Abstract:

[Objective] This study was conducted to assess the effects of partly replacing whole-plant corn silage with quinoa straw micro-silage on production performance, nutrient apparent digestibility, and serum indexes of fattening Simmental crossbred cattle. [Method] A total of 36 Simmental crossbred cattle with good physical condition and initial weight of around 450 kg were selected and randomly assigned into the following 4 groups： a control group and three experiment groups. There were 9 cattle in each group, and each head was a replicate. The control group fed a basal diet （TMR）, and quinoa straw micro-silage was used to replace whole-plant corn silage at ratios of 10%, 30%, and 50% on the basis of roughage in the basal diet in experiment group 1, experiment group 2, and experiment group 3, respectively. The pre-feeding period was 15 d, and the formal feeding period was 60 d. The body weight and feed intake status of the experimental beef cattle in each group during the experiment period was recorded to calculate the average daily gain, average daily feed intake, and average feed to gain ratio. Diet and fecal samples were collected to determine the contents of main nutrients, and to calculate the nutrient apparent digestibility. At the end of the feeding experiment, blood were collected to prepare serum samples, and the serum biochemical indexes, antioxidant capacity indexes, and immune indexes were measured. [Result] Compared with the control group, the experiment group 1 had significantly （P<0.05） increased average daily gain, while had significantly （P<0.05） reduced average feed to gain ratio. The apparent digestibilities of dry matter （DM）, crude protein （CP）, crude fiber （CF）, neutral detergent fiber （NDF）, and acidic detergent fiber （ADF） were significantly lower （P<0.05） in experiment group 1, experiment group 2, and experiment gruop 3 than those in the control group. In experiment group 1, the serum activities of aspartate aminotransferase （AST）, alanine aminotransferase （ALT）, superoxide dismutase （SOD）, and glutathione peroxidase （GSH-Px）, the total antioxidant capacity （T-AOC）, as well as the contents of IgG and IgM were significantly （P<0.05） higher than those in the control group, while the serum level of MDA was significantly （P<0.05） lower than that in the control group. [Conclusion] Partly replacing whole-plant corn silage with quinoa straw micro-silage in the diet of fattening Simmental crossbred cattle increased the daily gain, reduced feed to gain ratio, and enhanced the antioxidant and immune ability. Substitution at a ratio of 10% was recommended.

Key words: quinoa straw micro-silage, Simmental crossbred cattle, production performance, serum index, apparent digestibility