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.

该研究的目的是评估在自由选择的饮食和以后的总混合日粮中，早期采食乳牛犊中不同饲料对不同饲料的影响（EFE）对饲料偏好的影响。从出生后第2天到56天，三十（30）只雌性荷斯坦犊牛被随机分配到3种EFE处理中的1种-仅浓缩（CON），仅干草（HO）以及浓缩和干草（COH）。在d 57至70的不同桶中提供了精矿和干草，以便他们在2种饲料中自由选择。然后将小牛转移到小母牛房，成对饲养（每只小牛2只小牛），并在第71天至196天喂饲TMR。每天从第2天至70天记录采食量，以确定断奶前后的饲料偏好。在实验的最后一周（第190至196天）每天收集新鲜的TMR和杂物，以分析饲料的分类和摄入量。在第1、28、56、70和190天记录体重和结构生长。在第28、56、70和190天，采集用于测定葡萄糖的血液和用于确定瘤胃pH和挥发性脂肪酸浓度的瘤胃液。断奶前后的采食量不会影响采食量，体重，平均日增重，血糖和结构生长，但会影响采食和瘤胃发酵。过渡到自由选择的饮食之后，仅在第一天，HO犊牛的干草（550.2 g / d）比CON犊牛（177.4 g / d）和COH犊牛（396.4 g / d）多。但是，COH犊牛消耗了大量的干草，在第57至70天期间，与CON或HO犊牛相比，导致干草/总固形物的比率更高。在过渡到TMR时，处理之间表现出相似的分选模式，犊牛对长粒和细粒进行分选。尽管不同的EFE对瘤胃pH，挥发性脂肪酸和血糖的长期影响在第27周（从190到196天）没有持续存在，但与COH相比，早期暴露于COH的犊牛具有更好的分选长饲料颗粒的能力。 CON和HO在以后的生活中会犊牛。我们的结果表明，断奶后，EFE可能会影响饲料的选择，并且可能对以后的小母牛的饲料偏好产生长期影响。建议使用更多的犊牛进行进一步研究。处理之间表现出相似的分选模式，犊牛针对长粒和细粒进行分选。尽管不同的EFE对瘤胃pH，挥发性脂肪酸和血糖的长期影响一直持续到第27周（从d 190到196），但与COH相比，早期暴露于COH的犊牛对长饲料颗粒的分选能力有所提高。 CON和HO在以后的生活中会犊牛。我们的结果表明，断奶后，EFE可能会影响饲料的选择，并且可能对以后的小母牛的饲料偏好产生长期影响。建议使用更多的犊牛进行进一步研究。处理之间表现出相似的分选模式，犊牛针对长粒和细粒进行分选。尽管不同的EFE对瘤胃pH，挥发性脂肪酸和血糖的长期影响一直持续到第27周（从d 190到196），但与COH相比，早期暴露于COH的犊牛对长饲料颗粒的分选能力有所提高。 CON和HO在以后的生活中会犊牛。我们的结果表明，断奶后，EFE可能会影响饲料的选择，并且可能对以后的小母牛的饲料偏好产生长期影响。建议使用更多的犊牛进行进一步研究。并且血糖一直维持在27周（从190天到196天），与以后出生的CON和HO犊牛相比，早期暴露于COH的犊牛对长饲料颗粒的分选能力得到了改善。我们的结果表明，断奶后，EFE可能会影响饲料的选择，并且可能对以后的小母牛的饲料偏好产生长期影响。建议使用更多的犊牛进行进一步研究。并且血糖一直维持在27周（从190天到196天），与以后出生的CON和HO犊牛相比，早期暴露于COH的犊牛对长饲料颗粒的分选能力有所提高。我们的结果表明，断奶后，EFE可能会影响饲料的选择，并且可能对以后的小母牛的饲料偏好产生长期影响。建议使用更多的犊牛进行进一步研究。