Short-term feed intake is regulated by macronutrient oxidation in lactating Holstein cows

Area of Science:

• Animal Science
• Metabolic Physiology
• Nutritional Physiology

Background:

• Feed intake regulation involves humoral signals and peripheral organ oxidative processes.
• Periprandial (around feeding time) fuel oxidation patterns may influence feeding behavior in bovines.
• The relationship between oxidative metabolism and feed intake in dairy cows remains understudied.

Purpose of the Study:

• To investigate associations between individual feeding events and whole-body net fat and carbohydrate oxidation in dairy cows.
• To explore the relationship between oxidative metabolism and plasma metabolite concentrations during feeding and feed restriction.

Main Methods:

• Four late-lactating cows were housed in respiratory chambers for simultaneous gas exchange and feed intake monitoring.
• Animals experienced both ad libitum (AL) and feed-restricted (RE) periods (24h each).
• Blood samples were collected hourly to measure key metabolites and hormones (BHBA, glucose, NEFA, insulin, ghrelin).

Main Results:

• A 30-42 minute offset was observed between feeding events and peak/trough net fat oxidation (FOX(net)) and net carbohydrate oxidation (COX(net)).
• During AL feeding, COX(net) remained high (>6g/min) and FOX(net) low (<-0.2g/min) before the next meal.
• Strong inverse correlation between COX(net) and glucose; direct correlations found between COX(net)-insulin, heat production-BHBA, insulin-glucose, and BHBA-ghrelin.

Conclusions:

• Postprandial increases in oxidative metabolism appear to suppress feed intake in late-lactating cows.
• Preprandial acceleration of fat oxidation and deceleration of carbohydrate oxidation may initiate feeding.
• Metabolic oxidative signals play a crucial role in regulating feed intake behavior in dairy cows.