DeRamus H Alan, Clement Terry C, Giampola Dean D, Dickison Peter C
Dep. of Renewable Resources, Univ. of Louisiana-Lafayette, POB 44650, Lafayette, LA 70504, USA.
J Environ Qual. 2003 Jan-Feb;32(1):269-77. doi: 10.2134/jeq2003.2690.
Fermentation in the rumen of cattle produces methane (CH4). Methane may play a role in global warming scenarios. The linking of grazing management strategies to more efficient beef production while reducing the CH4 emitted by beef cattle is important. The sulfur hexafluoride (SF6) tracer technique was used to determine the effects of best management practices (BMP) grazing compared with continuous grazing on CH4 production in several Louisiana forages during 1996-1998. Cows and heifers (Bos taurus) grazed common bermudagrass [Cynodon dactylon (L.) Pers.], bahiagrass (Paspalum notatum Flugge), and ryegrass (Lolium multiflorum Lam.) pastures and were wintered on bahiagrass hay with supplements of protein molasses blocks (PMB), cottonseed meal and corn (CSMC), urea and corn (URC), or limited ryegrass grazing (LRG). Daily CH4 emissions were between 89 and 180 g d(-1) for young growing heifers and 165 to 294 g d(-1) for mature Simbrah cows. Heifers on "ad lib" ryegrass in March and April produced only one-tenth the CH4 per kg of gain as heifers on LRG of 1 h. Using BMP significantly reduced the emission of CH4 per unit of animal weight gain. Management-intensive grazing (MIG) is a BMP that offers the potential for more efficient utilization of grazed forage crops via controlled rotational grazing and more efficient conversion of forage into meat and milk. Projected CH4 annual emissions in cows reflect a 22% reduction from BMP when compared with continuous grazing in this study. With the BMP application of MIG, less methane was produced per kilogram of beef gain.
牛瘤胃中的发酵过程会产生甲烷（CH₄）。甲烷可能在全球变暖情况中发挥作用。将放牧管理策略与提高牛肉生产效率相联系，同时减少肉牛排放的CH₄，这一点很重要。1996年至1998年期间，采用六氟化硫（SF₆）示踪技术，测定了最佳管理措施（BMP）放牧与连续放牧相比，对路易斯安那州几种牧草甲烷产生量的影响。母牛和小母牛（Bos taurus）在普通百慕大草[Cynodon dactylon (L.) Pers.]、巴哈雀稗（Paspalum notatum Flugge）和黑麦草（Lolium multiflorum Lam.）牧场上放牧，并在冬季以巴哈雀稗干草为食，辅以蛋白质糖蜜块（PMB）、棉籽粕和玉米（CSMC）、尿素和玉米（URC），或有限的黑麦草放牧（LRG）。年轻的生长中小母牛每日CH₄排放量在89至180克/天之间，成熟的辛布拉母牛排放量在165至294克/天之间。3月和4月自由采食黑麦草的小母牛，每增重1千克产生的CH₄仅为每天放牧1小时的LRG小母牛的十分之一。采用BMP显著降低了单位动物体重增加时的CH₄排放量。管理集约型放牧（MIG）是一种BMP，它有可能通过控制轮牧更有效地利用放牧的饲料作物，并将饲料更有效地转化为肉和奶。在本研究中，预计母牛的CH₄年排放量与连续放牧相比，采用BMP可减少22%。随着MIG的BMP应用，每增重1千克牛肉产生的甲烷减少。
