Stable isotopes of C and N differ in their ability to reconstruct diets of cattle fed C3–C4 forage diets

• Published in: Scientific reports Vol. 12; no. 1; pp. 17138 - 12
• Main Authors: Jaramillo, David M., Dubeux, Jose C. B., Ruiz-Moreno, Martin, DiLorenzo, Nicolas, Vendramini, Joao M. B., Sollenberger, Lynn, Mackowiak, Cheryl, Queiroz, Luana M. D., Abreu, Daciele S., Garcia, Liza, Santos, Erick R. S., Kieke, Burney A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13.10.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 631/158/2466; 631/449; 704/158/2453; 704/158/2456; 704/158/2466; Arachis glabrata; Bos taurus; Cattle; Diet; Erythrocytes; Feces; Hair; Humanities and Social Sciences; Isotopes; Livestock; multidisciplinary; Paspalum notatum; Science; Science (multidisciplinary); Stable isotopes
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-022-21051-4

Stable isotopes are useful for estimating livestock diet selection. The objective was to compare δ 13 C and δ 15 N to estimate diet proportion of C 3 –C 4 forages when steers ( Bos spp.) were fed quantities of rhizoma peanut ( Arachis glabrata ; RP; C 3 ) and bahiagrass ( Paspalum notatum ; C 4 ).Treatments were proportions of RP with bahiagrass hay: 100% bahiagrass (0%RP); 25% RP + 75% bahiagrass (25%RP); 50% RP + 50% bahiagrass (50%RP); 75% RP + 25% bahiagrass (75%RP); and 100% RP (100% RP). Feces, plasma, red blood cell (RBC), and hair were collected at 8-days intervals, for 32 days. Two-pool mixing model was utilized to back-calculate the proportion of RP based on the sample and forage δ 13 C or δ 15 N. Feces showed changes using δ 13 C by 8 days, and adj. R 2 between predicted and observed RP proportion was 0.81 by 8 days. Plasma, hair, and RBC required beyond 32-days to reach equilibrium, therefore were not useful predictors of diet composition during the study. Diets were best represented using fecal δ 13 C at both 8-days and 32-days. By 32-days, fecal δ 15 N showed promise (R 2  = 0.71) for predicting diet composition in C 3 –C 4 diets. Further studies are warranted to further corroborate fecal δ 15 N as a predictor of diet composition in cattle.