Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science

First Advisor

Jerry W. Young


Effects on milk production and composition were investigated in fifty Holstein cows (20 primiparous and 30 multiparous) averaging 121 d postpartum. The five treatments were: control, calcium salts of fatty acids (2% of dietary dry matter), nicotinamide (12 g/d), and calcium salts of fatty acids plus nicotinamide blended during manufacture or added separately. Periods lasted 5 wk. During wk 1, all cows received the control diet. During wk 2, cows were gradually adapted to individual dietary treatments, which were continued through wk 5. Treatments containing calcium salts of fatty acids did not alter feed intake, but they increased production of milk and fat-corrected milk and tended to increase production of milk fat and protein. Treatments containing nicotinamide increased feed intake, body condition score, milk, fat-corrected milk, and milk protein production. Milk fat percentage and milk fat production was higher (3.54 vs. 3.33%, and 1.18 vs. 1.11 kg/d, respectively), but milk protein percentage and milk protein production were lower (3.11 vs. 3.28%, and 1.03 vs. 1.11 kg/d, respectively) for cows fed calcium salts of fatty acids plus nicotinamide compared with cows receiving nicotinamide. Treatments containing calcium salts of fatty acids increased plasma nonesterified fatty acids, decreased blood nicotinamide, but had no effect on plasma [beta]-hydroxybutyrate. Treatments containing nicotinamide increased plasma glucose, increased blood nicotinamide, and had no effect on plasma NEFA and [beta]-hydroxybutyrate;In a second experiment, six lactating cows in a switchback design were administered orally 12 g/d of either nicotinamide or nicotinic acid during the first five d of 9 d periods. Blood samples taken at specific intervals showed that blood nicotinamide concentration of cows in the nicotinamide group peaked earlier and higher than for cows in the nicotinic acid group (1 vs. 12 h and 2.48 vs. 2.01 [mu]g/ml). The area under the blood nicotinamide concentration curve was not different between the nicotinamide and the nicotinic acid supplemented groups at 8, 12, or 24 h after nicotinamide or nicotinic acid administration, but it was higher for the nicotinamide group at 1, 2, 3, 4, and 6 h. These results suggest that nicotinamide is absorbed from the rumen faster than nicotinic acid, probably because of its higher solubility and lower dissociation constant due to its higher pKa.



Digital Repository @ Iowa State University,

Copyright Owner

Antonio Cervantes-Nunez



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211 pages