Herselman M J, Hart S P, Sahlu T, Coleman S W, Goetsch A L
E (Kika) de la Garza Institute for Goat Research, Langston University, OK 73050, USA.
J Anim Sci. 1999 May;77(5):1258-65. doi: 10.2527/1999.7751258x.
Angora goat, Spanish goat, and Suffolk x Rambouillet sheep wethers (20 of each type; 30.4+/-.57, 31.3+/-.93, and 32.4+/-1.08 kg BW for Angora goats, Spanish goats, and sheep, respectively) were used to investigate influences of animal type and two grass-based pasture treatments on heat energy during summer grazing (mid-August through September in Oklahoma). The improved pasture treatment consisted of .7-ha paddocks primarily of Old World bluestem and johnsongrass, whereas the native pasture treatment entailed 10.8-ha paddocks dominated by big and little bluestems and indiangrass. Grasses were 95 to 100% of diets for the improved pasture treatment and 71 to 95% for the native pasture treatment; forbs were 2 to 25%, and shrubs were less than 4% of diets for the native pasture treatment. Metabolizable energy intake was similar (P > . 10) between pasture treatments but differed (P <.01) among animal types: 79, 99, and 113 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively; SE 7.1. Heat energy estimated via CO2 entry rate was affected by pasture treatment ( P = .08) and animal type (P < .001): improved pasture treatment 109, 132, and 151 kcal/(kg(.75) BW.d); native pasture treatment 126, 138, and 163 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively. Likewise, daylight grazing time was greater (P = .04) for the native than for the improved pasture treatment and differed (P < .01) among animal types: improved pasture treatment 5.3, 4.7, and 6.7 h; native pasture treatment 6.0, 5.7, and 8.1 h for Angora goats, Spanish goats, and sheep, respectively. In conclusion, heat energy during summer grazing of grass-based paddocks was less for goats than for sheep, and animal type can affect the increase in heat energy as energy intake and grazing time increase.
安哥拉山羊、西班牙山羊和萨福克×兰布耶杂交绵羊阉羊（每种20只；安哥拉山羊、西班牙山羊和绵羊的体重分别为30.4±0.57、31.3±0.93和32.4±1.08千克）被用于研究动物类型和两种基于草地的牧场处理方式对夏季放牧（俄克拉荷马州8月中旬至9月）期间热能的影响。改良牧场处理方式包括0.7公顷的围场，主要生长着旧世界蓝茎草和约翰逊草，而原生牧场处理方式则是10.8公顷的围场，以大蓝茎草、小蓝茎草和印第安草为主。改良牧场处理方式下，草类占日粮的95%至100%，原生牧场处理方式下草类占日粮的71%至95%；原生牧场处理方式下，杂类草占2%至25%，灌木占日粮不到4%。牧场处理方式之间的可代谢能量摄入量相似（P>.10），但动物类型之间存在差异（P<.01）：安哥拉山羊、西班牙山羊和绵羊的可代谢能量摄入量分别为79、99和113千卡/（千克（0.75）体重·天）；标准误为7.1。通过二氧化碳进入率估算的热能受牧场处理方式（P=.08）和动物类型（P<.001）影响：改良牧场处理方式下，安哥拉山羊、西班牙山羊和绵羊的热能分别为109、132和151千卡/（千克（0.75）体重·天）；原生牧场处理方式下分别为126、138和163千卡/（千克（0.75）体重·天）。同样，原生牧场的白天放牧时间比改良牧场长（P=.04），且动物类型之间存在差异（P<.01）：改良牧场处理方式下，安哥拉山羊、西班牙山羊和绵羊的白天放牧时间分别为5.3、4.7和6.7小时；原生牧场处理方式下分别为6.0、5.7和8.1小时。总之，基于草地围场夏季放牧期间，山羊的热能低于绵羊，且动物类型会随着能量摄入量和放牧时间的增加而影响热能的增加。
