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Waterfowl husbandry and medicine (Proceedings)

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Nov 01, 2010

Taxonomy

Waterfowl belong to the order Anseriformes which has 2 families; Anhimidae (screamers) and Anatidae (ducks, swans, and geese). This section will concentrate on Anatidae. Anseriformes have been domesticated since 2500 BC.

Anatomy and Physiology

Anhimidae
          • South American birds; unwebbed feet, hooked bill; gradual feather molt

Anatidae

Annual or biennial molt
          • Most ducks molt 2x/year and the breeding (nuptial) and non-breeding (winter or eclipse) plumage are distinct. Their plumage may have iridescent colors. Most swans and geese molt 1x/year and all the flight feathers are shed almost simultaneously so birds are unable to fly for 3-8 weeks. Their plumage lacks iridescent colors. All species have a highly developed uropygial (preen) gland

Broad or conical bill with serrated lamellae
          • The bill of ducks has "nail" at end of top beak to facilitate grasping slippery objects and also lamellae along edges to cut or filter food

Bristled tongue and lateral margin processes
          • Interdigitate with the bill lamellae
          • Allows for straining and retention of food particles
          • Facilitates cropping of vegetation

Bill tip organ at tip of upper and lower bill
          • Contains mechanoreceptors = Herbst's corpuscles; bill tips are extremely sensitive
          • Assist with food gathering

Osmoregulation
          • Nasal salt gland dorsal to the eye:Duct opens into the rostral nasal cavity; well-developed in species living in salt or brackish water; salt is extracted from blood and flows as a thick liquid to the bill tip
          • Retroperistalsis of urine from the ureter into the coprodeum and distal GIT; additional water resorption before excretion

Musculoskeletal
          • Totipalmate (all four toes are connected by webbing) and are really designed for swimming, not for walking.
          • Excavated cavity in the cranial sternum: swans; contains elongated tracheal coils
          • Swans have the most ribs (9 attached pairs) and cervical vertebrae (25)

Respiratory
          • syringeal bulla: male ducks; asymmetrical distension of the left syrinx; involved in vocalization
          • Nares communicate

Reproduction

Generally lay 3-10 eggs/clutch with an incubation period that ranges from 21-44 days, depending on species. Their chicks are precocious and can swim, walk, and feed themselves almost from birth. They are born covered in down and fledging usually occurs at 30-90 days. They have a relatively long life span; approximately 10+ years for ducks and 25+ years for geese and swans. The clinical chemistry values vary with species and should also be evaluated with respect to age, sex, and reproductive status of bird. Sexual Maturity: -Ducks approximately 1 year of age; Geese usually 2 years of age; -Swans about 5 years. Gender determination: -Ducks usually sexually dimorphic (except for some species such as Pekin); Swans and geese usually sexually monomorphic; Males of all species have an erectile phallus