Recent human biomedical research has focused on the role of increased visceral adipose tissue lipid accumulation in chronic disorders in humans, such as metabolic syndrome and intestinal inflammatory disorders. Relatively little is known about changes in mass or function of internal fat depots in dairy cows, particularly during the periparturient period.
An “overnutrition syndrome” in periparturient dairy cows has been identified that shares many common features with the metabolic syndrome in humans and rodent models.
The hypothesis was that nonlactating cows fed a high-energy (HE) diet similar to those that have caused fatty liver in other studies would accumulate more internal adipose tissue mass than cows fed a low-energy diet (LE). The objective was to determine dietary energy effects on feed and energy intake, BCS and BW, abdominal adipose tissue mass, carcass mass, visceral organs mass, and peripheral blood metabolites in nonlactating cows.
The studies’ results for differences of energy intake in nonlactating cows are consistent with previous reports in which increased energy balance during the dry period decreased postpartum energy balance and increased blood NEFA and BHBA. Results also substantiated previous findings that decreasing dietary energy density by including chopped straw in the TMR effectively limited energy intake in dry cows.
Final BW were greater for cows fed HE as expected, consistent with greater energy intake over the 8-wk period. Surprisingly, however, final BCS did not differ between groups, despite the markedly greater masses of omental, mesenteric, and perirenal adipose depots in HE cows. BCS assesses only the amount of subcutaneous fat at a given stage of production.
BCS is strongly predictive of overall body lipid storage in nonlactating Friesian and lactating Holstein cows, respectively. A limitation of our study is that we did not measure subcutaneous fat thickness or mass. In our study, however, the numerical difference in carcass weight between diets did not approach significance, which suggests that the internal adipose depots were relatively more responsible for overall increases in energy storage for cows fed HE. Although useful for long-term management of overall energy storage, our data indicate that assessing BCS changes during the relatively short duration of a dry period may not be sensitive enough to detect differences in internal fat storage that are potentially important physiologically.