Effects of hybrid Broussonetia papyrifera silage on growth performance, visceral organs, blood biochemical indices, antioxidant indices, and carcass traits in dairy goats

The crude protein content of hybrid Broussonetia papyrifera silage (HBPS) is close to that of alfalfa hay. In the present study, we substituted alfalfa hay with HBPS in diets for Saanen dairy goats, and tested a possibility of using HBPS as a feedstuff to provide protein. Thirty male Saanen dairy goats (6-months old, body weight 18.85 +/- 1.44 kg) were divided into three groups of 10, and randomly assigned to three diets: the control group (CN) fed the basal diet containing 600 g/kg (dry matter (DM) basis) of alfalfa hay, and the other two groups fed the diets with 33 % and 67 % of alfalfa hay being substituted with HBPS, so HBPS accounted for 198 g/kg (LB) and 402 g/kg (HB) of the diet respectively. The experiment lasted for 94 days. Compared with CN, feeding HBPS did not change feed intake, body weight gain, and the visceral organ coefficients (P > 0.05), but reduced the feed conversion ratio and the weight gain cost, particularly on the 198 g/kg HBPS diet (P < 0.05). Serum concentrations of total protein, albumin, and urea-nitrogen in both LB and HB groups and glucose in HB group decreased (P < 0.05), but their values remained within the normal range. Ammonia concentration in rumen fluid was reduced by feeding HBPS (P < 0.05). The serum activity of superoxide dismutase (SOD) was increased and the concentration of malondialdehyde (MDA) decreased (P < 0.05) in both LB and HB groups (P < 0.05), and the SOD activity in longissimus dorsi muscle (LDM) was increased only for LB treatment (P < 0.05). Feeding HBPS had no effect on the carcass traits and water holding capacity in LDM (P > 0.05). In conclusion, HBPS had similar effects to alfalfa hay on the growth performances, visceral organ development, and water holding capacity postmortem, but reduced the feed conversion ratio and the feed cost, and enhanced the antioxidant capacity of animals. Inclusion of 198 g/kg of HBPS in the diet would be a better choice for growing goats. Reduced ammonia concentration in the rumen, urea and protein concentrations in blood suggest dietary protein digestion in the gastrointestinal tract could be affected by feeding HBPS, which is worthy of further investigation.