Hiltz Rebecca L, McCurdy Dana E, Moreland Steven, Klanderman Keith, Laarman Anne H
Department of Animal and Veterinary Science, University of Idaho, Moscow 83844-2330.
Adisseo Inc., Hampshire, IL 60140.
JDS Commun. 2021 Sep 13;2(6):324-328. doi: 10.3168/jdsc.2021-0088. eCollection 2021 Nov.
This study examined the effects of changes in rumen fermentation during the weaning transition on abundance of transporters involved in volatile fatty acid (VFA) absorption or intracellular pH homeostasis. Holstein bull calves (n = 27) were assigned to 1 of 3 treatment groups in a randomized, complete block design: 2 preweaning groups [animals fed milk only (PRE-M) or milk, calf starter, and hay (PRE-S)] and 1 postweaning group (animals fed milk, starter, and hay with a 2-wk weaning transition; POST-S). Calves were euthanized at 42 d of age (PRE-M and PRE-S) or at 63 d of age (POST-S), and rumen epithelium and rumen fluid samples were collected. Rumen fluid was analyzed for VFA concentration, and rumen epithelium was analyzed for the abundance of VFA transporter monocarboxylate transporter isoform 1 (MCT1) and the intracellular pH regulators sodium bicarbonate co-transporter 1 (NBC1) and sodium-proton exchanger 3 (NHE3) protein. Preweaning, total VFA concentrations tended to increase and NBC1 abundance increased with starter intake. Between pre- and postweaning, total VFA concentrations increased but NHE3 protein abundance decreased. In calves, rumen epithelial development during the weaning transition appears to show more pronounced changes in intracellular pH homeostasis than in VFA transport capacity.
本研究考察了断奶过渡期瘤胃发酵变化对参与挥发性脂肪酸（VFA）吸收或细胞内pH稳态的转运蛋白丰度的影响。采用随机完全区组设计，将27头荷斯坦公牛犊分配到3个处理组中的1组：2个断奶前组[仅喂牛奶的动物（PRE-M）或喂牛奶、犊牛开食料和干草的动物（PRE-S）]和1个断奶后组（在2周断奶过渡期内喂牛奶、开食料和干草的动物；POST-S）。犊牛在42日龄（PRE-M和PRE-S）或63日龄（POST-S）时实施安乐死，并采集瘤胃上皮和瘤胃液样本。分析瘤胃液中的VFA浓度，分析瘤胃上皮中VFA转运蛋白单羧酸转运体亚型1（MCT1）以及细胞内pH调节剂碳酸氢钠协同转运体1（NBC1）和钠-质子交换体3（NHE3）蛋白的丰度。断奶前，随着开食料摄入量的增加，总VFA浓度呈上升趋势，NBC1丰度增加。断奶前后，总VFA浓度增加，但NHE3蛋白丰度降低。在犊牛中，断奶过渡期瘤胃上皮发育在细胞内pH稳态方面似乎比在VFA转运能力方面表现出更明显的变化。
