Use of internal markers to estimate feed intake and selection of forage in sheep fed grass and legume hay

Author(s)

Ovani, Vagner S. ; Abdalla, Adibe Luiz ; Marquez, Simon Perez ; da Costa, Wilian dos Santos ; Bizzuti, Beatriz Elisa ; Tavares Lima, Paulo de Mello ; Moreira, Guilherme Dias ; Gerdes, Luciana ; Louvandini, Helder

• Document type: Journal article
• Source: ANIMAL FEED SCIENCE AND TECHNOLOGY; v. 283, p. 13-pg., 2022-01-01.

Abstract

The accurate prediction of feed intake is the most important information required to assess the feed conversion efficiency of individual grazing animals. The objective of this study was to evaluate the accuracy of three approaches using the combined performance of four internal markers: indigestible dry matter (iDM); indigestible neutral detergent fiber (iNDF); titanium (Ti); and the isotopic signature of carbon (delta 13C). These markers were used to predict the individual intakes of sheep that were fed grass and forage legumes. Twenty-one Santa Ine<SIC>s sheep were randomly divided according to three diets: 100% Megathyrsus maximus cv. Aruana grass (CTL diet); 25% inclusion (as fed basis) of Macrotyloma axillare legume (MAC diet); and 50% inclusion (as fed basis) of Stizolobium aterrimum legume (MUC diet). After the 10-day diet adaptation period, the animals were transferred to individual metabolic cages, where they were kept for seven days with daily measurements and collection of feed offerings, feed leftovers, and feces samples. The iDM and iNDF fractions of the samples were determined after 240 h of in situ incubation. The natural Ti concentration was determined by benchtop energy dispersive X-ray fluorescence spectrometry (EDXRF). The abundance of 13C was determined by mass spectrometry. The accuracy of the predictions of digestibility and intake was increased when the fecal recovery rate of the internal markers (P < 0.05) was corrected. The proportion of grass and legumes in the feces was accurately predicted by the 13C method. The combined use of iNDF and 13C markers could be an alternative for predicting individual digestibility and intake of grasses and legumes by animals that are fed mixed diets. (AU)

• FAPESP's process: 13/02814-5 - Productive aspects and methane emission by Santa Inês sheep kept on tropical grass - legume consortium pasture
• Grantee: Paulo de Mello Tavares Lima
• Support Opportunities: Scholarships in Brazil - Doctorate