Sparkes et al., 2010. Asian-Aust. J. Anim. Sci., 23 (2): 197-204

Two studies were conducted to determine the effects of replacing30% (% in diet DM) of lucerne (Medicago sativa L) hay with citrus pulp inMerino ewe diets: i) an in vitro study which measured ruminal fermentation;and ii) an in vivo study in which twelve Merino ewes pre- and post-lambing were fed experimental diets in a cross-over design over 120 days to evaluate effects on ewe performance (i.e. DM intake, average daily gain (ADG) and wool growth). In both the in vitro and in vivo studies, the control treatment consisted of lucerne (91.3% in diet DM), lupins (8.3% in diet DM) and phosphate (0.42% in diet DM), while the citrus pulp treatment consisted of lucerne (57.7% in diet DM), lupins (9.5% in diet DM). phosphate (0.48% in dietDM) and fresh citrus pulp (32.3% in diet DM). Data were analysed using the mixed model procedure of SAS. In the in vitro study, gas production, total volatile fatty acid (VFA) yield, proportion of propionic acid to total VFA and in vitro dry matter digestibility (IVDMD) were higher (p<0.02) in the citrus pulp treatment compared to the control treatment. In contrast, in vitro ammonia production. pH and the acetate to propionate ratio were lower (p<0.03) for the citrus pulp treatment compared to the control treatment. In the in vivo study,DM intake of ewes fed the citrus pulp diet was lower than their control ewe counterparts throughout both the pre- and post-lambing periods (928.9 vs.1.115.0 g/d pre-: 1.285.0 vs. 1,620.3 g/d post-lambing, p<0.01), however ADG was similar (p = 0.12). Wool growth parameters and lamb performance did notdiffer (p>0.32) between treatments. In summary, the in vitro stud),demonstrated that the replacement of 30% of a lucerne diet with fresh citruspulp improved total VFA yield, increased total gas production and improvedIVDMD. while decreasing the production of ammonia. acetic acid and rumenpH. In addition, the it? vivo study demonstrated that the replacement of 30% ofa lucerne diet with fresh citrus pulp pre- and post-lambing decreased intake butdid not affect ewe performance in terms of ADG and wool growth. These findings, Of Course, would be of significant interest to sheep producers endeavouring to control cost of feed ingredients whilst maintaining productivity.