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Abstract
This paper summarizes three recent studies by the same authors with the objective
to study the effect of dietary energy source on the energy balance (EB) and risk for
metabolic and reproductive disorders in dairy cows in early lactation. The first study,
a literature survey, illustrated that feeding extra glucogenic nutrients relative
to lipogenic nutrients, decreased milk fat and seems to decrease plasma non-esterified
fatty acid (NEFA) and beta-hydroxybutyrate (BHBA) concentration. However studies are
scarce and mostly confound the effect of energy source with level of energy intake,
compromising eventual effects on EB and fertility. Therefore, in the second study,
16 dairy cows were either fed a glucogenic or a lipogenic diet (isocaloric) and EB
was determined in climate-controlled respiration chambers from week 2 until 9 of lactation.
Glucogenic diet decreased milk fat yield and milk energy and tended to decrease body
fat mobilization compared with lipogenic diet. The objective of the third study was
to study the effect of dietary energy source on EB, metabolites and reproduction variables.
Dairy cows (n=111) were fed glucogenic, lipogenic or mixed diet from week 3 until
week 9 relative to calving. Multiparous cows fed glucogenic diet had lower milk fat
yield, higher calculated EB, and lower plasma NEFA, BHBA and liver triacylglyceride
concentration and tended to have fewer days to first postpartum ovulation. In conclusion,
increasing the glucogenic nutrient availability improved the EB and had potential
to reduce the risk for metabolic disorders and to improve reproductive performance
in dairy cows.