State Key Laboratory of Animal Nutrition, Beijing Engineering Technology Research Center of Raw Milk Quality and Safety Control, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China.
State Key Laboratory of Animal Nutrition, Beijing Engineering Technology Research Center of Raw Milk Quality and Safety Control, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China.
J Dairy Sci. 2018 Sep;101(9):8169-8181. doi: 10.3168/jds.2018-14373. Epub 2018 Jun 21.
The aim of the study was to evaluate the effects of early feed exposure (EFE) to different feedstuffs in dairy calves on feed preference once fed a free-choice diet and a total mixed ration later in life. Thirty (30) female Holstein calves were randomly assigned at birth to 1 of 3 EFE treatments-concentrate only (CON), hay only (HO), and concentrate and hay (COH)-from d 2 to 56. After that, all calves were offered both concentrate and hay in different buckets from d 57 to 70 to allow them free choice between the 2 feedstuffs. Calves were then transferred to a heifer barn, housed within treatment in pairs (2 calves/pen), and fed TMR from d 71 to 196. Feed intake was recorded daily from d 2 to 70 to determine the feed preference before and after weaning. Fresh TMR and orts were collected daily in the last week of the experiment (d 190 to 196) for analysis of feed sorting and intake. Body weight and structural growth were recorded at d 1, 28, 56, 70, and 190. Blood for determining glucose and rumen fluid for determining ruminal pH and volatile fatty acids concentrations were sampled on d 28, 56, 70, and 190. Early feed exposure did not affect feed intake, body weight, average daily gain, blood glucose, and structural growth before and after weaning but did affect feed preference and rumen fermentation. After transition to a free-choice diet, HO calves consumed more hay (550.2 g/d) than CON (177.4 g/d) and COH (396.4 g/d) calves on the first day only. However, COH calves consumed a greater amount of hay, resulting in a higher ratio of hay to total solids compared with either CON or HO calves during d 57 to 70. Upon transition to a TMR, a similar sorting pattern was exhibited between treatments, with calves sorting against the long and for the fine particle fractions. Although no significant long-term effects of different EFE on rumen pH, volatile fatty acids, and blood glucose persisted at wk 27 (from d 190 to 196), calves exposed to COH early had an improved ability to sort for long feed particles compared with CON and HO calves later in life. Our results suggest that EFE could influence choice of feed immediately after weaning and may have long-lasting effects on feed preference in heifers later in life. Further studies with more calves are recommended.
本研究的目的是评估奶牛犊牛在生命早期接触不同饲料（早期饲料暴露，EFE）对其在生命后期自由选择采食和全混合日粮时的饲料偏好的影响。30 头荷斯坦雌性犊牛出生后随机分为 3 个 EFE 处理组之一，分别为仅浓缩饲料（CON）、仅干草（HO）和浓缩饲料与干草（COH），从第 2 天到第 56 天。此后，所有犊牛从第 57 天到第 70 天都在不同的桶中提供浓缩饲料和干草，以便它们在这两种饲料之间自由选择。犊牛随后被转移到一个小母牛牛舍，在 2 对（每栏 2 头）之间进行处理，从第 71 天到第 196 天饲喂 TMR。从第 2 天到第 70 天，每天记录饲料摄入量，以确定断奶前后的饲料偏好。在实验的最后一周（第 190 天至第 196 天），每天收集新鲜 TMR 和剩余物，以分析饲料分类和摄入量。在第 1、28、56、70 和 190 天记录体重和结构生长情况。在第 28、56、70 和 190 天采集血液以测定葡萄糖，采集瘤胃液以测定瘤胃 pH 和挥发性脂肪酸浓度。EFE 早期不会影响断奶前后的饲料摄入量、体重、平均日增重、血糖和结构生长，但会影响饲料偏好和瘤胃发酵。过渡到自由选择饮食后，仅干草组（HO）犊牛在第 1 天的干草摄入量（550.2g/d）多于仅浓缩饲料组（CON）（177.4g/d）和浓缩饲料与干草组（COH）（396.4g/d）。然而，COH 犊牛消耗了更多的干草，因此在第 57 天至第 70 天期间，与 CON 或 HO 犊牛相比，干草与总固体的比例更高。在过渡到 TMR 时，处理之间表现出类似的分类模式，犊牛对长颗粒进行分类，而对细颗粒进行分类。尽管不同 EFE 对瘤胃 pH、挥发性脂肪酸和血糖的长期影响在第 27 周（第 190 天至第 196 天）没有持续，但早期暴露于 COH 的犊牛在后期对长饲料颗粒的分类能力比 CON 和 HO 犊牛要好。我们的研究结果表明，EFE 可能会影响断奶后立即对饲料的选择，并且可能对小母牛后期的饲料偏好产生长期影响。建议进行更多的研究。
