CC BY
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Stanislaw Lapinski1, Joanna Bzymek1, Andrzej Zon2 ©
1Agricultural University, Krakow, Poland 2National Research Institute of Animal Production, Chorzelow, Poland
THE INFLUENCE OF WINTER FASTING ON SEXUAL ACTIVITY OF
MALE FINNRACOONS
Key words: Finnracoon, Nyctereutes procyonoides, fasting, reproduction, sexual activity
Introduction: The animals living in wilderness can be observed seasonal changes in body weight resulting in accessibility to food. Species, in which annual fluctuations of body weight are exceptionally high, and reach 30 - 40%, is finnracoon (Nyctereutes procyonoides) (Mustonen, 2003). There are connected with hypodermic fat storage, which is the main source of energy and ensure thermal isolation in winter (Korhonen, 1988, Mustonen, 2003). Wild finnracoons prepare for this period by increase intensity of autumn feeding. They consume at that time a huge amount of berries reaching the highest body weight in November and December (Mustonen, 2003). In the farm conditions animals received during this time especially balanced, high carbohydrate fodder (Barabasz, 2007). Together with the onset of winter, finnracoons decrease their locomotive activity and fodder consumption. They often fall asleep in 2 - 3 months gentle dormancy, during which metabolism decrease by 25% (Mustonen, 2003). When completely diet was used, the animals were using 1.5 kg of body weight monthly. After awakening finnracoons beginning to rebuild lost reserve of fat and fasting in any other way did not influence negatively on their health (Mustonen et al., 2004).
In many vertebrate species, seasonal inaccessibility of food cause decrease of testosterone concentration in blood (Nieminen, 2004). It does not concern finnracoons, for which winter fasting is a part of natural life cycle. The testosterone secretion in males will begin at the turn of January and February and its peak falls to reproduction season in February and March, when body weight of animals is the least during all year. After this period testes reduce their volume and testosterone production come back to the low level (Niedbala et al., 1994). The investigations carried out on finnracoons by other authors showed, that the winter fasting intensifies respond of steroid sexual hormones during reproduction season and blood testosterone level of individuals fed abundantly is lower than in individuals under fasting (Asikainan et al., 2003).
The aim. The aim of this study was comparison of male finnracoons sexual activity depends on their body weight and degree of winter slimming.
© Stanislaw Lapinski, Joanna Bzymek, Andrzej Zon, 2008
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Material and methods. The group of 20 males of breeding finnracoons were investigated on the farm of National Research Institute of Animal Production in Chorzelow (Poland). The control of body weight was done in November and in March, after completing of reproduction season. Based on obtained results, mean % decrease of finnracoons' body weight during winter rest was evaluated. The investigations on sexual activity were done only on 12 individuals what was due to mating plans on the farm. The dependence between autumn body weight, spring body weight, the difference between these data and sexual activity of males' finnracoons' evaluated on the number of covers done. The obtained numerical data were analyzed statistically using Statistica 6.0 suite. Mean arithmetical and standard deviations as well as polynomial regression were calculated.
Results of research. In November after fattening period, body weight of investigated finnracoons was average about 12 kg. After winter rest and reproduction season males' body weight was average 7.5 kg. For all investigated group, decrease of body weight was above 37% (Tab.1). The obtained results are comparable to results of other authors (Barabasz, 2007).
Tabela 1.
The body mass of finn raccoon after autumnal fatting (November) and after
re productive season (March) (kg 1.
N Mean SD Min. Max.
Body mass - November 20 11,90 1,02 10,15 13,55
Body mass - March 20 7,47 0,72 6,00 9,00
Lost body mass 20 4,42 0,75 2,95 5,80
Asikainen et al., (2002) carried out investigations on influence of winter dormancy on finnracoon reproduce, and presented that litters of animals treated with diet were more numerous than animals fed regularly during winter. They presented negatively correlation between female body weight and the number of litters. The most numerical litters were from females which body weight was within 5 - 7 kg. The results of present research indicated that in case of males, their body weight resulted on reproduction parameters. The highest sexual activity, estimated on the number of copulation, presented males which spring body weight was within 6.5 -7.5 kg (Fig. 1). It is interesting, that the autumn body weight (Fig. 2) and degree of slimming (Fig. 3) did not influence males' sexual activity.
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No of copulations = -147,8469+44,3611*x-3,123*xA2
62 64 66 68 7П 72 74 76 78 8П 82 84 86 88 90 92
March: r = -0,6177, p = 0,0323; y = 38,808583 - 4,14104409*x 'kg
marzec
Fig.1. Polynomial regression presents association between spring body weight of finnracoon males and the number of copulations.
No of copulations = -80,2394+16,8218*x-0,79*xA2
),0 10,5 11,0 11,5 12,0 12,5 13,0 13,5 November: r = -0,3957, p = 0,2030; y = 29,9249078 - 1,90975755*x
14,0
kg
Fig.2. Polynomial regression presents association between autumn body weight of finnracoon males and the number of copulations.
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No of copulations = 55,042-21,9886*x+2,4567*xA2
Fig.3. Polynomial regression presents association between winter decrease of body weight of finnracoon males and the number of copulations
The lack of such dependence can be as a result of good condition of all animals under the experiment. The finnracoons are well adapted to the long-lasting winter fasting, during which they consume stored fat. The low concentrations of hydroxycortisone and thyroid hormones during this time allow to not using proteins for energy production (Mustonen et al., 2004, 2007). In fact not amount of burned fat, but animal condition at the beginning of reproduction had deciding influence on sexual activity.
Conclusions. Summarize, obtained results allow us to conclude that about 40% decrease of finnracoon body weight during winter fasting did not reflect negatively on their health. The amount of fat burned during hibernate did not reflect directly on reproduction parameters. The most important is spring body weight of animal and it general condition. The body weight of male finnracoons approaching reproduction should be within 6.5 - 7.5 kg.
Reference
1. Asikainen J., Mustonen A.M., Hyvarinen H., Nieminen P. (2003) Seasonal
reproductive endocrine profile of the raccoon dog (Nyctereutes procyonoides) - effects of melatonin and food deprivation. J. Exp. Zool. 180-187.
2. Asikainen J., Mustonen A.M., Nieminen P., Pasanen S., Araja-Matilainen H.,
Hyvarinen H. (2002) Reproduction of the raccoon dog (Nyctereutes
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procyonoides) after feeding or food deprivation in winter. J. Anim. Phis. Anim. Nutr., 86, 367-375.
3. Barabasz B. (2007) Jenoty. Chow i hodowla. PWRiL, Warszawa.
4. Korhonen H. (1988) Regulation of energy economy in raccoon dogs and blue
foxes: a process of dynamic interactions. Comp. Biochem. Physiol. 91A, 263-268.
5. Mustonen A.M. (2003) Seasonality, photoperiod and nutritional status in the
control of endocrinological weight-regulation. University of Joensuu, PhD Dissertations in Biology.
6. Mustonen A.M., Nieminen P., Puukka M., Asikainen J., Saarela S., Karonen S.L,
Kukkonen J. V. K., Hyvarinen H. (2004) Physiological adaptations of the raccoon dog (Nyctereutes procyonoides) to seasonal fasting-fat and nitrogen metabolism and influence of continuous melatonin treatment. J. Comp. Phys. B: Bioch. Syst. Env. Phys., 174, 1-12.
7. Mustonen A.M., Asikainen J., Aho J., Nieminen P. (2007) Selective Seasonal
Fatty Acid Accumulation and Mobilization in the Wild Raccoon Dog (Nyctereutes procyonoides). Lipids, 42, 1155-1167.
8. Niedbala P., Szeleszczuk O., Jarosz S. (1994) Zmiany rozwojowe j^der w okresie
postnatalnym u jenotow hodowlanych. Zesz. Nauk. Przegl^du Hodowlanego, 15, 171-176.
9. Nieminen P., Pyykfnen T., Asikainen J., Mononen J., Mustonen A.M. (2004)
Effects of fasting and exogenous melatonin on annual rhythms in the blue fox (Alopex lagopus). Comp. Biochem. Phys., Part A 139, 183- 197
Summary
The finnracoon (Nyctereutes procyonoides) is the only one representative of family Canidae in Europe falling asleep dormancy. During this time by 2 months does not consume food. It's body weight can be decreased even by 40% without negative influence on health condition. The aim of our research was evaluation of sexual activity of male finnracoons depending on degree of slimming. In November and March the body weight of 20 males were investigated. Mean body weight loss after hibernation was 37%. The highest sexual activity based on the number of copulations presented males, which March body weight was 6.5 - 7.5 kg. There were not dependence between body weight in November, decrease of body weight and sexual activity, what can results from general good condition of all animals under experiment.
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