The objective of this experiment was to determine if titanium dioxide (TiO2) dosed through an automated head chamber system (GreenFeed; C-Lock Inc., Rapid City, SD, USA) is an acceptable method to measure fecal output. The GreenFeed used on this experiment had a 2-hopper bait dispensing system, where hopper 1 contained alfalfa pellets marked with 1% titanium dioxide (TiO2) and hopper 2 contained unmarked alfalfa pellets. Eleven heifers (BW = 394 ± 18.7 kg) grazing a common pasture were stratified by BW and then randomized to either 1) dosed with TiO2-marked pellets by hand feeding (HFD; n = 6) or 2) dosed with TiO2-marked pellets by the GreenFeed (GFFD; n = 5) for 19 d. During the morning (0800), all heifers were offered a pelleted, high-CP supplement at 0.25% of BW in individual feeding stanchions. The HFD heifers also received 32 g of TiO2-marked pellets at morning feeding, whereas the GFFD heifers received 32 g of unmarked pellets. The GFFD heifers received a single aliquot (32 ± 1.6 g; mean ± SD) of marked pellets at their first visit to the GreenFeed each day with all subsequent 32-g aliquots providing unmarked pellets; HFD heifers received only unmarked pellets. Starting on d 15, fecal samples were collected via rectal grab at feeding and every 12 h for 5 d. A two-one sided t-test method was used to determine agreement and it was determined that the fecal output estimates by HFD and GFFD methods were similar (P = 0.04). There was a difference (P < 0.01; Bartlett’s test for homogenous variances) in variability between the dosing methods for HFD and GFFD (SD = 0.1 and 0.7, respectively). This difference in fecal output variability may have been due to variability of dosing times-of-day for the GFFD heifers (0615 ± 6.2 h) relative to the constant dosing time-of-day for HFD and constant 0800 and 2000 sampling times-of-day for all animals. This research has highlighted the potential for dosing cattle with an external marker through a GreenFeed configured with two (or more) feed hoppers because estimated fecal output means were similar; however, consideration of the increased variability of the fecal output estimates is needed for future experimental designs.

中文翻译：

---

技术说明：使用自动头室系统管理外部标记来估计放牧肉牛的粪便产量


本实验的目的是确定通过自动头室系统（GreenFeed；C-Lock Inc.，拉皮德城，南达科他州，美国）投加的二氧化钛 (TiO2) 是否是测量粪便排出量的可接受方法。本实验中使用的 GreenFeed 具有 2 料斗诱饵分配系统，其中料斗 1 包含标记有 1% 二氧化钛 (TiO2) 的苜蓿颗粒，料斗 2 包含未标记的苜蓿颗粒。将在公共牧场放牧的 11 头小母牛（体重 = 394 ± 18.7 千克）按体重分层，然后随机分为 1) 人工喂养（HFD；n = 6）添加 TiO2 标记颗粒的组或 2）添加 TiO2 标记颗粒的组通过 GreenFeed (GFFD；n = 5) 持续 19 天。早上 (0800)，所有小母牛都在单独的饲喂支柱中添加了体重 0.25% 的颗粒状高 CP 补充剂。 HFD 小母牛在早晨饲喂时还接受了 32 克 TiO2 标记的颗粒，而 GFFD 小母牛则接受了 32 克未标记的颗粒。 GFFD 小母牛每天第一次访问 GreenFeed 时收到一份标记颗粒的等分试样（32 ± 1.6 g；平均值 ± SD），所有后续的 32 g 等分试样均提供未标记的颗粒； HFD 小母牛只接受未标记的颗粒。从第 15 天开始，在喂食时通过直肠抓取收集粪便样本，并且每 12 小时收集一次粪便样本，持续 5 天。使用双边 t 检验方法来确定一致性，并确定 HFD 和 GFFD 方法的粪便排出量估计值相似（P = 0.04）。 HFD 和 GFFD 的给药方法之间的变异性存在差异（P < 0.01；Bartlett 的同质方差检验）（SD 分别为 0.1 和 0.7）。粪便排出量变异性的这种差异可能是由于 GFFD 小母牛每天给药时间的变异性 (0615 ± 6.2 小时）相对于 HFD 的恒定给药时间以及所有动物的恒定 0800 和 2000 采样时间。这项研究强调了通过配置有两个（或更多）饲料斗的 GreenFeed 给牛添加外部标记的潜力，因为估计的粪便输出量是相似的；然而，未来的实验设计需要考虑粪便排出量估计值的增加的变异性。