Growth Performance and Plasma Metabolites of Growing Goats Grazing in Abandoned Paddy Fields for Meat Production

This study aimed to compare the growth of goats grazed in abandoned paddy fields with those raised in confined systems for meat production and to clarify the relationship between plasma metabolites including phytol derivatives and botanical conditions of the field. Eight Saanen goats at 4 months of age were allocated to the grazing and confined groups. Goats in the grazing group were grazed in an abandoned field with a concentrate supplement at 1.2% body weight (BW) from the end of May to early November. Grass silage and concentrate supplement at 1.0% BW were provided to the confined goats. Imperata cylindrica and Boehmeria nivea were the dominant plants in the grazing field. Plant biomass and its utilization reached a maximum in August and then decreased thereafter. Although the BW of goats in both groups was almost comparable until the end of September, the grazing goats showed a lower final BW than those in the confined group. Plasma concentrations of urea, total cholesterol, nonesterified fatty acids, lactate, amino acids, and phytanic acid in grazing goats fluctuated throughout the experimental period. These plasma metabolites can be used to monitor the nutritional condition of goats and botanical conditions of grazing fields.