Effects of astaxanthin on gut microbiota of polo ponies during deconditioning and reconditioning periods.

To determine the effects of astaxanthin (ASTX) supplementation on the equine gut microbiota during a deconditioning-reconditioning cycle, 12 polo ponies were assigned to a control (CON; n = 6) or supplemented (ASTX; 75 mg ASTX daily orally; n = 6) group. All horses underwent a 16-week deconditioning period, with no forced exercise, followed by a 16-week reconditioning program where physical activity gradually increased. Fecal samples were obtained at the beginning of the study (Baseline), after deconditioning (PostDecon), after reconditioning (PostRecon), and 16 weeks after the cessation of ASTX supplementation (Washout). Following DNA extraction from fecal samples, v4 of 16S was amplified and sequenced to determine operational taxonomic unit tables and α-diversity and ß-diversity indices. The total number of observed species was greater at Baseline than PostDecon, PostRecon, and Washout (p ≤ 0.02). A main effect of ASTX (p = 0.01) and timepoint (p = 0.01) was observed on ß-diversity, yet the variability of timepoint was greater (13%) than ASTX (6%), indicating a greater effect of timepoint than ASTX. Deconditioning and reconditioning periods affected the abundance of the Bacteroidetes and Fibrobacteres phyla. Physical activity and ASTX supplementation affect the equine gut microbiome, yet conditioning status may have a greater impact.

Restricted- and over-feeding during gestation decreases growth of offspring throughout maturity.

To determine the effects of poor maternal nutrition on the growth and metabolism of offspring into maturity, multiparous Dorset ewes pregnant with twins (n = 46) were fed to either 100% (control; n = 13), 60% (restricted; n = 17), or 140% (over; n = 16) of National Research Council requirements from day 30 ± 0.02 of gestation until parturition. Offspring of these ewes are referred to as CON (n = 10 ewes; 12 rams), RES (n = 13 ewes; 21 rams), or OVER (n = 16 ewes; 13 rams), respectively. Lamb body weights (BW) and blood samples were collected weekly from birth (day 0) to day 28 and then every 14 d until day 252. Intravenous glucose tolerance test (infusion of 0.25 g dextrose/kg BW) was performed at day 133 ± 0.25. At day 167 ± 1.42, individual daily intake was recorded over a 77 d feeding period to determine residual feed intake (RFI). Rams were euthanized at day 282 ± 1.82 and body morphometrics, loin eye area (LEA), back fat thickness, and organ weights were collected. The right leg was collected from rams at necropsy and dual-energy x-ray absorptiometry was used to determine bone mineral density (BMD) and length. Averaged from day 0 until day 252, RES and OVER offspring weighed 10.8% and 6.8% less than CON offspring, respectively (P ≤ 0.02). When adjusted for BW, liver and testes weights tended to be increased and decreased, respectively, in RES rams compared with CON rams (P ≤ 0.08). Additionally, RES BMD and bone length were less than CON rams (P ≤ 0.06). Treatment did not influence muscle mass, LEA, or adipose deposition (P ≥ 0.41). Rams (-0.17) were more feed efficient than ewes (0.23; P < 0.01); however, no effect of maternal diet was observed (P ≥ 0.57). At 2 min post glucose infusion, glucose concentrations in OVER offspring were greater than CON and RES offspring (P = 0.04). Concentrations of insulin in CON rams tended to be greater than OVER and RES ewes at 5 min (P ≤ 0.07). No differences were detected in insulin:glucose or area under the curve (AUC) for glucose or insulin (P ≤ 0.29). Maternal diet did not impact offspring triglycerides or cholesterol (P ≤ 0.35). Pre-weaning leptin tended to be 70% greater in OVER offspring than CON (P ≤ 0.07). These data indicate that poor maternal nutrition impairs offspring growth throughout maturity but does not affect RFI. Changes in metabolic factors and glucose tolerance are minimal, highlighting the need to investigate other mechanisms that may contribute to negative impacts of poor maternal diet.

Apparent digestibility, fecal particle size, and mean retention time of reduced lignin alfalfa hay fed to horses.

Reduced lignin alfalfa (Medicago sativa L.) has the potential to provide a higher-quality forage source for livestock by improving forage digestibility. This study was conducted to evaluate apparent digestibility when feeding reduced lignin and nonreduced lignin alfalfa hay to adult horses, and to examine mean fecal particle size (MFPS) and mean retention time (MRT) between alfalfa forage types. In 2017, reduced lignin ("54HVX41") and nonreduced lignin ("WL355.RR") alfalfa hay was harvested in Minnesota at the late-bud stage. Alfalfa hays were similar in crude protein (CP; 199 g/kg), neutral detergent fiber (NDF; 433 g/kg), and digestible energy (2.4 Mcal/kg). Acid detergent lignin concentrations were lower for reduced lignin alfalfa hay (74 g/kg) compared to nonreduced lignin alfalfa hay (81 g/kg). Dietary treatments were fed to six adult, stock-type horses in a crossover study. Experimental periods consisted of a 9-d dietary adaptation phase followed by a 5-d total fecal collection phase, during which horses were housed in individual boxstalls and manure was removed on a continuous 24-h basis. At 12-h intervals, feces were thoroughly mixed, subsampled in duplicate, and used for apparent digestibility and MFPS analysis. On day 2 of the fecal collection phase, horses were fed two indigestible markers, cobalt (Co) and ytterbium (Yb), which were fed as Co-ethylenediaminetetraacetic acid and Yb-labeled NDF residue, respectively. Additional fecal samples were taken at 2-h intervals following marker dosing until 96-h post-dosing to evaluate digesta MRT. Data were analyzed using the MIXED procedure of SAS, with statistical significance set at P ≤0.05. Dietary treatment (i.e., alfalfa hay type) was included as a fixed effect, while experimental period and horse were considered random effects. Dietary treatments were similar in dry matter intake (1.6% bodyweight) and time to consumption (7.6 h). Apparent dry matter digestibility (DMD) was greater for reduced lignin alfalfa (64.4%) compared to nonreduced lignin alfalfa (61.7%). Apparent CP and NDF digestibility did not differ between dietary treatments, averaging 78% and 45%, respectively. Dietary treatments were similar in MFPS (0.89 mm) and MRT for both liquid (23.7 h) and solid (27.4 h) phase material. These results indicate an improvement in DMD for reduced lignin alfalfa hay when fed to adult horses, with no change in forage consumption, fecal particle size, or digesta retention time.

Forage quality and beef cow preference is affected by wrap type of conventional and reduced-lignin alfalfa round bales stored outdoors.

Storing hay outdoors can result in detrimental changes in forage quality. Additionally, alfalfa (Medicago sativa L.) cultivar may influence dry matter intake (DMI) and hay waste when feeding livestock. The objectives were to determine the effects of conventional or reduced-lignin alfalfa round bales stored outdoors and wrapped with plastic twine, net wrap, or B-Wrap on forage quality, beef cow preference, and hay waste. Round bales made from reduced-lignin (n = 12) or conventional (n = 12) alfalfa cultivars were baled and stored outdoors for 16 mo. Within each cultivar, four bale replicates were bound with plastic twine, net wrap, or B-Wrap. After storage, bales were fed in a switchback design with period confounded with alfalfa cultivar to 18 lactating Angus cows (Bos Taurus L.). The pairs had ad libitum access to three round-bale feeders where bales of each wrap type were placed for eight 48 h periods. Position of round bale wrap type was rotated according to a Latin Square arrangement. Bales were weighed and waste surrounding each feeder was collected at 24 and 48 h to calculate DMI and hay waste. Statistical significance was set at P < 0.05. Alfalfa cultivar did not impact any of the response variables (P > 0.05). At feeding, round bales wrapped in net wrap had greater (P < 0.015) moisture content (16.4%) compared with those wrapped with B-Wrap (12.8%). Neutral detergent fiber was lower (P = 0.03) in bales wrapped in B-Wrap (46%) compared with twine-tied bales (49%) while net wrapped bales were not different. Total digestible nutrients (P = 0.02), and relative feed value (P = 0.04) were lower in twine-tied bales compared with B-Wrap while net wrapped bales were not different. Twine (7.1 × 106 colony forming units [CFU]/g) and net wrap (4.7 × 106 CFU/g) bales had greater (P < 0.0001) mold counts than B-Wrap bales (4.8 × 104 CFU/g), while concentrations of other forage components and yeast counts were not different among wrap types (P > 0.05). Total DMI, and DMI during the first 24 h, were greater (P ≤ 0.032) for B-Wrap bales compared to twine-tied bales indicating preference for hay wrapped in B-Wrap; net wrapped bales were not different. Dry matter intake in the first 24 h was negatively associated with the mold count (r = -0.52; P = 0.02), and hay waste was not affected by wrap type (P > 0.05). These results confirm that wrap type affected forage quality and mold counts, which in turn influenced beef cattle preference of round bales stored outdoors.

Glucose and Insulin Response of Horses Grazing Alfalfa, Perennial Cool-Season Grass, and Teff Across Seasons.

Elevated nonstructural carbohydrate (NSC) values in pasture forages can cause adverse health effects in some horses (Equus caballus L.). The objectives of this study were to determine the impact of different forage species on blood glucose and insulin concentrations of horses throughout the grazing season. Research was conducted in July (summer) and September (fall) in St. Paul, MN. Alfalfa (Medicago sativa L.), mixed perennial cool-season grasses (CSG), and teff (Eragrostis tef [Zucc.] Trotter) pastures were grazed by six horses (24 ± 2 years) that were randomly assigned to one of three forage types in a replicated Latin-square design. Jugular catheters were inserted 1 hour before the start of grazing and horses had access to pasture each day from 08:00 to 16:00 hours. Jugular venous blood samples were collected from each horse before being turned out (0 hours) and then at 2-hour intervals following turnout. Plasma and serum samples were collected and analyzed for glucose and insulin, respectively. Corresponding forage samples were taken by hand harvest. Seasons were analyzed separately and data were analyzed using the MIXED procedure in SAS with P ≤ .05. Teff generally had lower (P ≤ .05) equine digestible energy, crude protein, and NSC compared to the other forages. Differences in peak insulin were observed between horses grazing CSG and teff during the fall grazing (P ≤ .05). These results suggest grazing teff could lower the glucose and insulin response of some horses.