, there is a rise
in plasma LH due to an increase in the rate of pulsatile
LH discharges, which result in one or more of the
follicles developing towards the pre-ovulatory stage
and in a steady increase in oestradiol production Ð
which eventually activates the LH surge mechanism.
This is seen as a change in frequency, rather than
amplitude of pulsatile LH releases (Foster and Ryan,
1979). In the young, bodyweight is of great signi®cance in the attainment of puberty, as the occurrence
of puberty is dependant on the animal attaining a
certain critical bodyweight (Gordon, 1975). Generally
breeding in goats should be delayed until the animal
has attained 60±75% of its mature bodyweight (Smith,
1980).
There are several factors that could play a role in the
attainment of puberty in the female goat. These factors
include season of weaning, nutritional status and the
male-effect. The mean body weight at puberty of Boer
goat does has been set at 30.67.2 kg for animals on a
high energy diet (9.613 MJ/kg DM) and 27.54.3 kg
on a lower energy diet (7.688 MJ/kg DM) (Greyling,
1988). These body weights compare well to those for
Saanen goats and are heavier than that reported for
Creole goats (24 kg) in Venezuela and 25±30 kg in
northern Mexico (Delgadillo and Malpaux, 1996).
Boer goat kids weaned during the normal breeding
season (April/May) exhibit oestrus signi®cantly
(P