Plasma concentrations of prolactin, glucose, insulin, urea nitrogen, and total amino acids in stallions after ingestion of feed or gastric administration of feed components.

This research aimed to compare the impact of different feed components on the plasma concentrations of several substances (prolactin, glucose, insulin, urea nitrogen, and total amino acids) in stallions, finding noticeable differences based on whether the feed was ingested normally or entered the stomach directly.

Objective of the Study

• This study sought to assess and compare the effects of different feeding methods and feed components on the plasma concentrations of various key substances in stallions.

Methods

• The substances in question included prolactin, glucose, insulin, urea nitrogen, and total amino acids.
• The researchers compared values following the ingestion of standard pelleted feed against those from direct gastric administration of water, NaCl, egg albumin, or corn starch in the first experiment or water, egg albumin, hydrolyzed casein (Amicase), or a mixture of essential amino acids in the second experiment.
• Stallions were fed once daily over 30 days, with blood samples collected five times at 30-minute intervals encompassing the hour before and four after feeding or administration of the substance.

Findings from First Experiment

• In the first experiment, the results revealed a positive prolactin secretory response only after normal feeding.
• Glucose and insulin responses were notable both after the meal and following the direct gastric introduction of corn starch.
• Meanwhile, total amino acids increased only after the meal.

Results from Second Experiment

• In the second experiment, regular feeding again elicited a positive prolactin response.
• Additionally, the gastric administration of water virtually impeded the prolactin response, while Amicase administration caused an increase in prolactin, but after a 2.5-hour delay.
• Noticeable responses for glucose, insulin, and total amino acids were present after regular feeding and after the administration of Amicase or the amino acid mix.
• Administration of Amicase and the amino acid mix also resulted in a positive response of urea nitrogen.

In Conclusion

• A key takeaway from these experiments is that the method of administering food or feed components to stallions can significantly impact the animals’ plasma concentrations of prolactin, glucose, insulin, urea nitrogen, and total amino acids.