Glucose and insulin curve in pregnant mares and its relationship with clinical and biometric features of newborn foals

Abstract

The aim of the present study was to describe the dynamics of glucose and insulin curves in pregnant mares, and to evaluate the curves according to body condition score, identifying the presence of insulin resistance and correlating these values with the weight, height and clinical changes of the neonates. For this, pregnant mares were evaluated and then grouped according to body condition score during the gestation length until lactation. GrM corresponds to mares with moderate body score (BCS 5-6); GrOv were mares with overweight body score (BCS 7) and GrOb were obese mares (BCS 8-9). A two-step oral sugar test (OST) was used to determine the data. Cortisol analysis was performed with 300-320 days of gestation, at foaling and after parturition. For evaluation of the neonate, a general clinical examination and, weight and height measurements were performed. The results showed hyperglycemia in response to OST with normal insulin values at foaling with a subsequent fall in both values at lactation disregarding group division. Baseline glucose was decreased in GrM compared to GrOv and GrOb with 70-100 days of gestation and with 130-160 days of gestation. With 270-300 days of gestation and post-partum GrOb had increased baseline glucose than GrM. After OST, glucose at foaling day in GrOb presented increased values than GrM. Baseline insulin values did not differ between groups. Post OST insulin levels were higher in GrOb than GrM and GrOv at parturition. No difference in cortisol between moments was identified. GrOb and GrOv maintained increased concentrations after foaling while GrM had a decrease. No correlation was found between maternal glucose and insulin values with foal weight and height, however, a lower ratio between neonatal weight and mare’s weight in GrOb and GrOv was identified in relation to the GrM. At foaling, mares presented glucose dysregulation, with obese and overweight mares presenting a greater response to OST.

Energy and mineral metabolism of peripartum mares and foals of the Quarter Horse breed

“…However, glucose levels were higher at parturition in 62 Standardbred mares, 1 and 23 mares (four Percherons and 19 crossbred between Percheron, Belgian, and Breton heavy draft horses), 3 and 26 multiparous pony mares. 18 According to Aoki and Ishii, these alterations could have been due to the physical stress associated with foaling. In the present study, only Quarter Horse mares that delivered healthy, viable full-term foals, without assistance were included.…”

The effects of obesity and insulin dysregulation on mare reproduction, pregnancy, and foal health: a review

“…It has also been reported that obese mares generally tend to produce larger foals ( 123 ), which coincides with the previously mentioned findings, as both obese and multiparous mares are more likely to have a higher degree of IR ( 5 , 77 ). However, in studies that assessed the direct relationship between mare overnutrition, obesity and foal birth weight, elevated BCS was not found to result in heavier or taller foals ( 14 , 85 , 122 , 139 ), nor did the foal weight or height correlate with the plasma insulin and glucose concentrations of the mare ( 139 ).…”