Quiz 11 - Quiz 1 January 24, 2008 ADSC 4360/6360 Ruminant...

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Quiz 1 January 24, 2008 ADSC 4360/6360 Ruminant Nutrition Name________________________________ Graduate students answer 5/6 and undergraduate students answer 4/6 of the following questions. 1. Since the 1950’s milk production (rolling herd average= milk/cow/lactation) as increased approximately 1% per year. This represents approximately a 300% increase in milk production. This level of improved production is beyond comparison in regards to improvements made in any other food animal producing specie. Undoubtedly, improved genetics is the major factor responsible for improvements in milk production of dairy cows during this time period. This directly results from the progress made in genetic selection and reproductive technologies (mainly artificial insemination). Even if nutrition has not been the major factor responsible for these improvements in milk production it has had to change substantially in order to meet the nutritional requirements for higher levels of milk production in modern dairy cattle. List in order of importance five aspects of dairy feeding and nutrition that have changed to support current levels of milk production in dairy cattle. One of the most important aspects of dairy feeding that has changed in the last 50 years is the roughage to concentrate ratio of the ration. Related to this the energy density [NE L ] of the ration has increased and the amount of fiber in the ration has decreased. All of these aspects of dairy nutrition have change to support greater caloric intake and maximize productive efficiency (increasing caloric supports greater milk production above maintenance costs). The method of feeding lactating dairy cows has changed from greater use of pasture and separate feeding of concentrates (concentrates fed in the milking parlor) and forages to greater use of total mixed rations with silage and concentrate fed together. The TMR enables the cow to consume a more exact ration nutritionally that enables the cow to maximize its intake and milk production. Change in the protein feeding system from crude protein to metabolizable protein. The MP system is better than CP because it provides a more accurate measurement of the cows dietary protein needs based on the absorbable (digestible) ruminal undegradable protein and the absorbable (digestible) true ruminal microbial protein produced. The measurement or feeding standard for feeding energy/calories has changed from total digestible nutrients or digestible energy to net energy of lactation (TDN and/or
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DE to NE L ). NE L accounts for the energy used for maintenance and productive functions. It is more accurate than TDN or DE because it accounts for the heat production associated with feed/nutrient utilization for maintenance and milk
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Quiz 11 - Quiz 1 January 24, 2008 ADSC 4360/6360 Ruminant...

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