Publications by authors named "J L Leatherwood"

88 Publications

Effects of crude protein content on intake and digestion of coastal bermudagrass hay by horses.

Transl Anim Sci 2021 Jul 29;5(3):txab073. Epub 2021 Apr 29.

Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/tas/txab073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8379517PMC
July 2021

Effect of maternal overnutrition on predisposition to insulin resistance in the foal: Foal skeletal muscle development and insulin signaling.

Domest Anim Endocrinol 2021 Oct 2;77:106648. Epub 2021 Jul 2.

Department of Animal Science, Texas A&M University, College Station, Texas 77843. Electronic address:

Skeletal muscle plays an integral role in the ability of a horse to perform at high levels. Shifts in skeletal muscle development in response to maternal plane of nutrition may have substantial and lasting impacts on athletic performance and whole-body metabolism. Therefore, sixteen Quarter Horse mares were used in a completely randomized design and maintained at a body condition score (BCS) 6 until start of third trimester. On d 235 of gestation, mares were randomly assigned to receive one of two dietary treatments with a diet formulated to meet requirements during late gestation (CON; n = 8), and an overfed diet (HIGH; n = 8) where mares received an additional 40% above CON. Five h after parturition, foals were euthanized, and gluteus medius, triceps brachii, and semitendinosus were harvested for analyses. Gene expression was determined by qPCR and western immunoblotting was used to quantify total and phosphorylated forms of proteins involved in skeletal muscle metabolism with tubulin as the loading control. All data were analyzed using PROC MIXED of SAS. Foals from HIGH mares exhibited larger skeletal muscle fibers by area (P <0.05), and a shift in muscle fiber development towards type I slow twitch muscle fibers (P <0.05). Relative expression of glucose transporter 4 (GLUT4) was lower in HIGH foals compared to CON in gluteus medius (P = 0.05). Insulin receptor isoform B (INSR-B) and insulin-like growth factor 1 receptor (IGF1R) were greater in triceps brachii of HIGH foals compared to CON (P ≤ 0.03). Insulin receptor isoform A (INSR-A), however, tended to be lower in triceps brachii of HIGH compared to CON (P = 0.10). Ratios of phosphorylated to total extracellular signal-regulated protein kinase 1/2 (ERK1/2) and c-June N-terminal kinase (JNK) were higher in HIGH foals compared to CON (P ≤0.04) in gluteus medius. There were no differences observed for phosphorylated to total protein ratios in semitendinosus and triceps brachii muscles; however, total ERK1/2 tended to be elevated (P <0.10) in semitendinosus from CON foals compared to HIGH. There was no difference in phosphorylated or total protein kinase B (AKT) (P >0.14). These data indicate hypertrophy of skeletal muscle fibers and a shift towards type I slow twitch fibers in HIGH foals. Furthermore, this study identifies muscle specific changes in gene expression and downstream insulin receptor signaling, which may contribute to future metabolic abnormalities in response to maternal overnutrition.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.domaniend.2021.106648DOI Listing
October 2021

The effects of signalment, diet, geographic location, season, and colitis associated with antimicrobial use or Salmonella infection on the fecal microbiome of horses.

J Vet Intern Med 2021 Jul 16. Epub 2021 Jul 16.

Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA.

Background: The fecal microbiome of healthy horses may be influenced by signalment, diet, environmental factors, and disease.

Objectives: To assess the effects of age, breed, sex, geographic location, season, diet, and colitis caused by antibiotic use (antimicrobial-associated diarrhea [AAD]) and Salmonella infection on fecal microbiota.

Animals: Healthy horses (n = 80) were sampled from nonhospital environments across multiple geographical locations in the United States. Horses with AAD (n = 14) were defined as those that developed diarrhea secondary to antimicrobial use. Horses with Salmonella infection (n = 12) were presented with spontaneous onset of colitis and subsequently tested positive on Salmonella quantitative polymerase chain reaction. All horses were >1 year of age and stratified by a dietary scale that included forages (pasture and hay) and concentrates grouped by percentage of fiber and amount.

Methods: Illumina sequencing of 16S rRNA genes was performed on fecal DNA.

Results: Healthy horses fed higher amounts of grain clustered separately from those fed lower amounts of grain (analysis of similarities [ANOSIM], R = 0.356-0.385, Q = 0.002). Horses with AAD and Salmonella had decreased richness and evenness compared to healthy horses (P < .05). Univariable analysis of the 3 groups identified increases in Bacteroidetes (Q = 0.002) and Protebacteria (Q = 0.001) and decreases in Verrucomicrobia (Q = 0.001) in AAD horses whereas Salmonella horses had less Firmicutes (Q = 0.001) when compared to healthy horses.

Conclusions And Clinical Importance: Although the amount of grain in the diet had some impact on the fecal microbiome, colitis had a significantly larger influence. Horses with ADD have a more severe dysbiosis than do horses with Salmonella.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jvim.16206DOI Listing
July 2021

Dietary supplementation of a Saccharomyces cerevisiae fermentation product attenuates exercise-induced stress markers in young horses.

J Anim Sci 2021 Aug;99(8)

Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA.

Mitigation of exercise-induced stress is of key interest in determining ways to optimize performance horse health. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would decrease markers of exercise-induced stress and inflammation in young horses, Quarter Horse yearlings (mean ± SD; 9 ± 1 mo) were randomly assigned to receive either no supplementation (CON; n = 8) or 21 g/d S. cerevisiae fermentation product (10.5 g/feeding twice daily; SCFP; n = 10) top-dressed on a basal diet of custom-formulated grain as well as ad libitum Coastal bermudagrass hay. After 8 wk of dietary treatments, horses underwent a 2-h submaximal exercise test (SET) on a free-stall mechanical exerciser. Serum was collected before dietary treatment supplementation (week 0), at week 8 pre-SET, and 0, 1, and 6 h post-SET and analyzed for concentrations of cortisol and serum amyloid A (SAA) by commercial enzyme-linked immunosorbent assay (ELISA) and for cytokine concentrations by commercial bead-based ELISA. Data were analyzed using linear models with repeated measures in SAS v9.4. From week 0 to 8 (pre-SET), serum cortisol decreased (P = 0.01) and SAA did not change, but neither were affected by diet. Serum concentrations of all cytokines decreased from week 0 to 8 (P ≤ 0.008), but granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor, and interleukin-8 (IL-8) decreased to a greater extent in CON than in SCFP horses (P ≤0.003). In response to the week 8 SET, serum cortisol increased in all horses (P < 0.0001) but returned to pre-SET levels by 1 h post-SET in horses receiving SCFP. At 6 h post-SET, cortisol concentrations in CON horses returned to pre-SET concentrations, whereas cortisol declined further in SCFP horses to below pre-SET levels (P = 0.0002) and lower than CON (P = 0.003) at that time point. SAA increased at 6 h post-SET in CON (P < 0.0001) but was unchanged through 6 h in SCFP horses. All cytokines except G-CSF increased in response to the SET (P < 0.0001) but showed differing response patterns. Concentrations of IL-1β, IL-6, and tumor necrosis factor-alpha were lesser (P ≤ 0.05), and concentrations of G-CSF and IL-18 tended to be lesser (P ≤ 0.09) in SCFP compared with CON horses throughout recovery from the SET. In summary, 8 wk of dietary supplementation with 21 g/d of SCFP may mitigate cellular stress following a single, prolonged submaximal exercise bout in young horses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/jas/skab199DOI Listing
August 2021

Effect of bioactive proteins on gait kinematics and systemic inflammatory markers in mature horses.

Transl Anim Sci 2021 Jan 8;5(1):txab017. Epub 2021 Feb 8.

Department of Animal Science, Texas A&M University, College Station, TX 77843.

Twenty-seven mature Quarter horses were used in a randomized design to determine the effects of bioactive protein supplementation on gait kinematics and systemic inflammatory markers in a 34-d trial. Treatments consisted of oral doses of 230 g/d of pelleted supplements containing 0 g (CON; = 9), 40 g of bioactive protein (40BP; = 9; LIFELINE, APC, LLC, Ankeny, IA), and 80 g of bioactive protein (80BP; = 9) daily. Horses were fed a commercial concentrate at 0.5% BW (as-fed) and received coastal bermudagrass () hay daily. On day 33, horses consistent in exercise (CON, = 6; 40BP, = 8; 80BP, = 7) participated in a trailering and riding challenge. Kinematic gait analysis was performed on day 0 for use as a covariate, and on day 14, 28, and 34 to allow for the determination of potential time and dosage effects. Video footage was collected and analyzed using gait analysis software (EquineTec, Monroe, GA) for the determination of stride length (SL) and range of motion (ROM). Blood was collected via jugular venipuncture on days 0, 14, 28, and 34 for determination of systemic expression of tumor necrosis factor (TNF)-α and IL-1β. Data were analyzed using PROC MIXED of SAS. A trend towards treatment × time interaction was observed in ROM of the knee at the walk ( = 0.10), due to the increasing ROM for 40BP and 80BP as time increased and decreasing ROM for CON. A treatment × time interaction was observed ( < 0.01) for hock ROM at a walk resulting from CON and 80BP decreasing from day 14 to 28 with 40BP increasing, while from day 28 to 34 ROM at a walk decreased for 40BP and increased for 80BP. The main effect of treatment on hock ROM at the walk was quadratic ( < 0.01) and characterized by higher ROM values for 40BP compared to CON or 80BP. Dietary treatment lengthened ( = 0.04) SL of the hind limb at the walk for 40BP and 80BP compared to CON on both days 14 and 28. A significant treatment × time interaction was observed in the expression of IL-1β ( < 0.01) and can be explained by lower concentrations of IL-1β for 80BP on day 34 compared to the other treatments, with 40BP being intermediate and CON being the highest. Increased articular ROM with decreased expression of IL-1β may indicate potential anti-inflammatory effects of 80 g/d of bioactive proteins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/tas/txab017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7963040PMC
January 2021
-->