Date of Award

1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal Science (Animal, Dairy, and Poultry Sciences)

First Advisor

L. Dwain Bunting

Second Advisor

Cathleen C. Williams

Abstract

This study was conducted to determine whether supplemental rumen protected choline could improve lactation performance and lipid metabolism in cows in negative energy balance. In experiment 1, 19 primiparous Holstein cows were randomly assigned to dietary treatments consisting of either a control ration or control plus 15 g/d of supplemental rumen-protected choline (60 g/d of Cap-Shure, Balchem Corp., Slate Hill, NY). Close-up and early lactation rations were formulated from a grass hay and corn silage forage base, respectively, with a corn-soy concentrate, whole cottonseed. and alfalfa hay included as appropriate to meet nutrient requirements. Cows were milked twice daily. Cows were offered a total mixed ration twice daily through individual feeding gates. Supplemental choline was top-dressed onto the ration beginning 2 wk prepartum and continuing to the end of the experimental period at 8 wk postpartum. Prepartum DMI tended to be higher for supplemented cows. Treatment did not affect postpartum DMI. which declined from 10.6 to 9.0 kg/d from wk 2 to wk 1 prepartum but then increased to 23.5 kg/d by 8 wk postpartum. Supplemental choline did not affect total milk production or secretion of milk components. Peak concentrations of plasma NEFA (1.2 mM) and beta-hydroxybutyrate (1.3 mM) were reached in all cows between 5 and 10 d postpartum but were not influenced by supplemental choline. Prepartum beta-hydroxybutyrate and insulin tended to be lower and higher, respectively, in treated cows. Liver triglyceride levels 2 wk prior to calving (6.49% DMB), at calving (8.31%) and 4 wk postcalving (3.14%) were not affected by treatment. In experiment 2, 12 non-lactating, non-pregnant cows were fed the close-up diet of experiment 1, restricted to 0.5% of an energy intake (0.5% of BW). Blood insulin. glucose, NEFA, beta-hydroxybutyrate. and liver triglyceride concentrations at d 0 (1.60%) and d 21 ((3.33%) were affected by feed restriction but not by treatment. In conclusion, supplementing rumen protected choline to dairy cows in a negative energy balance did not affect production or metabolic variables. Results of blood insulin and selected metabolites were inconclusive. The choline levels used may have been too low to exert an effect.

ISBN

9780599636484

Pages

96

Share

COinS