Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
2010
Volume 13
Issue 4
Topic:
Veterinary Medicine
ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Jamroz D. , Kubizna J. 2010. CHEMICAL COMPOSITION OF DIGESTIVE TRACT CONTENTS AND CHARACTERISTICS OF FEMUR BONE OF BROWN HARE (Lepus europaeus Pallas,1778), EJPAU 13(4), #24.
Available Online: http://www.ejpau.media.pl/volume13/issue4/art-24.html

CHEMICAL COMPOSITION OF DIGESTIVE TRACT CONTENTS AND CHARACTERISTICS OF FEMUR BONE OF BROWN HARE (LEPUS EUROPAEUS PALLAS,1778)

Dorota Jamroz, Janusz Kubizna
Department of Animal Nutrition and Feed Management, Wrocław University of Environmental and Life Sciences, Wrocław, Poland

 

ABSTRACT

Thirty and seven hares catched in late Autumn and Winter were examined for the composition of digesta and for characteristics of femur bone. The very great variability among individuals was observed in analysed parameters. The average pH values of stomach content reached 3.4, in duodenum and in small intestine reached 6.4 and 6.3, respectively. Concentration of crude protein varied at range from 2.2 to about 7.7% and the crude fibre in content of stomach amounted to 24% in DM basis, in duodenum (2.6% in DM) and in subsequent small intestine parts. Concentration of  K, Cu and Zn gradually decreased during the passage of digesta through the intestine. The calcium content clearly increased along the gastrointestinal tract. The average crude ash content in femur bones was relatively high and amounted 43%. Conducted investigations confirms the substantial technical problems in estimation of nutritional statements and/or its tendencies in hare' organism.

Key words: hare, composition of digesta, femur bone.

INTRODUCTION

The European brown hares (Lepus europaeus, Pallas 1778) until recently were the very popular game animals living on the area of whole Europe, except Norway, northern Sweden, Finland and Russia. In Asia the range of this species occurrence is reaching the Ob river. In Poland the brown hare occurs on whole area of country [28].

During the recent decades in Poland as well as in other European countries the drastic decrease of hares number has been noted. In the investigations the various causes of decline in the hares population were considered. Many scientists hypothesized that this fall may result from the large number of predators, mainly from the violently enlarging the red fox (Vulpes vulpes L.)  population as an effect of rabies prevention or because of numerous predatory birds of whose diet consist of, among other, hares [23]. The cause of such situation may be also the increase of environment contamination with the harmful and heavy metals and with the different chemicals, in them also substances used for plants protection. Seasonal changes of climate [29] as well as the intensive mechanization of agricultural practices  and also the number of shooting these animals may be the factors affecting the hare population. Giardini et al. [6] studied the  effect of  huntings frequency on the number of hares in the central Italy. There the clear relationship between number of huntings on these rodents and decrease of their population during the hunting season were observed. However, during the seven years of  investigations the density of the hares' population was on the similar level.

Many scientists are looking for the causes of decrease of the brown hares population in enlarged number of parasitic infestations and other diseases decimating them. In these animals the parasitic infestations [20,22], myxomatoses [2] and other different diseases [14] were detected. As the most important the harmful activity of the EBHS (European Brown Hare Syndrome) virus is considered [4].

The hares are eating exclusively vegetable feeds, made up of the almost all cultivated plant species in different stages of their vegetation, grasses, herbs, buds and young shoots [10,16,19]. In the periods of reduced availability of plants they consume  even the bark of a trees and shrubs [11,17,18]. These animals almost do not drink water, because they efficiently use the moisture present in the eaten biomass as well as use water from the dew and rains.

From the investigations it could be concluded that the clear, positive dependence exists among the accessible biomass from the plants' vegetative parts and number of the individuals of Leporidae population on the definite area [9]. Progressive specialization in agricultural practices and large acreages of monoculture cultivations cause the essential limitation of the diet variety and competition for food occurring among herbivorous rodents [8,27,28].

The purpose of investigations (part of the greater scientific project) was to analyse the changes in the contents of hares digestive tract during the Autumn and Winter as well as to evaluate some parameters of their femoral bone.

MATERIALS AND METHODS

Investigations were carried out in the period of 2006 to 2008. Experimental material consist of 37 hares of both sexes, catched mainly in the period from October to January every year. The majority of animals come from the Center for the Research on the Forest Environment and Game Animals Breeding in Złotówek belonging to the Wroclaw University of Environmental and Life Sciences. The area of Center amounted 8.3 ha (breeding farm) and 35 ha were devoted for hunting purposes. Most of area was covered with forest (79.5%) and the meadows poses only 7.3%. Moreover, the additional feed mixture Mix Optima G 109 was given to hares in late Autumn and in the Winter time (Table 1).

Table 1. Composition of feed mixture used as additional feed during Autumn and Winter

Compounds

%

Chemical composition

%

Wheat

30.4

Crude protein

16.94

Maize

30.0

Crude fibre

7.99

Wheat bran

20.0

Crude fat

3.12

Soya bean meal

10.0

Ca

1.06

Rapeseed meal

6.0

P total

0.95

Chalk

2.2

   

Monocalcium phosphate

0.5

   

Premix

0.5

   

Salt

0.4

   

The catched animals, used for genetic, health and nutritional investigations had the average body mass ca. 3.5–3.7 kg and were in good condition [13,26]. After  slaughter, from each carcass the stomach and small intestine with duodenum were taken out as well as the femoral bone for its mineral composition were prepared out. In the content of digestive tract the substantial chemical components, and in the bone the main physical parameters and macro- and some microelements were estimated using standard methods [1]. The nitrogen was evaluated using the Kjeldahl method and Kjeltec 2300 Foss Tecator (Sweden) apparatus, the content of crude protein was calculated by the multiplication of nitrogen x 6.25, crude fat was determined by the etheric extraction in the Büchi Extraction System B 811. The content of crude fibre was evaluated using the Henneberg-Stohmann method with the Fibertec Tecator (Sweden) apparatus. The phosphorus content in samples of digesta was determined after earlier mineralization, using spektrofotometr Specol 11 (Carl Zeiss, Jena) at the wave length of  470 nm. Other minerals were estimated using the atomic absorption spectrophotometer AAS-3 EA-30 (Carl Zeiss, Jena). The pH value of the was estimated using N-512 pH-meter.

The sex of animals was established on the basis of gonads identification during sampling of  material after the animals' slaughter.

Numerical data  are presented in tables as average values and there the sex of animals was not taken into consideration. There the values of standard deviation as well as range of changeability of data were also given. All experimental procedures were advised by the Local Ethic Commission for the experiments with animals.

RESULTS AND DISCUSSION

The specialists in the fields of grassland, collaborators in the realized research project, have identified the most common grass and herbs species that occur on the area where the hares were catched. They were: Holcus lanatus, Pteridinum aquilinum Avena sativa, Milium effusum, Deschampsia caespitosa, Deschampsia flexuosa, Poa pratensis Anthoxanthum odoratum, Calamagrostis arundinacea, Molinia coerulea, Carex spp. [30]. Moreover, at the period of sampling the feeding base becomes poor. So, the hares fed the shoots and bark of different trees and shrub species, such as Vacinium myrtillus, Betula pendula, Prunus padus, Rubus spp., Viburnum opulus, Rubus ideaus,  Alnus glutinosa and Prunus spinosa [30]. In these feed constituents the crude protein varied between 3 and 15.5% and the crude fibre varied between 16 and 36% depending on the species and parts of plant.

The content of the particular parts of digestive tract determined in own investigations was to a high extent homogenated and contained a high amounts of water, despite of fact that animals were fed mainly dry or wilted plants. It was impossible to obtain some solid fragments of taken feed permitting identification of plant' kinds and species. In digesta the average dry matter content (DM) decreased from 18.4% in stomach to 12.8% in duodenum and in small intestine.

The very great variability was stated in chemical composition of digesta. The average values of other chemical compounds of the content of particular parts of digestive tract is presented in Table 2. The average pH values of stomach content reached 3.4; in duodenum and in small intestine reached 6.4 and 6.3, respectively. However, there the very great variability of such parameter was stated. Concentration of crude protein (CP) varied at range from 4.2 to about 7.7%. This very low level of CP result from the available feed – trees and shrubs and plants that becomes dry at the end of Autumn.

Table 2. Content of the chemical components in fresh contents (%) and in dry matter (g kg-1) of the segments of digestive tract

Item

pH value

Dry matter
%

Crude ash

Crude protein

Crude fat

Crude fibre

%

in DM

%

in DM

%

in DM

%

in DM

Stomach

Average

3.38

18.44

1.60

9.31

4.21

23.77

1.10

6.18

4.52

24.52

±SD

0.68

5.77

1.10

5.83

1.30

6.75

0.48

2.67

1.59

5.49

Min.

2.25

4.62

0.52

2.77

1.21

11.70

0.19

1.97

1.11

14.29

Max.

5.15

28.9

6.16

29.06

6.03

40.83

2.05

13.20

7.96

34.69

 

Duodenum

Average

6.45

12.84

1.00

8.59

7.77

60.94

0.37

4.84

0.23

2.65

±SD

1.40

4.87

0.43

4.19

4.17

11.55

0.31

3.45

0.16

1.25

Min.

4.25

2.58

0.28

2.66

1.22

38.46

0.09

0.96

0.06

1.27

Max.

8.47

20.12

1.96

20.54

14.62

73.58

0.71

9.04

0.47

4.47

 

Small intestine

Average

6.27

12.79

1.04

8.65

7.65

60.64

0.56

4.63

0.44

4.29

±SD

0.97

4.00

0.43

3.43

3.05

12.15

0.47

4.39

0.27

3.00

Min.

4.63

3.81

0.12

0.75

2.23

37.67

0.01

0.17

0.04

1.05

Max.

8.02

18.74

1.91

15.37

12.33

86.71

1.4

12.41

0.91

9.46

Interesting results were obtained in the analysis of the crude fibre in content of stomach (24% in DM), the duodenum (2.6% in DM) and 4.2% in DM in subsequent small intestine parts. In the case of observed reduction of digesta density it may indicate the fast passage of this fraction through the intestine. Such thesis may be confirmed by the investigations carried by Stott [25], who compared the rate of passage of digesta through the digestive tract of the rabbit and hare. Cited author stated that the passage rate is considerably faster in hare despite of the relatively smaller stomach and colon as accounted to the body weight. Hares are the remarkably herbivorous animals, however plant structural substances are poorly digested by them. Stott [25] stated, that the rabbits use the scissors to cutting and crushing of twigs, while the hare's nutritional behaviour depends on the stripping off the bark from plant, what permits more efficient use of soluble carbohydrates stored in the vascular rays. Garcia et al. [5] have studied the effect of source of fibre on the digestibility of cellular walls and on the rate of digesta passage through the rabbit intestine. There was stated that the source of fibre had the influence on the DM intake as well as on the apparent digestibility of DM, NDF, ADF, NSP. Moreover, from the investigations by Björnhag [3] it was concluded that one of functions of digestive tract in these rodents is the fast excretion of hardly digested structural parts of fodder, and keeping of easily digested fragments, which are further fermented in the colon. Hardly digested structural elements can make up the serious ballast in organism and may decrease the motoric ability of the hare, which must to avoid the meetings with foxes, which are main predators on them [15]. On the understanding that the rate of fox' and hare' run is similar the load of intestine with a hard digestible fibre can be very unfavourable for hare and may decrease his chance to survive.

Average content of phosphorus in dry matter of grass species varied at limits 0.1–0.2%, Ca – 0.1–0.4%; Mg 0.1–0.3; Na 0.01–0.19% while in trees and shrubs the concentration of these minerals was as follows: P – 0.04–0.12; Ca – 0.12–1.0; Mg – 0.13–0.30; Na 0.03–0.07% [30]. The concentration of mineral components in content of separate segments of digestive tract is presented in Table 3. Only a small amounts of data on the chemical composition of content were found in available literature, therefore the interpretation of obtained results is very difficult. However, on the basis of these data the different course of changes of minerals concentration could be seen. Concentration of  K, Cu and Zn gradually decreased during the passage of digesta through the intestine. The calcium amount clearly increased, clear is also rise of the concentration of sodium in duodenum and small intestine, what can be connected with decrease of dry matter in content of these parts of digestive tract. Similar changes of the minerals concentration were observed in investigations carried out by Staaland et al. [24].

Table 3. Contentration of the minerals in fresh content  and in g kg-1 of crude ash (CA) in content of the segments of digestive tract

Item

Crude ash
g/kg

Ca

P

Na

K

Mg

Cu

Zn

Mn

g kg-1

mg kg-1

%

in CA

%

in CA

%

in CA

%

in CA

%

in CA

%

in CA

%

in CA

%

in CA

Stomach

Average

15.95

0.34

33.1

1.16

92.5

0.27

23.2

0.85

68.8

0.19

16.1

2.88

218.3

14.86

4.2

33.35

2888.3

±SD

11.01

0.31

43.7

0.57

68.9

0.17

22.0

0.44

53.8

0.13

13.3

2.27

234.1

10.82

1189.5

31.24

2856.9

Min.

5.20

0.04

1.1

0.33

22.4

0.09

3.7

0.3

17.4

0.08

2.6

0.59

28.5

1.38

168.3

2.05

105.4

Max.

61.60

1.31

175.0

3.25

361.1

0.89

108.5

2.6

288.9

0.61

50.0

11.45

1272.2

57.63

6403.3

109.55

8677.4

 

Duodenum

Average

9.99

0.45

70.3

1.11

195.7

0.48

75.4

0.56

116.0

0.13

25.1

2.56

482.7

8.50

1429.1

20.30

3799.4

±SD

4.30

0.15

26.7

0.37

159.0

0.31

52.9

0.44

157.5

0.05

23.6

0.82

395.6

2.76

799.5

9.79

3845.9

Min.

2.80

0.25

39.8

0.52

98.1

0.1

14.7

0.16

30.2

0.07

10.6

1.7

227.1

4.72

674.3

7.12

1047.1

Max.

19.60

0.62

110.7

1.45

517.8

0.94

171.4

1.21

432.1

0.2

71.4

3.71

1200.0

12.89

2896.4

32.24

11514.

 

Small intestine

Average

10.41

0.44

110.2

1.27

378.8

0.85

251.6

0.50

210.7

0.13

49.9

2.44

818.1

8.08

2188.5

21.26

6656.5

±SD

4.53

0.12

127.4

0.41

541.9

0.31

380.0

0.36

399.8

0.08

90.0

0.83

1261.1

1.75

2876.1

7.17

9604.8

Min.

1.20

0.28

30.8

0.57

62.6

0.41

52.7

0.18

19.6

0.06

6.6

1.45

157.6

5.36

676.9

8.45

1111.8

Max.

19.10

0.59

366.7

1.77

1475.0

1.23

1025.0

1.23

1025.0

0.28

233.3

4.04

3366.7

10

8025.0

31.03

25858.3

Femoral bone is the largest and strongest bone in mammalian body. Data related to the physical features and content of mineral components are given in Table 4 and 5. In estimation of average values the effect of the sex was not taken into account. In the investigations carried out by Sobocińska-Janaszek [21] the influence of the sex on the physical parameters of long bones was not confirmed. Moreover, in other investigations no influence of hare' sex on the length of another bone (sternum) was stated [12]. Although the great variability of mineral contents in digesta was stated in own investigations, the parameters characterised femur bones pointed on the similar length, weight and thickness.

The average crude ash content in femur bones was relatively high and amounted to 43%; calcium level amounted to ca. 296 g and phosphorus ca. 123 g/kg DM (Table 5). The ash and minerals contents, especially Ca level in DM, are higher in hares in comparison to the other animals, e.g. young broilers. The P-level was distinctly lower in hares as compared to the chickens (123 g vs. 170 g/kg DM) [7].

Table 4. Physical parameters – femur bone

Femur bone

Length
mm

Weight
g

Thickness

Volume
cm3

diaphysis
mm

epiphysis
mm

Average

137

17.7

9.69

13.06

15.00

±SD

4.72

1.5

0.70

1.08

1.26

Min.

127

15.3

9

11.5

14

Max.

148

20.5

11

15.5

18

Table 5. Content of mineral elements – in crude ash of femur bone
 

Crude ash

Ca

P

Na

K

Mg

Cu

Zn

Mn

%

g kg-1

mg kg-1

Average

42.90

296.3

123.0

5.95

4.79

4.79

31.7

360.6

44.8

±SD

3.61

14.1

27.7

3.42

1.67

0.47

13.0

63.0

12.0

Min.

38.98

273.3

97.4

3.12

2.61

4.01

15.2

288.2

20.2

Max.

50.01

317.2

171.8

13.59

7.92

6.08

68.2

519.2

63.5

The selected data obtained for randomly chosen hares, catched in Autumn and Winter indicate the very great variability of chemical composition of digesta despite of similar nutritional base consisting of dry grasses and other plants, barks of trees, shrubs and small amounts of consumed feed mixture. The free choice of feed made impossible the precise determination of nutrients utilisation in these animals and pointed on the substantial difficulties in estimation of some nutritional regularities in these animals.

ACKNOWLEDGEMENTS

The investigations were realized as the part of the grant No 0607/R/P01/2007/03 – The protection of perishing species in Poland considering hare (Lepus europaeus Pallas, 1778) (Ochrona ginącego gatunku w Polsce na przykładzie zająca szaraka (Lepus europaeus Pallas, 1778)).

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Accepted for print: 3.11.2010


Dorota Jamroz
Department of Animal Nutrition and Feed Management,
Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Chełmońskiego 38 C, 51-631 Wrocław, Poland
phone: +48 71 3205 828
fax: +48 71 3205 965
email: dorota.jamroz@up.wroc.pl

Janusz Kubizna
Department of Animal Nutrition and Feed Management,
Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Chełmońskiego 38 C, 51-631 Wrocław, Poland
email: janusz.kubizna@up.wroc.pl

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