Research on some Biocharacteristics and Preservation
Technology of Rabbit Semen
Do Van Thu 1 and Nguyen Ba Mui 2, Vietnam
1. Biotechnology Institute
2. Hanoi University of Agriculture (nbmui@yahoo.com, 0945261112)
ASTRACT
A research was conducted to determine biocharacteristrics and conservation
technology of rabbit semen. 125 buck-rabbits of New Zealand, California, Panon, grey rabbit
and black rabbit were selected to inspect semen quality, to dilute and to conserv e semen. Roerabbits were strong, normal reproduction and later first litter used for artificial insemination.
It was shown that semen volume was low from 0.65 to 0.91 ml; Percent of the
swimming spermatozoa was 61.34 – 64.95%; Concentration of sperm was 263.46 – 291.03
million/ml; Total number of spermatozoa per the ejaculation was 263.46 – 291.03 million;
Percent of the alive spermatozoa was 69.82 – 72.52%; Rate of abnormality sperm was 18.47 –
19.09%; Resistance of sperm to NaCl 1% was 2584.09 – 2720.52. The interval between two
ejaculations was three or four days for many good quality of semen. Semen diluted (1:5) got
better result than diluted rate (1:10). Semen diluted in the Tris solution conserving at 15 oC
had percent of the alive spermatozoa better than 5 oC. The proportions of pregnant of
conserving semen were 75.00% in the first day, 71.43% in the second day and 50.00% in the
fourth day.
Key words: Rabbit, Conservation, Semen, Sperm, Artificial Insemination
1. Introduction
The rabbit is a species of domestic animal with many good points. In particular, they
do not compete with man and other livestocks for food, it can exploit argricutural wastes. In
addition, it can turn plant protein into animal protein with high value. Its protein
transformation rate from food absorbed to animal protein was 20% (that of chicken, pig and
cattle was 22-23%, 18%, 8- 12% respectively) (Nguyen Quang Suc, Đinh Văn Binh, 1998).
Rabbit-products are highly economically valuable; its meat is tasty, nutritious, rich in
protein, balanced in nutrients, and especially its cholesterol capacity is quite low with
1.36mg/100g raw material. Rabbit meat is used to treat cardiovascular problem stricken
victims, aged and obese people (Đinh Văn Binh, Ngo Tien Dung, 2005). In medicine, rabbits
are used as experimental subjects to test medicine and produce vaccine.
To satisfy the need of economical development programs and serve research, in 1977
our country imported some species of rabbits (New Zealand, California, Pon) and raised them
in Goat-Rabbit Researching Centre, Son Tay. Along with importing breeding animals, after
many years of research on cross-breeding, now we have had 5 rabbit species in production
including Vietnam New Zealand White, Panon, California, grey rabbits and black rabbits.
In artificial insemination, the biological criteria of semens are the basis of evaluating
their quality, it is closely related to the pregnant rate, productivity and the quality of the next
generations. The biological features of semens reflect the breeding ability of each individuals
and their adaptability to the environment. Doing research on biological features of rabbit
semens is the scientific basis of evaluating the quality of male gender, identifying the
components and the rate of substances in the medium and the suitable medium amount to
dilute and conserve semens. Researching biological features of semens enables us to se lect
good and qualified samples to put in the dilution, conservation to serve artificial
insemination, thenceforth, the management, caring and breeding regimes as well as proper
masculine gender exploitation system.
Now, in Vietnam artificial insemination of domestic animals and poultry has had
many achievements, the insemination net of frozen semens and diluted semens has covered
all over the country. Besides, the frozen semen bank has been built up to serve artificial
insemination and conservation of gene sources. Although rabbit cross-breeding and artificial
insemination are ugent, this issue has not been well attended to, there has not been any works
researching the biological features of rabbit semens systematically. The conservation of
rabbit semens is quite a new issue in Vietnam.
2. Objectives
- Identifying (systematically) the biological figures of rabbit semens to ground the evaluation
of the quality of semens and selection of buck rabbits.
- Identifying technical procedure of diluting and conserving rabbit semens.
- Doing experiment on rabbit artificial insemination with diluted semens
3. Materials and Methods
Location and duration
The research was carried out in Goat and Rabbit Research Centre, Son Tay district,
Hatay province and technology department of reproductive cell, Biotechnology Institute. The
research was conducted for 12 months from December, 2006 to November, 2007.
Rabbit selection
Semens of 125 male rabbits of New Zealand, California, Panon, grey and black rabbit
species raised in Goat and Rabbit Research Centre, Son Tay. They weighed between 2,5 and
4,5kg, aging from 8 months to 40 months, being healthy, matting skillfully. Additionally,
they all were in sperm provision period to serve breeding and under the diet o f Goat and
Rabbit Research Centre, Son Tay including concentration with 16% protein, 80gram per day
and 1 kg of roughage.
Female rabbits used in the artificial insemination were in the species of New Zealand,
California, Panon, grey and black rabbits, they are healthy, being able to give norml birth and
having already given birth once.
Research methodology and focus
The volum of semens V (ml/ejaculation), motility A (%), Concentration of semens C
(million/ml) were determined following Milovanov (1962). The rate of survial spermatozoa
LS (%) was determined following Chemineau et all (1991).
Abnormality of spermatozoa K (%) was determined following Villiam (1921), total of
motility spermatozoa was V.A.C (million/ejaculation).
pH of semen was determined meter (pH: 0 - 14 - model METTLER DELTA 320.
Osmotic pressure of semen (Miliosmol/kg ) was determined by osmometre). The change of
biological figures of rabbits throughout a year’s month. The influence of the interval between
two ejaculations on biological figures
Diluting solutions of rabbit semen were Tris (Tris 3.80gram; acid Citric 2.1659gram;
glucose 0.6gram; penicillin 60mg, streptomycin 60mg; distilled water 100ml) and Citrate
(Trisodium citrate 1.323gram; glucose 0.59466gram; fructose 0.59466gra m; penicillin 60mg,
streptomycin 60mg; distilled water 100ml).
The influence of the preservation temperature on quality of rabbit semens and the
influence of the dilution rate on quality of rabbit semens. Artificial insemination for rabbits
was used following method of Chemineau (1991)
Statistical analysis
Data collected were analyzed by analysis of variance (ANOVA) using the General
Linear Model procedure of MINITAB software (Version 13.31 2000).
4. Results and discussion
4.1 Biological characteristics of rabbits' semen
Some biological criteria of rabbits' semen
We have studied on 125 buck rabbits of New Zealand, California, Panon, Grey and
Black genotypes which were kept at Goat and Rabbit Research Center, Son Tay. With 434
semen samples, biological criteria of rabbits' semen were shown in Table 1.
Table 1: Biological characteristics of rabbits' semen
Genotypes
Volume V
(ml/ejaculation)
California
(n = 44)
a
a
Grey
(n = 56)
Black
(n = 50)
[
0.65 b
± 0.03
[
0.66 a b
± 0.04
61.34 b
± 1.26
61.80 b
± 1.15
Motility A (%)
64.95 a
± 0.55
64.66 a
± 1.64
Concentration C
(million/ml)
263.46 b
± 2.54
276.39 a
± 5.47
291.03 a
± 3.80
285.21 a
± 2.98
281.81 a
± 6.95
V.A.C
(million/time)
152.69 a
± 4.57
164.69 a
± 11.27
147.84 a
± 6.09
111.75 b
± 4.65
113.65 b
± 6.63
71.82
± 0.56
72.52
± 1.60
70.86
± 0.96
69.82
± 1.18
[
70.94
± 1.19
18.52a
± 0.07
18.47 a
± 0.17
18.63 a
± 0.13
19.09b
± 0.13
19.07 ab
± 0.32
2652.43
± 19.32
2584.09
± 42.45
2690.40
± 17.36
2720.52
± 44.21
2712.00
± 51.97
Resistance to
NaCl 1%
0.91
± 0.05
Panon
(n = 99)
0.80
± 0.03
[
62.12 b
± 0.94
Living
proportion=
LS (%)
Abnormality
proportion=
K (% )
a,b
New
Zealand
( n = 185)
[
0.87a
± 0.02
Different letters in superscript in rows indicate significant difference (P<0.05)
It can be seen from Table 1 that:
- The average volume of semen/ejaculation of rabbits was low, varying from 0.65 to 0.91 ml.
Our finding confirmed results reported by Viudes – de- Castro, et al. (1996) with 0.80ml/time
(varying from 0.5 to 1.8 ml). Đao Đuc Tha and Nguyen Tan Anh (1989) reported that local
rabbits could produce 0.35ml/ejaculation; and 0.38 ml for exotic goats. Their findings were
lower than ours.
- Motility of spermatozoa was differed among rabbit genotypes (P<0.05). Motility of
spermatozoa of studied genotypes was rather high (61.34 – 64.95%), which meets standards
for dilution and AI.
Our findings were lower than that reported by Viudes – de - Castro, et al., (1996) with
motility of 80% (varying from 62 to 93%). Đo Van Thu et al. (2004) reported that the
motility (A) of New Zealand, California, Panon, Grey and Black rabbits were 70%; 72%;
74%; 65%; and 69%, respectively. Đao Đuc Tha and Nguyen Ten Anh (1989) reported that
the motility of local and exotic rabbits was 65%; and 61%, respectively. Nguyen Quang Suc
and Đinh Van Binh (1998) reported the motility of rabbit semen was varying from 55 to
65%.
- Concentration ( million/ml)
Concentration of rabbits' semen was rather high, varying from 263.46 – 291.03 million/ml.
Semen concentration has negative relationship with semen volume. Genotypes differed in
terms of semen concentration (P<0.05) (highest with Panon 291.03 million/ml; Grey 285.21
million/ml; Black 281.81 million/ml; California 276.39 million/ml and lowest with New
Zealan with, 263.46 million/ml).
Our findings on rabbit semen concentration were in agreement with findings of Viudes
– de- Castro, et al. (1996) with C = 267 million/ml (varying from 104 – 570 million) and
findings of Đao Đuc Tha, Nguyen Tan Anh (1989) with C = 320 million/ml and 247
million/ml, respectively for local and exotic rabbits.
Although semen volume of rabbits is not much, semen concentration is rather high that
can be diluted to increase does for AI. This helps to increase reproductive performance of
nucleus sires.
- V.A.C (million/time)
The higher V.A.C is, the better semen quality and the higher AI efficiency are.
Different rabbit genotypes produce semen with different V.A.C. Our findings on V.A.C of
New Zealand, California, Panon, Grey and Black rabbits were 152.69, 164.69, 147.84,
111.75, and 113.65 million/ejaculation, respectively.
Our findings on V.A.C of rabbit semen were in agreement with findings reported by
Đo Van Thu, et al. (2004) with V.A.C of New Zealand, California, Panon, Grey and Black
rabbits of 159.96, 167.95, 158.94, 111.06 and 117.86 million/time, respectively. Our findings
were higher than those reported by Đào Đao Đuc Tha, Nguyen Tan Anh (1989) who declared
that V.A.C of local and exotic rabbits were 94, and 82 million/ejaculation, respectively.
It can also be seen from Table 1 that V.A.C varied a lot, which requires to be checked
to determine a relevant dilution ration.
Changes of biological characteristics of rabbits' semen over time
Volume of rabbits' semen significantly varied according to months of the year
(P<0.05). V of rabbit semen was high in Jan, Feb and Mar with 0.92ml; 0.92ml and
0.95ml/time, respectively. V was gradually lower in May and Jun (hot season) with 0.73ml
and 0.59ml/ejaculation, respectively.
Motility of rabbits' semen changed according to months, lowest in May and Jun (hot
season) with 61.39% and 54.17%, respectively; for other months motility of rabbit semen
changed little, high in Jan and Feb. and gradually decreased from March onwards.
Table 2: Changes of biological characteristics of New Zealand rabbits' semen
Month
N
ơ
12/2006 17
[[[
1/2007
ơ
60
2/2007
ơ
23
ơ
3/2007
ơ
4/2007
25
ơ
30
5/2007
ơ
18
6/2007
ơ
12
V (ml)
A(%)
[
0.81a
± 0.08
ơ
0.92 a
± 0.03
ơ
0.92 a
± 0.06
ơ
0.95 a
± 0.07
ơ
0.88 a
± 0.06
[
64.41 a
± 2.80
ơ
66.42 a
± 0.43
ơ
66.96 a
± 0.98
ơ
66.20 a
± 1.64
0.73 ab
± 0.06
ơ
0.59 b
± 0.07
ơ
66.17 a
± 0.78
61.39 ab
± 2.21
ơ
54.17b
± 3.13
Living Abnormal
V.A.C
C
proporti
ity
(million/time
(million/ml)
on
proportion
)
LS (%)
K (%)
ơ
ơ
Ơ
258.37
134.46 a
71.31
18.70
± 10.70
± 13.36
± 2.63
± 0.15
ơ
ơ
[
a
265.88
164.16
72.92
18.28
± 3.29
± 6.99
± 0.57
± 0.05
ơ
ơ
Ơ
274.80
170.50 a
74.35
18.32
± 5.04
± 12.02
± 1.06
± 0.11
[ơ
ơ
ơ
267.63
176.42 a
72.06
18.66
± 11.62
± 14.49
± 1.83
± 0.36
ơ
ơ
Ơ
a
261.47
159.23
73.13
18.55
± 5.01
± 11.13
± 0.96
± 0.13
ơ
ơ
ơ
256.45
118.45 ab
69.34
18.88
± 7.99
± 11.78
± 2.12
± 0.26
243.68
± 6.57
72.58 b
± 7.04
62.15
± 3.18
19.08
± 0.12
a,b Different letters in superscript in column indicate significant difference (P<0.05)
Our findings on A of rabbit semen from Jan to Jun were lower than those reported by
Đo Van Thu (2004) with 73.9%; 71.7%; 77.1%; 74.0%; 73.6% and 73.9%, respectively.
C of rabbit semen changed over the months, high from Jan to Mar with C of 265.88;
274.80 and 267.63 million/ml, respectively; low from April to Jun with 261.47; 256.45 and
243.68 million/ml, respectively.
V.A.C
(milion/time
200
170.5 176.42
164.16
160
159.23
134.46
120
118.45
80
72.58
40
Months
0
12
2006
1
2
3
4
5
6
2007
Graph 1. Effects of semen collecting time on V.A.C
V.A.C of rabbit semen significantly differed between months of the year (P<0.05).
V.A.C was high in Jan, Feb and March with 164.16; 170.50 and 176.42 million/ ejaculatio,
and lowest in Jun with 72.58 million/ejaculatio.
Effects of semen collecting time on semen quality implicates that rabbit semen should
be collected when the weather is cool. During the hot season, the semen quality is decreased.
To increase semen quality in the hot season, heat stress should be prevented and relevant feed
and feeding should be provided for rabbits. In addition semen collection should be done in the
morning when the weather is still cool.
Effects of semen collection interval
Semen quality is affected by many factors. One of the factors is semen collection
interval. To identify appropriate semen collection interval, we studied biological
characteristics of New Zealand rabbit semen with collection interval of 1, 2, 3 and 4 days The
results are shown in Table 3.
Table 3: Effects of collection interval on semen quality of New Zealand rabbit
Interval
(days)
n
1
46
2
3
4
32
36
36
V (ml)
0.75b
± 0.05
0.90a
± 0.05
0.96 a
± 0.04
1.03 a
± 0.08
C
V.A.C
Living Abnomality
A (%) (million/ml (million/tim proportion proportion
)
e)
LS (%)
K (%)
64.35 b
259.68
128.72 b
70.49
18.89 b
± 0.99
± 6.50
± 9.39
± 1.09
± 0.19
66.25 ab
266.12
164.44 a
72.06
18.40 ab
± 0.67
± 5.78
± 12.04
± 0.80
± 0.13
67.50 a
268.60
179.51 a
74.60
18.24 a
± 1.25
± 3.79
± 6.20
± 0.74
± 0.08
67.92 a
275.72
191.90 a
75.69
18.10 a
± 0.58
± 3.67
± 5.82
± 0.59
± 0.10
a,b Different letters in superscript in column indicate significant difference (P<0.05)
It can be seen in Table 3 that semen collection interval affected V, C, A, living proportion,
abnormality proportion of semen.
Semen collection interval significantly affected V (P <0.05). One day collection interval produced less
semen than 2, 3 and 4 day collection interval. The V of 1, 2, 3 and 4 day collection interval was V =
0.75; 0.90 ml; 0.96 ml and 1.03ml, respectively.
Our findings were consistent with findings reported by Đo Van Thu, et al. (2004), in which
V of 1, 2, 3 and 4 day collection interval was 0.806ml, 0.886ml; 1.006ml and 1.045ml,
respectively.
V.A.C (million/time)
A (%)
70
64.35
66.25
67.5
67.92
((triệu/lần)
200
191.9
179.51
60
164.44
150
50
128.72
40
100
30
20
50
10
0
0
1 ngµy
2 ngµy
3 ngµy
4 ngµy
1 day
Collection interval
Fig.1. Effects of semen collection interval on
A
2 day
3 day
4 day
Collection interval
Fig. 2. Effects of semen collection
interval on V.A.C
Collection interval significantly affected motility and abnormality proportion of rabbit semen
(P<0.05). If the collection interval is too short, the motility in living sperms is decreased. This is
probably due to stems of young sperms attach each other making them unable to move straightly.
Collection interval affected C and V.A.C. With one day collection interval, C and V.A.C was
259.68 million/ml and 128.72 million/ejaculatio, respectively. With two day collection interval, these
values were 266.12 million/ml and 164.44 million/time, respectively. With 3 day collection interval,
these values were 268.60 million/ml and 179.51 million/ejaculatio, respectively. With 4 day collection
interval, these values were 275.72 million/ml and 191.90 million/ejaculatio.
Our findings showed that 03 and 04 day collection interval produced better semen quality than
01 or 02 days.
Physical and chemical characteristics of rabbit semen
To provide a basis for making diluting medium which meets the demands osmotic
pressure, viscosity and density of semen living outside the body, we studied physical and
chemical characteristics of semen of some rabbit genotypes keeping in Vietnam. Results are
shown in Table 4. It can be seen from the table that different rabbit genotypes had different
physical and chemical characteristics of semen. Osmotic pressure of rabbit semen was in
equilibrated zone. New Zealand rabbits had highest osmotic pressure with 366.09
miliosmol/kg; lowest was for California rabbits with 318.95 miliosmol/kg. Osmotic pressure
of semen is a basic to make medium preserving semen outside living bodies.
Table 4: Physical and chemical characteristics of rabbit semen
Genotypes
New Zealand
California
Panon
Grey
Black
N
34
28
31
26
25
osmotic
pressure
(miliosmol/kg)
366.09
± 6.670
318.95
± 3.460
322.12
± 4.370
322.09
± 4.610
322.36
± 4.168
Buffer ()
Density
(d)
Viscosity
()
pH
1178.02
± 13.690
1138.93
± 15.499
1314.72
± 14.164
1217.53
± 22.338
1263.03
± 21.250
1.023
± 0.001
1.023
± 0.001
1.025
± 0.001
1.024
± 0.001
1.024
± 0.001
2.78
± 0.015
2.96
± 0.029
2.82
± 0.017
2.81
± 0.027
2.80
± 0.025
6.89
± 0.056
6.74
± 0.032
6.69
± 0.032
6.88
± 0.027
6.76
± 0.056
pH of rabbit semen varied 6.69 – 6.89. pH of semen depends on V, metabolic
activities, hormone. pH of semen is different among semen collections. When semen is
diluted with medium with lightly acid, it creates a favorable condition for sperms, because
sperms are less active that saves reserved energy. This makes sperms live longer. Living
ability of sperms during preservation depends very much on dilution medium. Dilution
medium must have a buffering ability to maintain favorable pH for sperms. Watson (1990)
cited by Roca (2000) reported that sperms had higher living ability in pH =6.9 of dilution
medium than pH = 7.05. Roca (2000) reported that rabbit sperms can survive in dilution
medium with osmotic pressure between 333 - 336 mosm/l. Dalimata (1997) diluted rabbit
semen in medium with osmotic pressure of 300 mosm/l.
4.2 Diluting and preserving rabbit semen
Preserving rabbit semen in Tris and Citrate environments
The quality of diluted semen can be evaluated via living ability of sperms. Living
ability of sperms depends on not only semen quality but also dilution medium and preserving
temperature. After studying physical and chemical characteristics of rabbit semen and
dilution medium, we diluted semen in two types of environment and preserved semen at 15
0C. We evaluated motility, living proportion, abnormality proportion at 0, 24, 48, 72 hours
after dilution. When evaluating diluted semen quality, semen samples were stored at 37 0C.
Results showed in Table 5.
Table 5: Motility, living proportion, abnormality proportion of rabbit semen preserving
in Tris and Citrate environments (n = 41)
Preserving
duration
(hours)
0
Motility A (%)
Tris
65.73a
± 0.93
Citrate
63.17b
± 0.78
Living proportion LS
(%)
Tris
77.92
± 1.16
Citrate
76.36
± 1.25
Abnormality
proportion K (%)
Tris
17.37
± 0.21
Citrate
17.71
± 0.19
24
48
72
58.29 a
± 0.85
46.71 a
± 0.77
33.41 a
± 0.88
54.15 b
± 0.80
41.63 b
± 0.89
25.73 b
± 0.87
67.69 a
± 0.71
57.24 a
± 0.76
41.88 a
± 0.75
65.22 b
± 0.74
53.89 b
± 0.87
37.10 b
± 0.81
18.49 a
± 0.18
20.87 a
± 0.21
24.11 a
± 0.30
18.99 b
± 0.17
21.88 b
± 0.23
25.05 b
± 0.32
a,b Different letters in superscript in rows indicate significant difference (P<0.05)
MT Tris
A (%)
MT Citrate
80
65.73
58.29
60
63.17
46.71
54.15
40
41.63
33.41
25.73
20
0
0 giê
24 giê
48 giê
72 giê
Graph 2. Effects of dilution medium on motility of rabbit sperms
Table 5 was shown that semen diluted with Tris solution had motility of spermatozoa higher
than Citrate solution (P<0.05). Motility of spermatozoa reduced following conserving times, at 0
hour (after diluting semen with solution), motility of spermatozoa were different in two solutions
(P<0.05), A = 65.73% in Tris solution; A = 63.17% in Citrate solution. After conserving 24 hours,
motility of spermatozoa were 58.29% in Tris solution, and were 54.15% in Citrate solution, it was
enough criteria for insemination. After conserving 72 hours, motility of spermatozoa reduced rapid,
it was not enough criteria for insemination.
Our results were lower than Do Van Thu et al (2004) reported in Tris – Citrate – Glucose
solution, at 15oC, The motility of spermatozoa of 0, 24, 48, 72 and 96 conserving hour were
70.71%, 65.29%, 54.38%, 31.25% and 21.75%, respectively. The rate of survial spermatozoa had
higher in Tris solution comparision with Citrate solution (P<0.05).
We thought that Tris solution had vitality of rabbit spermatozoa better than Citrate solution
in conserving and maintaining. It can explain, Tris solution preserved acrosome of sperms, pH of
Tris solution (6.90) was equivalent with pH of rabbit semen (6.69-6.89). Buffer ability of Tris
solution (1583.16) had higher than it of rabbit semen, It had signification in conserving semen,
because it maintained stable pH of solution during conserving times.
Effect of conserving temperature on quality of rabbit semen
Table 6: Effect of conserving temperature on quality of rabbit semen
(Conserving solution of Tris, n = 29)
conserving
duration
(hours)
0
Motility A (%)
50 C
62.07
± 1.25
150C
63.97
± 1.12
Living proportion LS
(%)
50 C
150C
74.80
75.97
± 1.01
± 0.99
Abnormality
proportion K (%)
50 C
150C
17.60b
17.01 a
± 0.15
± 0.13
24
54.31
± 1.54
38.79 b
± 1.39
25.00 b
± 1.55
48
72
62.71 b
± 1.14
50.41 b
± 1.58
33.82 b
± 1.49
58.45
± 1.43
45.17 a
± 1.37
35.52 a
±1.30
67.37 a
± 0.91
58.81 a
± 1.11
44.88 a
±1.30
19.51 b
± 0.11
24.08 b
± 0.25
27.31 b
± 0.23
18.63 a
± 0.11
21.11 a
± 0.23
23.48 a
± 0.19
a,b Different letters in superscript in rows indicate significant difference (P<0.05)
It can be seen in Table 6 that the vitality of rabbit spermatozoa effected by conserving
temperature. The vitality of rabbit spermatozoa reduced gradually following conserving time. The
semen diluted with Tris solution at 15oC had motility of sperms higher than it at 5oC calculation
untill 72 conserving hours (P<0.05).
A (%)
0
550C
C 0C
15
150
80
63.97
60
C
58.45
62.07
54.31
45.17
40
35.52
38.79
25
20
0
0
hour
24
hour
48
hour
72
hour
Graph 3. Effect of conserving temperature on quality of rabbit semen
Results above were shown that the semen diluted with Tris solution at 15oC had motility
of sperms higher than it at 5oC. Because diluting semen conserved at 5oC, the spermatozoa were in
a state of shock, the rabbit spermatozoa were very sensitive to temperature, chemical… So motility
of sperms reduced quicker than it at 15oC. Our results were corresponding with Roca (2000)
reported that rabbit semen diluted with Tris solution maitaining at 15oC was more suitable than at
5oC.
Effect of dilute multiple (semen: solution) on quality of rabbit semen
Vitality of rabbit spermatozoa influence on dilute multiple was influenced by dilute
multiple between semens and solutions. The dilute multiple depended on concentration and
motility of spermatozoa. If dilute multiple was high, it would reduce pregnant rate and
vitality of spermatozoa. If dilute multiple was low, it would increase the cost of semens. To
determine suitable dilute multiple, we carried out to dilute the semens and the Tris solutions
following multiples 1:5 and 1:10, conserving at 15 oC. The results were described in table 7.
Table 7: Effect of dilute multiple on quality of rabbit semen (n = 36)
conserving
duration
Motility
A (%)
Rate of survial
Sperm LS (%)
Abnormality rate
K (%)
(hours)
0h
24 hours
48 hours
72 hours
1:5
62.64a
± 1.01
51.94 a
± 1.00
41.53 a
± 1.01
31.11 a
± 1.02
1:10
56.67b
± 0.96
45.42 b
± 0.92
33.89 b
± 0.98
21.94 b
± 1.06
1:5
70.73 a
± 0.99
59.82 a
± 0.99
48.69 a
± 1.05
37.82 a
± 0.94
1:10
64.55 b
± 0.95
53.23 b
± 0.98
41.76 b
± 0.93
29.24 b
± 1.01
1:5
17.44 a
± 0.10
19.39 a
± 0.10
22.61 a
± 0.12
25.58 a
± 0.12
1:10
18.38 b
± 0.10
20.78 b
± 0.16
24.28 b
± 0.15
28.39 b
± 0.19
a,b Different letters in superscript indicate significant difference (P<0.05)
A (%)
1:05
70
1:10
62.64
60
50
51.94
56.67
41.53
45.42
40
31.11
30
33.89
21.94
20
0 hour
24 hour
48 hour
72 hour
Graph 4: Effects of dilute multiple on motility of rabbit spermatoa
Table 7 shown that rabbit semens were diluted 1:5 (semen : solution) had motility of
spermatozoa higher than 1:10 (p<0.05). After 72 conserving hours, the motility of
spermatozoa with diluting 1:5 (31.11%) were higher than diluting1:10 (21.94%) (p<0.05).
Rate of survial sperm diluted with 1:5 had higher than 1:10 (P<0.05). So rabbit semen diluted
with 1:5 (semen: solution) was more suitable than 1:10.
4.3 Artificial insemination for rabbit by dilute semen
The results of artificial insemination for rabbit by dilute semen conserving Tris
environment
Tris solution is mixed simple, low cost and no effect on The proportions of pregnant.
Therefore, we took dilute semen with Tris solution conserving at 15 oC to inseminate for the
bucks of New Zealand and black rabbit by artificial insemanation method in repeated two
times. The first time was in the morning, the second was in the afternoon after 6 – 8 hours.
Table 8 showed that rabbit semens diluted with Tris solution conserving at 15 oC after
0, 24, 48 hours maintained the alive and insemination abilities. Total of inseminated females
were 21 heads, number of fregnant buck-rabbits were 14. The proportions of pregnant of
conserving semen were 75.00% in the first day, 71.43% in the second day and 50.00% in the
fourth day.
Table 8: Results of artificial insemination
Conserving
time
A before
insemination
(hour)
(%)
Number of
inseminated
females (head)
Number of
fregnant
Proportions of
pregnant (%)
females
(head)
0
60
8
6
75.00
24
50
7
5
71.43
48
40
6
3
50.00
Average
50
21
14
66.67
According to Nguyen Quang Suc and Dinh Van Binh (1998) showed that the
proportions of pregnant of direct insemination were 55 – 75%. Roca (2000) used semen
diluting with solution of Tris – acid Citric – glucose conserving at 15 oC inseminated buckrabbits to attain 77.1 % of the proportions of pregnant.
In research of Lopez et al., (2005) as shown the proportion of pregnant of rabbits
inseminated with semen supplementing gelatin conserving at 15 oC were 88% after 48 hours,
83% after 72 hours. The author concluded that rabbit semen conserving at 15 oC until 5 days
of semen storage still get pregnancy.
Monitoring young rabbits born by artificial insemination
Table 8 and table 9 shown that total of pregnant roe-rabbits were 14 heads. Total of
young rabbits at birth were 91, average 7.58 head/litter, number of live baby rabbits at 1
month were 76 (rate of live was 73.63%). Live weight at birth was 51.73 gram/head, 566.54
gram/head at 1 month.
According to Nguyen Quang Suc and Dinh Van Binh (1998) informed that the roe rabbits mated for 50-60 gram per head at birth, 500-600 gram per head at 1 month and
average number of live rabbits were 4.5 – 7.5 head/litter. Local rabbit got 5 – 6 head/litter,
rabbit of New Zealand had 6 – 8 head/litter, 55 – 60 gram/head at birth and 650 – 700
gram/head at weaning.
Table 9: Results of young rabbits born by artificial insemination
Number
of
mother
Day of
birth
Number of rabbits
(head/litter)
Live rabbits
until month
(head/litter)
Live weight
at born
(gam/litter)
Live weight
at 1 month
(gam/litter)
67
5/5/2007
10
10
478.0
5290.0
199
5/5/2007
8
8
403.2
4451.2
129
11/5/2007
8
8
410.4
4276.8
139
14/5/2007
7
7
382.2
4160.1
60
14/5/2007
5
5
276.5
2937.5
188
27/5/2007
7
6
375.2
3529.8
147
8/6/2007
7
6
380.8
3471.6
237
8/6/2007
6
5
339.6
2938.0
234
15/6/2007
7
7
382.2
4058.6
01
23/6/2007
8
5
419.2
2844.5
66
29/6/2007
9
0
421.2
0
62
29/6/2007
9
0
439.2
0
7.58 (head/litter)
5.58
(head/litter)
51.73
(gam/head)
566.54
(gam/head)
Average
5. Conclusions
- The volume of rabbit semens per ejaculation was low 0.65 – 0.91 ml. Percent of the
swimming spermatozoa was 61.34 – 64.95%. Concentration of sperm was 263.46 – 291.03
million/ml. Total number of spermatozoa per the ejaculation was 263.46 – 291.03 million.
Percent of the alive spermatozoa was 69.82 – 72.52%. Rate of sperm of abnormality was
18.47 – 19.09%. Resistance of sperm to NaCl 1% was 2584.09 – 2720.52.
- The osmotic pressure of rabbit semens was 318.95 – 366.09 miliosmol/kg. Buffer ability of
rabbit semens was 1138.93 – 1314.72. The viscosity of semens was 2.78 – 2.96. The density
of semen was 1.023 – 1.025. The pH of semens was 6.69 – 6.89.
- The rabbit semen should be ejaculated in the cool months for better quality than the hot
months. The interval between two ejaculations was three or four days for many good quality
of semens.
- Semen diluted (1:5) got better result than diluted rate (1:10). Semen diluted in the Tris
solution conserving at 15 oC had percent of the alive spermatozoa better than 5 oC.
- The proportions of pregnant of conserving semen was 75.00% in the first day, 71.43% in the
second day and 50.00% in the fourth day.
References
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