Dietary crude protein intake influences rates of whole-body protein synthesis in weanling horses.

This study investigates how the intake of crude protein impacts the rate of protein synthesis in young horses. Two different types of protein concentrates were used in this research: a commercial crude protein (CCP) concentrate and a recommended crude protein (RCP) concentrate. The study found significant differences in the horses’ bodies in terms of plasma amino acid concentrations and protein synthesis rates, depending on the type of protein concentrate consumed.

Methods and Experimentation

• The researchers used weanling horses for the study. These horses were fed with forage and one of two different concentrates: CCP and RCP.
• The CCP concentrate, supplemented with the forage, provided 4.1 g of crude protein per kilogram of body weight per day and 189 mg of Lysine per kilogram of body weight daily.
• The RCP concentrate offered 3.1 g of crude protein per kilogram of body weight per day and 194 mg of Lysine per kilogram of body weight per day with the same forage.
• The researchers observed the plasma amino acid concentrations by taking blood samples. They made these observations after feeding the horses with half their daily concentrate allocation.
• The researchers measured breath [(13)CO2] and blood [(13)C]phenylalanine enrichment using a primed, constant infusion of [(13)C]sodium bicarbonate and [1-(13)C]phenylalanine.

Observations and Findings

• Horses on the CCP diet showed a significant increase from the baseline in plasma of several amino acids 120 minutes post-feeding.
• Comparatively, the horses on the CCP diet had greater baseline plasma amino acid concentrations for certain amino acids compared to the RCP diet.
• The plasma of horses receiving the RCP treatment had greater amounts of three specific amino acids at the beginning and end of the 120 minute period.
• The researchers ensured phenylalanine intake was the same for all horses, but they noticed significant variations in phenylalanine oxidation rates and non-oxidative phenylalanine disposal, with the RCP diet yielding higher oxidation rates and lower disposal rates.
• The difference in the rates of phenylalanine oxidation and disposal was because of a limiting amino acid in the RCP diet, hinting that it led to lower whole-body protein synthesis rates.

Conclusion

• The study concluded that the dietary intake of crude protein plays an influential role in the rates of whole-body protein synthesis in weanling horses, with different kinds of protein concentrates yielding different results.
• The RCP diet seemed to limit the protein synthesis rate due to a limiting amino acid.
• This research provides valuable insights but further studies would be necessary to identify the possible amino acid that limits protein synthesis and to investigate the long-term impacts of these protein concentrates on the horses.