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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #422332
Research Project: Applying Nutritional Strategies to Improve Early Embryonic Development and Progeny Performance in Beef Cows

Location: Livestock Bio-Systems

Title: The influence of source and level of ruminal undegradable protein on antral follicle count and circulating concentrations of urea, glucose, and insulin in beef heifers grazing native rangelands

Author
item AIZPURU, A - New Mexico State University
item ANDREWS, TAYLOR - New Mexico State University
item BEDKE, CLAYTON - New Mexico State University
item COOPER, JOYCE - New Mexico State University
item RICHARDSON, KATY - New Mexico State University
item DUNLAP, RICHARD - New Mexico State University
item COX, SHAD - New Mexico State University
item Cushman, Robert
item Snider, Alexandria
item FONTES, PEDRO - University Of Georgia
item SMITH, M - University Of Georgia
item MESEN, E - Reprologix
item SUMMER, ADAM - New Mexico State University
item SCHOLLJEGERDES, ERIC - New Mexico State University

Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/11/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The provision of supplements formulated to contain 50% animal sourced ruminal undegradable protein(RUP) compared to heifers supplemented animal sourced 36% RUP had greater pregnancy rates. However, the effects of plant sourced RUP at similar levels of RUP on heifer metabolism is unknown. The objective of this study is to investigate the influence of source and level of RUP on circulating insulin, glucose, and urea concentrations in beef heifers grazing native rangelands. Beef heifers (n=32;10 months of age:233.4±3.8kg) were randomly assigned one of the four diets: 1) animal sourced 36% RUP(n=8;36A), 2)animal sourced 50% RUP (n=8;50A), 3)plant sourced 36%RUP(n=8;36P), and 4)plant sourced 50% RUP(n=8;50P). Heifers were individually fed three times a week for 110 d and heifers were offered dietary treatments at a rate of 1.13 kg • hd -1 • d -1. Blood samples were collected on d 35, 63, 91, 103, and 110 and analyzed for urea, glucose, and insulin concentrations. Antral follicle counts (AFC) were conducted via transrectal ultrasonography 75 d after diets began. Serum metabolites were analyzed using repeated measures of the MIXED procedure of SAS (v9.4). Antral follicle count data was analyzed using MIXED procedure (SAS v9.4). Urea was not impacted by level, source or their subsequent interaction (P >/= 0.38). Glucose concentrations were not affected by level and source (P >/= 0.23). Heifers offered the 50A diet tended to have increased glucose concentrations compared to 36A heifers (P = 0.06). Insulin was not affected by source (P = 0.14), however level 50 heifers tended to have elevated insulin concentration than level 36 heifers (P = 0.08). Level × source influenced insulin (P = 0.02) with 50P heifers having increased insulin concentrations compared to 36P, 36A and 50A heifers (P /= 0.77). Level × day, source × day and level × source × day did not affect urea and glucose concentrations (P >/= 0.31). Source, level, source × level did not influence AFC (P >/= 0.74). In conclusion, supplementing increased levels of RUP increased insulin concentrations, but the elevated insulin concentrations did not stimulate follicular activation. The elevated insulin concentrations in response to the levels of the RUP may be affecting other reproductive tissues, thus improving reproductive success.