Division of Plant Sciences, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2010 May;88(5):1880-90. doi: 10.2527/jas.2009-2128. Epub 2009 Dec 30.
A 2-yr production study was conducted to evaluate 3 systems of growing stocker calves under rotational stocking. One group of steers was stocked on pasture from early April to mid August (spring-stocked steers = SSS), and another group of steers was stocked from early July to late October (fall-stocked steers = FSS). Steers were stratified by BW (n = 72, BW = 229 +/- 11 kg for SSS; n = 72, BW = 248 +/- 18 kg for FSS) and randomly assigned to 1 of 3 treatments. The 3 treatments were 1) rotationally stocked only (control; CON), steers rotated to a new paddock as forage availability dropped below acceptable levels in the occupied paddock; 2) rotationally stocked with distillers grains (DIST); this was the same as CON except steers were supplemented with varying amounts of distillers dried grains with solubles (DDGS) based on forage nutritive value; and 3) rotationally stocked with round-bale silage (SIL); excess forage in spring was harvested and stored as round-bale silage and fed back as needed. Total BW gain/ha over the entire grazing season did not differ between DIST and SIL (P = 0.09) steers, but both were greater than CON (P < 0.01). Total BW gain/ha for DIST, SIL, and CON was 459 (SEM = 11.5), 402 (SEM = 31.0), and 276 (SEM = 26.2) kg, respectively. For ADG, there was a group x year (P < 0.01) and group x treatment (P = 0.02) interaction. Steer ADG for SSS did not differ between SIL and DIST (P = 0.51), but was greater than the CON (P = 0.01). The ADG for SSS was 0.79 (SEM = 0.04), 0.81 (SEM = 0.05), and 0.62 (SEM = 0.05) kg for DIST, SIL, and CON, respectively. For the FSS, ADG for all 3 treatments was different (P = 0.02). The FSS ADG was 0.72 (SEM = 0.03), 0.53 (SEM = 0.04), and 0.29 (SEM = 0.04) kg for DIST, SIL, and CON, respectively. The only treatment with equivalent (P = 0.07) ADG between early and late-stocked steers (SSS vs. FSS) was DIST. Adjusting the amount of DDGS supplemented to steers based on forage nutritive value resulted in consistent BW gains throughout the grazing study, whereas steers in the SIL and CON treatments gained less BW during the latter portion of the season. Controlling forage maturity by removal in the SIL treatment resulted in total BW gains/ha that were not different than the DIST treatment.
进行了一项为期 2 年的生产研究，以评估在轮牧制度下饲养育肥牛的 3 种系统。一组公牛从 4 月初到 8 月中旬（春季饲养的公牛 = SSS），另一组公牛从 7 月初到 10 月下旬（秋季饲养的公牛 = FSS）。根据体重（n = 72，SSS 的 BW = 229 +/- 11 公斤；n = 72，FSS 的 BW = 248 +/- 18 公斤）将公牛分层，并随机分配到 3 种处理之一。这 3 种处理方法是：1）仅轮牧（对照；CON），当占用的牧场上的饲料可用性降至可接受水平以下时，牛群被转移到新的牧场上；2）轮牧加蒸馏器谷物（DIST）；这与 CON 相同，只是根据饲料营养价值，牛群补充了不同量的蒸馏器干燥谷物与可溶性（DDGS）；3）轮牧加圆捆青贮（SIL）；春季多余的饲料收获并储存为圆捆青贮饲料，并根据需要回喂。整个放牧季节的总 BW 增重/公顷在 DIST 和 SIL（P = 0.09）牛群之间没有差异，但均大于 CON（P < 0.01）。DIST、SIL 和 CON 的总 BW 增重/公顷分别为 459（SEM = 11.5）、402（SEM = 31.0）和 276（SEM = 26.2）公斤。对于 ADG，存在群体 x 年份（P < 0.01）和群体 x 处理（P = 0.02）的交互作用。SSS 的公牛 ADG 在 SIL 和 DIST 之间没有差异（P = 0.51），但大于 CON（P = 0.01）。SSS 的 ADG 分别为 DIST、SIL 和 CON 的 0.79（SEM = 0.04）、0.81（SEM = 0.05）和 0.62（SEM = 0.05）公斤。对于 FSS，所有 3 种处理的 ADG 均不同（P = 0.02）。FSS 的 ADG 分别为 DIST、SIL 和 CON 的 0.72（SEM = 0.03）、0.53（SEM = 0.04）和 0.29（SEM = 0.04）公斤。唯一具有相同（P = 0.07）早期和晚期饲养牛 ADG 的处理是 DIST。根据饲料营养价值补充 DDGS 的量可使 BW 增重在整个放牧研究中保持一致，而 SIL 和 CON 处理的牛在季节后期的 BW 增重较少。通过 SIL 处理控制饲料成熟度，导致的总 BW 增重/公顷与 DIST 处理没有差异。
