Carrier bulls are designated with a w genetic defects

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Unformatted text preview: myeloencephalopathy – A wasting away of the peripheral nerves leading to loss of locomotion – Heterozygotes appear to have higher milk yield, a PTA milk advantage of over 740 pounds! • Carrier bulls are designated with a W Genetic Defects of Brown Swiss • Spinal Muscular Atrophy – Calves lose their ability to stand on their rear legs by 3-6 weeks of age and their muscles atrophy • A popular sire- Jetway is a carrier of this defect which apparently is not common in the breed. Genetic Defects of Jersey Cattle • Recto-vaginal constriction – viable but difficult to AI and to calve due to this constriction • Limber leg – live calves are never able to stand – found in calves linebred to Marlu Milady GENETIC DEFECTS FOUND IN BEEF CATTLE BREEDS • Arthrogryposis (bent leg/cleft palate) • Mannosidosis • Muscular hypertrophy (doublemuscling) • Dwarfism • Osteopetrosis (marble bone disease) • Hydrocephalus • Hypotrichosis • Protoporphyria (pink tooth) • Syndactylism (mule-foot) Arthrogryposis (bent leg/cleft palate) • Lethal when homozygous recessive • Calves are born with a combination of malformed legs and cleft palates • Has been found in Charolais cattle • Cases may also occur spontaneously • Bluetongue and bovine virus diarrhea (BVD) viruses also appear to be common causes of this condition Mannosidosis • Mannosidosis is a lyosomal storage disease associated with accumulation and storage of the enzyme amannosidase in Angus cattle. • It is characterized by ataxia, lack of coordination, head tremor, aggression, and reduced growth. • Calves may be affected at birth, but clinical signs usually do not appear until they are several weeks or months of age. The most affected cattle die within the first 12 months of life. Muscular HypertrophyDouble Muscling • This trait is found in the Angus, Charolais, Piemontese, and Belgian Blue breeds • It appears to be incompletely dominant in mode of inheritance • Double-muscled animals usually have problems giving birth and are more sensitive to heat stress. • Meat to bone ratio in the carcass is substantially increased Why use the double-muscling gene? • Heterozygotes have superior muscling without the undesirable characteristics of the homozygotes – Higher muscle/bone with adequate marbling and tenderness • Thus, homozygous DM bulls can be effectively used as terminal-cross sires A Terminal Crossbreeding System for Beef Cattle Belgian Blue Bulls Braford Co...
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