Khan M A, Bach A, Castells Ll, Weary D M, von Keyserlingk M A G
1Animal Welfare Program,University of British Columbia,2357 Mall,Vancouver,BC,Canada V6T 1Z4.
2ICREA,Institució Catalana de Recerca i Estudis Avançats,23 08010 Barcelona,Spain.
Animal. 2014 Oct;8(10):1722-7. doi: 10.1017/S1751731114001487. Epub 2014 Jun 11.
Two experiments on replacement heifers (175±12 days of age) assessed the effects of forage particle length and moisture on feeding behavior. Both experiments used a replicated 3×3 Latin square design, with nine heifers per replication and three periods of 9 days each. Each group of nine heifers was housed in one pen with access to three electronic feed bins. In Experiment 1, hay chopped at different lengths was incorporated into three total mixed rations (TMR) all having the same ingredient and nutrient composition but differing in the percentage of long particles (>19 mm): 60% (Short), 64% (Medium) and 72% (Long). In Experiment 2, heifers were fed a TMR with the same ingredient and nutrient composition but differing in moisture content: 65% DM (Dry), 50% DM (Moderate), and 35% DM (Wet). In both experiments, feeding behavior during the last 5 days of each period was analyzed using a mixed model accounting for the fixed effects of treatment and period, and the random effects of replication and animal. In Experiment 1, dry matter intake (DMI) and eating rate (DMI/min) tended to increase, whereas daily eating time decreased as the feed particle size decreased. Heifers fed the Long diet selected in favor of long particles (>19 mm) and against Short (1.18 to 8 mm) and fine (<1.18 mm) particles; heifers fed the Short diet selected against long particles and in favor of short and fine particles. Heifers fed the Medium diet showed a preference for medium particles with no preference for the other particle sizes. In Experiment 2, heifers fed the Dry diet tended to consume more feed than those fed the Moderate and Wet diets, with no differences in feeding behavior or sorting activity. In conclusion the Medium diet minimized sorting without reducing eating rates and intake, and adding water to TMR to achieve a dry matter less than 65% tended to decrease DMI without reducing sorting.
两项针对后备小母牛（175±12日龄）的试验评估了饲草颗粒长度和水分对采食行为的影响。两项试验均采用重复的3×3拉丁方设计，每次重复有9头小母牛，共三个阶段，每个阶段9天。每组9头小母牛饲养在一个围栏中，可使用三个电子饲料槽。在试验1中，将不同长度切碎的干草混入三种全混合日粮（TMR）中，这三种日粮的成分和营养组成相同，但长颗粒（>19毫米）的比例不同：60%（短）、64%（中）和72%（长）。在试验2中，给小母牛饲喂成分和营养组成相同但水分含量不同的TMR：65%干物质（干）、50%干物质（适中）和35%干物质（湿）。在两项试验中，使用混合模型分析每个阶段最后5天的采食行为，该模型考虑了处理和阶段的固定效应以及重复和动物的随机效应。在试验1中，随着饲料颗粒尺寸减小，干物质摄入量（DMI）和采食率（DMI/分钟）趋于增加，而每日采食时间减少。采食长颗粒日粮的小母牛偏好长颗粒（>19毫米），而不喜欢短颗粒（1.18至8毫米）和细颗粒（<1.18毫米）；采食短颗粒日粮的小母牛不喜欢长颗粒，而偏好短颗粒和细颗粒。采食中等颗粒日粮的小母牛偏好中等颗粒，对其他颗粒尺寸无偏好。在试验2中，采食干颗粒日粮的小母牛比采食适中颗粒和湿颗粒日粮的小母牛采食的饲料更多，采食行为或分选活动无差异。总之，中等颗粒日粮在不降低采食率和摄入量的情况下使分选最小化，向TMR中加水以使干物质含量低于65%往往会降低DMI而不减少分选。
