Tomato pomace as a protein supplement for growing lambs

A barley-based diet (B) with 115 g CP/kg DM was supplemented, on DM basis, with 100 (T1), 200 (T2) or 300 (T3) g tomato pomace/kg to achieve final CP contents of 136, 156 and 172 g/kg DM, respectively, and fed to four growing lambs each. DM intake was adjusted to achieve the same energy intake for all diets (50 g DOM/kg BW0.75). N retention increased from 0.50 to 0.69 g/kg BW0.75 between diets B and T1, but higher levels of supplementation did not improve N retention. In a second balance trial, a barley-based diet (B) with 122 g CP/kg DM was supplemented, per kg ration DM, with 200 g tomato pomace untreated (TU) or treated with 50 g NaOH/kg DM (TT). The supplemented diets, containing 155 and 151 g CP/kg DM, respectively, were compared to an isonitrogenous soybean meal diet (SL; 145 g CP/kg DM), and a higher protein soybean meal diet (SH; 163 g CP/kg DM). All diets were fed ad libitum to four lambs per treatment. There were no differences in DM or DOM intake, mean values being 99.1 ± 1.66 and 65.3 ± 1.24 g/kg BW0.75, respectively. N retention (g/kg BW0.75) increased significantly from 0.84 on diet B to 1.07 on diets TU, TT and SL, but diet SH did not promote a significantly higher N retention. In a growth trial, diets TU, TT, SL and SH were fed to seven lambs each for an experimental period of 6 wk. Mean live weight increased from 15.5 ± 0.56 to 28.2 ± 0.44 kg final weight. DM intake (g/kg BW0.75) was not affected by dietary treatment and was 95.4, 97.1, 102.3 and 97.0 for TU, TT, SL and SH, respectively. Growth rates ( g d) and feed conversion rates (kg DM/kg gain) were 304, 318, 337, 329 and 3.20, 2.95, 3.10 and 2.95 for the same diets. It was concluded that supplementation of barley-based diets with tomato pomace at a rate of 200 g/kg ration DM promote similar N retentions and growth performances to soybean protein in young lambs up to 28 kg BW. © 1994.