Bennett Madeline N, McCurdy Dana E, Laarman Anne H
Department of Animal, Veterinary and Food Science, University of Idaho, Moscow, 83844, United States.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
Vet Anim Sci. 2024 Jul 26;26:100384. doi: 10.1016/j.vas.2024.100384. eCollection 2024 Dec.
The objective of this study was to determine the effect of limiting forage provision in pre-weaned calves on ruminal pH and short chain fatty acid (SCFA) transport capacity during the pre-weaning period. Twelve Jersey bull calves (age = 1.9 ± 0.8 d) were housed individually on sand. All calves were fed milk replacer at 1,200 g/d and texturized grain-based starter ad libitum from birth. Calves were randomly assigned one of two treatments: ad libitum forage () or limited forage provision, where forage was limited to 90 g/d as-fed (). Individual feed intake was recorded daily, calf weights, and jugular blood samples were collected weekly. Once calves consumed 680 g/d of calf starter, ruminal pH was measured for seven days after which calves were humanely killed and rumen fluid sampled. During the pre-weaning period, starter intake, feed efficiency, plasma glucose and β-hydroxybutyrate (BHB) concentration, SCFA concentration, average daily gain, and body weight were not different between treatments. Forage intake for ALF calves was greater than LFP beginning at wk 9 (255 ± 34 vs. 71 ± 40 g/d, respectively). Compared to ALF, LFP decreased mean ruminal pH (6.38 ± 0.16 vs. 5.98 ± 0.23) and duration of time where rumen pH was below 5.8 (796 ± 145 vs. 261 ± 133 min/d). Epithelial markers of SCFA transport and cell homeostasis (MCT1, NBC1, NHE3) were not affected by treatment. In conclusion, incidence of sub-acute ruminal acidosis in limited forage-fed calves did not have the same effects on intake and nutrient transporters seen in adult cows.
本研究的目的是确定断奶前犊牛限制粗饲料供应对断奶前期瘤胃pH值和短链脂肪酸（SCFA）转运能力的影响。12头泽西公牛犊（年龄 = 1.9 ± 0.8天）单独饲养在沙地上。所有犊牛从出生起每天饲喂1200克代乳粉，并随意采食经加工的谷物型开食料。犊牛被随机分配到两种处理之一：自由采食粗饲料（）或限制粗饲料供应，即粗饲料限制为每天90克（按饲喂时计）（）。每天记录个体采食量、犊牛体重，并每周采集颈静脉血样。一旦犊牛每天采食680克犊牛开食料，测量瘤胃pH值7天，之后对犊牛实施安乐死并采集瘤胃液。在断奶前期，两种处理之间的开食料摄入量、饲料效率、血浆葡萄糖和β-羟基丁酸（BHB）浓度、SCFA浓度、平均日增重和体重没有差异。从第9周开始，自由采食粗饲料组犊牛的粗饲料摄入量大于限制粗饲料供应组（分别为255 ± 34克/天和71 ± 40克/天）。与自由采食粗饲料组相比，限制粗饲料供应组降低了瘤胃平均pH值（6.38 ± 0.16对5.98 ± 0.23）以及瘤胃pH值低于5.8的持续时间（796 ± 145对261 ± 133分钟/天）。SCFA转运和细胞内稳态的上皮标志物（MCT1、NBC1、NHE3）不受处理影响。总之，限制粗饲料饲喂的犊牛亚急性瘤胃酸中毒的发生率对采食量和营养物质转运体的影响与成年母牛不同。
