Coleman S W, Phillips W A, Volesky J D, Buchanan D
USDA-ARS, Subtropical Agricultural Research Station, Brooksville, FL 34601, USA.
J Anim Sci. 2001 Jul;79(7):1697-705. doi: 10.2527/2001.7971697x.
The objective of this study was to compare an introduced warm-season perennial grass (plains bluestem, Bothriochloa ischaemum) to native tallgrass prairie for cow-calf production. Three systems were used, two based on tallgrass prairie with two different forms of protein supplementation and one based on plains bluestem as the primary forage. The systems were as follows: 1) native tallgrass prairie with pelleted oilseed meal as the winter protein supplement (native-control); 2) native tallgrass prairie with limited access to wheat pasture as the winter protein supplement (native-wheat); and 3) plains bluestem with limited access to wheat pasture as the protein supplement (bluestem-wheat). Oilseed meal protein supplements were fed twice weekly. Cows grazing wheat pasture were allowed 6 h of grazing twice weekly. Ninety-nine cows per year were used over the 3-yr study. Cows were sired by either Charolais, Gelbvieh, Angus, or Hereford bulls out of commercial Angus-Hereford dams. Calves were sired by Simmental bulls. Calving and weaning rate increased over time but did not differ among systems or breed types. System did not influence the size or body condition score of cows or the performance of calves, but changes in the weight and condition scores of cows were greater on either native system than on the bluestem-wheat system. Cows from Charolais and Gelbvieh bulls were taller (P < 0.05), and heavier (P < 0.05), and weaned heavier (P < 0.05) calves than cows from Angus or Hereford bulls. The weight of cows on the bluestem-wheat system tended to decrease over time, whereas cows grazing on the native systems tended to gain weight over time. The native-control system was the most profitable system based on cow production. If excess hay produced from the bluestem-wheat system was sold as a cash crop, then this system was the most profitable. In general, we conclude that limit-grazing wheat pasture is a viable alternative to oilseed meal as protein supplement for wintering dry cows. Although the bluestem system had 2.5 times the carrying capacity of the native prairie systems, increased productivity was offset by increased production costs. All systems were equal on a cow basis for providing nutrients for the cow-calf production system.
本研究的目的是比较引进的暖季多年生草本植物（平原须芒草，白羊草）与原生高草草原用于肉牛生产的情况。采用了三种系统，两种基于高草草原，有两种不同形式的蛋白质补充剂，一种以平原须芒草作为主要草料。系统如下：1）以颗粒状油籽粕作为冬季蛋白质补充剂的原生高草草原（原生对照）；2）以有限获取小麦牧场作为冬季蛋白质补充剂的原生高草草原（原生 - 小麦）；3）以有限获取小麦牧场作为蛋白质补充剂的平原须芒草（须芒草 - 小麦）。油籽粕蛋白质补充剂每周投喂两次。放牧小麦牧场的母牛每周允许放牧两次，每次6小时。在为期3年的研究中，每年使用99头母牛。母牛由夏洛莱、吉尔维耶、安格斯或赫里福德公牛与商业化安格斯 - 赫里福德母牛杂交所生。犊牛由西门塔尔公牛所生。产犊率和断奶率随时间增加，但在各系统或品种类型之间没有差异。系统对母牛的体型或体况评分以及犊牛的性能没有影响，但在原生系统中，母牛体重和体况评分的变化比须芒草 - 小麦系统更大。来自夏洛莱和吉尔维耶公牛的母牛比来自安格斯或赫里福德公牛的母牛更高（P < 0.05）、更重（P < 0.05），并且断奶的犊牛更重（P < 0.05）。须芒草 - 小麦系统中母牛的体重随时间趋于下降，而在原生系统中放牧的母牛体重随时间趋于增加。基于母牛生产，原生对照系统是最盈利的系统。如果将须芒草 - 小麦系统生产的多余干草作为经济作物出售，那么这个系统是最盈利的。总体而言，我们得出结论，限量放牧小麦牧场是作为冬季干奶牛蛋白质补充剂替代油籽粕的可行选择。尽管须芒草系统的载畜量是原生草原系统的2.5倍，但生产力的提高被生产成本的增加所抵消。在为肉牛生产系统提供养分方面，所有系统在每头母牛的基础上是相等的。
