这项研究检查了在妊娠中期补充母体蛋白质对后代的影响,考虑潜在的性别相关影响。43头怀孕的纯种Tabapuã肉牛(20头雌性;23头雄性胎儿)在牧场中集体管理,直到妊娠100天。从妊娠100到200天,他们被随机分配到限制组[(RES)-基础饮食(75%玉米青贮+25%甘蔗渣+矿物质混合物);n=24]或对照组[(CON)-相同的基础饮食+基于植物的补充[40%的粗蛋白,3.5g/kg体重(BW);n=19]。从怀孕200天到分娩,所有奶牛都同样饲喂玉米青贮饲料和矿物质混合物。在牛小腿阶段,奶牛和小牛被饲养在牧场。断奶后,小牛在接地期间(255-320天)被单独饲养和评估,生长1(321-381天),和增长2(382-445天)阶段。在210和445日龄收集后代的血液样本。在7、30和445日龄时通过活检收集骨骼肌组织的样品。对肌肉组织样品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)被认为是固定效应。显著性水平设定为5%。在妊娠中期,补充蛋白质的奶牛达到其蛋白质和能量需求的98%和92%,而未补充的奶牛只达到了这些要求的30%和50%,分别。RES的后代出生时更轻(27公斤vs.31千克),断奶(197公斤vs.214千克),和445天的年龄(398公斤与429kg)(P≤0.05)。CON小牛的总体形态测量值更高(P<0.05)。CON后代的肌纤维面积增加了约26%(P≤0.01)。在7日龄时,CON组胸背肌中雷帕霉素激酶mRNA表达的机制靶标有更大的趋势(P=0.06)。RES-雌性中的肌源性分化1表达更高(P=0.02)。在445天的RES后代中观察到肉碱棕榈酰转移酶2的上调(P=0.04)。脂肪酸结合蛋白4的表达(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)在CON雌性中上调。因此,在妊娠期间补充蛋白质可增强后代的生长并促进对脂肪生成的有利反应,尤其是女性。
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 and 23 male fetuses) were collectively managed in a pasture until 100 d of gestation. From 100 to 200 d 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 d 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 to 320 d), growing 1 (321 to 381 d), and growing 2 (382 to 445 d) phases. Offspring\'s blood samples were collected at 210 and 445 d of age. Samples of skeletal muscle tissue were collected through biopsies at 7, 30, and 445 d 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 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 nonsupplemented cows attained only 30% and 50% of these requirements, respectively. The RES offspring were lighter at birth (27 vs. 31 kg), weaning (197 vs. 214 kg), and 445 d of age (398 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 d of age. The Myogenic differentiation 1 expression was greater (P = 0.02) in RES-females. Upregulation of Carnitine palmitoyltransferase 2 was observed in RES offspring at 445 d (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.
In tropical conditions, beef cows on pasture often experience protein restriction during mid-to-late gestation, potentially impacting offspring development negatively. To address this, we investigated the effects of strategic protein supplementation for pregnant beef cows fed low-quality forage during mid-gestation on the postnatal growth trajectory of their offspring. The supplementation program, implemented during mid-gestation, increased dry matter intake by addressing nitrogen deficiency in the rumen, resulting in meeting 98% and 92% of protein and energy requirements in supplemented cows. In contrast, nonsupplemented cows met only 30% and 50% of these requirements, respectively. Consequently, protein supplementation positively influenced the postnatal growth trajectory of the offspring, attributed to beneficial changes in secondary myogenesis and hypertrophy processes. Supplementing cows with crude protein also stimulated lipogenesis, potentially contributing to intramuscular fat deposition, particularly in females. Therefore, this study emphasizes the importance of nutritional interventions for pregnant beef cows fed low-quality forage.