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 d 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 (d 0) to d 28 and then every 14 d until d 252. Intravenous glucose tolerance test (infusion of 0.25 g dextrose/kg BW) was performed at d 133 ± 0.25. At d 167 ± 1.42, individual daily intake was recorded over a 77 d feeding period to determine residual feed intake (RFI). Rams were euthanized at d 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 d 0 until d 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.

Oxidative status is impacted by fitness and dietary nutrients, such as antioxidants. We hypothesized that astaxanthin (ASTX) supplementation would improve oxidative status in the circulation and muscle in response to exercise following deconditioning and reconditioning in horses. Twelve conditioned polo ponies (14.8 ± 1.7 yr) were assigned to control (CON; n = 6) or astaxanthin supplemented (ASTX; n = 6; 75 mg ASTX daily) groups. Horses performed 26 min submaximal exercise tests (SET) followed by 30 min of recovery while in condition (SET1), after 16 wk of deconditioning (SET2), and after 16 wk of reconditioning (SET3). Blood samples were collected 30 min before and 0, 15, 30, and 60 min after each SET. Semitendinosus muscle biopsies were collected 2 wk before and 2 hr after each SET. Using commercially available kits, plasma and muscle superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and plasma malondialdehyde (MDA) concentrations were determined. At SET2, ASTX had 116% greater plasma SOD activities than CON (P=0.001). Both treatment groups increased from SET2 to SET3 (P< 0.001), but there were no treatment effects at SET3 (P=0.788). At SET2, plasma GPX activities were 49.3% greater in ASTX than CON (P=0.012), and ASTX tended to be 21.2% greater than CON at SET3 (P=0.096). Plasma MDA concentrations were 22.2% greater in CON than ASTX at SET2 (P=0.034), but not at SET1 or SET3 (P≥0.449). There were no detectable differences in muscle SOD or GPX activities 2 wk before or 2 hr after any SET (P≥0.309). In conclusion, ASTX supplementation maintained circulating antioxidant capacity and minimized oxidant activities during deconditioning, reducing oxidative stress in response to the SET in the circulation but not in the skeletal muscle. This may enable horses to adjust to strenuous exercise more efficiently, improving athletic performance, especially when they are re-introduced to exercise after deconditioning.

Poor maternal nutrition (over- and restricted-feeding) alters growth and metabolism in offspring after birth; however, the mechanisms are not well understood. Epigenetics, the heritable changes in gene expression without altering the DNA sequence, is a possible mechanism. We hypothesized that mRNA expression of epigenetic factors in livers of male offspring would be altered as a result of poor maternal diet during gestation. Multiparous Dorset ewes (n = 46) pregnant with twins were fed 100%, 60% or 140% of NRC requirements from d 30 ± 0.02 of gestation until parturition. Male offspring are referred to as CON (n=12), RES (n=21), and OVER (n=13), respectively. Ram lambs were euthanized at d 284±1.82, and liver tissue was immediately snap-frozen. RNA was isolated from liver and gene expression was quantified using real-time (RT)-PCR. Epigenetic factors of interest included DNA methyltransferases (DNMT; DNMT1, DNMT3B), ten eleven translocation enzyme 2 (TET2), lysine acetyltransferases (KAT; KAT1, KAT2B, KAT6A, KAT8), histone deacetylases (HDAC; HDAC1, HDAC2, HDAC3, HDAC4, HDAC5, HDAC6, HDAC8, HDAC11, sirtuin1), and histone methyltransferases [ASH1 like histone lysine methyltransferase (ASH1L), euchromatic histone lysine methyltransferase (EHMT)1, EHMT2, SET domain bifurcated histone lysine methyltransferase 2 (SETDB2)]. Gene expression of ASH1L and KAT6A were decreased in liver tissue of RES compared with OVER by 42.8% and 59.7%, respectively (P≤0.017). Gene expression of DNMT1 and HDAC3 were decreased in RES compared with CON by 38.3% and 35.0%, respectively (P≤0.045). Gene expression of EHMT1 and HDAC8 were increased in OVER compared with CON by 19.3% and 37.4%, respectively (P≤0.045). There were no differences detected in expression of other genes (P≥0.060). Thus, maternal diet affects hepatic mRNA expression of specific epigenetic factors which may contribute to altered metabolism and liver function. Further investigation is warranted to determine how epigenetic modifications impact offspring growth and metabolism long-term.

To evaluate the hypothesis that offspring born to restricted- and over-fed ewes would exhibit decreased glucose tolerance, total cholesterol (TC), and triglyceride (TG), and increased leptin, multiparous Dorset ewes (n = 46) pregnant with twins were fed 100%, 60% or 140% of National Research Council (NRC) requirements from d30±0.02 of gestation until parturition. Offspring are referred to as CON (n=10 ewes; 12 rams), RES (n=13 ewes; 21 rams), and OVER (n =16 ewes; 15 rams), respectively. Blood samples were collected from offspring at d0, 7, 14, 58, 210, and 252 of age and plasma TC, plasma TG, and serum leptin were analyzed with commercial kits. Concentrations of TG were greater in rams than ewes (P=0.029). Leptin was greater (P< 0.0001) in ewes than rams at d30 and 36, and greater in CON than RES and OVER at d252 (P=0.058). At d133±0.25 an intravenous glucose tolerance test was performed, and blood samples collected at -30, -15, 0, 2, 5, 10, 15, 30, 60, and 120 min relative to glucose infusion (0.25 g/kg body weight of a 50% dextrose solution). Glucose and insulin concentrations were determined using commercial kits. Glucose concentrations were greater at 5 and 15 min in ewes than rams (P≤0.04) and at 2 min, OVER were greater than CON and RES (P=0.03). Insulin concentrations were greater in rams than ewes between 5 and 15 min (P=0.0251). Insulin in RES rams tended to be greater than OVER and RES ewes between 5 and 10 min (P=0.06) and continued to be greater than RES ewes at 15 min (P=0.05). First-phase response of insulin tended to be greater in RES compared with CON and OVER (P=0.092). There were no differences detected in insulin:glucose (P=0.312). In conclusion, poor maternal nutrition negatively impacts key metabolic hormones in offspring thereby contributing to altered growth and metabolism.

To test the hypothesis that poor maternal nutrition during gestation would alter offspring muscle shear force and adipogenesis, fibrogenesis, and myogenesis mRNA expression, Dorset ewes (n=46) pregnant with twins were fed 100%, 60% or 140% of NRC requirements from d30±0.02 of gestation until parturition. Male offspring from CON (n=12), OVER (n=13), and RES (n=21) ewes were euthanized at d284±1.82 and longissimus muscle (LM) was harvested for shear force and gene expression. Vacuum-sealed LM steaks were aged for 10 d postmortem (4℃) and tenderness was measured using Warner-Bratzler shear force (WBSF) methodology. RNA was isolated from the LM to quantify mRNA expression of genes related to adipogenesis (fatty acid binding protein 4, CCAAT/enhancer-binding protein α, and peroxisome proliferator-activated receptor γ), fibrogenesis [collagen A1A (COLA1A), COL3A1, cystain-c, fibronectin (FN1), and lysyl oxidase (LOX)], and myogenesis [bone-morphogenic protein (BMP)-1, myostatin, myogenin, and myogenic differentiation 1). The WBSF decreased by 21% and 18% in OVER relative to CON (P=0.01) and RES (P=0.03), respectively, but CON and RES were not different (P=0.60). Expression of BMP1 was 1.5- and 1.8-fold greater in RES than OVER and CON, respectively (P≤0.03). Expression of FN1 was 1.6-fold greater in RES than OVER (P=0.02). Expression of COL1A1 was 2.2-fold greater in RES than CON (P=0.05) and was 1.6-fold greater in RES than OVER (P=0.07). Expression of LOX was decreased 37% in OVER compared with CON (P=0.04) and decreased 21% compared with RES (P=0.08). An effect of diet was not observed for other genes (P≥0.18). In summary, RES offspring had greater expression of genes related to fibrogenesis, but no observed difference in tenderness relative to CON. Over-feeding during gestation increased meat tenderness, which may be due to reduced collagen cross-linking by LOX.