Laserfiche WebLink
4 <br />less dry matter per hectare than the moderate or heavy treatments (Table 1). This <br />decrease in available forage produced a marked reduction in the animal performance <br />in 1977 compared with 1976,. as determined by average daily gain (ADG) and the <br />kilograms of beef. produced per hectare. _ <br />DISCUSSION <br />- Our results include only 1 year's .data in which the influence of different <br />grazing intensities were expressed on the vegetation produced and animal weight <br />gains on reclaimed-"strip-mined land.: . _.._. :. __. _.... .. - ..- .,. _. - <br />=.Forage-produced during the 2 years differed since 1976 had good early rain- <br />fall, whereas 1977 began dry with very poor early vegetative growth. In 1977, <br />7-cm rain-fell at the site during the last 2 weeks in May which increased growth <br />but the grass ahd legume plants lacked vigor and matured earlier than normal. <br />Drought_stress_~peared_to.be more_severe_.on the__heavysrazed treatment,__which had <br />less ground cover. This was reflected by the significantly lower amount of dry <br />matter when plants were sampled on-May._26,_1977. Probably, a combination of <br />drought st_ress_and_physiological__st;esses, caused_by removal of.large_portions__of <br />top growth, affected the plant's ability to produce early. However, from June 1 <br />through 26, 1977, an additional 5 cm rainfall increased growth under the cages <br />which had been previously heavily grazed. The data are too variable and incomplete <br />to make definite conclusions. At this point we can not separate stress caused by <br />drought from that caused by topgrowth removal, but we will determine these effects <br />in future years by measuring yield and making point frame counts. <br />Table 2. Initial and final yearling steer weights, average daily gain (ADG), <br />and total beef production of pastures with light, moderate, and heavy graz- <br />ing intensities in 1976 and 1977. <br />Grazing Avg. weight <br />intensity Initial Final ADG Beef produced <br /> kg/head kg/head/day kg/ha <br />19761/ <br />Light 236 293 1.0 61 <br />Moderate 236 281 0.8 96 <br />Heavy 240 279 0.7 167 <br />1977?/ <br />Light 296 325 0.9 41 <br />Moderate 300 327 0.9 58 <br />Heavy 296 309 0.4 55 <br />1/ 55-day grazing season in 1976. <br />?/ 30-day grazing season in 1977. <br />Steer performance in 1976 resembled that experienced from grazing similar <br />species on undisturbed land. As stocking rate is increased, average daily gains <br />decrease but beef production per hectare increases (2), if animals are removed from <br />