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dc.contributor.author Glover, Nanette D. en_US
dc.date.accessioned 2007-06-01T19:19:19Z
dc.date.available 2007-06-01T19:19:19Z
dc.date.issued 2000-05-01T00:00:00Z en_US
dc.identifier.uri http://hdl.handle.net/1993/2271
dc.description.abstract The effects of photoperiod on the development of beef replacement heifers from weaning until first lactation were determined by assigning 144 crossbred heifers on the basis of weaning weight (225 +- 23 kg) and sire breed (British/Continental) to two outdoor housing facilities, with different photoperiod treatments, in a completely randomized design. From December 1, 1998 (day 0) until May 20, 1999, heifers in one facility received supplemental light (423 lux, 1 m above ground) to extend the daily photoperiod (natural + supplemental light) to 16 hours (EP). Heifers in the other facility experienced natural photoperiod only (NP). Measurements of body weight gain, backfat, and concentration of prolactin in blood serum were made every 28 d. Observations for estrus behaviour were made twice daily, in the morning and evening, and were confirmed by serum progesterone concentration in blood samples taken 8-12 d after observed estrus. Two methods of estrous synchronization and timed artificial insemination (AI) were used for first service. Maternal performance as two-year olds was evaluated in terms of calving date (n = 105), milk production and composition during the period of peak lactation (n = 32), and calf weight. (Abstract shortened by UMI.) en_US
dc.format.extent 6901457 bytes
dc.format.extent 184 bytes
dc.format.mimetype application/pdf
dc.format.mimetype text/plain
dc.language en en_US
dc.language.iso en_US
dc.title Effects of photoperiod on the development of beef replacement heifers from weaning until first lactation en_US
dc.degree.discipline Animal Science en_US
dc.degree.level Master of Science (M.Sc.) en_US


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