Protein requirements of mature working horses.

This academic research investigated the protein needs of mature working horses. The study found that even the lowest protein diet tested (containing 1.9 g digestible protein/W.75) appeared to be adequate for both bodyweight maintenance and exercise, with no significant depletion of the horses’ protein reserves observed.

Experimental Setup and Design

• In the study, eighteen mature horses were used to understand the requirements of proteins among working horses. The study involved three levels of calculated dietary crude protein (CP; 8.5, 7.0, and 5.5%) and varying exercise levels – intense, medium, and no exercise as maintenance, arranged in a 3 X 3 factorial pattern.

Duration and Measurement

• The horses were subjected to these varying exercise-protein treatments for a total of 60 days, followed by 4 days of fasting. This fasting was designed to help understand their nitrogen (N) status following the treatment period. The bodyweight of the horses was consistently measured throughout the feeding and fasting periods to monitor any weight changes due to exercise or protein treatment.

Results on Body Weight and Protein Deficiency

• It was found that neither different exercise levels nor protein treatments have any significant effect on the horses’ body weight. The study did not observe the usual low albumin or total protein levels that one would see in protein-deficient or malnourished animals following any of the exercise-protein treatments.

Plasma Urea Nitrogen (PUN) Concentrations

• However, the study found a correlation between Plasma urea N (PUN) concentrations and the protein amount in the horse’s diet. Horses on a high-protein diet showed a higher PUN concentration compared to those on medium or low protein diets.

Impact of Fasting on Protein Excretion

• Fasting resulted in a significant rise in the excretion of urea and NH3 Nitrogen, expected from the breakdown of amino acids in the protein metabolism process. The study noticed that the horses fed the highest protein diet also excreted the highest percentage of urea and NH3 Nitrogen during the fasting period.

Verdict on Protein Requirement

• Reserves of plasma protein and labile protein were maintained even in horses on the lowest protein diet, suggesting that these horses were deriving adequate protein from this diet, regardless of their workload. Hence, the study concluded that even the diet with the lowest protein content was sufficient for these working horses.