Effects of day length on performance traits of commercial poultry
Vision is likely the most important sensory tool available to domestic poultry. Poultry birds (broiler and layers) rely on vision more than any other sense (Prescott et al., 2003). Light is the primary zeitgeber in the control of biological rhythms (Kristensen et al., 2006), and to be able to do this, it must be perceived by the brain. Light is the primary tool used by the body to entrain circadian rhythms (Rattenborg et al., 2005). Constant or near-constant lighting programs had been a traditional choice of farmers, primarily with the thought that it could provide constant visual access to feeders and water troughs, which ultimately resulted in maximize feed consumption and growth. Although various lighting programs involving more darkness exposure have been studied and recommended, nearly continuous day length is still common in commercial broiler production. The 1 hour (h) of darkness in the 23 light (L):1 dark (D) schedule has not been provided as a period for rest or sleep (Savory and Duncan, 1982).
Light is an important management technique in broiler production and is composed of three aspects, light wavelength, light intensity and photoperiod length & distribution (Lewis et al., 1998). In environmentally controlled housing systems, birds are exposed to artificial light. So source, intensity, spectra and regimen of light had major impact in modern broiler management (Rozenboim et al., 1999). Long dark periods enhanced the growth more than continuous light but extended darkness without light provision resulted in impaired growth (Deaton et al., 1970). Gorden (1994) concluded that maximum benefit could be obtained by rearing broilers under lighting regimen of 1...
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...ncentrations and age at first egg in layer strains of domestic pullets. British poultry science 39(5):662-670.
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Reiter, R. 1993. Static and extremely low frequency electromagnetic field exposure: reported effects on the circadian production of melatonin. Journal of cellular biochemistry 51(4):394-403.
Rozenboim, I., B. Robinzon, and A. Rosenstrauch. 1999. Effect of light source and regimen on growing broilers. British poultry science 40(4):452.
Schwean-Lardner, K., B. I. Fancher, and H. L. Classen. 2012. Impact of daylength on the productivity of two commercial broiler strains. British poultry science 53(1):7-18.
Methionine represents the first limiting amino acid in broiler nutrition, thus different sources are available to balance diets based of corn and soybean. Bioavailability is different for each methionine source because of its rate of absorption and metabolic pathways. A broiler experiment was conducted to determine the relative bioavailability of Hydroxyl Methyl Analog Calcium (HMA-Ca) relative to DL-Methionine(DL-Met). The experiment was conducted at at Lavinesp (Unesp, Jaboticabal). It was used 1890 male broiler Cobb 500 of 21 days old, they were weighted and distributed homogeneously in a complete randomized design with 13 treatments and 7 replicates each. All birds fed either a basal diet deficient in sulphur amino acids, digestible methionine and cysteine (dig Met+Cys), or the basal diet with four levels of HMA-Ca (0.063, 0.183, 0.302 and 0.540%) and DL-Met (0.054, 0.156, 0.259 and 0.463%) to achieve increasing levels of dig Met+Cys. For the analysis, 5% of significance was considered and procedures of non-linear model were used by SAS. Exponential regression determinates bioavailability of HMA-Ca relative to DL-Met by calculating the relation of the slope of HMA-Ca relative to DL-Met
More reliable data can be obtained if more techniques are used to measure metabolic rate. By measuring the heat flow from an organism to its surroundings using a calorimeter, a more accurate metabolic rate can be measured (De V. Weir, 1949). The ratio of the quantity of food an animal consumes and the amount it excretes can also indicate the metabolic rate of that animal (Paradis et al., n.d.). Determining the water flux in animals with tritium labelled water is another valid method of measuring metabolic rates (Paradis et al., n.d.).
produced is by three or four chickens or hens in a small cage that do
Broiler chickens, luckily for them, only live up to 7 weeks old until they are big enough to be slaughtered. Their life starts out in incubator trays with hundreds and thousands of other chicks without enough head room to stand up, and not enough room to take 2 tiny steps. So for the first week of their lives it goes from cramp trays, to cramp boxes, to getting dumped onto the filthy floors of t...
4. Circadian Cancer Therapy. William J. M. Hrushesky, Ed. CRC Press, Inc., MI, 1994. pp 3-9, 279-281.
Feathers are complex, branched, keratinized epidermal features commonly associated with Class Aves, or birds (Bock, 2000). Cells in the epidermis called keratinocytes are the structural components of feathers; however, the protein keratin varies in its distribution and can be of different types (Prum, 2002). Many functions involved with feathers include thermal insulation, flight, cleaning of plumage, heat protection, sound production, chemical defenses, water repulsion of plumage, social communication, streamlining the body, and the sensation of touch (Bock, 2000; Prum, 2002). A wide variety of feathers have been characterized. Feathers covering the body are known as contour feathers (Bock, 2000). Contour feathers covering the wings are called remiges, while those covering the tails are called retrices (Bock, 2000). Additional types of feathers include semiplumes, down and powdered down feathers, bristles and semibristles, filoplumes, courtship plumes, and oil gland feathers (Bock, 2000). General characteristics of feathers include the presence of a calamus, which anchors the feather into the bird’s integument (Bock, 2000). Barbs, or closely spaced branches, are attached to the central shaft known as the rachis (Bock, 2000). Barbs on each side of the rachis form a vane (Bock, 2000). Proximal and distal barbules originate from barbs; proximal barbules are near the base of the feather while distal barbules are at the tip of the feather (Bock, 2000; Prum, 2002). When these barbules interlock, the structure of the vane is preserved (Bock, 2000).
Circadian rhythms are endogenous and self sustaining in all animals and plants. These rhythms are present in the absence of environment clues such as light, temperature and social clues. In absence of clues, animals free run in constant darkness due to programmed genetic interactions. Some of the genes involve in this processes are Per, Clock and Cry. The expressions of these genes are tightly regulated at molecular level by proteins which bind to promoters and repressors to create a rhythm throughout the day. For example, bmal and clock bind to ebox region to produce cry and mper proteins (Hong and Chong, 2007). These proteins are concentration dependant which means high level binds to repressor region to avoid further transcription. Such oscillations work on close to 24 hour cycle in animals and plants. These processes occur without any environmental clues. In case the environment clues are introduced to animals, they tend to synchronize internal clock with external signals. One such example of synchronization is shown in dorsophilia which increase Tim protein at night and the presence of external light decrease the production of Tim protein. This results into phase delay in dorsophilia (Leuloup and Goldbeter, 2001).
Another reason for the difficulty of sleep research is the pace of discovery. The field moves too fast for its own good. As a result, no comprehensive beginner’s text is available in the field of circadian rhythms. By the time...
Welch Jr., K. C., & Suarez, R. K. (2008). Altitude and temperature effects on the energetic cost of hover-feeding in migratory rufous hummingbirds, Selasphorus rufus. Canadian Journal of Zoology, 86(3), 161-169. doi:10.1139/Z07-127
Lloyd, Robin. Theory of Flightless Birds Shot Down. 8 September 2008. Web. 1 March 2014.
Sleep deprivation in hospitalized patients can result in increased morbidity and mortality, and can lower their quality of life. Hospitalized patients require more than the average amount of sleep to aid in recovery, but often get an inadequate amount of sleep or experience poor quality sleep. There are increased frequencies of awakening or being awakened too early in the morning, difficulty falling asleep, an increased need for sleep medications, poor sleep quality, an increase in frequency of napping and nightmares. Sleep-wake cycles contribute to adequate protein synthesis and cellular division that is crucial to sustaining the healing process and maintaining immunity. Sleep deprivation changes normal circadian cycles, resu...
Hirsch, Veronica. "Legal Protections of the Domestic Chicken in the United States and Europe." . N.p., 1 Jan. 2003. Web. 13 May 2014. .
Marzluff, J., Angell, T. & Elliot, B. (2013, May. - Jun.). Birds: Brains over brawn. Audubon, 115(3), 40-41.
Poultry production is a very important and diverse component of Northern American agriculture. Poultry products including eggs, chicken and turkey meat have been an essential part of the diets of most Americans throughout history and other individuals all arou...
British Charolais Cattle Society. (2012). Charolais. Retrieved December 10, 2013, from British Charolais Cattle Society: http://www.charolais.co.uk/