Effects of addition of food by-products on the fermentation quality of a total mixed ration with whole crop rice and its digestibility, preference, and rumen fermentation in sheep

Four sheep were used in a 4 × 4 Latin square design experiment to study fermentation quality, digestibility, and preference of a whole crop rice (WCR) total mixed ration (TMR) silage with food by-products. Experimental treatments included control silage (i.e., no food by-product) and 300 g/kg each of TMR dry matter (DM) as dry tofu cake (DTC), rice bran (RB) or wet green tea waste (WGTW). Silages ensiled for 60 days were well preserved with low pH (<4.06) and NH3–N contents, and high lactic acid content. A higher (P<0.05) content of lactic acid was observed in the DTC silage. In addition, compared to the control, the DTC and RB treatments increased the CP, EE and GE contents of the silages, and WGTW treatments increased the CP and ADFom contents of the silages. Preference was affected by inclusion of food by-products. The mean relative intake of TMR for the control, DTC, RB and WGTW silages were 0.485, 0.671, 0.397 and 0.447, respectively. Compared to the control, the DTC treatment increased silage preference, while RB and WGTW treatments decreased silage preference. No differences were observed among treatments in ruminal pH or total volatile fatty acid concentrations, but ruminal NH3–N content was highest in the DTC silage (P=0.0191) 2 h after feeding. The molar proportion of acetic acid in ruminal fluid was highest for the WGTW silage (P=0.0004) 4 h after feeding. Molar proportions of propionic acid and isobutyric acid in ruminal fluid were higher for the RB silage (P=0.0277 and P=0.0368, respectively) than for the WGTW silage before feeding, and the molar proportions of isovaleric acid and valeric acid in ruminal fluid were higher for the RB silage (P=0.0183 and P=0.0113, respectively) than for either the WGTW or control silage before feeding. Among the three food by-products, the digestibility of DTC was highest. Findings suggest that food by-products can be used in WCR TMR silage, that the silages can be of good quality, and that silage with added DTC has high digestibility and good preference.