摘要：To assess the impact of nitrogen (N) fertilizer on ryegrass (Lolium multiflorum) quality and mineral metabolism in the Wumeng semi-fine wool sheep, two studies were conducted. Pasture replicates (20ha; n=2/treatment) received the same fertilizer treatment during the summer growing season in 2016 and 2017 (20 ha), consisting of 1) 70kgN/ha from quickly available nitrogen (QAN), 2) 70kg N/ha from ammonium sulfate (AS), and 3) control (no fertilizer; C). Forage sampling was conducted at 30 d intervals following fertilization, and analyzed for crude protein (CP), in vitro organic matter digestibility (IVOMD), phosphorus(P), calcium (Ca), sodium (Na), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), selenium (Se) and sulfur (S). To determine the effect of fertilizer treatment on mineral contents in blood and liver in grazing the Wumeng semi-fine wool sheep, liver biopsies and blood samples were collected (n=30; ten/treatment) at the start and end of the experiment period in 2017. Ammonium sulfate fertilization significantly increased forage S content in both years (P<0.01). Plant N contents were significantly increased by N fertilization, regardless of source, in 2017, but not in 2016. The Wumeng semi-fine wool sheep grazing AS pastured had very lower (P < 0.05) Cu contents of the liver and blood at the end of the experiment period in 2017 compared to QAN and C. In Exp.2, 20 copper deficient Wumeng semi-fine wool sheep grazing AS fertilized pastured were obtained and allocated to one of two treatments, consisting of supplements providing 30 mg/d of either organic (availa-copper, n=10) or inorganic (copper sulfate, n=10) copper. Experiment was delivered for 90 d. Liver copper significantly increased over time in all animals regardless of treatment. The Wumeng semi-fine wool sheep supplemented with available-copper tended (P=0.09) to have higher mean copper contents in liver and blood than those receiving copper sulfate. The results of these experiments indicated that AS fertilization of ryegrass increased forage sulfur contents. Therefore, Ammonium sulfate application to ryegrass pastures was not detrimental to mineral status except for significantly declining copper stores in the Wumeng semi-fine wool sheep.
关键词：The Wumeng semi-fine wool sheep;Ammonium sulfate;fertilization;mineral;liver and blood
