Genetics of Cattle, The

Dorian Garrick, Anatoly Ruvinsky, Dorian J Garrick, Anatoly Ruvinsky

• Publisher: CAB International
• Year: 2014
• Print ISBN: 9781780642215
• eBook ISBN: 9781789244038
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Veterinary Medicine
• Index: Biological Sciences

Since the time of domestication more than 10, 000 years ago, cattle have played an increasingly crucial role in the development of human civilizations. Progress has been quite remarkable since the turn of the century; the sequencing of the bovine genome in 2009 launched new avenues for furthering our understanding of theoretical and practical aspects of cattle genetics.Covering a vast array of questions, this book reviews major topics from molecular and developmental genetics, disease resistance and immunogenetics to genetic improvement of dairy and beef breeds, addressing all current problems in the field. This second edition includes a new team of authors and completely new chapters on the genetics of fat production, nutrition, feed intake and efficiency, growth and body composition. Fully updated throughout, it provides a valuable resource on cattle genetics for researchers, breeders, veterinarians and postgraduate students.

1	Systematics and Phylogeny of Cattle

AlexandreHassanin

Université Pierre et Marie Curie and Muséum national d’Histoire naturelle, Paris, France

Introduction

Systematic Position of the Genus Bos

Description of Bos Species

Bos primigenius Bojanus, 1827

Bos bison Linnaeus, 1758

Bos gaurus C.H. Smith, 1827

Bos javanicus d’Alton, 1823

Bos mutus (Przewalski, 1883)

Bos sauveli Urbain, 1937

Phylogenetic Relationships Among Species of Bovina

Classifications of the tribe Bovina based on morphology

Molecular phylogenies

Fossil Record and Biogeography

Rapid radiation and dispersal of Bovina during the Middle Pliocene

Evolution of the yak–bison lineage in the northern hemisphere

Acknowledgements

References

Introduction

Cattle belong to the subtribe Bovina, a taxonomic group represented by a single genus, Bos , which contains six wild species that were widely distributed in the Palearctic, Nearctic and Indomalayan regions during the Late Pleistocene and Holocene epochs (Plate 1): (i) Bos primigenus – aurochs (now only represented by domestic forms, humpless cattle and humped cattle or zebu); (ii) Bos bison – American bison (in the western half of North America) and European bison (reintroduced in Poland and a few adjacent countries); (iii) Bos gaurus – gaur (in India and mainland Southeast Asia); (iv) Bos javanicus – banteng (in Southeast Asia); (v) Bos mutus – yak (throughout the Tibetan Plateau); and (vi) Bos sauveli – kouprey (formerly in northern and eastern Cambodia and adjacent countries). The present classification differs from that of the IUCN (2012) by the fact that American and European bison are not considered as two separate species of the genus Bison , but are treated as two subspecies of Bos bison (see below for details).

The most fascinating aspect in the evolution of Bos is that four species have been domesticated since the Neolithic period: B. primigenius , B. mutus , B. javanicus and B. gaurus . Today, there are more than 1.5 billion cattle and zebu around the world (FAO, 2011), 14 million domestic yaks in the Tibetan Plateau and adjacent Asian highlands (Leslie and Schaller, 2009), 2.6 million Bali cattle, a domesticated banteng of Indonesia (Martojo, 2012) and more than 100,000 mithun (or gayal), a domesticated form of gaur found in the hill regions of Bangladesh, Bhutan, northeast India, Myanmar and China (Simoons and Simoons, 1968; Mondal et al., 2010). Domestic cattle provide an important part of the food supply for many of the world’s people, either as livestock for meat or as dairy animals for milk. In many rural areas, they are still used as draught animals. Before the Neolithic period, populations of wild cattle were very successful and widely distributed across Europe, North Africa, Asia and North America (Plate 1). Today, domestic forms are present on all arable land on Earth, whereas wild species are restricted to small and isolated populations in a few countries. The aurochs, Bos primigenius , which was the ancestor of most breeds of domestic cattle, became extinct in 1627 (Van Vuure, 2005). Field scientists have not reported a living specimen of kouprey (B. sauveli ) in Southeast Asia since the 1980s, suggesting that it is also extinct (IUCN, 2012).

Despite the obvious importance of cattle in the emergence and development of human civilizations, several aspects of their evolutionary history still remain poorly understood. In this chapter, I review the systematic position of the genus Bos , give a brief description of wild species and discuss ancient and recent phylogenetic hypotheses of interspecies relationships. I also propose a biogeographic scenario explaining their past and current geographic distributions.

Systematic Position of the Genus Bos

Cattle belong to the order Cetartiodactyla (Fig. 1.1), which is the second most diversified order of large mammals after Primates (IUCN, 2012). Members of this taxonomic group were originally divided into two different orders: Artio­dactyla and Cetacea (e.g. Wilson and Reeder, 2005). Artiodactyls are even-toed ungulates including ruminants, pigs, hippos and camels. They were originally present on all continents, except Antarctica and Australasia, and most domestic livestock come from this group, including cattle, sheep, goats, pigs and camels. They are characterized by two main limb features: a paraxonic foot, which means that the axis of the limb support passes between the third and fourth digits; and in the ankle, the astragalus is ‘double-pulleyed’, i.e. with a trochlea for the tibia and an opposing trochlea for the navicular, which enhances hind limb flexion and extension and allows very limited lateral rotation of the foot. Cetaceans include whales, dolphins and porpoises. All are marine animals except a few species of freshwater dolphins. The common ancestor of Cetacea acquired many adaptations for an aquatic life, such as a fusiform body, forelimbs modified into flippers, no hindlimbs or rudiments and a tail fin (fluke) used for propulsion (Muizon, 2009; Uhen, 2010).

Fig. 1.1. Systematic position of the genus Bos . The tree is a chronogram, which means that branch lengths are proportional to divergence times. A time scale is provided at the bottom. Divergence times were deduced from the molecular studies of Meredith et al. (2011) and Hassanin et al. (2012). The number of species is indicated on the nodes for higher taxa, and between round brackets for terminal taxa(data extracted from IUCN, 2012).

Molecular studies have recovered a sister-group relationship between cetaceans and hippos, indicating that Artiodactyla is paraphyletic (Irwin and Arnason, 1994; Gatesy et al., 1996; Montgelard et al. , 1997). In addition, they have shown that Ruminantia, Cetacea and Hippopot­amidae form a clade named the Cetruminantia by Waddell et al. (1999) (e.g. Shimamura et al. ,1997; Gatesy et al. , 1999; Hassanin et al., 2012). To render the classification compatible with the molecular phylogeny, Montgelard et al. (1997) proposed to place all species of Artiodactyla and Cetacea into the same order, called Cetartiodactyla. After several years of controversy between molecular biologists and morphologists, a paraxonic foot and a double-pulley astragalus were found in Eocene whales (Gingerich et al., 2001), confirming that cetaceans evolved from terrestrial cetartiodactyls.

Cattle belong to the suborder Ruminantia (Fig. 1.1), which is the most diversified group of Cetartiodactyla, with 214 species related to goats, sheep, deer, pronghorn, giraffes and chevrotains. Ruminants are herbivores, which are primarily defined by rumination, i.e. the digestion is done through a process of regurgitation, rechewing and reswallowing of foregut digesta (Mackie, 2002). Since this process greatly facilitates the digestion of plant fibres, it is clear that rumination largely explains the evolutionary success of ruminants. All ruminants are able to digest cellulose through the enzymes produced by various microorganisms (bacteria and eukaryotes, such as ciliates and fungi) that are contained in the rumen, the most developed compartment in their stomach. The ruminant stomach is composed of three other compartments: the reticulum, omasum and abomasum. The reticulum retains particles larger than 1 mm in the rumen (Zharova et al., 2011). The main function of the omasum remains little known, but it filters particles depending on their size, serves as a suction pump controlling the flow of digesta (liquid and particles) between the reticulum and abomasum, facilitates the reabsorption of water, volatile fatty acids, ammonia, sodium, potassium and carbon dioxide, and participates in fibre digestion (Hackmann and Spain, 2010). The last compartment, the abomasum, corresponds to the glandular stomach: secreting acid, its function is very similar to that of the stomach of monogastric mammals such as humans.

Ruminants have well-adapted teeth characterized by the presence of an incisiform lower canine, which is adjacent to the lower incisors, and a horny pad that replaces the upper incisors. All modern and fossil representatives of the group are diagnosed by an osteological autapomorphy, which corresponds to the fusion of the cuboid and navicular bones in the tarsus. Molecular studies have confirmed the monophyly of Ruminantia, as well as the major division between Tragulina and Pecora (Hassanin and Douzery, 2003; Matthee et al. , 2007; Hassanin et al., 2012). The infra-order Tragulina is represented by only a few species of chevrotains, which are found in tropical forests of the Old World. The infra-order Pecora contains all other families, i.e. Bovidae (see below), Cervidae (deer), Moschidae (musk deer), Giraffidae (giraffes and okapi) and Antilocapridae (pronghorn). According to the most recent estimations (Hassanin et al., 2012), Pecoran families diverged rapidly from each other at the Oligocene/Miocene boundary, between 27.6 ± 3.8 Ma and 22.4 ± 2.4 Ma. During the Early Miocene, most habitats in Western Europe and Africa were forested; whereas those of Eastern Europe, Asia and North America were more open (Prothero and Foss, 2007). The spread of open habitat grasses at the Oligocene/Miocene was promoted by a global environmental change, when the warming Late Oligocene was interrupted by a brief but deep glacial maximum at the Oligocene/Miocene boundary (Stromberg, 2005). All these paleoecological data suggest that the emergence of modern pecoran families took place in the northern hemisphere, most probably in Eastern Eurasia. Then, the families dispersed and diversified rapidly: Antilocapridae and a group of extinct Moschidae (Blastomery­cinae) entered into North America; Cervidae and other Moschidae stayed in Eurasia; Bovidae and Giraffidae appeared suddenly throughout the Old World (Prothero and Foss, 2007).

Cattle belong to the family Bovidae (Fig. 1.1), which is the most successful family of the suborder Ruminantia (139 species). Bovids are characterized by the structure of the horns. Present in all males and sometimes females, these consist of a permanent bone core covered by a non-branched and non-deciduous sheath of keratin. Wild representatives of the family are found on all continents except Australia, Antarctica and South America. Most older classifications recognize between five and eight subfamilies within the Bovidae (e.g. Simpson, 1945; McKenna and Bell, 1997; Wilson and Reeder, 2005), but molecular studies have concluded there exists a major divis...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Content
• Contributors
• Preface
• 1 Systematics and Phylogeny of Cattle
• 2 Genetic Aspects of Domestication
• 3 Breeds of Cattle
• 4 Molecular Genetics of Coat Colour Variation
• 5 Genetics of Morphological Traits and Inherited Disorders
• 6 Cytogenetics and Chromosome Maps
• 7 Bovine Genomics
• 8 Bovine Immunogenetics
• 9 Genetics of Disease Resistance
• 10 Molecular Biology and Genetics of Bovine Spongiform Encephalopathy
• 11 Genetics of Behaviour in Cattle
• 12 Genetics of Reproduction in Cattle
• 13 Modern Reproductive Technologies and Breed Improvement
• 14 Developmental Genetics
• 15 Genetic Improvement of Dairy Cattle
• 16 Molecular Genetics of Milk Protein Production
• 17 Genetics of Fatty Acid Composition in Bovine Milk and Beef
• 18 Genetic Improvement of Beef Cattle
• 19 Influence Genomic Prediction and Genome-wide Association Studies in Beef and Dairy Cattle
• 20 Genetics of Feed Intake and Efficiency
• 21 Genetics of Growth and Body Composition
• 22 Genetics of Meat Quality
• 23 Genetic Aspects of Cattle Adaptation in the Tropics
• 24 Standard Genetic Nomenclature
• Index