Biologia 69/9: 1247—1249, 2014 Section Zoology DOI: 10.2478/s11756-014-0419-z
Changes of the testes parameters, carcasses and antlers mass of harvested roe deer (Capreolus capreolus) bucks Mikolaj Jakubowski1, Grzegorz Górecki1, Marcin Komosa2, Hieronim Fr˛ ackowiak2, Malgorzata Dzierz˛ecka3, Jacek Skubis1 & Maciej Skorupski1* 1
Department of Game Management and Forest Protection, Pozna´ n University of Life Sciences, Wojska Polskiego 71 d, 60-625 Pozna´ n, Poland; e-mail:
[email protected] 2 Department of Animal Anatomy, Institute of Zoology, Pozna´ n University of Life Sciences, Wojska Polskiego 71 c, 60-625 Pozna´ n, Poland 3 Department of Morphological Science, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 166, 02-776 Warsaw, Poland
Abstract: The research was conducted during the hunting season in Poland from May to September 2012 in which materials of 58 roe deer bucks carcass, antler and testis masses were compared. In addition, the size of testes with epididymides was assessed. Significantly enlarged testes masses were observed in May till July (one-way ANOVA and LSD test). In August and September, the testes underwent abrupt involution. According to the literature and the results of this study, the enlargement of the testes which starts from the end of February, indicates that spring time is a preparatory period for the rut. On the other hand, monthly carcass mass fluctuations were not observed. There is, however, a trend suggesting that heavier roe deer individuals can display larger antler mass. Key words: Cervidae; roe deer; rut; body mass; antler mass; testes
Introduction In the recent years, many studies have confirmed the thesis that in Artiodactyla siring success depends on body size and mass, testes size and even the chemical constituents of the urine (Preston et al. 2003; Binerowska & Baranowski 2010; Rajagopal et al. 2011). These rules also apply in the Cervidae family but here antler mass plays an important role as well. The roe deer is quite a specific species in this family due to, e.g., low sexual size-dimorphism. This is why the mating system in the roe deer is based on the territorial strategy rather than the harem strategy (Emlen & Oring 1977). Cervids that form a harem during the mating season are more sexually dimorphic in body size than males with monogamous mating systems or with territorial polygynous mating systems like the roe deer (Weckerly 1998; Pagon 2010). However, as Vanp`e et al. (2010) claim, also in this species both body mass and antler length have a positive effect on male yearly breeding success. In the light of the above data, it is worth analyzing body mass in bucks throughout several months until and after mating. During the rut, the organism of the male is particularly stimulated, which is evidenced by enlarged testes and mineralized and hard antlers. The aim of our study was to present changes and possible in* Corresponding author
c 2014 Institute of Zoology, Slovak Academy of Sciences
terrelations between testis parameters, body mass and antler mass in the course of several months.
Material and methods The tested material comprised males of the roe deer bagged in four months during hunting season for the animals in Poland, in the same calendar year (2012). The study area is the agriculture lowland with 30% of in-field forests, in Wielkopolska Region, near Kórnik (W Poland). Overall, 58 individuals were studied; May: n = 28, July: n = 11, August: n = 8 and September n = 11. Each buck was characterized by 9 parameters (Table 1). In each case, the head was dissected from the carcass at the level of the first cervical vertebra. Then, the eviscerated carcass was weighted. The head and antlers were subjected to maceration, which was followed by weight determination. The parameter which for the purposes of the present study is referred to as “antler weight” in fact comprises the weight of antlers and skull. In post mortem conditions, the circumference of the scrotum was measured. Then, the right and left testes together with the epididymis were dissected. In the next stage, the testes were weighted. Each testis was subjected to the following measurements: length, thickness, height and circumference. Since the epididymis is anatomically connected to the testis, its length was also measured.
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Table 1. Mean values and standard deviations of characteristics of Capreolus capreolus bucks in respective month. Feature
May
Carcass mass (kg)ns Antlers mass (g)ns Scrotum circumference (cm)*** Testis mass (g)*** Testis circumference (cm)*** Testis length (cm)*** Testis height (cm)*** Testis thickness (cm)*** Epididymis length (cm)*** Explanations:
ns
17.1 328.9 16.3 26.3 8.8 5.1 3.2 2.8 5.5
± ± ± ± ± ± ± ± ±
2.3 75.7 1.2 5.7 0.7 0.4 0.3 0.3 0.5
July 17.4 287.1 17.5 32.4 9.9 5.3 3.4 3.0 5.8
± ± ± ± ± ± ± ± ±
August 1.9 93.8 2.0 5.1 0.7 0.3 0.3 0.2 0.3
17.6 258.8 15.1 21.4 8.2 4.7 2.8 2.5 5.3
± ± ± ± ± ± ± ± ±
2.1 60.7 1.3 6.4 0.8 0.6 0.3 0.4 0.6
September 16.0 360.2 14.1 16.5 7.6 4.3 2.6 2.3 4.8
± ± ± ± ± ± ± ± ±
2.2 150.0 1.3 4.2 0.8 0.4 0.3 0.3 0.5
not significant; *** P ≤ 0.001.
Discussion
Fig. 1. Right testis mass (in g) of Capreolus capreolus bucks. Vertical bars indicate 0.95 confidence intervals.
In the study basic statistics (one-way ANOVA and LSD test) were used. Analyses were conducted with the use of Statistica ver. 10.0.
Results The mean values and standard deviations with respect to the investigated traits were presented by month (Table 1). Next, one-way ANOVA was conducted. The grouping variable was the month when a given animal was bagged. There were no significant differences observed for the carcass mass and antler mass. However, the analysis showed that bucks from particular months differ as to all testis parameters and scrotum circumference. These traits were analysed in a post hoc LSD test. Between most of the analyzed months there were differences observed at the significance level of P ≤ 0.01 or P ≤ 0.05. All the testis traits presented the same pattern of changes. Figure 1 presents this trend on the example of the testis mass. Interesting is the correlation between length, thickness and height of testes. It was significant reduction of mentioned parameters in August and September in comparison to May and July. When it comes to length of epididymis – it was very similar in May, July and August. Length of epididymis decreased in September.
It is known that the roe deer, as a seasonal breeder, reaches the highest mass and size of testes in the mating period, which is between mid-July and mid-August. Therefore, just as we had expected, testis parameters in bucks presented the highest values in July. However, we observed their abrupt involution already in August. Blottner et al. (1996) proved that enlargement of testis depends on increase of testosterone level. Schams & Barth (1982) write that increase of testosterone level starts with occupying of the territories and begins even in end of February. Our study showed that bucks bagged in May had much heavier and larger testes already at that time compared to August and September. This was very clear because even the scrotum circumference turned out to be significantly higher in May compared to late summer and fall. This means that intensified physiological processes in testes can take place several months before the mating period. However, spermatogenesis takes place only in the latter period. Thus, the increase of the testis parameters in spring, confirmed in our study since May, indicates hormonal activity of the organs. Our observations were also confirmed by Roelants et al. (2002) and HombachKlonisch et al. (2004), who found a high level of gonadotropins and INSL3 (Isulin-like Factor 3) in the serum of the male roe deer in spring. These observations prove the existence of over a 3 month rut preparatory period during which differentiation of Leydig cells and gradual increase in testosterone production take place in the testes until the peak in early August. In this period also tubuli seminiferi contorti develop. Testosterone production is also related to antler hardening. Despite changes in testis size and in testosterone concentration, indicated by other authors, in our study we did not observe significant differences in carcass mass of the analyzed males in the investigated months. It is a rather surprising conclusion as the daily activity of the roe deer clearly changes depending on the season, especially in the mating period. On the other hand, Pélabon & Van Breukelen (1998) observed the correlation between other factors like environmental stress and population density as those which influence the increasing carcass mass and antler mass. Komosa et al. (2013) evaluated changes in carcass mass and antler mass in
Testes, carcasses and antlers parameters of roe deer bucks the roe deer in three consecutive years and observed a medium correlation between those variables (r = 0.43). Vanpé et al. (2007) reached a more radical conclusion, stating that only the heavy bucks can afford long, costly antlers. References Binerowska B. & Baranowski P. 2010. Wybrane cechy fizyczne i wska´ zniki biochemiczne osocza krwi rosn˛acych i doroslych tryków rasy wrzosówka polska w cyklu sezonowym Cz. 2. St˛ez˙ enie testosteronu, albumin, glukozy i aktywno´s´ c fosfatazy zasadowej w osoczu oraz procentowy udzial j˛ader w masie ciala tryków [Some body features and biochemical indices of blood plasma of growing and adult polish heath sheep rams in the seasonal rhythm. Part 2. The testosterone concentration, albumin, glucose and AP-activity in blood plasma, and the proportional participation of testis in rams body weight]. Acta Sci. Polon. Zootechn. 9 (4): 25–38. Blottner S., Hingst O. & Meyer H.H. 1996. Seasonal spermatogenesis and testosterone production in roe deer (Capreolus capreolus). J. Reprod. Fertil. 108 (2): 299–305. DOI: 10.1530/jrf.0.1080299 Emlen S.T. & Oring L.W. 1977. Ecology, sexual selection and the evolution of mating systems. Science 197 (4300): 215–233. DOI: 10.1126/science.327542 Hombach-Klonisch S., Sch¨ on J., Kehlen A., Blottner S. & Klonisch T. 2004. Seasonal expression of INSL3 and Lgr8/ Insl3 receptor transcripts indicates variable differentiation of Leydig cells in roe deer testis. Biol. Reprod. 71 (4): 1079– 1087. DOI: 10.1095/biolreprod.103.024752 Komosa M., Fr˛ackowiak H. & Purzyc H. 2013. Changes in testis parameters and the weight of antlers and carcass in males of the European roe deer (Capreolus capreolus) between 2009 and 2011. Biol. Rhythm Res. 44 (1): 151–161. DOI: 10.1080/09291016.2012.656246 Pagon N. 2010. Aspect of some ecological characteristics of roe deer (Capreolus capreolus L., 1758) population in northeastern apennines, Arezzo province, Italy. Doctoral Thesis. Dissertation for the degree of doctor of philosophy in Environmental Biology, cycle 23, University of Sassari, Ph.D. School in Natural Sciences, Department of Zoology and Evolutionary Genetics, Sassari, Italy, 159 pp.
1249 Pélabon C. & Van Breukelen L. 1998. Asymmetry in antler size in roe deer (Capreolus capreolus?): an index of individual and population conditions. Oecologia 116 (1-2): 1–8. DOI: 10.1007/s004420050557 Preston B.T., Stevenson I.R., Pemberton J.M., Coltman D.W. & Wilson K. 2003. Overt and covert competition in a promiscuous mammal: the importance of weaponry and testes size to male reproductive success. Proc. Roy. Soc. B Biol. Sci. 270 (1515): 633–640. DOI: 10.1098/rspb.2002.2268 Rajagopal T., Manimozhi A. & Archunan G. 2011. Diurnal variation in preorbital gland scent marking behaviour of captive male Indian Blackbuck (Antelope cervicapra L.) and its territorial significance. Biol. Rhythm Res. 42 (1): 27–38. DOI: 10.1080/09291011003693161 Roelants H., Schneider F., G¨ oritz F., Streich J. & Blottner S. 2002. Seasonal changes of spermatogonial proliferation in roe deer, demonstrated by flow cytometric analysis of c-kit receptor, in relation to follicle-stimulating hormone, luteinizing hormone, and testosterone. Biol. Reprod. 66 (2): 305–312. DOI: 10.1095/biolreprod66.2.305 Schams D. & Barth D. 1982. Annual profiles of reproductive hormones in peripheral plasma of the male roe deer (Capreolus capreolus). J. Reprod. Fertil. 66 (2): 463–468. DOI: 10.1530/jrf.0.0660463 Vanpé C., Gaillard J.M., Kjellander P., Liberg O., Delorme D. & Hewison A.J.M. 2010. Assessing the intensity of sexual selection on male body mass and antler length in roe deer Capreolus capreolus: is bigger better in a weakly dimorphic species? Oikos 119 (9): 1484–1492. DOI: 10.1111/j.16000706.2010.18312.x Vanpé C., Gaillard J.M., Kjellander P., Mysterud A., Magnien P., Delorme D., Van Laere G., Klein F., Liberg O. & Hewison A.J.M. 2007. Antler size provides an honest signal of male phenotypic quality in roe deer. Amer. Natur. 169 (4): 481– 493. PMID: 17273980 Weckerly F.W. 1998. Sexual-size dimorphism: influence of mass and mating systems in the most dimorphic mammals. J. Mammal. 79 (1): 33–52. DOI: 10.2307/1382840 Received October 22, 2013 Accepted July 20, 2014
