Im concerned with some of the reslts which seem strange. why such a big difference between species can this be explained.  

When we instead compared unirrigated sheep-grazed systems with irrigated cattle-grazed systems, SOC was 13.9 ± 1.5 tC ha?1 lower under the unirrigated sheep system than under the irrigated cattle system. The mean C removed in animal products was 0.67 ± 0.02, 0.06 ± 0.02, and 0.32 ± 0.04 tC ha?1 y?1 for the irrigated dairy, unirrigated dairy, and unirrigated sheep-grazed systems, respectively. 