Quiz 3 key - Quiz 3 key ADSC 4360/6360 Ruminant Nutrition...

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Quiz 3 key ADSC 4360/6360 Ruminant Nutrition March 9, 2007 Answer 4 of the following questions: Name ___________________________ 1) The newborn dairy calf is born with an underdeveloped reticulo-rumen. It is premature in both capacity and function. After it receives colustrum, the newborn dairy calf, is removed from the cow, usually within the first 24 h after calving. Initially the calf is raised a milk diet (waste-milk, saleable milk or milk-replacer), “artificially” from a bottle or preferentially a bucket until weaning. Milk-replacer or cow’s milk is very expensive (~$1 to 2/lb) encouraging a dairy producer to hasten rumen development and wean calves from milk diets as soon as possible. Thus, hastening the development of a functional reticulo-rumen and the associated capacity of the animal to ferment and utilize fibrous feedstuffs in its diet is an important strategy in raising dairy calves. a. How early can dairy farmers wean a calf from milk or milk-replacer to dry feed. Name three physiological parameters that signal when the reticulo-rumen is developed enough for the calf to be weaned Calves can be weaned as early as eight weeks. Dry feed intake should be > than 1-2 lbs per day. Blood glucose should drop and blood VFA (acetate, propionate and butyrate) should increase. b. Can dairy producers hasten reticulo-ruminal development and weaning of artificially reared dairy calves? Ingestion of starter feed will stimulate development. Ingestion of fiber from roughage as chopped hay or cottonseed hulls is thought to enhance RR volume and musculature but intake of roughage is delayed and occurs weeks after calves are eating starter feed. Palatability of starter feed is important. Use palatable ingredients such as oats and molasses. Grain retained in the developing rumen will ferment. The VFA fermentation acids, especially butyrate will stimulate development. VFA that are metabolized in the rumen wall will stimulate cell division. Putrescine a decarboxylated form of ornithine and/or arginine, serves as a cationic bridge stabilizing DNA during replication and may also stimulate rumen growth and development. c. Speculate on a pharmacological approach that could be used to stimulate reticulo-ruminal development and early weaning of the milk-fed dairy calves? Add butyrate and putrescine (as mentioned above) to milk replacer or supply as an oral drench. Rumen active pharmaceuticals added to milk or milk replacer may bypass the rumen by being shunted to the omasum through the esophageal. Possibly could investigate growth factors such as IGF or EGF. These growth factors are found in salivary tissue and salivary secretions. 2) Reticulo-ruminal motility is of vital importance to the ruminant animal. The following statement that describes the impact of removing vagal stimulation of reticulo-ruminal motility was taken from the textbook, The Ruminant Animal Digestive Physiology and Nutrition by D. C. Church. “These contractions (extrinsic contractions) are dependent on bursts of efferent
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Quiz 3 key - Quiz 3 key ADSC 4360/6360 Ruminant Nutrition...

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