ISRAEL JOURNAL OF
VETERINARY MEDICINE
Vol. 60 (1) 2005
TESTOSTERONE PROFILES IN THE CAMEL (C.
DROMEDARIUS) DURING THE RUTTING SEASON
Deen, A.*, Vyas, S. and Sahani, M.S.
National Research Centre on Camel,P.B. No. 07, BIKANER- 334001, INDIA
*Corresponding author
E-mail: aminudeen @ scientist.com
Abstract
The present study was conducted on 10 adult male camels over a period of 2 consecutive years to
characterize peripheral plasma testosterone profiles in relation to rutting activity. Blood plasma
testosterone profiles were monitored during pre-rut, rut and post-rut stages at weekly intervals by
RIA. Testosterone concentration in peripheral plasma is low during the pre- rut period
(342.93±43.90 ng/ml). Onset of rut activity is associated with significant rise in testosterone
concentration (4213.94±278 ng/dl), which is maintained for 11-18 weeks followed by decline to
basal levels. The onset of rise as well as decline varied individually. It is also not uncommon to
observe complete absence of endocrine surge and rut behavior in some (1/5 in present study) males
throughout breeding season. Genetic, nutritional, management, environmental or other possible
reasons for this remains to be explored. It is not uncommon for certain young males to exhibit
complete shyness when attempted for semen collection despite high testosterone concentration and
other external sexual behavior symptoms, which apparently may be due to lack of exposure. The
libido and production of semen into AV is maintained for 3-5 months followed by cessation, which
also varied individually. Libido subsides in some males in March, in few more in April. Some males
continue to have good libido by the end of May. After May, majority of the males lose libido and are
rendered unable to copulate in AV. Cessation of libido and ability to copulate appears to be
associated with decline in testosterone concentration. Cessation of libido appears to be due to erectile
impotence. The critical level of testosterone required for erectile potency needs to be worked out.
This work shows the correlation between hormone profiles and ambient temperature.
Key words: testosterone, semen, rut, draft dromedary.
Introduction
The camel is a seasonal breeder, and the breeding season is confined to the cool winter
months of the year. In the rut the male exhibits morphological, behavioral and
endocrinological changes (1,2). The rut stage of a male can last from 50 to 100 days (3).
Rutting activity in the male is characterized by a change from a docile to aggressive
temperament such that it may often bite strangers. Its wet lips foam with saliva; it grinds its
teeth and makes a typical whistling sound. It intermittently extrudes its soft palate which is
accompanied by a bubbling sound and bending of its head slightly backwards. The legs are
often spread apart, and the penis is rhythmically beaten with the tail, urine sporadically
splashes on the tail and is whisked on its back. The poll glands secrete a coffee-colored,
acrid-smelling fluid. The male in rut may become completely off its feed, loses weight and its
abdomen becomes tucked up. A confined rutting male may show increased anxiety, pacing
and strike itself against the walls and manger. All these behavioral changes disappear after
the rut is over, and it becomes calm, quite and obedient again. A rutting male chases female
camels and force them to sit down on the ground for copulation. The males will not copulate
with the female after cessation of rut (4). Our observations indicated that this is due to erectile
impotence. The onset and duration of rut in a camel is affected by the type of management
and the individual male. Males that are loose in the herd tend to come into season earlier and
remain in rut longer than confined males.
Libido and semen collections with an artificial vagina differ tremendously between males
and seasons. In general, libido and semen production is at a peak during the cool winter
months of mid-January to February (Bikaner, India). Semen production and libido subside at
variable stages, some males have been observed to lose libido during March while others
may sustain it during March, April and even May. By the end of May, the majority of males
lose their libido and ability to copulate in an artificial vagina (5). Libido and semen collection is
adversely affected in camels used for draft work (6). Various workers have observed high
levels of testosterone in rutting camels compared to the non- rutting stages (1,2,7) and some
have correlated these changes in the peripheral circulation with changes in the release of
pituitary hormones like FSH, LH and PRL (8). It is held that problems like delayed maturity in
the male, absence of rut in adults, shyness and refusal to mate females in young rutting
camels need to be appropriately addressed and resolved. This study on peripheral plasma
testosterone profiles was planned to characterize them in rutting camels during pre-rut, rut
and post-rut stages, in camels not showing rut symptoms and in those with rut symptoms but
are
shy
and
refuse
to
mate.
Materials and Methods
Plasma testosterone profiles were monitored at weekly intervals from a total of 10 adult
males (7-14 yrs of age) around the rutting season over 2 consecutive years; 5 camels were
used in the first year and 5 in the second year. They were kept free during the non-rutting
season, but were restrained with a nose halter and rope prior to the onset of rutting and until it
was over. Meteorological data were collected from Central Arid Zone Research Institute,
Bikaner. The ambient temperature and humidity data were averaged on a weekly basis along
with the collection of blood samples. During the first year, the camels were monitored from the
first week of December to mid-May. The results indicated that monitoring needed to be
programmed in order to characterize pre-rut profiles. With a view to cover the pre-rut period,
monitoring during second year was programmed from over the last week of September to
mid-April.
Blood collections were made by jugular venepuncture into heparinized tubes. Plasma was
harvested by centrifugation at 2500 rpm for 15 minutes in a refrigerated centrifuge (C-24,
Remi, India). Plasma aliquots were kept at -20 C. RIA kits (TKTT5; Diagnostic Products
Corporation, California) were used for analysis. Count disintegrations per minute were
recorded in I125 Gamma counter IC-4072 serial 315 of Electronics Co. of India Limited,
Hydrabad,
India.
Correlations were studied between testosterone profiles and ambient temperature and
humidity
using
custom
type
graphical
software
(Microsoft
Excel).
Nutrition
and
husbandry
The camels were confined in stables and offered dry fodder. Oil and jaggery were fed prior to
the
breeding
season.
Statistical
analysis:
The data of peripheral plasma testosterone concentrations during pre-rut, rut and post-rut
stages of 4 males were analyzed by analysis of variance using least squares maximum
likelihood program (9).
Results
First
Year
Plasma testosterone profiles of 5 male camels monitored during first year of this study are
presented in Table 1. The testosterone concentration was elevated at the time of first
sampling in all except one camel (B-418), which exhibited a delayed rise during the third week
of monitoring. High concentrations were maintained for 11 to 18 weeks before declining to
basal levels.
Table 1: Plasma testosterone concentration (ng/dl) of male camels during pre-rut, rut and
post-rut stages.
Second
Year
Since most of the camels monitored during the first year had higher levels of testosterone
at the beginning of monitoring in December, it was felt that this period should characterize
pre-rut profiles. Thus, the study was revised during the second year with an extended
monitoring period to include the pre-rut period (from last week of September). Plasma
testosterone profiles of 5 adult male camels monitored during this year at pre-rut, rut and
post-rut stages are presented as a line diagram in Figure 2 and Table 1. Four out of five
camels exhibited a rise in testosterone concentration during the rutting season. The average
concentrations of testosterone during the pre-rut, rut and post-rut stages of four camels is
tabulated. The testosterone concentration was significantly higher during rut (4213.94±278.00
ng/dl) as compared to the pre-rut (342.93 ± 43.90 ng/dl) and post-rut (400.17±73.24 ng/dl)
stages. The commencement of the rise of testosterone concentration varied individually. In
one male, the rise occurred early (October), but was delayed in the remaining three males
(mid-November). Accordingly, the decline also commenced earlier in one (January) compared
to remaining three males (March). The period during which high concentrations of
testosterone were maintained was more or less similar (11 to 13 weeks). An absence of
testosterone rise and rut symptoms were observed in one male (series 5) throughout the
breeding season.
In general, copulation reaction, copulation time and volume of semen were observed to
improve during last week of December and peaked during January and February. This
coincides with the pattern of endocrine surge of testosterone in peripheral plasma. Cessation
of libido varies, some males lose libido early in March and stop serving in AV while others
maintain it into April and May (Table 2). By the end of May, majority of males lose libido and
ability to achieve an erect penis. This may be due to a very low concentration of testosterone
in peripheral plasma. Table 2 presents the data on copulation time for the 6 camels used for
artificial collection of semen at weekly intervals. A biological variation with regards to
copulation time exists between animals. In camel no. 1, the data shows that libido was
maintained from December to April followed by a decline in May. In camel no.2 libido was
optimal in the last week of March and April. In animal no. 3 libido was optimal from December
to February followed by cessation. In animal no.4, libido was optimum from last week of
December and maintained till May. In animal no. 5, libido was maintained throughout the
entire season (December to June). In camel no. 6, the libido was maintained from December
to March followed by its decline and cessation.
It is worth mentioning that it is not uncommon to observe many young rutting males that are
completely shy and refuse to copulate with females. These have high peripheral testosterone
profiles especially in the presence of personnel involved in AV semen collection.
Correlation between testosterone hormone profile and ambient temperature is presented in
Figs. 3. These show that the testosterone peak was correlated with low ambient temperatures
in
most
of
the
animals.
Table 2: Average copulation time (in seconds) in artificial vagina for 6 camels throughout rutting
season
Camel No./Week & Month
1
2
3
4
5
6
Average
December, 1st
-
140
-
115
112,170
232
153.8
December, 2nd
244
103
-
110
114
133
140.8
December, 3rd
-
238
250
81
220
328
223.4
December, 4th
242
135
-
349
406
150
256.4
January,1st
227
94
159
251
231
232
199.0
January, 2nd
246
122
106
250
264
114
183.6
January, 3rd
0
0
0
231
205
164
91.6
January, 4th
242
135
171
247
158
192
190.8
February, 1st
213
-
92
201
540,272
252
261.6
February, 2nd
381
0
106
305
214
250
209.3
February, 3rd
464
407
201
179
187
195
272.1
February,4th
509
-
87
216
300,353
239,184
269.7
March, 1st
365
-
-
285
-
-
325.0
March, 2nd
333
-
207
203
670
400
362.6
March, 3rd
279
0
0
156
360,284
241,174
186.7
March, 4th
332
431
-
301
367, 472
117, 45, 131 274.5
April, 1st
356
456
-
180
293
65
270.0
April, 2nd
372
295
0
206
330
42
207.5
April, 3rd
496
341
0
173
181
37
204.6
April, 4th
244
546
-
244
307,220
24
264.1
May, 1st
-
379
-
0
318
51
187.0
May, 2nd
131
291
0
313
309
0
174.0
May,3rd
179
199
-
101
159
-
159.5
May, 4th
131
170
-
-
255
-
185.3
June, 1st
June, 2nd
407
-
264
-
0
130
181
124
146
271
0
192
166.3
179.2
Fig1: Testosterone profiles of male camels during and after the rutting season.
Discussion
The camel is a short day breeder. Typical dramatic sexual behavior changes are
manifested in males with the onset of rut during the cooler winter months. Such behavioral
changes are not observed in males of other species of domestic animals except possibly, the
domestic elephant, but these resemble other wild species like deer (2). These changes
persist in an individual camel for around one hundred days on average and are followed by
the resumption of a calm and quiet temperament. Testosterone concentrations in peripheral
plasma at the pre-rut and post-rut stages were observed to be significantly lower than at the
rut stage. There is a tremendous increase over basal levels in plasma testosterone
concentration, which is maintained for a period of 11-18 weeks before declining back to basal
levels. Similar changes in the camel during rut, pre-rut and post-rut stages have been
reported from Morrocco (1) and the Negev and Judean deserts (2). Azouz et al (8) reported
that libido and sexual activity during rutting may be attributed to the increased concentrations
of FSH, LH and testosterone; conversely decreased sexual activity and low fertility during the
non-rutting season is linked to decreased levels of FSH, LH, testosterone and increased
prolactin levels. Higher testosterone levels apparently affect the brain centers to manifest
typical rut symptoms exhibited by the male. The onset of rise in testosterone as well as its
decline varied individually but the length of period of high testosterone concentration and
rutting symptoms is more or less similar and lasted 11 to 13 weeks. Tibary and Anouassi (3)
also indicated that individual rutting activity lasts for 90-100 days. Individual male effects and
effects of type of management are thought to be responsible for such variations, particularly
males that are left loose may come in rut earlier. Though the symptoms of rut have been
found to be associated with higher testosterone concentration, they also coincide with libido
and semen production Complete shyness during the attempt to collect semen was also not
uncommon in the young males which otherwise had high testosterone concentrations and
external rutting symptoms. Apparently lack of exposure appears to be the major factor, and
suitable training schedules need to be explored to improve their artificial semen production
efficiency. It is also not uncommon to observe an absence of elevated testosterone and rut
symptoms in some males throughout the breeding season. Genetic, nutritional, management,
environmental or other possible reasons remain to be explored. In general, libido and
donation of semen is at peak during the cool winter months of mid January-February, when
the testosterone levels also peak in most of the males. Loss of complete libido was observed
to be due to erectile impotence.
It is concluded that typical rutting behavioral changes exhibited by male camel are due to
manifold changes in peripheral plasma testosterone concentration, A definite correlation with
low ambient temperature was evident, and the peak was maintained around 11-13 weeks
followed by a decline. These hormone profiles affect libido and semen production. Complete
cessation of libido is probably accomplished with testosterone levels falling below a critical
level, which may lead to a condition such as erectile impotence. Absence of rutting behavior
in the adult male camel was observed to be due to a failure of initiation of the endocrine
changes. Shyness to mate females shown by young rutting males may be due to a lack of
exposure.
LINKS TO OTHER ARTICLES IN THIS ISSUE
References
1. Marie, M. E., Bases endoceiniennes de la fonction sexualle chez le
dromadaire (Camelus Dromedarius). These de doctorat de L'Universite. Paris
6,
1987.
2. Yagil, R. and Etzion, Z., Hormonal and behavioural patterns in the male
camel (Camelus dromedarius). J. Reprod. Fert. 58: 61-65, 1980.
3. Tibary, A. and Anouassi, A., Male breeding soundness. In Theriogenology
in Camelidae, 1st Ed.,Published by ministry of Agriculture and Information,
UAE.:79-114,
1997.
4. Zhao, X. X. Reproduction in the Bactrian camel. In Selected topics on
camelids, Ed. T.K. Gahlot, The camelid Publishers, Camel House 67, Gandhi
Nagar West, Near Lalgarh Palace, Bikaner-334001, India, P,No.499-538,
2000.
5. Aminu Deen, Vyas, S., Sahani, M. S.,Semen collection, cryopreservation
and artificial insemination in the dromedary camel. Animal Reproduction
Science,
77
(3-4),
223-233,
2003.
6. Aminu Deen, Vyas, S., Jain, M., Sahani., A note on effect of carting on
libido and semen production in camel (Camelus dromedarius). J. of Camel
Practice
and
Research.
9
(2),
151-152,
2002.
7. Dixit, V.P., Mehta, S.N., Georgie, G.C. and Singal, S.P., Serum
testosterone and cortisol in rutting and non rutting Indian male camel. Indian
J.
Animal
Science,
57(11):1191-1193,
1987.
8. Azouz, A., Ateia, M.Z. Shawki, H., Zakasia, A.D., Farahat, A.A., Hormonal
variations during rutting and nonrutting season in the male dromedary camel.
First International Camel Symposium, 2-6 February 1992, World Trade
Centre,
United
Arab
Emirates.
pp
45,
1992.
9. Harvey, W.R., Mixed model least squares and maximum likelihood
computer
program
PC-1,
1987.
1.