Digestive physiology and feeding behaviour of equids a comparative approach

Transcription

1 Digestive physiology and feeding behaviour of equids a comparative approach Marcus Clauss Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Switzerland Gent 2013

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5 8 species Large herbivore diversity: Equids

6 Digestive tract: Equids from Stevens und Hume (1995), Clauss et al. (2008)

7 Large herbivore diversity: Perissodactyls 16 species

8 Digestive tract: Perissodactyls from Stevens und Hume (1995), Clauss et al. (2008), Müller et al. (in prep.)

9 Large herbivore diversity: hoofed mammals 16 species > 300 species

10 Digestive tract: Perissodactyls vs. Artiodactyls Stevens und Hume (1995), Clauss et al. (2008), Schwarm et al. (2010), Müller et al. (in prep.)

11 Large herbivore diversity: hoofed mammals 16 species > 300 species

12 Large herbivore diversity: Europe

13 Large herbivore diversity: Europe

14 Large herbivore diversity in deep time: Perissodactyls

15 Large herbivore diversity in deep time: Perissodactyls Chalicotheres

16 Large herbivore diversity in deep time: Perissodactyls Brontotheres Chalicotheres

17 Large herbivore diversity in deep time: Perissodactyls Brontotheres Chalicotheres

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25 from Janis et al. (1994)

26 from Janis et al. (1994)

27 from Janis et al. (1994)

28 from Janis et al. (1994)

29 from Janis et al. (1994)

30 from Janis et al. (1994)

31 from Janis et al. (1994)

32 from Janis et al. (1994)

33 from Janis et al. (1994)

34 from Janis et al. (1994)

35 from Janis et al. (1994)

36 from Janis et al. (1994)

37 from Janis et al. (1994)

38 from Janis et al. (1994)

39 from Janis et al. (1994)

40 Large herbivore diversity: hoofed mammals 16 species > 300 species

41 Large herbivore diversity: hoofed mammals 16 species > 300 species

42 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times).

43 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times). Days of gestation period (to apparently similar level of precociality) Cattle: app. 280 days Horse: app. 340 days Dromedary: app. 390 days Okapi: app. 440 days

44 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times). Days of gestation period (to apparently similar level of precociality) Cattle: app. 280 days Horse: app. 340 days Dromedary: app. 390 days Okapi: app. 440 days The difference cannot be due to body size!

45 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times). Days of gestation period (to apparently similar level of precociality) Cattle: app. 280 days Horse: app. 340 days Dromedary: app. 390 days nearly extinct in a Okapi: app. 440 days very limited geographical range

46 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times). Days of gestation period (to apparently similar level of precociality) Cattle: app. 280 days Horse: app. 340 days only in extreme, Dromedary: app. 390 days resource-poor Okapi: app. 440 days habitats

47 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times). Days of gestation period (to apparently similar level of precociality) Cattle: app. 280 days rule the world!! Horse: app. 340 days Dromedary: app. 390 days Okapi: app. 440 days

48 Mammal gestation period For any mammal, achieving the same degree of neonatal development in a shorter gestation period if not associated with higher costs should be advantageous (higher fecundity due to shorter generation times). Days of gestation period (to apparently similar level of precociality) Cattle: app. 280 days Horse: app. 340 days Dromedary: app. 390 days Okapi: app. 440 days We would predict that animals with a shorter gestation period should be particularly successful (e.g. in terms of species diversity).

49 (Precocial) Mammal gestation period 1000 Gestation period (d) Body mass (g) from Clauss et al. (2013)

50 (Precocial) Mammal gestation period 1000 Gestation period (d) Body mass (g) from Clauss et al. (2013)

51 (Precocial) Mammal gestation period 1000 Gestation period (d) Body mass (g) from Clauss et al. (2013)

52 Mammal chewing efficiency For any herbivore, increasing chewing efficiency if not associated with higher costs should be advantageous (higher feeding efficiency due to higher digestibility) because there is

53 Mammal chewing efficiency For any herbivore, increasing chewing efficiency if not associated with higher costs should be advantageous (higher feeding efficiency due to higher digestibility) because there is

54 Mammal chewing efficiency For any herbivore, increasing chewing efficiency if not associated with higher costs should be advantageous (higher feeding efficiency due to higher digestibility) because there is and therefore

55 Mammal chewing efficiency For any herbivore, increasing chewing efficiency if not associated with higher costs should be advantageous (higher feeding efficiency due to higher digestibility) because there is and therefore

56 Mammal chewing efficiency 100 MPS (mm) BM (kg) Simple-stomached Nonruminant ff from Fritz et al. (2009)

57 Mammal chewing efficiency 100 MPS (mm) BM (kg) Simple-stomached Nonruminant ff from Fritz et al. (2009)

58 Mammal chewing efficiency 100 MPS (mm) BM (kg) Simple-stomached Nonruminant ff Ruminants from Fritz et al. (2009)

59 Large mammal molar surfaces from Jernvall et al. (1996)

60 Large mammal molar surfaces from Jernvall et al. (1996)

61 Large mammal molar surfaces from Jernvall et al. (1996)

62 Large mammal molar surfaces from Jernvall et al. (1996), Schwarm et al. (2008)

63 Ruminant sorting mechanism from Jernvall et al. (1996), Schwarm et al. (2008)

64 Parallel evolution? Perissodactyls Artiodactyls

65 Parallel evolution? among Perissodactyls Artiodactyls

66 Parallel evolution? among Perissodactyls Artiodactyls Equids Ruminants

67 Parallel evolution? among Perissodactyls Artiodactyls Equids Ruminants achieve comparatively high chewing efficiencies and food intakes

68 Parallel evolution? among Perissodactyls Artiodactyls Equids Ruminants achieve comparatively high chewing efficiencies and food intakes but

69 Advantage ruminants? Due to their superior chewing efficiency, ruminants achieve higher digestibilities... from Clauss et al. (2009; data from Foose 1982)

70 Advantage ruminants? Due to their superior chewing efficiency, ruminants achieve higher digestibilities... from Clauss et al. (2009; data from Foose 1982)

71 Advantage ruminants? Due to their superior chewing efficiency, ruminants achieve higher digestibilities... and therefore do not require as high a food intake.

72 Advantage ruminants? Due to their superior chewing efficiency, ruminants achieve higher digestibilities... and therefore do not require as high a food intake.

73 Advantage ruminants? Because they need to feed more (and do not have rumination breaks ), equids nearly feed continuously.

74 Advantage ruminants? Because they need to feed more (and do not have rumination breaks ), equids nearly feed continuously. Grazing

75 Advantage ruminants? Because they need to feed more (and do not have rumination breaks ), equids nearly feed continuously. Grazing

76 Advantage ruminants? Because do not have rumination breaks, equids have higher ingestive mastication activity.

77 Advantage ruminants? Are horses more susceptible to low food intake than ruminants?

78 Advantage ruminants? Horses cannot achieve the difference between particle and fluid retention (SF selectivity factor) as observed in ruminants.

79 Advantage ruminants? In spite of theoretical concept

80 Advantage ruminants? In spite of theoretical concept no net empirical indication for differentiated passage in horses. from Lechner et al. (2010), Clauss et al. (pers. obs.)

81 Other differences: Calcium digestibility

82 Other differences: Calcium digestibility Phosphorus is supplied directly to microbes via saliva P from Stevens & Hume (1995)

83 Other differences: Calcium digestibility Phosphorus is supplied directly to microbes via saliva P Ca In order to guarantee phosphorus availability in the hindgut, calcium is actively absorbed from ingesta and excreted via urine from Stevens & Hume (1995) hypothesis by Clauss & Hummel (2008)

84 Why equids? Other perissodactyls survive in body size ranges beyond the ruminant range (rhinos) or in absence of ruminant competition (tapirs). Why / how do equids survive (only in the upper ruminant body size range, and only in the grazing niche)?

85 Other differences: Methane production? Methane (l/d) Ruminants Camelid Equids Elephant Wallaby Hyrax Rabbit Guinea pig Body mass (kg) from Franz et al. (2010)

86 Other differences: Methane production? Methane (l/d) Ruminants Camelid Equids Elephant Wallaby Hyrax Rabbit Guinea pig Body mass (kg) from Franz et al. (2010)

87 Other differences: Methane production? Methane (l/d) Ruminants Camelid Equids Elephant Wallaby Hyrax Rabbit Guinea pig Body mass (kg) from Franz et al. (2010)

88 Other differences: Methane production? Methane (%DE) Ruminants Equids Rabbits Guinea pigs Body mass (kg) from Franz et al. (2010)

89 Equid-ruminant facilitation?

90 Digestive advantage for equids? When resources are scarce on African game farms, the ruminants lose condition first but it is when the zebras lose condition that you need to start to worry. (Adrian Shrader, pers. comm.)

91 The traditional view of foregut vs. hindgut fermentation Janis (1976)

92 Do you believe it? if diet quality gets lower, a horse simply eats more

93 Data in sheep

94 The traditional view of foregut vs. hindgut fermentation

95 DMI (g kg d -1 ) Sheep Sheep (this study) Mountain sheep Forage NDF (%DM)

96 DMI (g kg d -1 ) Sheep Sheep (this study) Mountain sheep Forage NDF (%DM)

97 DMI (g kg d -1 ) Sheep Sheep (this study) Mountain sheep Forage NDF (%DM)

98 DMI (g kg d -1 ) Sheep Cattle Bison Banteng/Gaur Yak Water buffalo S. caffer Muskox Forage NDF (%DM)

99 DMI (g kg d -1 ) Sheep Cattle Bison Banteng/Gaur Yak Water buffalo S. caffer Muskox Forage NDF (%DM)

100 DMI (g kg d -1 ) Sheep Cattle Bison Banteng/Gaur Yak Water buffalo S. caffer Muskox Forage NDF (%DM)

101 DMI (g kg d -1 ) Sheep Cattle Donkey Forage NDF (%DM) Meyer et al. (2010)

102 DMI (g kg d -1 ) Sheep Cattle Donkey Forage NDF (%DM) Meyer et al. (2010)

103 DMI (g kg d -1 ) Sheep Cattle Horses Forage NDF (%DM) Meyer et al. (2010)

104 DMI (g kg d -1 ) Sheep Cattle Horses Forage NDF (%DM) Meyer et al. (2010)

105 DMI (g kg d -1 ) Sheep Cattle Horses Wild equids Forage NDF (%DM) Meyer et al. (2010)

106 DMI (g kg d -1 ) Sheep Cattle Horses Wild equids DMI (g kg d -1 ) Sheep Cattle White rhino Indian rhino Black rhino Forage NDF (%DM) Forage NDF (%DM)

107 DMI (g kg d -1 ) Sheep Cattle Horses Wild equids DMI (g kg d -1 ) Sheep Cattle White rhino Indian rhino Black rhino Forage NDF (%DM) Forage NDF (%DM)

108 Misinterpretation of anatomical features? DMI (g kg d -1 ) Sheep Cattle Horses Wild equids DMI (g kg d -1 ) Sheep Cattle White rhino Indian rhino Black rhino Forage NDF (%DM) Forage NDF (%DM) from Stevens und Hume (1995), Clauss et al. (2008)

109 The traditional view of foregut vs. hindgut fermentation Janis (1976)

110 Extant horses are grazers

111 Diet and mesowear Kaiser and Fortelius (2003)

112 Diet and mesowear

113 Diet and mesowear

114 Adapted to abrasive diets

115 Diet and mesowear: zoo vs. wild Difference in score Less abrasion than in the wild More abrasion than in the wild from Kaiser et al. (2009)

116 Diet and mesowear: zoo vs. wild Difference in score Less abrasion than in the wild More abrasion than in the wild from Kaiser et al. (2009), Taylor et al. (in prep.)

117 Wild equids in captivity Similar as in grazing ruminants, few health problems related to nutrition in captive wild equids (because zoo diets are typically more forage dominated?)

118 Wild equids in captivity Similar as in grazing ruminants, few health problems related to nutrition in captive wild equids (because zoo diets are typically more forage dominated?) - Incidents of dental abnormalities (a) Free-ranging (b) Captive from Taylor et al. (in prep.)

119 Wild equids in captivity Similar as in grazing ruminants, few health problems related to nutrition in captive wild equids (because zoo diets are typically more forage dominated?) - Incidents of dental abnormalities Hoyer et al. (2012)

120 Wild equids in captivity Similar as in grazing ruminants, few health problems related to nutrition in captive wild equids (because zoo diets are typically more forage dominated?) - Incidents of dental abnormalities - Hoof overgrowth/laminitis

121 Equid seasonality

122 Wild equids in captivity Similar as in grazing ruminants, few health problems related to nutrition in captive wild equids (because zoo diets are typically more forage dominated?) - Incidents of dental abnormalities - Hoof overgrowth/laminitis - Obesity

123 Equid seasonality

124 Equid seasonality

125 Equid seasonality

126 Wild equids in captivity Similar as in grazing ruminants, few health problems related to nutrition in captive wild equids (because zoo diets are typically more forage dominated?) - Incidents of dental abnormalities - Hoof overgrowth/laminitis - Obesity - Colic - Vitamin E deficiency

127 Conclusion From a nutritional point of view, wild equids appear well understood: (grass) forage diets available at all times, ideally with mimicking seasonal patterns in the wild. How the digestive physiology of equids differs from that of ruminants, especially in terms of minimum intake tolerable and differential digesta movements, remain to be investigated. The sequence, and the mechanisms, of the equid-ruminant diversification and competition in evolution remain to be explained in a way that matches empirical data.

128 thank you for your attention

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