Acidification is a practical way of preserving the bacteriological quality of milk so that it can be fed to calves under free-access conditions. The objectives of this study were to evaluate how milk replacer acidification and free-access feeding affect dairy calf behavior during the first week of life. Sixteen Holstein male calves were purchased at birth and transported to the University of Guelph Kemptville Campus Dairy Education and Research Centre. Calves were randomly assigned to 1 of 4 milk feeding programs: (1) free-access (ad libitum) feeding of acidified milk replacer (22% crude protein and 17% fat, 150 g/L; FA); (2) restricted (6 L/d, 150 g/L) feeding of acidified milk replacer (RA); (3) free-access feeding of nonacidified milk replacer (FN); and (4) restricted feeding of nonacidified milk replacer (RN). Formic acid was used to acidify milk replacer to a target pH between 4.0 and 4.5. Video recordings of each calf at 1, 2, and 6 d were analyzed continuously over 24 h for all occurrences of each behavior in the ethogram. Feeding behavior observations were organized into sucking bouts, from which feeding behavior outcome variables were calculated. Calves consuming acidified milk replacer demonstrated more fragmented feeding patterns, characterized by more pauses within a sucking bout (FA, FN, RA, and RN calves = 12.4, 4.4, 13.7, and 11.9 pauses/bout, respectively) and longer sucking bout duration (FA, FN, RA, and RN calves = 8.8, 5.2, 9.3, and 8.1 min/bout, respectively), than calves fed nonacidified milk replacer. Restricted-fed calves tended to have longer sucking bouts and performed more within-bout sucks (FA, FN, RA, and RN calves = 10.7, 5.8, 13.5, and 14.1, respectively) and pauses than free-access calves. Acidification and free-access feeding did not affect lying duration. Calves assigned to the acidified feeding treatments tended to perform more grooming behavior than those fed nonacidified milk replacer (FA, FN, RA, and RN calves = 0.9, 0.5, 0.8, and 0.6 h/d, respectively). Free-access feeding did not affect grooming duration. The observed differences in feeding and grooming behavior suggest that acidification to a pH between 4.0 and 4.5 may have altered the palatability of milk replacer. Calves assigned to the acidified milk replacer feeding treatments did not, however, show avoidance toward this feedstuff during the first week of life.

酸化是保持牛奶细菌品质的一种实用方法，因此可以在自由接触的条件下将其喂给犊牛。这项研究的目的是评估在出生后第一周内代乳品的酸化和自由进食如何影响奶牛的行为。出生时购买了16头荷斯坦公犊牛，并运往圭尔夫大学肯普维尔大学校园奶牛教育和研究中心。将犊牛随机分配到4个奶喂养计划中的1个：（1）自由进食（随意采食）酸化的代乳牛奶（22％的粗蛋白和17％的脂肪，150 g / L； FA）；（2）限制（6 L / d，150 g / L）的酸化牛奶替代品（RA）加料；（3）自由进食非酸化的代乳品（FN）；（4）限制饲喂非酸化的代乳品（RN）。甲酸用于将代乳品酸化至4.0至4.5的目标pH。在24小时内，连续分析每个小牛在1、2和6 d时的视频记录，以了解每种行为在心电图中的所有发生情况。喂食行为观察被组织成吮吸动作，从中计算出喂食行为结果变量。食用酸化牛奶替代品的犊牛表现出更零碎的喂养方式，其特点是吸吮回合中有更多的停顿（FA，FN，RA和RN犊牛分别为12.4、4.4、13.7和11.9停顿/回合）和更长的吸吮回合持续时间（ FA，FN，RA和RN犊牛分别为8.8、5.2、9.3和8.1 min / bout），比饲喂非酸化牛奶代用品的犊牛要高。限饲小牛的吸吮回潮时间较长，而回合内的吮吸次数更多（FA，FN，RA和RN犊牛= 10.7、5.8，分别是13.5和14.1），并且比免费使用的犊牛要暂停。酸化和自由进食不会影响躺卧时间。相比于未酸化的牛奶代乳品，分配给酸化的奶牛处理的犊牛倾向于表现出更多的修饰行为（FA，FN，RA和RN犊牛分别为0.9、0.5、0.8和0.6 h / d）。自由进食并没有影响梳理时间。观察到的进食和梳理行为差异表明，酸化至4.0至4.5之间的pH值可能会改变代乳品的适口性。但是，分配给酸化牛奶替代品喂养处理的犊牛在出生后的第一周内并未表现出对这种饲料的回避。相比于未酸化的牛奶代乳品，分配给酸化的奶牛处理的犊牛倾向于表现出更多的修饰行为（FA，FN，RA和RN犊牛分别为0.9、0.5、0.8和0.6 h / d）。自由进食并没有影响梳理时间。观察到的进食和梳理行为差异表明，酸化至4.0至4.5之间的pH值可能会改变代乳品的适口性。但是，分配给酸化牛奶替代品喂养处理的犊牛在出生后的第一周内并未表现出对这种饲料的回避。相比于未酸化的牛奶代乳品，分配给酸化的奶牛处理的犊牛倾向于表现出更多的修饰行为（FA，FN，RA和RN犊牛分别为0.9、0.5、0.8和0.6 h / d）。自由进食并没有影响梳理时间。观察到的进食和梳理行为差异表明，酸化至4.0至4.5之间的pH值可能会改变代乳品的适口性。但是，分配给酸化牛奶替代品喂养处理的犊牛在出生后的第一周内并未表现出对这种饲料的回避。观察到的进食和梳理行为差异表明，酸化至4.0至4.5之间的pH值可能会改变代乳品的适口性。但是，分配给酸化牛奶替代品喂养处理的犊牛在出生后的第一周内并未表现出对这种饲料的回避。观察到的进食和梳理行为差异表明，酸化至4.0至4.5之间的pH值可能会改变代乳品的适口性。但是，分配给酸化牛奶替代品喂养处理的犊牛在出生后的第一周内并未表现出对这种饲料的回避。