The effects of Aspergillus niger on the production performance, rumen fermentation parameters and methane emissions of Hu sheep

Abstract: To investigate the effects of Aspergillus niger on the production performance, rumen fermentation parameters, and methane emissions of Hu sheep, 15 male, approximately 3-month-old fattening Hu sheep weighing (21.69±1.19) kg were randomly divided into three groups: a control group, a 7.5 g Aspergillus niger group, and a 10 g Aspergillus niger group, with 5 replicates per group and 1 sheep per replicate. The pre-trial period was 7 days, and the formal trial period was 28 days. After the experiment, the average daily weight gain, average daily feed intake, and feed conversion ratio of each group were recorded, and an economic benefit analysis was conducted. The emissions of CO2 and CH4 in the environment were measured. Rumen fluid was collected to detect rumen pH, ammonia nitrogen (NH3-N), microbial protein (MCP), and volatile fatty acid (VFA) concentrations. The results showed that compared with the control group, the average daily feed intake of the 7.5 g Aspergillus niger group and the 10 g Aspergillus niger group was significantly reduced (P<0.05), the rumen pH value was significantly increased (P<0.05), and the rumen NH3-N and MCP concentrations were significantly reduced (P<0.05). The concentrations of total volatile fatty acids, valeric acid, and propionic acid were significantly reduced (P<0.05), while the acetic acid/propionic acid ratio was significantly increased (P<0.05). Furthermore, the butyric acid concentration in the 7.5 g Aspergillus niger group was significantly reduced (P<0.05). CH4, CO2 emissions, and CO2 equivalent (CO2-eq) were all significantly reduced (P<0.05), and the daily profit increased by 25.00% and 39.29%, respectively. This indicates that Aspergillus niger can reduce the average daily feed intake of Hu sheep, improving economic benefits without affecting their growth performance, while also reducing CH4 and CO2 emissions.