Effects of crude protein content on intake and digestion of coastal bermudagrass hay by horses.
Abstract: This study was conducted to determine the effects of forage crude protein () level on intake and digestion of Coastal bermudagrass hay by horses. Four cecally fistulated geldings were used in a 4 × 4 Latin square design with four treatments and four periods. Horses were fed one of four Coastal bermudagrass hays consisting of 7%, 10%, 13%, or 16% CP during each of the four 15-d periods. Intake and apparent digestibility were determined for each horse at the end of each period by total fecal collection. In addition, cecal fluid and blood samples were collected on the last day of each period for the determination of cecal ammonia, cecal pH, plasma urea nitrogen (), and plasma glucose concentrations. Data were analyzed using PROC MIXED of SAS. CP concentration of Coastal bermudagrass hay influenced equine intake and digestion. Increasing CP concentration linearly increased digestible organic matter intake () from 3.79 to 5.98 kg/d for 7% and 16% CP hay, respectively ( = 0.04). Furthermore, as the forage CP level increased, CP intake increased linearly ( < 0.01). The forage CP level had no effect on forage dry matter intake. Quadratic effects ( ≤ 0.05) were observed for forage OM, neutral detergent fiber, acid detergent fiber, and digestible energy. Overall digestibility was lowest for the 7% CP hay and highest for the 10% CP hay. Cecal pH remained above 6.62 irrespective of treatment and time, indicating that cecal pH was suitable for microbial growth. As the forage CP level increased, cecal ammonia concentration increased linearly from 0.03 mM for the 7% to 1.74 mM for the 16% CP hay ( < 0.01). Concentration of plasma glucose also linearly increased ( = 0.04) from 68.77 to 73.68 mg/dL as CP concentration increased from 7% to 16% CP. PUN exhibited a quadratic effect as concentration increased ( < 0.01) from 4.34 to 5.61 mM for the 7% and 16% CP hays, respectively. Overall, the 10% CP hay had the highest digestibility due to its higher OM digestion. As forage OMI increased, digestible OM increased until physiological capacity for digestion is exceeded. At that point, digestion will decline with the decrease in OMI, explaining the lower digestion for other forages fed.
© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science.
Publication Date: 2021-04-29 PubMed ID: 34430798PubMed Central: PMC8379517DOI: 10.1093/tas/txab073Google Scholar: Lookup
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Summary
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The research explores the impact of different crude protein (CP) levels in coastal bermudagrass hay on its intake and digestion by horses. The study found that the concentration of CP in the hay affected the intake and digestion, with higher protein levels leading to increased digestible organic matter intake and changes in cecal ammonia and plasma glucose levels.
Methods of the Study
- The research was carried out using four cecally fistulated geldings in a 4 × 4 Latin square experimental design.
- The horses were fed four types of Coastal bermudagrass hays with varying crude protein (CP) content: 7%, 10%, 13%, or 16%.
- Each of the four, 15-day periods saw the horses fed a different CP level hay.
- The intake and apparent digestibility of the hays were calculated by collecting total fecal matter from each horse after every feeding period.
- On the final day of each period, cecal fluid and blood samples were collected to measure cecal ammonia, cecal pH, plasma urea nitrogen (PUN), and plasma glucose concentrations.
Findings of the Study
- An increase in CP concentration in the hay resulted in a linear increase in digestible organic matter intake, from 3.79 to 5.98 kg/day for 7% and 16% CP hay respectively.
- There was also a linear increase in CP intake as the forage CP level increased.
- The forage dry matter intake remained the same, irrespective of the forage CP level.
- Quadratic effects were observed for forage organic matter (OM), neutral detergent fiber, acid detergent fiber, and digestible energy.
- Digestibility was found to be the lowest for 7% CP hay, and highest for 10% CP hay.
- The cecal pH stayed above 6.62, signifying a suitable pH level for microbial growth.
- An increase in forage CP level led to a linear increase in cecal ammonia concentration.
- As the CP concentration increased, plasma glucose concentration also increased linearly.
- There was a quadratic effect on PUN concentration as it increased.
Conclusions from the Study
- The 10% CP hay had the highest digestibility due to its higher OM digestion.
- An increase in forage organic matter intake (OMI) led to an increase in digestible OM, until the point where the physiological capacity for digestion is exceeded, after which digestion decreases in parallel with the decrease in OMI.
This research provides valuable insights into the effects of varying crude protein levels in horse feed and may help in formulating effective dietary plans for healthy horse growth and development.
Cite This Article
APA
Spurgin CL, Coverdale JA, Leatherwood JL, Redmon LA, Bradbery AN, Wickersham TA.
(2021).
Effects of crude protein content on intake and digestion of coastal bermudagrass hay by horses.
Transl Anim Sci, 5(3), txab073.
https://doi.org/10.1093/tas/txab073 Publication
Researcher Affiliations
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843, USA.
- Department of Animal and Range Science, Montana State University, Bozeman, MT 59717, USA.
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
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