Lammoglia M A, Bellows R A, Grings E E, Bergman J W
BovaGen, San Antonio, TX 78216, USA.
J Anim Sci. 1999 Aug;77(8):2227-33. doi: 10.2527/1999.7782227x.
Effects of feeding pregnant dams supplemental dietary fat during the last 55 d of gestation on cold tolerance of newborn crossbred calves with (Piedmontese cross, P, n = 15) or without (Hereford cross, H, n = 16) the muscle hypertrophy allele was determined. Primiparous F1 dams gestating F2 calves of the respective breeds were assigned randomly within breed to receive gestation diets containing either 2.2 (Low Fat; LF) or 5.1% fat (High Fat; HF). Safflower (Carthamus tinctorius L.) seeds containing 37% oil with 79% linoleic acid were the supplemental fat source in diets formulated to be isocaloric-isonitrogenous. At parturition, calves were separated from their dams, fed 38 degrees C pooled dairy cow colostrum (30 mL/kg BW), muzzled to prevent suckling, and returned to their dams in a heated (22 degrees C) room for 3.5 h. At 4 h of age (birth = 0 h), a catheter was inserted into the jugular vein. At 5 h of age, calves were placed in a 0 degrees C room for 140 min, and rectal temperatures and blood samples were obtained at 10- and 20-min intervals. Blood was assayed for cortisol and glucose. Rectal temperature was affected by diet (P<.05), time, diet x time, and breed x time (P<.01 for time and the interactions). Cortisol and glucose concentrations were not affected by diet, breed, or the diet x breed interaction, but they were affected by time, breed x time (both P<.01), and diet x time (P = .06). Calves from HF dams had higher rectal temperatures than calves from LF dams, and the HF calves maintained higher rectal temperatures throughout cold exposure. Cortisol concentrations were lower (P = .06) in calves from HF dams, and these calves had more (P = .06) glucose available for metabolic heat production than calves from LF dams. Piedmontese-cross calves maintained higher (P<.01) rectal temperatures and had higher cortisol and glucose (both P<.01) concentrations than did H-cross calves. We conclude that feeding dams supplemental fat during late gestation increased heat production in newborn calves and potentially could increase calf survival; calves with muscle hypertrophy may have a different ratio of shivering vs nonshivering thermogenesis due to differences in body composition or relationships among uncoupling proteins.
研究了在妊娠最后55天给怀孕母畜补充膳食脂肪，对携带（皮埃蒙特杂交牛，P，n = 15）或不携带（赫里福德杂交牛，H，n = 16）肌肉肥大等位基因的新生杂交犊牛耐寒性的影响。将怀有各自品种F2犊牛的初产F1代母畜在品种内随机分配，以接受含有2.2%（低脂；LF）或5.1%脂肪（高脂；HF）的妊娠日粮。含37%油且79%为亚油酸的红花（Carthamus tinctorius L.）种子是配制为等热量 - 等氮量日粮中的补充脂肪来源。分娩时，犊牛与母畜分离，饲喂38摄氏度的混合奶牛初乳（30 mL/kg体重），戴上口套以防吮乳，然后在加热至22摄氏度的房间中与母畜一起待3.5小时。在4小时龄（出生 = 0小时）时，将导管插入颈静脉。在5小时龄时，将犊牛放入0摄氏度的房间中140分钟，并每隔10分钟和20分钟测量直肠温度并采集血样。检测血液中的皮质醇和葡萄糖含量。直肠温度受日粮（P<0.05）、时间、日粮×时间以及品种×时间（时间及相互作用P<0.01）的影响。皮质醇和葡萄糖浓度不受日粮、品种或日粮×品种相互作用的影响，但受时间、品种×时间（均P<0.01）和日粮×时间（P = 0.06）的影响。来自高脂日粮母畜的犊牛直肠温度高于来自低脂日粮母畜的犊牛，并且在整个冷暴露过程中，高脂犊牛能维持较高的直肠温度。来自高脂日粮母畜的犊牛皮质醇浓度较低（P = 0.06），并且与来自低脂日粮母畜的犊牛相比，这些犊牛有更多（P = 0.06）可用于产热代谢的葡萄糖。皮埃蒙特杂交犊牛比赫里福德杂交犊牛维持更高（P<0.01）的直肠温度，并且皮质醇和葡萄糖浓度也更高（均P<0.01）。我们得出结论，在妊娠后期给母畜补充脂肪可增加新生犊牛的产热，并可能提高犊牛存活率；由于身体组成或解偶联蛋白之间关系的差异，携带肌肉肥大等位基因的犊牛在颤抖性与非颤抖性产热方面可能具有不同的比例。
