Effects of Substitution of Wheat Straw by Giant Reed on Growth Performance, Serum Biochemical Parameters, Nutrient Digestibility, and Antioxidant Properties of Sheep

The development and utilization of unconventional forage resources is crucial to alleviating the current situation of shortage of forage resources. Giant reed (<i>Arundo donax</i>) is a promising forage resource from the Poaceae family, one of the largest herbaceous plants globally, with fast growth, high biomass yield, and strong ecological adaptability. However, there are still very few reports on the use of giant reed in livestock and poultry production. The purpose of this study was to evaluate the effects of adding giant reed instead of wheat straw in total mixed ration (TMR) diets on growth performance, blood biochemical indexes, nutrient digestibility, and antioxidant properties of sheep, thereby providing a theoretical basis for the development and utilization of giant reed herbage resources. A total of 24 fattening sheep (Han × Duper) with similar body weight (20 kg), age (2 months), and health status were randomly divided into four groups with six replicates per group. Sheep in the control group were fed a basal diet (CON), and those in the experimental groups were fed giant reed Lvzhou No. 1 instead of wheat straw, with replacement proportions of 10% (GR10), 20% (GR20), and 30% (GR30) of the total diet, respectively. The results showed that (1) the body weight (FBW) and average daily gain (ADG) of sheep in the GR20 and GR30 groups were higher than those of sheep in the CON and GR10 groups (<i>p</i> < 0.05). Meanwhile, the feed to gain ratio (F/G) of sheep in the GR20 and GR30 groups was lower than those sheep in the CON and GR10 groups (<i>p</i> < 0.05), and the F/G of the GR30 group was lower than that of the GR20 group (<i>p</i> < 0.05). (2) The apparent digestibility of DM and CP in groups GR10, GR20 and GR30 was significantly higher than that in group CON (<i>p</i> < 0.005). The digestibility of NDF and ADF in groups GR20, and GR30 was significantly higher than that in the CON and GR10 groups (<i>p</i> < 0.05). (3) dietary substitution of giant reed for wheat straw had no effect on serum biochemical indices, except serum glucose (GLU, <i>p</i> = 0.014) of sheep. In addition, the substitution of giant reed for wheat straw had a tendency to decrease serum urea content of sheep (<i>p</i> = 0.098). (4) Dietary substitution of giant reed for wheat straw significantly improved serum T-SOD (<i>p</i> < 0.001) and T-AOC (<i>p</i> < 0.001), and significantly decreased MDA (<i>p</i> < 0.001) of sheep. In conclusion, replacing wheat straw with giant reed can significantly enhance growth performance, nutrient digestibility, and antioxidant capacity in sheep without adverse effects on their normal physiological functions.