Anthony R V, Bellows R A, Short R E, Staigmiller R B, Kaltenbach C C, Dunn T G
J Anim Sci. 1986 May;62(5):1375-87. doi: 10.2527/jas1986.6251375x.
Fifteen Hereford and 47 crossbred heifers were allotted by breed and body weight to be artificially inseminated to one of two Angus sires selected for progeny birth weights (L = low; H = high). Forty-two of the heifers were randomly assigned to be slaughtered at 200, 215, 230, 245 or 260 d of gestation for measurement of fetal and placental characteristics. Twenty heifers were allowed to go to term and five calves from each sire group were randomly assigned to be euthanized and dissected within 24 h after birth. Sire differences in birth weight (BW) and dystocia score (32.9 vs 35.4 kg; 1.8 vs 3.1, L vs H sires, respectively) existed (P less than .01), and there was a sire effect (P less than .01) for fetal calf weights (FW) and eviscerated calf weights (EW). However, there was a sire X calf sex interaction for BW (P less than .05), EW (P less than .01), FW (P less than .01), femur length (P less than .05), heart weight (P less than .05), kidney weight (P less than .01) and pituitary weight (P less than .01). Weight differences suggested these interactions were a result of the relationship of the organ weights to fetal body weights and the interaction effects on calf weights resulted from limitations in the maternal environment which restricted growth of H-sired male calves in utero. Sire X fetal age interaction effects were all nonsignificant (P greater than .10) except for cerebrum weight. This finding indicates that fetus and calf growth rates were parallel for the L and H sires. A sire effect was found for biceps (P less than .01) and liver weights (P less than .01), but not for cerebrum weights (P greater than .10). Increasing weight due to fetal age was attributed to hypertrophy for the cerebrum (P less than .05) and liver (P approximately equal to .01), while the biceps increased (P less than .05) by both hypertrophy and hyperplasia, as determined from deoxyribonucleic acid and protein analyses. All measured fetal organ weights except heart, when expressed as a ratio with EW, decreased (P less than .05) with increasing fetal age. Brain (cerebrum + cerebellum):liver weight ratios were higher (P less than .01) in L-sired calves (.32 vs. .28) than in H-sired calves. Total placentome weight (b' = 91; P less than .01) and placental fluid volume (b' = .32; P less than .01) were highly associated with FW, accounting for 84% of the variation in FW.(ABSTRACT TRUNCATED AT 400 WORDS)
根据品种和体重，将15头赫里福德小母牛和47头杂交小母牛分配给两头为后代出生体重挑选的安格斯种公牛之一（L = 低出生体重；H = 高出生体重）进行人工授精。42头小母牛被随机分配在妊娠200、215、230、245或260天时屠宰，以测量胎儿和胎盘特征。20头小母牛足月分娩，每个种公牛组的5头犊牛在出生后24小时内被随机分配安乐死并解剖。出生体重（BW）和难产评分存在种公牛差异（分别为32.9对35.4千克；1.8对3.1，L对H种公牛）（P < 0.01），胎儿犊牛体重（FW）和去内脏犊牛体重（EW）存在种公牛效应（P < 0.01）。然而，BW（P < 0.05）、EW（P < 0.01）、FW（P < 0.01）、股骨长度（P < 0.05）、心脏重量（P < 0.05）、肾脏重量（P < 0.01）和垂体重量（P < 0.01）存在种公牛×犊牛性别交互作用。体重差异表明这些交互作用是器官重量与胎儿体重关系的结果，对犊牛体重的交互作用影响是由于母体环境的限制，限制了子宫内H种公牛雄性犊牛的生长。除大脑重量外，种公牛×胎儿年龄交互作用效应均不显著（P > 0.10）。这一发现表明，L和H种公牛的胎儿和犊牛生长速率是平行的。发现种公牛对二头肌（P < 0.01）和肝脏重量（P < 0.01）有影响，但对大脑重量没有影响（P > 0.10）。由于胎儿年龄导致的体重增加归因于大脑（P < 0.05）和肝脏（P ≈ 0.01）的肥大，而二头肌通过肥大和增生增加（P < 0.05），这是通过脱氧核糖核酸和蛋白质分析确定的。所有测量的胎儿器官重量（心脏除外）与EW的比值随胎儿年龄增加而降低（P < 0.05）。L种公牛犊牛的脑（大脑 + 小脑）：肝脏重量比（0.32对0.28）高于H种公牛犊牛（P < 0.01）。胎盘总重量（b' = 91；P < 0.01）和胎盘液体体积（b' = 0.32；P < 0.01）与FW高度相关，占FW变异的84%。（摘要截取自400字）
