Bethancourt-Garcia Javier A, Ladeira Marcio M, Nascimento Karolina B, Ramírez-Zamudio Germán D, Meneses Javier A Moreno, Galvão Matheus C, Bernardes Thiago F, Gionbelli Mateus P
Department of Animal Science - Universidade Federal de Lavras, Lavras, MG, Brazil.
Department of Medicine Veterinary and Animal Science, Universidad de Ciencias Aplicadas y Ambientales (UDCA), Cartagena, Bolivar, Colombia.
Transl Anim Sci. 2024 Sep 13;8:txae131. doi: 10.1093/tas/txae131. eCollection 2024.
This study aimed to evaluate the effects of a blend of different sources of magnesium oxide associated or not with monensin, on productive, ruminal, and nutritional parameters of steers. Eighty-four Nellore steers with an initial body weight (BW) of 367.3 ± 37.9 kg were allocated to one of 28 pens, with three steers per pen. Each pen was considered an experimental unit. Using a completely randomized design with a 2 × 2 factorial arrangement, the following treatments were assigned to each pen: 1) Control (CON)-a basal diet without additive inclusion; 2) Magnesium oxide blend (MG)-basal diet plus a magnesium-based product (pHix-up, Timab Magnesium, Dinard, France) provided at 0.50% of dry matter (DM); 3) Monensin (MON)-basal diet plus 25 mg/ kg of DM of sodium monensin (Rumensin, Elanco Animal Health, Greenfield, IN); and 4) MG association with MON-basal diet plus MG + MON, at the same doses of the individual treatments. The experimental period lasted 100 d. Blood samples were collected on days 0, 13, and 70 to determine d-lactate levels. Daily feed intake was recorded, and animal ingestive behavior was visually observed on days 66 and 67. On day 70, skeletal muscle tissue samples were obtained through biopsy for gene expression analysis. At the end of the experimental period, carcass ultrasonography was conducted. Subsequently, the steers were slaughtered, and rumen epithelium samples were collected for morphometric analysis. The use of monensin, of magnesium oxide blend, and their interactions, were treated as fixed effects, while the pens were considered as a random effect. Statistical differences were considered when < 0.05. Steers-fed MG-containing diets consumed approximately 0.6 kg more DM per day than those fed diets without this additive ( = 0.01; 11.3 vs. 11.9 kg/d). The inclusion of MG in the diet increased ( = 0.02) the average daily gain. There was a greater Longissimus muscle area (LMA) and LMA per 100 kg of BW ( ≤ 0.03) for steers-fed diets with MG. Steers-fed MON exhibited reduced mRNA expression of the Atrogin-1 and compared to steers-fed MG + MON diets (MON × MG: ≤ 0.04). Steers-fed MON had 6.9% greater feed efficiency ( = 0.02). Papillae width was lesser for CON than other treatments (MON × MG: = 0.02). In conclusion, the magnesium oxide blend improved performance and carcass traits in high-energy feedlot diets, while monensin enhanced feed efficiency, suggesting potential for their use as alternatives or complements in beef cattle nutrition.
本研究旨在评估不同来源的氧化镁混合物单独或与莫能菌素联合使用，对阉牛生产性能、瘤胃和营养参数的影响。84头初始体重（BW）为367.3 ± 37.9千克的内洛尔阉牛被分配到28个围栏中的一个，每个围栏三头牛。每个围栏被视为一个实验单位。采用完全随机设计和2 × 2析因安排，给每个围栏分配以下处理：1）对照（CON）——不添加添加剂的基础日粮；2）氧化镁混合物（MG）——基础日粮加一种镁基产品（pHix-up，法国迪纳尔的蒂马镁业公司），按干物质（DM）的0.50%添加；3）莫能菌素（MON）——基础日粮加25毫克/千克DM的莫能菌素钠（瘤胃素，美国印第安纳州格林菲尔德的伊兰科动物保健公司）；4）MG与MON联合——基础日粮加MG + MON，剂量与单独处理相同。实验期持续100天。在第0、13和70天采集血样以测定d - 乳酸水平。记录每日采食量，并在第66和67天目视观察动物采食行为。在第70天，通过活检获取骨骼肌组织样本进行基因表达分析。实验期结束时，进行胴体超声检查。随后，屠宰阉牛，采集瘤胃上皮样本进行形态计量分析。莫能菌素、氧化镁混合物及其相互作用作为固定效应处理，而围栏作为随机效应处理。当 < 0.05时认为存在统计学差异。饲喂含MG日粮的阉牛每天消耗的DM比不添加该添加剂的日粮多约0.6千克（ = 0.01；11.3对11.9千克/天）。日粮中添加MG提高了（ = 0.02）平均日增重。饲喂含MG日粮的阉牛的背最长肌面积（LMA）和每100千克BW的LMA更大（ ≤ 0.03）。与饲喂MG + MON日粮的阉牛相比，饲喂MON的阉牛Atrogin - 1和的mRNA表达降低（MON × MG： ≤ 0.04）。饲喂MON的阉牛饲料效率高6.9%（ = 0.02）。CON组的乳头宽度小于其他处理（MON × MG： = 0.02）。总之，氧化镁混合物改善了高能育肥牛日粮的性能和胴体性状，而莫能菌素提高了饲料效率，表明它们有潜力作为肉牛营养中的替代品或补充剂使用。
