Week 2: What are the key physiologic principles underlying your principle?

The most important role of a dairy calf is to grow efficiently. In any growing animal, growth hormone plays a key role. During this time, the dairy calf is not only increasing it’s body size, but also is have changes occur to it’s gastrointestinal tract. Proper rumen development is another key principle during this time to ensure that when the calve needs to be transitioned to solid feed only, that it’s rumen can properly digest the solid feeds. (1)

Growth Hormone: Rumen development:
 * Released from anterior pituitary
 * Stimulated release by growth hormone releasing hormone (GHRH) from hypothalamus
 * Inhibited by growth hormone inhibiting hormone (somatostatin)
 * Effects
 * Bone growth- through protein metabolism
 * Muscle growth- through carbohydrate metabolism
 * Liver- produces IGF-1
 * Inhibits growth hormone
 * Probiotics - these can help minimize any damaging actions of pathogenic bacteria by (2):
 * Supporting immune development
 * Assist in developing the lower GIT
 * Aiding in transitioning to solid feed
 * Concentrate feeds -fed to properly develop the rumen
 * When digested, broken down to propionic and butyric acids
 * These acids stimulate rumen papillae growth
 * Needs to be fed in addition to milk or milk replacer for 3-4 weeks to fully develop rumen papillae (2)

References:

(1) http://www.extension.umn.edu/agriculture/dairy/feed-and-nutrition/feeding-the-dairy-herd/ruminant-anatomy-and-physiology.html

(2) http://www.wcds.ca/proc/2005/Manuscripts/Heinrichs.pdf