Beta-hydroxy-beta-methylbutyrate (HMB) Supplementation to Mouse Dams in Gestation Does Not Affect Fetal Weight Variation of Offspring or Placental Development (P09-003-19).

Objectives: The objective of this study was to determine if supplementing mouse dam diets with β-hydroxy-β-methylbutyrate ( HMB ) calcium salt throughout gestation would improve pup fetal weight uniformity and placental development.

Methods: Data were collected from 27 genetically identical mouse dams and their offspring. Dams were assigned to one of 4 dietary treatments: Control ( CON ; n = 7), Low HMB ( LHMB ; 3.5 mg/g diet; n = 6), High HMB ( HHMB ; 35 mg/g diet; n = 7), and low HMB pulse dose ( PUL ; 3.5 mg/g diet; n = 7) from days 6 to 10 of gestation. All dams were fed a swine lactation derived corn-soy diet with HMB supplementation only during gestation. Dams were euthanized on day 18 of gestation.

Results: Dietary treatment did not affect total number of pups per litter, but fetal weight was greater ( P  < 0.05) for pups from PUL dams (1.05 ± 0.02 g) than LHMB (0.94 ± 0.02 g) or HHMB (0.95 ± 0.02 g) dams. Within-litter variation (standard deviation and coefficient of variation) and range of fetal weights was not different among treatments. Differences between the median fetal weight within litter and weight of the lowest weight fetal pup in each litter were similar among treatments. Supplementation with HMB did not influence weight of placentae or area of the placental labyrinth. Placental efficiency, measured as fetal weight/placental weight, was less ( P  < 0.05) for LHMB dams compared to CON dams.

Conclusions: In conclusion, dietary supplementation of HMB for pregnant mice had no effect on fetal weight variation within litter. Supplementing diets with β-hydroxy-β-methylbutyrate had no effect on placental weight or labyrinth area but reduced placental efficiency in dams fed LHMB.

Funding Sources: This research has been supported and funded by BioMatrix International, Princeton, MN.