Dietary requirements of geriatric horses are different than those under 20 years of age. Body condition scores become harder to maintain in some horses as they age. However, supplementation with rice bran has the potential to improve endurance without excessive energy. Polish researchers evaluated the use of rice bran to potentially mitigate and delay aging changes in the intestinal tract [Filpiak, W.; Cieslak, A.; Gogulsk, M.; et al. Rice Bran in Old Horses Nutrition and Its Influence on Condition, Blood Biochemical Parameters, Total Feces Bacteria and Methanogen Population. Ann Anim Sci 2023, Vol 23, No. 1; pp. 173 – 183; DOI: 10.2478/aoas-2022-0051].
Benefits of Rice Bran for Horses
The type of feed that horses eat has an impactful influence on the number and type of microbial organisms that reside in the gut. Rice bran contains highly digestible fiber as well as 20% fat and 17% protein. Methanogens are bacteria that produce methane in a low-oxygen environment and stimulate the breakdown of carbohydrates by cellulolytic bacteria. They can therefore influence a horse’s body weight. An abundance of intestinal methanogens is associated with a healthy horse.
Effects of Rice Bran on Senior Horses
The study sought to review the effects of feeding rice bran on body condition and the abundance of microorganisms in the cecum—both bacteria and methanogens, as well as body condition score and biochemistry of the blood. Six healthy, non-working horses over age 20 were fed only meadow hay in the first four months of the study conducted between September 2020 and April 2021. Then, in the second four-month period, they were fed meadow hay plus rice bran (1 pound/day). Body condition was scored, and blood and feces collected at the start and end of the experiment. The results are as follows:
- When the horses were supplemented with rice bran, their body condition score (BCS) increased by a value of 1.17—from BCS 3 to BCS 4.17 (on a scale of 9).
- The BCS improvements in this study were not associated with biochemistry or hematological parameter changes.
- Numbers of cecal bacteria—based on fecal evaluation—increased in the rice bran-supplemented diet from 2.77 x 109 ml (hay only controls) to 5.24 x 109 ml.
- In addition, when horses were on the rice bran supplement, the appearance of their hair coat improved.
Rice bran is a water-soluble fiber that is a good nutrient for intestinal bacteria. Stabilized rice bran is useful as a “prebiotic” that feeds the symbiotic diversity of intestinal microorganisms. Its high protein and low sugar content is useful to provide geriatric horses with twice as much protein as fed to younger horses without incurring an additional burden on the gastrointestinal tract due to its high digestibility. Stabilization of rice bran during processing maintains the calcium: phosphorous ratio at a safe value of ≤ 2.5:1. Increases in cecal bacteria, including methanogens, further helps with both carbohydrate digestion and protein absorption to improve the condition of geriatric horses.
The authors also noted that after 10-12 weeks, horses completely adapt to fat supplementation with stabilized rice bran. Rice bran provides more polyunsaturated fatty acids than monounsaturated fatty acids, particularly n-6 fatty acids. Previous studies indicate that a high n-6 to n-3 ratio of fatty acids might have a role in improving exercise tolerance, reducing inflammation, and improving reproductive function.