Stable isotopes in the determination of greenhouse gases from integrated systems: in vivo and in vitro approaches

• Grant number: 21/11644-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: June 01, 2022
• End date: September 30, 2024
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Adibe Luiz Abdalla
• Grantee: Flavia de Oliveira Scarpino Van Cleef
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The stable isotope technique will be used on in vivo and in vitro studies to determine the Dry Matter (DM) and nutrient intakes and the contribution of forage legumes in the enteric methane (CH4) emitted by ruminants. In experiment 1, two trials will be conducted, one, using Pigeon pea (Cajanus cajan) intercropped with Brachiaria decumbens in degraded or recovered pastures and the another, using Macrotyloma axillare intercropped with Brachiaria brizantha cv. Marandu. Canchin steers (280 kg of Body Weight - BW) will be blocked by initial BW distributed in a randomized complete block design and assigned to one of three experimental treatments: 1) degraded pasture (DP); 2) Recovering Pasture (RP) and 3) grass and legume intercropped (G+L). The second in vivo trial will be carried out using Jersey heifers (150 kg of BW), distributed three treatments: 1) exclusively grass pasture without supplementation (Gr); 2) grass pasture plus protein supplementation (Gr+Pt); and 3) grass and legume mixed pasture (Gr+Leg). It will be determined Dry Matter (DM) and nutrient intake and digestibility using external and internal markers as well as the methane (CH4) emission from animals and the isotopic composition of C from treatments containing legumes. In experiment 2, in vitro trials will test different legumes in different proportions in grass-based diets at short and long terms. At short terms, substrates grass only, or binary mixtures of grass and legumes will be incubated in bottles. At longer terms, RUSITEC apparatus will be used. Both will estimate in vitro digestible organic matter (IVDOM), CH4 produced and the isotopic signature of 13C and 15N in the incubated substrate, in the undegraded residue and the 13C in the fermentation gases CO2 and CH4. (AU)