Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


osu1070372167.pdf (2.37 MB)

ETD Abstract Container

Abstract Header

Nutritional strategies to improve nitrogen efficiency and reduce nitrogen excretion of lactating dairy cows

Noftsger, Susan M
http://rave.ohiolink.edu/etdc/view?acc_num=osu1070372167

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Animal Science.
The mechanism of action of 2-hydroxy-4-(methylthio) butanoic acid and its effects on N efficiency, ruminal variables, and milk production and composition were examined. In Trial 1, metabolizable protein (MP) supply and AA balance was manipulated through selection of highly digestible RUP sources and Met supplementation. Treatments were: 1) 18.3 % crude protein with low estimated intestinal digestibility of RUP; 2) 18.3 % CP with high digestibility RUP; 3) 16.9 % CP with high digestibility RUP; and 4) 17.0 % CP with high digestibility RUP and supplemental Met. Supplementing the highly digestible RUP source with rumen available and rumen escape sources of Met resulted in maximal milk and protein production and maximum N efficiency by cows during the production trial. In Trial 2, continuous culture fermenters were used to determine the optimal concentration of HMB for digestibility of carbohydrates and synthesis of microbial N. Treatments were three concentrations of HMB (0, 0.055, and 0.110 %) and one concentration of dl-Met (0.097 %). Digestibility of carbohydrate, other than ADF, was largely insensitive to treatment. Differences in concentration and production of individual VFA were seen and the proportion of bacterial N produced from NH3-N decreased linearly with increasing HMB. This suggests that supplementation of HMB may have a sparing effect on branched chain volatile fatty acids. In trial 3, eight cows were used to examine the passage of HMB from the rumen, ruminal effects of HMB, and effects on production, N utilization, VFA, and protozoa. Samples of omasal fluid were used to determine the amount of Met supplements passing out of the rumen. Treatments were: (1) no methionine (2) 2-hydroxy-4-methylthiobutanoic acid at 0.10% of DM; (3) isopropyl HMB at 0.13 % of DM; and (4) dl-methionine at 0.088% of DM. Digestibility in the rumen was not different. Protozoa were increased numerically in the omasum by HMB and HMBi treatments. The percentage of HMB that passed into the omasum was 5.3%. Only a small amount of HMBi was found as HMB in the omasum (2.3%). The mechanism of action of 2-hydroxy-4-(methylthio) butanoic acid and its effects on N efficiency, ruminal variables, and milk production and composition were examined. In Trial 1, metabolizable protein (MP) supply and AA balance was manipulated through selection of highly digestible RUP sources and Met supplementation. Treatments were: 1) 18.3 % crude protein with low estimated intestinal digestibility of RUP; 2) 18.3 % CP with high digestibility RUP; 3) 16.9 % CP with high digestibility RUP; and 4) 17.0 % CP with high digestibility RUP and supplemental Met. Supplementing the highly digestible RUP source with rumen available and rumen escape sources of Met resulted in maximal milk and protein production and maximum N efficiency by cows during the production trial. In Trial 2, continuous culture fermenters were used to determine the optimal concentration of HMB for digestibility of carbohydrates and synthesis of microbial N. Treatments were three concentrations of HMB (0, 0.055, and 0.110 %) and one concentration of dl-Met (0.097 %). Digestibility of carbohydrate, other than ADF, was largely insensitive to treatment. Differences in concentration and production of individual VFA were seen and the proportion of bacterial N produced from NH3-N decreased linearly with increasing HMB. This suggests that supplementation of HMB may have a sparing effect on branched chain volatile fatty acids. In trial 3, eight cows were used to examine the passage of HMB from the rumen, ruminal effects of HMB, and effects on production, N utilization, VFA, and protozoa. Samples of omasal fluid were used to determine the amount of Met supplements passing out of the rumen. Treatments were: (1) no methionine (2) 2-hydroxy-4-methylthiobutanoic acid at 0.10% of DM; (3) isopropyl HMB at 0.13 % of DM; and (4) dl-methionine at 0.088% of DM. Digestibility in the rumen was not different. Protozoa were increased numerically in the omasum by HMB and HMBi treatments. The percentage of HMB that passed into the omasum was 5.3%. Only a small amount of HMBi was found as HMB in the omasum (2.3%).
Normand St-Pierre (Advisor)
159 p.
Dairy; Methionine; Nitrogen Excretion; 2-hydroxy-4(methylthio) butanoic acid; HMB

Recommended Citations

Citations

  • Noftsger, S. M. (2003). Nutritional strategies to improve nitrogen efficiency and reduce nitrogen excretion of lactating dairy cows [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1070372167

    APA Style (7th edition)

  • Noftsger, Susan. Nutritional strategies to improve nitrogen efficiency and reduce nitrogen excretion of lactating dairy cows. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1070372167.

    MLA Style (8th edition)

  • Noftsger, Susan. "Nutritional strategies to improve nitrogen efficiency and reduce nitrogen excretion of lactating dairy cows." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1070372167

    Chicago Manual of Style (17th edition)

osu1070372167
2,242
© 2003, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.