Reis M M, Cooke R F, Cappellozza B I, Marques R S, Guarnieri Filho T A, Rodrigues M C, Bradley J S, Mueller C J, Keisler D H, Johnson S E, Bohnert D W
1Eastern Oregon Agricultural Research Center,Oregon State University,Burns,OR 97720,USA.
3Department of Animal and Poultry Sciences,Virginia Tech University.Blacksburg,VA 24061,USA.
Animal. 2015 Sep;9(9):1500-8. doi: 10.1017/S1751731115000828. Epub 2015 May 20.
This experiment compared growth, physiological, and reproductive responses of beef heifers with (MI) or without (CON) access to a creep-feeder, as a manner to stimulate metabolic imprinting while nursing their dams. On day 0, 60 Angus × Hereford heifers were ranked by BW and age (140 ± 3 kg and 68±3 days), and assigned to pairs so all ranking criteria were similar between heifers within each pair. On day 1, pairs were randomly assigned to MI (n=15) or CON (n=15). From day 1 to 51, MI pairs and their dams were allocated to 15 drylot pens where heifers had ad libitum access to a corn-based supplement through a creep-feeder. The CON pairs and their dams were maintained in an adjacent single drylot pen. From day 52 to 111, treatments were managed as a single group on a semiarid range pasture. On day 111, heifers were weaned and allocated to two pastures (one pasture/treatment), receiving hay and a corn-based concentrate until day 326. Heifer BW was recorded before and at the end of the creep-feeding period (day 1 to 51), and on days 112 and 326. On days 0, 51, 111, 187, 261, and 325, jugular blood was collected and real-time ultrasonography for longissimus muscle depth and backfat thickness assessment was performed. Blood was also collected every 10 days from days 113 to 323 for puberty evaluation via plasma progesterone. Liver and subcutaneous fat biopsies were performed on days 51, 111, 261 and 325. Average daily gain was greater (P<0.01) for MI than CON from day 1 to 51, tended (P=0.09) to be greater for CON than MI from day 112 to 326, while BW on day 326 was similar between treatments. On day 51, MI had greater (P ⩽ 0.01) plasma IGF-I and glucose concentrations, as well as mRNA expression of hepatic pyruvate carboxylase and adipose fatty acid synthase than CON. On days 261 and 325, plasma insulin concentrations were greater (P ⩽ 0.03) in CON than MI. Mean mRNA expression of hepatic IGF-I and adipose peroxisome proliferator-activated receptor gamma were greater (P ⩽ 0.05) in MI than CON. No treatment effects were detected for puberty attainment rate. In conclusion, supplementing nursing heifers via creep-feeding for 50 days altered physiological and biochemical variables suggestive of a metabolic imprinting effect, but did not hasten their puberty attainment.
本试验比较了能（MI）或不能（CON）使用补饲槽的小母牛在生长、生理和繁殖方面的反应，以此作为在吮乳期刺激代谢印记的一种方式。在第0天，根据体重和年龄（140±3千克和68±3天）对60头安格斯×海福特小母牛进行排名，并配对分组，以使每组内小母牛的所有排名标准相似。在第1天，将配对的小母牛随机分配到MI组（n = 15）或CON组（n = 15）。从第1天到第51天，MI组的小母牛及其母牛被分配到15个干栏式畜栏中，小母牛可通过补饲槽自由采食以玉米为基础的补充料。CON组的小母牛及其母牛被饲养在相邻的单个干栏式畜栏中。从第52天到第111天，将各处理作为一个单一组在半干旱放牧草地上进行管理。在第111天，小母牛断奶并分配到两个牧场（每个处理一个牧场），在第326天之前一直采食干草和以玉米为基础的精料。在补饲期（第1天到第51天）开始前和结束时，以及在第112天和第326天记录小母牛的体重。在第0天、第51天、第111天、第187天、第261天和第325天，采集颈静脉血，并进行实时超声检查以评估背最长肌深度和背膘厚度。从第113天到第323天，每10天采集一次血液，通过血浆孕酮评估青春期。在第51天、第111天、第261天和第325天进行肝脏和皮下脂肪活检。从第1天到第5
