Effects of Reduced in Utero and Post-Weaning Nutrition on Glucose Clearance Measures and Serum Metabolites

Lowering production costs while maintaining an optimal level of production is important to producers in extensive environments. Efforts that strive to match the environment to the nutritional requirements of the grazing animal will substantially improve economic returns to the producer. Therefore, a 3-yr study was implemented that evaluated glucose clearance and serum metabolites in primiparous beef heifers (n = 48; 16/yr) from two different feeding regimes. Serum metabolites and glucose clearance measures were analyzed by fitting a repeated measure mixed model using the MIXED procedure of SAS 9.4 (SAS Inst., Inc., Cary, NC). Heifers dams received adequate 1.8 (ADEQ) or marginal 1.2 (MARG) kg/d winter supplementation for approximately 80 d prior to parturition and their heifer calves were then randomly assigned to heifer development treatments that provided ad-libitum (AL) or 80% of ad-libitum (LAL) feed post weaning. Heifers that received the AL treatment during the developmental period were then assigned the 1.8 kg/d winter supplementation for life, whereas heifers that received the LAL treatment during development were assigned the 1.2 kg/d winter supplementation for life. Peak glucose concentrations in response to a bolus dose of glucose changed in magnitude between ADEQ and MARG in utero treatments and decreased further removed from parturition (P = 0.05). However, these changes did not manifest along with other glucose clearance measures (P u003e 0.17) indicating that regardless of in utero treatment or heifer development treatment the reduction in feed input did not greatly influence glucose clearance measures or baseline serum metabolites throughout postpartum, first parity period.