Effects of Moderate Amounts of Barley in Late Pregnancy on Growth, Glucose Metabolism and Osteoarticular Status of Pre-Weaning Horses

Abstract

In stud management, broodmares are commonly fed concentrates in late pregnancy. This practice, however, was shown to correlate with an increased incidence of osteochondrosis in foals, which may be related to insulin sensitivity. We hypothesized that supplementation of the mare with barley in the last trimester of pregnancy alters the pre-weaning foal growth, glucose metabolism and osteoarticular status. Here, pregnant multiparous saddlebred mares were fed forage only (group F, n=13) or both forage and cracked barley (group B, n=12) from the 7th month of pregnancy until term, as calculated to cover nutritional needs of broodmares. Diets were given in two daily meals. All mares and foals returned to pasture after parturition. Post-natal growth, glucose metabolism and osteoarticular status were investigated in pre-weaning foals. B mares maintained an optimal body condition score (>3.5), whereas that of F mares decreased and remained low (<2.5) up to 3 months of lactation, with a significantly lower bodyweight (-7%) than B mares throughout the last 2 months of pregnancy. B mares had increased plasma glucose and insulin after the first meal and after the second meal to a lesser extent, which was not observed in F mares. B mares also had increased insulin secretion during an intravenous glucose tolerance test (IVGTT). Plasma NEFA and leptin were only temporarily affected by diet in mares during pregnancy or in early lactation. Neonatal B foals had increased serum osteocalcin and slightly increased glucose increments and clearance after glucose injection, but these effects had vanished at weaning. Body measurements, plasma IGF-1, T4, T3, NEFA and leptin concentrations, insulin secretion during IVGTT, as well as glucose metabolism rate during euglycemic hyperinsulinemic clamps after weaning, did not differ between groups. Radiographic examination of joints indicated increased osteochondrosis relative risk in B foals, but this was not significant. These data demonstrate that B or F maternal nutrition has very few effects on foal growth, endocrinology and glucose homeostasis until weaning, but may induce cartilage lesions.

Maternal Nutrition during Pregnancy Affects Testicular and Bone Development, Glucose Metabolism and Response to Overnutrition in Weaned Horses Up to Two Years

“…Management of mares and foals from insemination to weaning has been described previously by Peugnet et al . [31]. …”

“…From the 7 th month of gestation, they were housed in individual boxes and allocated to one of two groups: fed with forage only (F, n = 12) or with forage and flattened barley (B, n = 12) until foaling. From 3 days until 6 months of age, foals were in pasture with their dams [31]. They were weaned at 6 months and housed in open barns and fed the same amount of feed, following the INRA recommendations for growing foals [29].…”

“…In their first winter, foals were housed in open barns and fed hay and concentrates in agreement with current INRA recommendations for growing foals [31]. Six months after weaning (April 25 th , at 11 months of age), yearlings returned to pasture and were managed in one same herd with free access to water and minerals salts.…”

“…The present study is a follow-up of previous work in which broodmares were supplemented (group B) or not (group F) with concentrates from mid-gestation to term [31]. Briefly, the daily supplementation of B mares with flattened barley (2 to 3 kg) provided additional net energy and digestible proteins from the 7 th until the 10 th month of gestation compared to F mares, allowing them to maintain optimal body condition throughout pregnancy and lactation.…”

“…F foals, however, tended to have decreased glucose tolerance and lower osteocalcin concentrations at 3 days of age. At 6 months of age (weaning), these differences had disappeared and osteoarticular status did not differ between both groups of foals at that stage [31]. …”