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Effects on exercise response, fluid and acid-base balance of protein intake from forage-only diets in standardbred horses.
Equine Vet J Suppl. 2006 AugEV

Abstract

REASON FOR PERFORMING STUDY

High-energy forage might be an alternative to concentrates for performance horses and such forage can be produced by an early cut. However, early cut forage is high in crude protein (CP), which may result in an excessive CP intake.

OBJECTIVES

To investigate how CP intake affects nitrogen (N), fluid and acid-base balance, and exercise response in horses fed high-energy forage diets. The hypothesis was that high CP intake causes acidosis, and alters fluid balance and response to intensive exercise.

METHODS

Two forage-only diets based on high-energy grass forage were fed for 23 days in a crossover design to 6 Standardbred horses in racing condition. One forage diet provided a high (HP) CP (16.6%) intake and the other diet provided recommended intake (RP) of CP (12.5%) for racehorses. The horses had intensive exercise twice and slow exercise 1-3 times every week. At the beginning and end of each period, faeces and urine were collected for 48 and 72 h, respectively and analysed for dry matter, pH and N content. At Days 19 and 23 in each period 2 race-like exercise tests were performed, a standardised treadmill test and a field test on a race track. Blood samples were taken before, during and after the tests and analysed for sodium (Na), potassium (K), chloride (CI), total plasma proteins (TPP), TCO2, urea, pH and lactate. The strong ion difference (SID) was calculated and heart rate and respiratory rate was also recorded.

RESULTS

There was a decrease in urinary pH and an increase in N excretion, blood urea, water intake, urine volume and faecal water content on the HP diet. Total water intake was higher than the increase in urinary and faecal water loss indicating increased evaporative losses on the HP diet. During the exercise tests there were no significant differences between diets in TPP, plasma lactate, blood Na, K, Cl, TCO2, pH, SID and respiratory or heart rates.

CONCLUSION

Feeding a forage-only diet with a CP intake corresponding to 160% of the requirement caused an increase in N excretion within 36-48 h after the diet was introduced and alterations in fluid and acid base balance at rest.

POTENTIAL RELEVANCE

The increased urine and probably also evaporative fluid losses suggest that feeding a HP diet will cause an unnecessary challenge for horses during prolonged exercise.

Authors+Show Affiliations

Deptartment of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Box 7018, S-750 07 Uppsala, Sweden.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17402499

Citation

Connysson, M, et al. "Effects On Exercise Response, Fluid and Acid-base Balance of Protein Intake From Forage-only Diets in Standardbred Horses." Equine Veterinary Journal. Supplement, 2006, pp. 648-53.
Connysson M, Muhonen S, Lindberg JE, et al. Effects on exercise response, fluid and acid-base balance of protein intake from forage-only diets in standardbred horses. Equine Vet J Suppl. 2006.
Connysson, M., Muhonen, S., Lindberg, J. E., Essén-Gustavsson, B., Nyman, G., Nostell, K., & Jansson, A. (2006). Effects on exercise response, fluid and acid-base balance of protein intake from forage-only diets in standardbred horses. Equine Veterinary Journal. Supplement, (36), 648-53.
Connysson M, et al. Effects On Exercise Response, Fluid and Acid-base Balance of Protein Intake From Forage-only Diets in Standardbred Horses. Equine Vet J Suppl. 2006;(36)648-53. PubMed PMID: 17402499.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects on exercise response, fluid and acid-base balance of protein intake from forage-only diets in standardbred horses. AU - Connysson,M, AU - Muhonen,S, AU - Lindberg,J E, AU - Essén-Gustavsson,B, AU - Nyman,G, AU - Nostell,K, AU - Jansson,A, PY - 2007/4/4/pubmed PY - 2007/5/3/medline PY - 2007/4/4/entrez SP - 648 EP - 53 JF - Equine veterinary journal. Supplement JO - Equine Vet J Suppl IS - 36 N2 - REASON FOR PERFORMING STUDY: High-energy forage might be an alternative to concentrates for performance horses and such forage can be produced by an early cut. However, early cut forage is high in crude protein (CP), which may result in an excessive CP intake. OBJECTIVES: To investigate how CP intake affects nitrogen (N), fluid and acid-base balance, and exercise response in horses fed high-energy forage diets. The hypothesis was that high CP intake causes acidosis, and alters fluid balance and response to intensive exercise. METHODS: Two forage-only diets based on high-energy grass forage were fed for 23 days in a crossover design to 6 Standardbred horses in racing condition. One forage diet provided a high (HP) CP (16.6%) intake and the other diet provided recommended intake (RP) of CP (12.5%) for racehorses. The horses had intensive exercise twice and slow exercise 1-3 times every week. At the beginning and end of each period, faeces and urine were collected for 48 and 72 h, respectively and analysed for dry matter, pH and N content. At Days 19 and 23 in each period 2 race-like exercise tests were performed, a standardised treadmill test and a field test on a race track. Blood samples were taken before, during and after the tests and analysed for sodium (Na), potassium (K), chloride (CI), total plasma proteins (TPP), TCO2, urea, pH and lactate. The strong ion difference (SID) was calculated and heart rate and respiratory rate was also recorded. RESULTS: There was a decrease in urinary pH and an increase in N excretion, blood urea, water intake, urine volume and faecal water content on the HP diet. Total water intake was higher than the increase in urinary and faecal water loss indicating increased evaporative losses on the HP diet. During the exercise tests there were no significant differences between diets in TPP, plasma lactate, blood Na, K, Cl, TCO2, pH, SID and respiratory or heart rates. CONCLUSION: Feeding a forage-only diet with a CP intake corresponding to 160% of the requirement caused an increase in N excretion within 36-48 h after the diet was introduced and alterations in fluid and acid base balance at rest. POTENTIAL RELEVANCE: The increased urine and probably also evaporative fluid losses suggest that feeding a HP diet will cause an unnecessary challenge for horses during prolonged exercise. UR - https://www.unboundmedicine.com/medline/citation/17402499/Effects_on_exercise_response_fluid_and_acid_base_balance_of_protein_intake_from_forage_only_diets_in_standardbred_horses_ L2 - https://medlineplus.gov/urineandurination.html DB - PRIME DP - Unbound Medicine ER -