Effects of dried distiller's grains and lasalocid on feedlot lamb growth, carcass traits, nutrient digestibility, ruminal fluid volatile fatty acid concentrations, and ruminal hydrogen sulfide concentration

Abstract Text: Our hypothesis was increasing the inclusion level of dried distiller’s grains with solubles (DDG) to feedlot lambs would increase growth, while the inclusion of lasalocid (LAS; Bovatec, Alpharma, LLC, Bridgewater, NJ) would increase ADG and G:F, while not affecting digestibility, ruminal VFA concentration, and pH in the rumen fluid. Furthermore, we hypothesized that rations including LAS and higher levels of DDG would cause increased ruminal hydrogen sulfide gas (H₂S) concentrations. To test this hypothesis, two hundred forty crossbred (Suffolk × Rambouillet) lambs (31.9 ± 5.87 kg BW; approximately 90 d of age) were allocated to 6 treatments in a completely random design with a 3 x 2 factorial arrangement of treatments. Lambs were placed into 24 feedlot pens (4 pens/treatment; 10 lambs/pen) for a 111 d finishing study. Main effects included concentration of DDG (0, 15, or 30% DM basis) and inclusion of LAS (0 or 20 g/ton LAS) resulting in treatments of 1) 0% DDG without LAS (0DDG-NL), 2) 0% DDG with LAS (0DDG-L), 3) 15% DDG without LAS (15DDG-NL), 4) 15% DDG with LAS (15DDG-L), 5) 30% DDG without LAS (30DDG-NL), and 6) 30% DDG with LAS (30DDG-L). Two-day weights were taken at the beginning and end of the trial. Two hundred eighteen lambs (63.7 ± 8.78 kg) were harvested on d 112 at a commercial abattoir and carcass data collected after a 24 h chill. The inclusion of LAS increased (P ≤ 0.02) final BW, ADG, G:F, and HCW. As DDG in the ration increased to 30%, DMI decreased linearly (P = 0.03) while G:F increased linearly (P = 0.03). A second study was conducted utilizing the same treatments to evaluate N and S balance, ruminal VFA and H₂S concentration, and ruminal pH in 24 crossbred wethers (Suffolk × Rambouillet; 41.2 ± 12.23 kg BW). Daily urinary sulfur excretion and H₂S production were linearly increased (P < 0.001) as DDG increased in the ration. Total ruminal VFA concentration linearly decreased (P = 0.002) as DDG increased in the ration. The inclusion of LAS increased (P = 0.02) ruminal pH. The results confirm our hypothesis that LAS increased overall growth and increasing DDG increased ruminal H₂S concentration, however, DDG inclusion did not increase growth. Additionally, we reject the hypothesis that the combined effects of LAS and DDG would have no effect on rumen pH and VFA concentrations.

Keywords: dried distiller's grains with solubles, ionophores, lambs