This study examined the impact of maternal protein supplementation during mid-gestation on offspring, considering potential sex-related effects. Forty-three pregnant purebred Tabapuã beef cows (20 female; 23 male fetuses) were collectively managed in a pasture until 100 days of gestation. From 100 to 200 days of gestation, they were randomly assigned to the Restricted group [(RES) - basal diet (75% corn silage + 25% sugar cane bagasse + mineral mixture); n = 24] or Control group [(CON) – same basal diet + based-plant supplement [40% of crude protein, 3.5 g/kg of body weight (BW); n = 19]. From 200 days of gestation until parturition, all cows were equally fed corn silage and mineral mixture. During the cow-calf phase, cows and their calves were maintained in a pasture area. After weaning, calves were individually housed and evaluated during the backgrounding (255–320 days), growing 1 (321–381 days), and growing 2 (382–445 days) phases. Offspring’s blood samples were collected at 210 and 445 days of age. Samples of skeletal muscle tissue were collected through biopsies at 7, 30, and 445 days of age. Muscle tissue samples were subjected to reverse-transcription quantitative polymerase chain reaction analysis. Prenatal treatment and offspring's sex (when pertinent) were considered as fixed effects. The significance level was set at 5%. At mid-gestation, cows supplemented with protein reached 98% and 92% of their protein and energy requirements, while non-supplemented cows attained only 30% and 50% of these requirements, respectively. The RES offspring were lighter at birth (27 kg vs. 31 kg), weaning (197 kg vs. 214 kg), and 445 days of age (398 kg vs. 429 kg) (P ≤ 0.05). The CON calves had greater (P < 0.05) morphometric measurements overall. The CON offspring had ~26% greater muscle fiber area (P ≤ 0.01). There was a trend (P = 0.06) for a greater Mechanistic target of rapamycin kinase mRNA expression in the Longissimus thoracis in the CON group at 7 days of age. The Myogenic differentiation 1 expression was greater (P = 0.02) in RES-females. Up-regulation of Carnitine palmitoyltransferase 2 was observed in RES offspring at 445 days (P = 0.04). Expression of Fatty acid binding protein 4 (P < 0.001), Peroxisome proliferator-activated receptor gamma (P < 0.001), and Stearoyl-Coenzyme A desaturase (P < 0.001) was upregulated in CON females. Therefore, protein supplementation during gestation enhances offspring growth and promotes favorable responses to lipogenesis, particularly in females.

中文翻译：

---

妊娠中期母体蛋白质补充可改善肉牛后代的生产性能和新陈代谢

这项研究探讨了妊娠中期母体蛋白质补充对后代的影响，考虑到潜在的性别相关影响。43 头怀孕的纯种 Tabapuã 肉牛（20 头母牛；23 头雄性胎儿）在牧场集中饲养，直至怀孕 100 天。从妊娠100到200天，他们被随机分配到限制组[(RES)——基础日粮（75%玉米青贮饲料+25%甘蔗渣+矿物质混合物）；n = 24] 或对照组 [(CON) – 相同的基础饮食 + 以植物为基础的补充剂 [40% 的粗蛋白，3.5 g/kg 体重 (BW)；n = 19]。从妊娠 200 天到分娩，所有奶牛均等饲喂玉米青贮饲料和矿物质混合物。在母牛-小牛阶段，母牛及其小牛被饲养在牧场地区。断奶后，将犊牛单独饲养并在背景阶段（255-320 天）、生长 1（321-381 天）和生长 2（382-445 天）阶段进行评估。后代的血液样本在 210 天和 445 天时采集。在 7、30 和 445 天龄时通过活检收集骨骼肌组织样本。对肌肉组织样本进行逆转录定量聚合酶链反应分析。产前治疗和后代性别（相关时）被视为固定效应。显着性水平设定为5%。在妊娠中期，补充蛋白质的奶牛达到了其蛋白质和能量需求的 98% 和 92%，而未补充蛋白质的奶牛分别仅达到了这些需求的 30% 和 50%。RES后代在出生时（27公斤对31公斤）、断奶时（197公斤对214公斤）和445日龄时（398公斤对429公斤）体重较轻（P≤0.05）。CON小牛总体上具有更大的形态测量值(P＜0.05)。CON 后代的肌纤维面积增加了约 26% (P ≤ 0.01)。7 日龄时 CON 组胸最长肌中雷帕霉素激酶 mRNA 表达的机械靶标有更大的趋势 (P = 0.06)。RES-女性中肌源性分化 1 的表达更高（P = 0.02）。445 天时，在 RES 后代中观察到肉毒碱棕榈酰转移酶 2 的上调（P = 0.04）。CON雌性中脂肪酸结合蛋白4(P＜0.001)、过氧化物酶体增殖物激活受体γ(P＜0.001)和硬脂酰辅酶A去饱和酶(P＜0.001)的表达上调。因此，妊娠期间补充蛋白质可以促进后代生长并促进对脂肪生成的有利反应，特别是在雌性中。