Substituting ground woody plants for cottonseed hulls in lamb feedlot diets: Growth performance, blood serum chemistry, and rumen fluid parameters

Abstract

Effects of using ground woody plants in Rambouillet wether lamb feedlot diets on growth performance, blood serum, and rumen parameters were evaluated. A randomized design study was used with 2 feeding periods (70% concentrate diet from d 0 to 27 [Period 1] and 86% concentrate diet from d 28 to 57 [Period 2]); the concentrate portion of the diets mainly consisted of dried distiller’s grains with solubles and sorghum grain. Lambs were individually fed 6 diets that differed only by roughage source (n = 8 animals/ treatment; 32.9 ± 3.2 kg initial BW): either cottonseed hulls (CSH; control) or ground wood consisting of redberry juniper (RED), blueberry juniper (BLUE), one-seeded juniper (ONE), or eastern red cedar (ERC) Juniperus spp. or honey mesquite (MESQ; Prosopis glandulosa). Using ground wood vs. CSH as the roughage source did not affect (P > 0.12) BW. There tended to be a treatment × day interaction (P = 0.07) for lamb DMI, attributed to Period 1 when DMI was greater (P < 0.05) for lambs fed CSH vs. RED, ONE, ERC, or MESQ during the first 14 d and greater (P < 0.05) during d 14 to 28 vs. lambs fed ERC. Overall, ADG was less for lambs fed ERC (P < 0.10) or MESQ (P < 0.05) vs. lambs fed CSH, but G:F was similar (P > 0.10) among all lambs. Dietary treatments did not affect (P > 0.15) ruminal pH, but treatment × day interactions (P < 0.05) were observed for rumen fluid ammonia N or molar proportions of propionate and butyrate; few differences were observed within day. However, overall, lambs fed RED or MESQ had greater (P < 0.05) total rumen VFA than lambs fed CSH. A treatment × day interaction (P = 0.04) was observed for the acetate:propionate ratio, but no differences (P > 0.10) were observed within day. Treatment × day interactions (P < 0.05) were observed for blood serum glucose, γ-glutamyl transferase, the albumin:globulin ratio, total bilirubin, β-hydroxybutyrate, P, Cl, and Mg, with most results being less for lambs fed the wood-based diets than for lambs fed the CSH diets. Results suggested that even though lamb DMI was reduced during the growing period when diets contained 30% ground woody products (RED, ONE, ERC, and MESQ), animal health and rumen fluid parameters were not negatively affected by ground woody plants.