Tracing back sheep diet composition feeding grass-legume mixtures using fecal δ13C

This study tested different proportions of C4 grass and legume and the correlation between dietary δ13C with fecal δ13C. Forty lambs, male, with average body weight of 20.4 kg, were randomized in a complete block design and fed Tifton-85 (Cynodon spp.) and Alfalfa (Medicago sativa) hays, at different levels of substitution composing five treatments: 1) 100% Tifton-85 hay; 2) 75% Tifton-85 + 25% alfalfa hay; 3) 50% Tifton-85 + 50% alfalfa hay; 4) 75% alfalfa + 25% Tifton-85 hay; 5) 100% alfalfa hay. The trial lasted 27 days, consisting of 22 days for adaptation and 5 days for collection of orts, feed, and feces. Fecal samples were collected directly from the rectum, to avoid contamination. All samples were collected during the 5-d sampling period, being composited at the end. Feed and fecal samples were dried for 72 hours in an oven (55ºC) and ground in a Willey mill to pass a 2-mm sieve, incubated for 288 hours in situ to obtain the indigestibility. All collected samples were subjected to indigestible neutral detergent fiber (iNDF) and carbon stable isotope analysis. Dietary isotopic composition (δ13C) in the iNDF residue processing was -14.98, -18.22, -23.85, -25.99, and -30.64‰ for treatments 1 to 5, respectively. The δ13C of dietary samples iNDF treated was -17.41, -20.27, -26.06, -27.83, and -31.67‰, respectively for diets 1 to 5. Fecal δ13C for non-treated samples was -16.23, -20.79, -25.10, -28.8, and -32.31‰, and for iNDF-treated sample -16.65, -21.52, -26....
Source: Small Ruminant Research - Category: Zoology Source Type: research