Bio-economic efficiency of creep supplementation of forage legumes or concentrate in pasture-based lamb production system

A 2-year study in the Central Anatolian Region of Turkey compared the performance of pasture-fed suckling lambs and their dams, set-stocked on grass-legume pastures supplemented either with forage legumes or concentrate through a creep grazing/feeding system in a randomized block design. The treatments included continuous pasture grazing + creep grazing alfalfa; continuous pasture grazing + creep grazing birdsfoot trefoil; continuous pasture grazing + creep feeding concentrate (170 g kg(-1) CP; 11.3 ME MJ kg(-1) DM); and continuous grazing without creep feeding (control). In both years, creep feeding/grazing commenced in early June following a 42-day pasture grazing period (period 1) and continued until mid-summer for two separate periods of 21 days each (periods 2 and 3). Creep-supplemented lambs grew faster (p<.001) than those that grazed pasture alone, with no significant difference across all creep supplementation treatments. Across the years, the lambs grew at 223 and 161 g per head day(-1) for creep-supplemented and control groups respectively. None of the lamb feeding strategies affected the ewe live-weight gains (p>.05). Results from a bio-economic optimization model, however, showed that supplementing the pasture with birdsfoot trefoil and alfalfa in periods 2 and 3, respectively, maximized economic returns with an extra profit of US$88.83 per lamb above those that grazed the pasture alone.