Influence of Guar Meal from Pig Compound Feed on Productive Performance, Nitrogen Metabolism, and Greenhouse Gas Emissions

Abstract

Guar (Cyamopsis tetragonoloba) is an annual legume tolerant to drought. Guar meal (GM) is a protein- and carbohydrate-rich co-product generated after the mechanical separation of the endosperm from the germ and hull of guar seed. GM has received considerable interest in animal feed as an alternative to soybean meal (SM). In this study, we aimed to assess the nitrogen (N) balance indicators, performance, carcass traits, and main greenhouse gas (GHG) emissions resulting from enteric fermentation (E-CH4) and manure (M-CH4 and N2O). Two tests were performed: (i) a biological trial on 45 pigs (15 animals/group) and (ii) a digestibility test in metabolism cages (N = 15, 5 replicates/group). Three different diets were given to the pigs: one diet was based on 0% GM (SM diet); in the second, GM-50%, GM replaced 50% of the SM; and the third was GM-100%, in which GM fully replaced the SM. The GM and SM diets were analyzed for their proximate composition. A model based on prediction equations was used to estimate the GHGs. GM up to 10% in the diets of finishing pigs did not significantly impact growth performance or carcass traits, although a slight increase in neutral detergent fiber (NDF) was observed. GM up to 10% improved N digestibility (p < 0.0001), net protein utilization (p < 0.0001), the biological value of protein, coefficients of metabolizability, and the coefficient of the total tract’s apparent digestibility. Irrespective of its dietary proportion, GM decreased total nitrogen output (TNO, p = 0.11). A highly significant impact was noted for N2O and E-CH4 (for DM, p < 0.0001), as well as a significant impact for E-CH4, expressed as g CO2 Eq (p = 0.007), and g CO2 Eq. LU (livestock unit, p = 0.005), also reported as ADG (p = 0.024). Manure, M-CH4, was not significantly influenced. In conclusion, GM can replace up to 100% SM and is thus a valuable byproduct that does not alter animal performance and can positively impact N2O and E-CH4.

Animal Nutrition and Productions: Series II

“…The authors concluded that WDGSs can be used in the liquid feeding of pigs in a proportion of up to 15% of the DM, without affecting the pig performance, carcass traits, meat quality, proximate composition, or physical-chemical traits of pork. Similar topics were also addressed in the papers of Chiofalo et al [21] and Mihaila et al [22]. Chiofalo et al [21] evaluated the agronomic traits, chemical composition, fatty acid profile, and in vitro fermentation characteristics of twelve varieties of Amaranthus spp.…”

“…Among the varieties studied, A. hypochondriacus proved to have the best agronomic traits and the seeds had the best nutritional value (high protein and starch content and a good fatty acid profile), being potential ingredients for pig diets. Mihaila et al [22] investigated the possibility of substituting soybean meal in pig feed with guar meal, which is a by-product rich in protein and carbohydrates, obtained after mechanical separation of the endosperm from the germ and coat of guar seeds. The obtained results demonstrated that guar flour can replace 100% soybean meal in a pig finishing diet, without changing animal performance or carcass traits, and can have a positive impact on the main greenhouse gas emissions resulting from enteric fermentation (E-CH 4 ) and manure (M-CH 4 and NO 2 ).…”