Research Article
Lidia Felska-Błaszczyk 
1 , Beata Seremak 2
1Department of Animal Anatomy and Zoology, West Pomeranian University of Technology, Klemensa Janickiego 33, 71-270 Szczecin, Poland, Poland
2Department of Animal Reproduction Biotechnology and Environmental Hygiene, West Pomeranian University of Technology, Klemensa Janickiego 29, 71-270 Szczecin, Poland
Abstrakt. Badanie miało na celu ocenę wpływu kondycji ciała samic norek hodowlanych (Neovison vison) w momencie zapłodnienia na ich rozmnażanie i zachowanie. 601 samic norek odmiany perła w wieku 1 i 2 lat podzielono na pięć grup zgodnie z ich kondycją ciała. Przeanalizowano następujące parametry: długość ciąży i długość diapauzy, wielkość miotu, liczba żywo urodzonych młodych w miocie, liczba odsadzonych młodych z miotu, procent samic jałowych i występowanie zjawiska gryzienia futra (fur-chewing). Wpływ kondycji ciała był bardziej wyraźny u samic rocznych, w których największe mioty, najwyższą liczbę żywo urodzonych młodych w miocie i najwyższą liczbę odsadzonych młodych stwierdzono w grupie o idealnej kondycji ciała. W obu grupach wiekowych najkrótsze ciąże i okresy diapauzy obserwowano u najchudszych samic. Gryzienie futra było najczęściej zauważane u najchudszych i najbardziej otyłych zwierząt; samice z tych grup również wykazywały najwyższe wskaźniki jałowości. Najmniejszy procent samic, które wygryzały futro i najmniejszy procent samic jałowych stwierdzono u zwierząt z idealną kondycją ciała.
Słowa kluczowe: norka, kondycja ciała, behawior, rozród, krycie
Mink autumn feeding is highly intensive and involves an energy-rich diet, since the breeding stock animals must accumulate necessary reserves of fat before winter. The same feeding system is applied to slaughter animals, in order to obtain the largest possible body size and, in consequence, the largest and the most valued pelt. Regardless of its purpose, however, the high-intensity nutrition regimen inevitably leads to obesity, especially as the feed often contains crude fat. Consequently, the prospective breeders should be brought back to the so called breeding condition; the low-intensity feeding regimen involves a short period of applying a poorer diet in terms of both quantity and energy, especially low in fat. This feeding mode ends 4–5 days before initiation of matings, when the flush feeding, i.e. the full ration of high-energy feed, is applied [Tauson 1985Tauson, A.H. (1985). Flushing of mink. Effects of level of flushing on reproductive performance, ovulation rate and plasma progesterone levels in mink. Acta Agric. Scan., 35, 295–309. https://doi.org/10.1080/00015128509435786, Tauson 1988Tauson, A.H. (1988). Flushing of mink. Effects of level of preceding feed restriction and length of flushing period on reproductive performance. Anim. Reprod. Sci., 17, 243–250. https://doi.org/10.1016/0378-4320(88)90061-9, Tauson 2001Tauson, A.H. (2001). Links between nutrition and the reproductive axis in a seasonal breeder, the mink (Mustela vison). J. Reprod. Fert. Supplement, 57, 97–101. Google Scholar]. Despite the conditioning of the breeders, however, some females will fail to return to the ideal condition; some may grow too lean while others will remain too fat. Bis-Wencel et al. [2018]Bis-Wencel, H., Rowicka, A., Klimek, K., Nowakowicz-Dębek, B., Wlazło, Ł., Bryl, M., Trawińska, B., Bełkot, Z. (2018). Glycemic control in minks with tendency to obesity in the perinatal period with the use of HbA1C. R. Bras. Zootec., 47, e20160391. https://doi.org/10.1590/rbz4720160391 emphasize that breeding stock animals are primarily susceptible to obesity, which may also lead to health problems. The authors found that both an excess and a deficit of fat in the nutrition for mink may result in diabetes, whereas hyperglycemia or glucose deficiencies may significantly affect reproduction [Hynes et al. 2004Hynes, A.M.J., Rouvinen-Watt, K., Armstrong, D. (2004). Body condition and glycemic control in mink females during reproduction and lactation. Scientifur, 28, 79–86. Google Scholar, Rouvinen-Watt and Armstrong 2004Rouvinen-Watt, K., Armstrong, D. (2004). Body condition scoring of mink using a five-point scale. Appendix A. In: Hynes, A.M., Rouvinen-Watt, K. and Armstrong, D. Body condition and glycemic control in mink females during reproduction and lactation. Scientifur, 28(3), 79–86. Google Scholar, Hynes and Rouvinen-Watt 2007Hynes, A.M.J., Rouvinen-Watt, K. (2007). Monitoring blood glucose levels in female mink during the reproductive cycle: 1. Prevention of hyperglycemia during the nursing period. Can. J. Vet. Res., 71(4), 241–248. Google Scholar, Bis-Wencel et al. 2018Bis-Wencel, H., Rowicka, A., Klimek, K., Nowakowicz-Dębek, B., Wlazło, Ł., Bryl, M., Trawińska, B., Bełkot, Z. (2018). Glycemic control in minks with tendency to obesity in the perinatal period with the use of HbA1C. R. Bras. Zootec., 47, e20160391. https://doi.org/10.1590/rbz4720160391].
Many authors report that the appropriate body condition in the breeding stock is the key to a satisfactory breeding performance [Baekgaard et al. 2008Baekgaard, H., Larsen, P.F., Sønderup, M. (2008). Female body condition and early kit mortality: A description from practice. Scientifur, 32(4), 18–19. Google Scholar, Boudreau 2012Boudreau, L. (2012). Effect of moderate diet restriction on body condition, health, and reproductive performance in female mink (Neovison vison). Submitted in partial fulfillment of the requirements for the degree of Master of Science, Dalhousie University Halifax, Nova Scotia. Google Scholar, Boudreau et al. 2014Boudreau, L., Benkel, B., Astatkie, T., Rouvinen-Watt, K. (2014). Ideal body condition improves reproductive performance and influences genetic health in female mink. Anim. Reprod. Sci., 145, 86–98. https://doi.org/10.1016/j.anireprosci.2014.01.004]. Boudreau [2012]Boudreau, L. (2012). Effect of moderate diet restriction on body condition, health, and reproductive performance in female mink (Neovison vison). Submitted in partial fulfillment of the requirements for the degree of Master of Science, Dalhousie University Halifax, Nova Scotia. Google Scholar and Boudreau et al. [2014]Boudreau, L., Benkel, B., Astatkie, T., Rouvinen-Watt, K. (2014). Ideal body condition improves reproductive performance and influences genetic health in female mink. Anim. Reprod. Sci., 145, 86–98. https://doi.org/10.1016/j.anireprosci.2014.01.004 stated that selection of mink for large body size may lead to obesity and, in consequence, to a poor reproduction results. This was previously demonstrated by Tinggaard et al. [2012]Tinggaard, L., Clausen, T.N., Larsen, P.F. (2012). Investigation of placental scars in mink females. Scientifur, 36(3–4), 270–274. https://doi.org/10.3920/978-90-8686-760-8_41, who observed that obese females gave birth to poorer litters, compared to those in the ideal body condition, despite the same number of placental scars indicating embryonic implantations. Similar observations were reported by Lagerkvist et al. [1994]Lagerkvist, G., Johansson, K., Lundeheim, N. (1994). Selection for litter size, body weight, and pelt quality in mink (Mustela vison): correlated responses. J. Anim. Sci., 72, 1126–1137. https://doi.org/10.2527/1994.7251126x, who found that females selected for large body size produced smaller litters with a higher offspring mortality, and their coat was of poorer quality compared to that of smaller females. According to Rouvinen-Watt [2003]Rouvinen-Watt, K. (2003). Nursing sickness in the mink – a metabolic mystery or a familiar foe? Can. J. Vet. Res., 67, 161–168. Google Scholar, female mink that exhibit an abnormal body condition before breeding are predisposed to lactation anemia that occur in pregnancy and offspring nursing.
There is a linkage between body condition and stereotypy. Jeppesen et al. [2004]Jeppesen, L.L., Heller, K.E., Bildsøe, M. (2004). Stereotypies in female farm mink (Mustela vison) may be genetically transmitted and associated with higher fertility due to effects on body weight. Appl. Anim. Behav. Sci., 86, 137–143. https://doi.org/10.1016/j.applanim.2003.11.011 found that females showing a higher incidence of stereotypic behaviors were smaller in size, livelier and gave birth to larger litters of kits that weaned better. The authors reported that better reproduction performance achieved by such females may be a result of their better response to the full-ration, high-energy feeding regimen starting 4–5 days prior to mating (flush feeding) and that is why the females exhibit better physical condition. Our previous another studies reported that studies [Felska-Błaszczyk et al. 2017Felska-Błaszczyk, L., Dziadosz-Styś, M., Ławrów, N. (2017). Body condition of male farm mink (Neovison vison) during a mating season. Folia Pomer. Univ. Technol. Stetin., Agric., Aliment., Pisc., Zootech., 334 (42) 2, 29–34. https://doi.org/10.21005/AAPZ2017.42.2.03] showed that body condition of males had no effect on the number of matings, although it significantly altered the animals’ behavior during the breeding season, especially if we look at the aggressive behavior of males against females, and fur-chewing. The highest number of aggression incidents was observed in males of a very thin to ideal body condition, whereas – in contrast – about half of these behaviors happened among obese mink males. Males which were either very thin or obese exhibited the fur-chewing stereotype, which was otherwise absent among males of a thin and ideal body condition.
The aim of this study was to evaluate the impact of the body condition of breeding females on their reproduction performance and their behavior in pregnancy and during lactation.
This study was carried out in strict accordance with the recommendations of the Polish Act dated 21 January 2005 on Animal Experiments (Journal of Laws 2005, no. 33, pos. 289). The protocol was approved by the Local Ethical Committee for Experiments on Animals at the West Pomeranian University of Technology, Szczecin, Poland (permit number: 10/2015, dated 15 May 2015). The study was carried out on a commercial mink farm located in the north-western part of Poland. Females of Perl mink (n = 601) at age 1 (311 females) and 2 years (290 females) were housed in standard mink cages and fed a feed composed according to generally accepted standards [PAN 2011PAN (2011). Zalecenia żywieniowe i wartość pokarmowa pasz – zwierzęta futerkowe. A. Gugołek (red.) [Nutritional recommendations and nutritional value of feed – fur animals. A. Gugołek (ed.)], Wydaw. Inst. Fizjol. Żyw. Zwierz. PAN, Jabłonna [in Polish]. Google Scholar]. Supplied by an independent producer, the semi-liquid feed was based on chicken and fish. The feed was provided 3 times using semi-automatic feeders, with a portion of feed being placed directly on top of the cage. All animals had equal access to both drinking water and food.
All the data for the study were obtained through uninvasive, contactless observations carried out during normal farm operations. Shortly (4–5 days) before mating, a mink evaluation expert rated the body condition of each animal on the 5-point scale, and the females were accordingly assigned to the following groups [Hynes et al. 2004Hynes, A.M.J., Rouvinen-Watt, K., Armstrong, D. (2004). Body condition and glycemic control in mink females during reproduction and lactation. Scientifur, 28, 79–86. Google Scholar, Møller et al. 2015Møller, S.H., Hansen, S.W., Malmkvist, J., Vinke, C.M., Lidfors, L., Gaborit, M., Botreau, R. (2015). WelFur – Welfare assessment protocol for mink. FurEurope, 182, 978–2-9601617-2-4. Google Scholar]:
Condition group sizes are presented in Table 1. Matings took place in basically the same period, the first breeding was between 1 through 5 of March; females were mated 3 or 4 times.
Table
1. The number of mink groups
used in the experiment in relation to their body condition
|
|||||
Age, years |
Body condition group – Grupy kondycyji ciała |
||||
1 |
2 |
3 |
4 |
5 |
|
1 |
53 |
78 |
67 |
54 |
59 |
2 |
57 |
50 |
61 |
69 |
53 |
Total – Razem |
110 |
128 |
128 |
123 |
112 |
The following reproduction parameters and behavior types were analyzed:
The datasets were processed statistically using the STATISTICA 13.3 package. The statistical description involved the mean (m), standard deviation (SD), and the coefficient of variability (V%).
As can be concluded from Table 2, there is a number of significant (P ≤ 0.01 and P ≤ 0.05) differences in the length of both diapause and gestation depending on the body condition. Significant (P ≤ 0.01) differences were also found in relation to age; yearling females had a shorter diapause and gestation, as compared with two-year-old dams. Females of the condition group 1 in either age group featured the shortest diapause and gestation periods. On the other hand, the longest diapause and gestations were noted in group–5 yearling females and group–3 two-year-old ones.
Table
2. Statistical description of diapause and
gestation lengths in relation to age and body condition score |
|||||||
Item |
Age, years |
Body condition score |
Mean, days |
SD |
V% |
Min. |
Max. |
Diapause |
1 |
1 |
15.71Aabc |
6.02 |
38.34 |
5 |
45 |
2 |
16.13def |
4.34 |
26.93 |
5 |
25 |
||
3 |
15.90Bghi |
7.02 |
44.14 |
0 |
58 |
||
4 |
16.25jkl |
4.79 |
29.47 |
0 |
25 |
||
5 |
16.41l |
6.76 |
41.20 |
3 |
48 |
||
Total – Razem |
16.09** |
5.81 |
36.11 |
0 |
58 |
||
2 |
1 |
17.88 |
4.97 |
27.81 |
6 |
30 |
|
2 |
18.72adgjl |
3.80 |
20.30 |
10 |
26 |
||
3 |
19.14ABekl |
6.00 |
31.35 |
5 |
43 |
||
4 |
18.33bh |
3.61 |
19.70 |
9 |
27 |
||
5 |
18.50cfi |
4.33 |
23.39 |
9 |
29 |
||
Total – Razem |
18.52** |
4.65 |
25.13 |
5 |
43 |
||
Total diapause – Razem diapauza |
17.27 |
5.42 |
31.36 |
0 |
58 |
||
Gestation length |
1 |
1 |
51.71Aabc |
6.02 |
11.65 |
41 |
81 |
2 |
52.13def |
4.34 |
8.33 |
41 |
61 |
||
3 |
51.90Bghi |
7.02 |
13.52 |
36 |
94 |
||
4 |
52.25jkl |
4.79 |
9.17 |
36 |
61 |
||
5 |
52.41l |
6.76 |
12.90 |
39 |
84 |
||
Total – Razem |
52.09** |
5.81 |
11.15 |
36 |
94 |
||
2 |
1 |
53.88 |
4.97 |
9.23 |
42 |
66 |
|
2 |
54.72adgjl |
3.80 |
6.94 |
46 |
62 |
||
3 |
55.14ABekl |
6.00 |
10.88 |
41 |
79 |
||
4 |
54.33bh |
3.61 |
6.65 |
45 |
63 |
||
5 |
54.50cfi |
4.33 |
7.94 |
45 |
65 |
||
Total – Razem |
54.52** |
4.65 |
8.54 |
41 |
79 |
||
Total gestation – Razem ciąża |
53.27 |
5.42 |
10.17 |
36 |
94 |
||
A, B – differences within column significant at P ≤
0.01. |
|||||||
The extreme values illustrate the wide range of length in both the diapause and, consequently, the gestation. There were yearling females which actually never entered diapause; this pertained to females of the condition groups 3 and 4, which also exhibited very long diapause periods (e.g. 58 days in group 3). Two-year-old females did not show such a high variation, which can be concluded from the coefficient of variability, higher in the yearling females compared to the adult age group.
The effect of body condition on female mink reproduction performance is more strongly pronounced in yearling females, which was also noted by Tauson [1993]Tauson, A.H. (1993). Effect of body condition and dietary energy supply on reproductive processes in the female mink (Mustela vison). J. Reprod. Fert., 47 (Suppl.), 37–45. Google Scholar. The shortest gestation lengths were observed in one-year-old females, both of the thinnest and the ideal-condition groups.
Body condition exerted a more pronounced influence on the analyzed parameters in one-year-old females; the largest litter sizes and the greatest numbers of live-born and weaned kits per litter were noted for females with the best body condition score (Table 3, group 3). There was no such association among two-year-old females, where the extreme litter parameters were observed in various condition groups. Higher values of these parameters were observed in yearling females. Boudreau et al. [2014]Boudreau, L., Benkel, B., Astatkie, T., Rouvinen-Watt, K. (2014). Ideal body condition improves reproductive performance and influences genetic health in female mink. Anim. Reprod. Sci., 145, 86–98. https://doi.org/10.1016/j.anireprosci.2014.01.004 also report that females with lower body weight produce larger litters and nurse their offspring better (with lower kit mortality rates). Similar results were reported by Lagerkvist et al. [1994]Lagerkvist, G., Johansson, K., Lundeheim, N. (1994). Selection for litter size, body weight, and pelt quality in mink (Mustela vison): correlated responses. J. Anim. Sci., 72, 1126–1137. https://doi.org/10.2527/1994.7251126x and Tinggaard et al. [2012]Tinggaard, L., Clausen, T.N., Larsen, P.F. (2012). Investigation of placental scars in mink females. Scientifur, 36(3–4), 270–274. https://doi.org/10.3920/978-90-8686-760-8_41, who found that heavier females exhibited poorer reproduction performance. Baekgaard et al. [2006]Baekgaard, H., Hansen, M.U., Sønderup, M., Clausen, T. (2006). Connection between early kit mortality and the body condition of the females and feed consumption from January to birth. Annual Report 2006, Danish Fur Breeders Research Center, Holstebro, Denmark, 185–192 [in Danish]. Google Scholar and Clausen et al. [2006]Clausen, T.N., Sandbol, P., Hejlesen, C. (2006). Body score of females in the winter and breeding period. Annual Report 2006, Danish Fur Breeders Research Center, Holstebro, Denmark, 181–184 [in Danish]. Google Scholar observed smaller litters in females that were obese at the moment of parturition.
Table
3. Statistical characteristics of litter size,
live-born per litter and weaned offspring per litter in relation
to dam’s age and body condition |
|||||||
Item |
Age, years |
Body condition score |
Mean |
SD |
V% |
Min. |
Max. |
Litter size |
1 |
1 |
6.63 |
1.89 |
28.55 |
2 |
13 |
2 |
6.37 |
1.90 |
29.90 |
2 |
11 |
||
3 |
7.06ab |
1.63 |
23.05 |
2 |
10 |
||
4 |
6.67 |
1.57 |
23.56 |
2 |
9 |
||
5 |
6.57 |
1.96 |
29.87 |
2 |
11 |
||
Total – Razem |
6.66 |
1.80 |
27.00 |
2 |
13 |
||
2 |
1 |
6.42 |
1.53 |
23.78 |
3 |
9 |
|
2 |
6.63 |
1.91 |
28.89 |
2 |
11 |
||
3 |
6.23a |
1.71 |
27.45 |
2 |
10 |
||
4 |
6.20b |
1.66 |
26.86 |
2 |
10 |
||
5 |
6.59 |
1.53 |
23.21 |
2 |
9 |
||
Total – Razem |
6.39 |
1.67 |
26.12 |
2 |
11 |
||
Total litter size – Razem wielkość miotu |
6.53 |
1.74 |
26.66 |
2 |
13 |
||
Live-born per litter |
1 |
1 |
6.32 |
1.97 |
31.15 |
2 |
13 |
2 |
6.31 |
1.90 |
30.10 |
2 |
11 |
||
3 |
6.81abc |
1.50 |
22.07 |
2 |
10 |
||
4 |
6.49 |
1.53 |
23.54 |
2 |
9 |
||
5 |
6.27 |
1.70 |
27.06 |
2 |
10 |
||
Total – Razem |
6.45 |
1.72 |
26.68 |
2 |
13 |
||
2 |
1 |
6.20 |
1.46 |
23.50 |
3 |
9 |
|
2 |
6.16 |
2.07 |
33.58 |
0 |
11 |
||
3 |
5.93c |
1.54 |
25.94 |
2 |
8 |
||
4 |
5.98a |
1.59 |
26.56 |
2 |
10 |
||
5 |
6.34b |
1.52 |
24.04 |
2 |
9 |
||
Total – Razem |
6.10 |
1.63 |
26.66 |
0 |
11 |
||
Total live-born – Razem żywo urodzone |
6.28 |
1.68 |
26.80 |
0 |
13 |
||
Weaned per litter |
1 |
1 |
5.76 |
1.61 |
27.95 |
2 |
9 |
2 |
5.97 |
1.70 |
28.56 |
2 |
8 |
||
3 |
6.31 |
1.43 |
22.71 |
2 |
8 |
||
4 |
6.12 |
1.39 |
22.80 |
2 |
9 |
||
5 |
5.74 |
1.51 |
26.25 |
2 |
8 |
||
Total – Razem |
6.00 |
1.54 |
25.69 |
2 |
8 |
||
2 |
1 |
5.84 |
1.43 |
24.55 |
3 |
8 |
|
2 |
5.88 |
1.81 |
30.85 |
0 |
8 |
||
3 |
5.72 |
1.64 |
28.64 |
2 |
8 |
||
4 |
5.62 |
1.57 |
28.02 |
2 |
8 |
||
5 |
6.00 |
1.54 |
25.67 |
2 |
9 |
||
Total – Razem |
5.79 |
1.59 |
27.50 |
0 |
9 |
||
Total weaned – Razem odchowane |
5.90 |
1.57 |
26.59 |
0 |
9 |
||
a, b – differences within column significant at P ≤
0.05. |
|||||||
The long term selection process of farm mink has produced varieties with larger body sizes, with a consequence in their bodies being prone to excessive fat deposition [Boudreau et al. 2014Boudreau, L., Benkel, B., Astatkie, T., Rouvinen-Watt, K. (2014). Ideal body condition improves reproductive performance and influences genetic health in female mink. Anim. Reprod. Sci., 145, 86–98. https://doi.org/10.1016/j.anireprosci.2014.01.004]. Farmers should focus on the diet that will bring the animals to the ideal condition before every breeding season. Obesity control in mink will also reduce the risk of diabetes or fatty liver disease [Rouvinen-Watt 2003Rouvinen-Watt, K. (2003). Nursing sickness in the mink – a metabolic mystery or a familiar foe? Can. J. Vet. Res., 67, 161–168. Google Scholar, Rouvinen-Watt et al. 2010Rouvinen-Watt, K., Mustonen, A.M., Conway, R., Pal, C., Harris, L., Saarela, S., Strandberg, U., Nieminen, P. (2010). Rapid development of fasting-induced hepatic lipidosis in the American mink (Neovison vison): effects of food deprivation and re-alimentation on body fat depots, tissue fatty acid profiles, hematology and endocrinology. Lipids, 45, 111–128. https://doi.org/10.1007/s11745-009-3377-4]. Boudreau et al. [2014]Boudreau, L., Benkel, B., Astatkie, T., Rouvinen-Watt, K. (2014). Ideal body condition improves reproductive performance and influences genetic health in female mink. Anim. Reprod. Sci., 145, 86–98. https://doi.org/10.1016/j.anireprosci.2014.01.004 noted that females that had been brought to ideal condition before breeding maintained that condition throughout lactation, and also recovered better during the period following it. The fact that body condition has been included as an evaluated parameter in the WelFur certification program [Mononen et al. 2012Mononen, J., Møller, S.H., Hansen, S.W., Hovland, A.L., Koistinen, T., Lidfors, L., Malmkvist, J., Vinke, C.M., Ahola, L. (2012). The development of on-farm welfare assessment protocols for foxes and mink: the WelFur project. Anim. Welfare, 21, 363–371. https://doi.org/10.7120/09627286.21.3.363, Boudreau et al. 2014Boudreau, L., Benkel, B., Astatkie, T., Rouvinen-Watt, K. (2014). Ideal body condition improves reproductive performance and influences genetic health in female mink. Anim. Reprod. Sci., 145, 86–98. https://doi.org/10.1016/j.anireprosci.2014.01.004] shows, how important it is for the welfare of the animals.
Table 4 displays the percentage of females showing the stereotypical behavior in pregnancy, i.e. fur chewing. This undesirable effect was observed more frequently in the thinnest and the most obese females (condition groups 1 and 5), in both age groups; in two-year-old females, however, fur chewing was less frequent compared to yearling females. The highest number of barren females were among very thin animals (group 1), in both one- and two-year-old females, and among the obese females (group 5), which also pertained to both age groups. The lowest barrenness, on the other hand, was found among females in the ideal body condition (group 3). We found that the percentage of barren females was more than twice lower in the older females compared to the younger age group of females.
Table
4. The percentAge, years of fur-chewing
females, and barren females in relation to age and body
condition |
|||
Age, years |
Body condition score |
Percentage of females, % – Procent samic, % |
|
fur-chewing – gryzących futro |
barren – jałowych |
||
1 |
1 |
3.85 |
18.52 |
2 |
1.85 |
7.69 |
|
3 |
0.00 |
5.56 |
|
4 |
0.00 |
5.97 |
|
5 |
1.69 |
10.17 |
|
Total – Razem |
1.61 |
9.32 |
|
2 |
1 |
1.64 |
13.21 |
2 |
0.00 |
5.26 |
|
3 |
0.00 |
0.00 |
|
4 |
0.00 |
2.90 |
|
5 |
1.89 |
8.00 |
|
Total – Razem |
0.69 |
3.45 |
|
Total age – Razem wiek |
1.16 |
7.49 |
|
The results of our study also suggest that body condition is a factor in terms of stereotypical behaviors, such as fur-chewing studied here, since their highest incidence was noted in both the thinnest and most obese females (groups 1 and 5). Jeppesen et al. [2004]Jeppesen, L.L., Heller, K.E., Bildsøe, M. (2004). Stereotypies in female farm mink (Mustela vison) may be genetically transmitted and associated with higher fertility due to effects on body weight. Appl. Anim. Behav. Sci., 86, 137–143. https://doi.org/10.1016/j.applanim.2003.11.011 found that stereotypy-affected females were lighter in body weight, as compared with unaffected females, yet they were characteristic for a higher fertility, lower barrenness rates, larger litters and a lower pre-weaning mortality of the offspring. Similar pattern emerged in our previous analysis of mink body condition in relation to male mating behavior [Felska-Błaszczyk et al. 2017Felska-Błaszczyk, L., Dziadosz-Styś, M., Ławrów, N. (2017). Body condition of male farm mink (Neovison vison) during a mating season. Folia Pomer. Univ. Technol. Stetin., Agric., Aliment., Pisc., Zootech., 334 (42) 2, 29–34. https://doi.org/10.21005/AAPZ2017.42.2.03]. Namely, no fur-chewing was observed among ideal-condition males, which otherwise was very common in the groups of heavy and obese animals. On the contrary, the pattern of aggressive behavior incidents was reversed; aggression was the most common among the thinnest males, but also those with ideal condition. About a half of such aggression incidents only happened among obese males. Mason [1993]Mason, G.J. (1993). Age and context affect the stereotypies of caged mink. Behaviour, 127 (3-4), 191–229. https://doi.org/10.1163/156853993X00029 suggests that stereotypic behaviors may be a result of increased appetite and are related to the natural foraging behavior; this may explain why obese animals, which obtain reduced rations before the mating season, exhibit abnormal behaviors. This idea was also supported by Malmkvist et al. [2013]Malmkvist, J., Palme, R., Svendsen, P.M., Hansen, S.W. (2013). Additional foraging elements reduce abnormal behaviour – fur-chewing and stereotypic behaviour – in farmed mink (Neovison vison). Appl. Anim. Behav. Sci., 149, 77–86. https://doi.org/10.1016/j.applanim.2013.10.001, who noted more cases of fur-chewing during the period of restricted feeding.
Body condition was of greater importance in relation to reproduction performance in yearling females, where the largest litters and highest rates of live-born and weaned per litter were recorded in females of ideal condition. In both age groups, the shortest diapause gestation periods were noted in the thinnest females, i.e. in group 1. The fur-chewing behavior was more often found in the extremes, the thinnest and obese females; these two groups also exhibited the highest barrenness rate. On the other hand, animals of ideal condition had the lowest percentage of fur-chewing behaviors and barrenness. These results suggest that both obesity and emaciation should be avoided in the breeding stock. Both adequate body condition evaluation and application of appropriate feeding will help to accomplish this task.
The Authors wish to thank Mr Maciej Buczek for his kind permition to carry out the observations on his farm, and Małgorzata Dziadosz-Styś, PhD, a professional mink selection expert, for scoring the condition of the animals. We also thank Piotr Błaszczyk, PhD, for his scholarly translation of the manuscript into English.
Received: 16.09.2020
Accepted: 16.09.2020
Published online: 16.09.2020
Accesses: 1034
Felska-Błaszczyk, L., Seremak, B., (2020). Body condition of female mink (Neovison vison) affects reproduction performance and behavior in pregnancy and nursing. Acta Sci. Pol. Zootechnica, 19(3), 23–30. DOI: 10.21005/asp.2020.19.3.03.