11:067:330 Lecture Notes - Lecture 18: Gilt-Edged Securities, Mammary Gland, Estrous Cycle
21 Jul 2017
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Document Summary
Reproduction is a luxury that occurs only after animal has met nutritional requirements. Nutritional status impacts various phases of reproduction. Affects number of eggs ovulated, impacts birth weight, alters milk production, etc. Producers have developed feeds that provide pregnant / lactating animals with appropriate nutrients. Allow dam to reproduce, gestate, and lactate, and maintain dam"s body condition for rebreeding. Sheep are short photoperiod breeders bred in autumn when day length is decreasing; gestation ~145 days. During both early and midgestation, nutrition held constant; increase during last month due to rapid fetal growth. Once ewe lambs, nutritional needs immediately rise due to lactation. Once lamb is weaned, nutrient requirements fall dramatically because ewe no longer has to produce milk. During ~16 week dry period, ewe fed to meet maintenance and maintain good (not too fat, not too thin) body condition. Can increase nutrients given to ewe during short period just prior to breeding flushing.
