NUTRITIONAL AND ENVIRONMENTAL IMPLICATIONS OF STARCH DEGRADABILITY AND NITROGEN FERTILIZATION OF ORCHARDGRASS SILAGE IN TOTAL MIXED RATIONS FED TO LACTATING COWS

Woodward-Greene, Mary Jennifer

NUTRITIONAL AND ENVIRONMENTAL IMPLICATIONS OF STARCH DEGRADABILITY AND NITROGEN FERTILIZATION OF ORCHARDGRASS SILAGE IN TOTAL MIXED RATIONS FED TO LACTATING COWS

dc.contributor.advisor	Erdman, Richard
dc.contributor.author	Woodward-Greene, Mary Jennifer
dc.contributor.department	Animal & Avian Sciences
dc.contributor.publisher	University of Maryland, College Park, Md.
dc.contributor.publisher	Digital Repository at the University of Maryland
dc.date.accessioned	2010-03-10T18:15:07Z
dc.date.available	2010-03-10T18:15:07Z
dc.date.issued	2003
dc.description.abstract	The objectives of this research were to determine the effect of starch and nitrogen (N) availability on microbial protein production and N efficiency, ruminal N efficiency and ammonia, and to assess forage fertilization and grain selection decisions. Diets were incubated in vitro batch culture, and fed in a 6 x 6 Latin square in vivo digestion trial. Total mixed rations (TMR) contained 50:50 forage:concentrate (dry matter (DM) basis) of second-cutting orchardgrass silage fertilized with 200 (OG200) or 400 (OG400) pounds per acre N, plus concentrate mixes using high to low rumen available starches: barley, corn, and milo. TMR crude protein (CP) was 17% and 18% for in vivo, and 20% and 21% for in vitro OG200 and OG400 diets, respectively. Synchronous diets were low:low or high:high rumen starch availability:diet N (corn or milo withOG200, and barley with OG400). No effects on ruminal microbial protein synthesis and flow, N flow, or milk production were observed. DM, organic matter (OM) (P<0.01), N, and neutral detergent fiber (NDF) (P<0.02) total digestibilities increased with synchronous diets. N digestibility was depressed in diets of low:high rumen starch availability:diet N, due to increased hindgut fermentation adding microbial protein to the feces (P<0.001). All OG400 diets had higher fecal N percentage (P<0.001). OG400 had higher ruminal ammonia both in vitro and in vivo (P<0.05), and higher total in vivo volatile fatty acid (VFA) concentration (P<0.001), but rumen pH was stable due to increased recycling of urea. Orchardgrass fertilized at high N can be digested as well as lower N fertilized forages when combined with a rapidly available ruminal starch such as barley, and decrease outputs of fecal DM by up to 401.5 and N by nearly 22 kilograms per year per cow. Crop fertilization and grain selection decisions affect forage composition, rumen fermentation, ration digestibility, and fecal DM and N output.	en_US
dc.identifier.uri	http://hdl.handle.net/1903/10046
dc.language.iso	en_US	en_US
dc.title	NUTRITIONAL AND ENVIRONMENTAL IMPLICATIONS OF STARCH DEGRADABILITY AND NITROGEN FERTILIZATION OF ORCHARDGRASS SILAGE IN TOTAL MIXED RATIONS FED TO LACTATING COWS	en_US
dc.type	Thesis	en_US