Use of the Penn State particle separator to determine if molasses can reduce sorting of ground juniper when juniper is used as a feed intake limiter for lambs

The Penn State particle separator (PSPS) was used to determine if molasses can reduce sorting of ground juniper when juniper is used as a feed intake limiter for lambs. Rambouillet wether lambs (n = 21) were fed ad libitum treatments in the morning that consisted of coarse-ground juniper material, dried distillers grains with solubles (DDGS), and either no water or molasses (CNTL; 50:50:0), water (WAT; 45:45:10), or a 50:50 water:cane molasses solution (MOL; 45:45:10); lambs were fed an ad libitum basal pelleted diet in the afternoon. Lamb body weight, average daily gain, basal diet and total dry matter intake (DMI), and gain to feed efficiency were similar (P>0.17) among treatments, but DMI of MOL was greater than CNTL (P<0.09). Particle size distributions of each treatment and feed refusals were determined by the PSPS, which contains a series of 3 sieves and a solid bottom pan. Treatment×sieve interactions (P<0.001) were observed for g/kg of dry matter (DM) under and retained on sieves and for neutral detergent fiber (aNDF) expressed as g/kg of total DM. The WAT and MOL had less (P<0.001) DM under and greater (P<0.001) DM retained on the 8.0- and 1.18-mm sieves than CNTL, suggesting that molasses adhered to small and large juniper particles and DDGS. When material >19.0 mm was excluded from calculations, geometric mean length and standard deviation decreased for all treatments, but CNTL still had less (P<0.001) geometric mean length than WAT or MOL and MOL had less material in the bottom pan (<1.18 mm; P<0.001) than WAT. For treatment refusals, treatment×sieve interactions (P<0.04) were observed for g/kg of DM under and retained on sieves, but g/kg of DM under and retained on the 19.0- and 8.0-mm sieves were similar (P>0.10) among treatments. The CNTL and MOL had greater (P<0.001) DM under the 1.18-mm sieve (bottom pan) as compared to WAT, suggesting that lambs sorted WAT more than CNTL or MOL. However, chemical composition of treatment refusals suggested that lambs sorted the treatments at similar extents. The PSPS was effective in determining particle size distribution of diets and feed refusals containing coarse-ground woody forage material. Removing coarse-ground juniper material greater than 19-mm from the treatments does not currently seem warranted, but should be considered if it is going to be ground finer and included in non-agglomerated or pelleted diets that reduce or eliminate sorting, respectively.