19Chicken Respiratory system The respiratory cycle of birds consists of two inhalations and two exhalations. During the first inhalation, air passes from the nares, through the larynx and trachea, into the caudal air sacs (abdominal air sacs). From here, air is pushed into the lungs during the second exhalation. In the lungs, oxygen and carbon dioxide are exchanged at the junction of air and blood capillaries. Unlike mammals, birds do not have alveoli-air capillaries formed from the branching of bronchi and bronchioles are the avian functional equivalent to alveoli. Following gas exchange in the lungs, oxygen-poor and carbon dioxide-rich air is drawn into the cranial air sacs (cervicocephalic, clavicular and thoracic air sacs) during the second inhalation. The second exhalation then pushes air from the cranial air sacs through the syrinx, into the trachea, and finally through the nasal cavity and out to the environment through the nostrils. Because birds have air sacs that reach into some bones (the clavicular air sacs extend into the humerus and the cranial abdominal air sacs extend into the femur), and have no diaphragm, it is possible for respiratory infections to spread into the abdominal cavity and bones.
20The Broiler IndustryToday, almost all of the poultry is raised in large operationsThe term broiler refers to chickens which are about 7-8 weeks of age and are raised for meat.Generally lighted 24 hours a dayHelps cut down on cannibalismProcess begins with the production of eggs that will be hatched into chicks.Parents are selected from breeds that are large and muscularMost are hybrids derived from mating of different breedsusually mated through artificial insemination results in hybrid vigor
21Egg ProductionEggs are expelled from the hens body and the embryo develops outside the mother’s body.Eggs are encased in a hard shell and can weigh several ouncesProcess begins with the release of the ovum (yolk) from the ovaryIf the female has been mated, the ovum will be fertilized within the infundibulum.The albumin or white of the egg is secreted by cells in the magnum.Chalazae is formed, It is a ropelike substance which holds the yolk in place in the center of the egg.
22Egg ProductionInner and outer shell membranes are formed in the isthmusThe shell is formed in the uterusIn hours the shell is completed and moves to the vagina and out of the hens body.Some facilities collect eggs with the use of a conveyor beltThe egg rolls out of the nest box and onto the beltEggs must be kept clean and free from contamination
23Egg hatchingEggs are stored at degrees until being placed in the hatcherywithin 48 hours after incubation begins the embryo has developed a circulatory systemCirculatory system sustains life by carrying nourishment from the yolk to the embryoEggs are turned at least two times per dayTurning eggs keeps the embryo from sticking to the inside of the shellBy the end of the first week, embryos are recognizable as chickens
25Egg hatching After two weeks, the chicks are covered with down incubation takes about 21 days.After hatching, chicks are removed from the incubator, dried off, cleaned, and placed in a warm dry environment.The chicks are sexed and separated into groups.At one day of age chicks are vaccinated and the beaks are trimmed to prevent canabalism.Chicks are then placed in ventilated cardboard boxes to be shipped to the broiler house.