Prenatal exposure to different diets influences programming of glucose and insulin metabolism in dairy ewes

Insulin resistance and dyslipidemia in low-birth-weight goat kids

Low birth weight (LBW) impairs the development and health of livestock by affecting postnatal growth performance and metabolic health in adulthood. Previous studies on indigenous goats in southwest China showed that LBW goat kids had higher mortality and morbidity rates, including hepatic dyslipidemia and liver damage. However, the mechanism of insulin resistance affecting lipid metabolism under LBW conditions remains unclear. In this study, we conducted in vivo glucose-insulin metabolic studies, measured biochemical parameters, and analyzed related regulatory pathways. Both glucose tolerance tests and insulin tolerance tests indicated insulin resistance in LBW goat kids compared to controls (p < 0.05). The marker of insulin resistance, homeostasis model assessment (HOMA), was 2.85-fold higher in LBW than in control goats (p < 0.01). Additionally, elevated levels of free fatty acids in both plasma and skeletal muscle were observed in LBW goats compared to normal birth weight (NBW) goats (p < 0.05). Transcriptome analysis revealed impairments in lipid metabolism and insulin signaling in LBW goats. The observed lipid accumulation was associated with the upregulation of genes linked to fatty acid uptake and transport (FABP3), fatty acid oxidation (PPARA), triacylglycerol synthesis (LPIN1 and DGAT1), oxidative stress (ANKRD2), and insulin resistance (PGC1α). Furthermore, the insulin receptor substrate 2 (IRS2) was lower in the liver of LBW goat kids (p < 0.05). While there was no change in insulin function in skeletal muscle, LBW may lead to lipid accumulation in skeletal muscle by interfering with insulin function in the liver. These findings collectively impact the health and growth performance of livestock.

Effect of glucose infusion on glucose and insulin metabolism in early- and mid-lactation ewes and goats fed diets differing in starch and highly digestible fiber concentration

This study aimed to test possible metabolic differences between ewes and goats in response to an intravenous glucose infusion. Thirty-six animals, 18 mature Sarda dairy ewes and 18 mature Saanen goats (from 15 to 150 ± 11 d in milk [DIM], mean ± SD; body weight: 49.8 ± 6.8 kg for ewes, 60.6 ± 7.3 kg for goats) were compared simultaneously. In early lactation, both species received the same high-starch diet (HS: 20.4% starch, 35.4% neutral detergent fiber [NDF], on dry matter [DM] basis), whereas from 92 ± 11 DIM both species were randomly allocated to 2 dietary treatments: HS (20.0% starch, 36.7% NDF, on DM basis) and low-starch (LS: 7.8% starch, 48.8% NDF, on DM basis) diets. At 50 and 150 ± 11 DIM, ewes and goats were challenged with an intravenous glucose tolerance test and peripheral concentrations of glucose and insulin were determined 15 min before and 5, 10, 15, 30, 45, 90, and 180 min after glucose infusion. In early lactation, baseline plasma glucose and insulin concentrations tended to be higher in ewes than in goats (glucose: 55.8 vs. 42.9 ± 7.3 mg/dL; insulin: 0.13 vs. 0.05 ± 0.04 µg/L). After glucose infusion, glucose and insulin concentrations were higher in ewes than in goats (278.6 vs. 247.6 ± 13.1 mg/dL; 0.82 vs. 0.46 ± 0.12 µg/L). In mid-lactation, the dietary treatment (HS vs. LS) did not affect glucose and insulin metabolism. Baseline plasma glucose was numerically highest in ewes, while baseline insulin was higher in ewes than in goats (0.39 vs. 0.12 ± 0.099 µg/L). After glucose infusion, glucose concentration did not differ between ewes and goats, while insulin concentration was highest in ewes. Compared with goats, ewes showed in both periods a higher peak insulin, insulin increment, linear insulin area under the curve, insulin resistance index, and lower insulin sensitivity indices. In conclusion, despite the limitations associated with the use of intravenous glucose tolerance test to assess glucose regulation mechanisms, this study indicated large species differences in both early and mid-lactation and a more evident anabolic status in the ewes compared with the goats.

Developmental Programming, Evolution, and Animal Welfare: A Case for Evolutionary Veterinary Science

The conditions animals experience during the early developmental stages of their lives can have critical ongoing effects on their future health, welfare, and proper development. In this paper we draw on evolutionary theory to improve our understanding of the processes of developmental programming, particularly Predictive Adaptive Responses (PAR) that serve to match offspring phenotype with predicted future environmental conditions. When these predictions fail, a mismatch occurs between offspring phenotype and the environment, which can have long-lasting health and welfare effects. Examples include metabolic diseases resulting from maternal nutrition and behavioral changes from maternal stress. An understanding of these processes and their evolutionary origins will help in identifying and providing appropriate developmental conditions to optimize offspring welfare. This serves as an example of the benefits of using evolutionary thinking within veterinary science and we suggest that in the same way that evolutionary medicine has helped our understanding of human health, the implementation of evolutionary veterinary science (EvoVetSci) could be a useful way forward for research in animal health and welfare.

Oral Administration of Spirulina platensis at Early Gestation Modulates Litter Size and the Expression of Inhibin, Insulin, IGF-I, CO Q10, and BMP-15 in Ewes Induced for Twinning

Gestation in sheep necessitates the support of nutrients to avoid early embryonic mortalities. Therefore, this study investigates the effects of supplementing either L-arginine or Spirulina alga in the first trimester on the pregnancy rate, litter size, inhibin, insulin, IGF-I, CO Q10, and bone morphogenetic peptide 15 (BMP15) in maternal circulation. Animals were offered barley (500 g/head/day, 14% CP), alfalfa hay (1 kg/head/day, 12% CP), clean water, and balanced salt block licks as free choices. Forty Noemi and Najdi ewes were randomly allotted into three groups: control (C, n = 8), L-arginine (ARG, n = 16), and Spirulina (SP, n = 16). All females were implanted with CIDR for ten days. On days 8, 9, and 10, treated ewes were given a protocol comprised of human recombinant FSH at descending doses (50, 50, 40, 40, and 30, 30 IU, A.M, and P.M, respectively). At the fifth dose, animals were given an equivalent dose of hCG (240 IU). After CIDR withdrawal, ewes were exposed to fertile rams for mating. SP-ewes were orally given 50 ml (2%) Spirulina, and ARG-ewes were given 50 ml (35 mg/kg BW) L-arginine daily for 50 days postbreeding. Blood inhibin, insulin, IGF-I, CO Q10, and BMP15 were determined throughout gestation until parturition. The findings indicated that the conception rates were 25, 75, and 87.5% in C, ARG, and SP, respectively (P < 0.05). The percent of ewes giving birth to twins was 0, 25, and 50% in C, ARG, and SP, respectively (P < 0.05). The survival rates were 100, 81.8, and 83.3%, respectively. Birth weight was 5.6, 3.2, and 3.4 kg in C, ARG, and SP, respectively. Weaning weights were 28.3, 25.6, and 27.2 kg in C, ARG, and SP, respectively. BMP-15 was reduced (P < 0.05) in ARG than in C and SP. However, SP decreased (P < 0.05) inhibin more than in C and ARG. ARG and SP increased (P < 0.05) insulin than in C, whereas SP decreased (P < 0.05) IGF-I. SP increased CO Q10 compared with ARG. Ewes bearing twins revealed higher (P < 0.05) IGF-I (8.57 ng/ml) than those bearing singles (4.63 ng/ml); however, BMP-15 was higher in single (796.6 pg/ml) than in twin-bearing (387.5 pg/ml) ewes. In conclusion, providing early-gestating ewes with Spirulina enhances maternal health, productivity, and reproductive outcomes.

Metabolic and hormonal control of energy utilization and partitioning from early to mid lactation in Sarda ewes and Saanen goats

In a recent study, we observed that starch-rich diets used in mid lactation induced lower milk production persistency and higher body fat accumulation in dairy ewes compared with dairy goats. Because these species differences could be linked to hormonal mechanisms that drive energy partitioning, in the same experiment, we explored the evolution of metabolic and hormonal status during lactation to test this hypothesis. Twenty mature Sarda dairy ewes and 20 mature Saanen goats [15-134 ± 11 d in milk (DIM), mean ± SD] were compared simultaneously. In early lactation, each species was allocated to one dietary treatment: high-starch diet [HS: 20.4% starch, on dry matter (DM) basis], whereas from 92 ± 11 DIM, each species was allocated to 1 of 2 dietary treatments: HS (20.0% starch, on DM basis) and low-starch (LS: 7.8% starch, on DM basis) diets. Blood samples were collected in the morning to analyze glucose, nonesterified fatty acids (NEFA), growth hormone (GH), insulin, and insulin-like growth factor I (IGF-I). Data were analyzed using the PROC MIXED procedure of SAS with repeated measurements (SAS Version 9.0). The HS and LS diets applied in mid lactation did not affect metabolic status of the animal within species; thus, only a comparison between species was carried out. From early to mid lactation, plasma glucose concentration was higher in ewes than in goats (54.57 vs. 48.35 ± 1.18 mg/dL), whereas plasma NEFA concentration was greater in goats than in ewes (0.31 vs. 0.25 ± 0.03 mmol/L). Goats had higher plasma GH concentration and lower plasma insulin content than ewes (4.78 vs. 1.31 ng/mL ± 0.47; 0.11 vs. 0.26 μg/L ± 0.02). Plasma IGF-I concentration did not vary between species. The comparison of metabolic and hormonal status of lactating Sarda dairy ewes and Saanen goats, carried out by studying simultaneously the 2 species in the same stage of lactation and experimental conditions, suggests that the higher insulin and glucose concentration observed in Sarda ewes explains why they partitioned more energy toward body reserves than to the mammary gland, especially in mid lactation. This can justify the negative effect of high-starch diets in mid-lactating Sarda ewes. Conversely, the highest GH and NEFA concentration observed in Saanen goats explain why they partitioned more energy of starch diets toward the mammary gland than to body reserves and justify the positive effect of high-starch diet in mid lactation. Together, these different responses contribute to explain why specialized dairy goats, such as the Saanen breed, have a higher milk production persistency than specialized dairy sheep breeds, such as the Sarda.