Influence of Diet Fortification on Mature Horses at Maintenance: Performance Characteristics
Twenty mature horses (413 to 551 kg and 5 to 10 yr) were utilized in a randomized complete block design to evaluate the effect of dietary fortification on performance variables and immune status in mature horses. Horses were blocked by BW, with BCS, age, and sex randomly assigned and evenly distributed across treatments for a 154-d trial. Dietary treatments consisted of a pellet meeting NRC 2007 requirements (Control; n = 10), or the same pellet (Fortified; n = 10) including: enhanced amino acids, increased vitamin E, complexed trace minerals, prebiotic (140 g per d dehydrated Saccharomyces cerevisiae yeast fermentation product), and probiotic (min 2.3 million CFU/kg each of Lactobacillus acidophilus, Lactobacillus casei, Bifido bacterium bifidium, Enterococcus faecium) fermentation products dehydrated. Dietary treatments were offered individually at 0.25% BW at 12-h intervals. Horses were housed by block and maintained in adjacent dry lots with ad libitium access to coastal Bermudagrass (Cynodon dactylon) hay. Body weight and BCS were obtained every 14 d with concentrate adjusted accordingly. Ultrasound images were obtained every 28 d to determine rump fat (RF), longissimus dorsi area (LDA), and longissimus dorsi fat thickness (LDF). Blood samples were also collected at 28 d intervals to determine circulating white blood cell counts (WBC) utilizing a Celdyne 3700 Cell Counter. Data were analyzed using the PROC MIXED procedure of SAS. Body weight and BCS were not influenced (P = 0.11 and P = 0.25, respectively) by dietary treatment. However, all horses gained BW and BCS throughout the trial (P ≤ 0.01). Longissimus dorsi area and LDF were greater (P ≤ 0.01) for horses fed Fortified pellets compared to Control. Similarly, RF measurements increased (P ≤ 0.01) in the Fortified diet beginning at d 56 of the trial. Whole blood WBC was greater (P ≤ 0.01) in the Fortified diet when compared to Control. These results indicate the addition of fortification may improve the ability of horses to mount an immune response as well as increase muscling and rump fat when fed to mature horses.
Organic trace mineral, Amino acid probiotic, Horse, Immune Response