Huerta-Leidenz N O, Cross H R, Savell J W, Lunt D K, Baker J F, Smith S B
Department of Animal Science, Texas Agricultural Experiment Station, Texas A&M University, College Station 77843-2471, USA.
J Anim Sci. 1996 Jun;74(6):1256-64. doi: 10.2527/1996.7461256x.
The objective of this investigation was to compare fatty acid composition of calves from Bos taurus and Bos indicus cows across different stages of growth. Hereford (H) and Brahman (B) embryos were transferred to H or B cows (n = 58) to produce purebred Brahman (BB), purebred Hereford (HH), Hereford x Brahman (HB), and Brahman x Hereford (BH) offspring. Calves were castrated at 2 to 3 wk of age. Before weaning (210 d of age), calves were fed native grasses. After weaning, calves were fed a concentrate diet in dry-lot pens. Adipose tissue was obtained by biopsy at two times: at weaning during forage feeding and 3 mo after weaning when placed on feed. A third sample was collected from the fed steers at slaughter (approximately 430 d of age). Samples obtained by biopsy and after death were collected from the perianal region. Fatty acid composition for each sample was determined as the normalized percentage area means from the duplicate measures. Generally, BB calves grew slowest and BH steers grew fastest (P < .05). The BH steers exhibited 15 and 20% heavier (P < .05) carcasses per day of age than H-sired steers and BB steers, respectively. Adipose tissue samples from calves from Brahman sires or dams were less saturated (P < .05) than samples from calves from Hereford sires or dams. Differences in degree of unsaturation primarily were due to the percentages of monounsaturated fatty acids (MUFA). As calves became older, MUFA increased markedly, polyunsaturated fatty acids increased slightly (due to inverse, nearly proportional changes in 18:2 and 18:3), and saturated fatty acids decreased by 10 percentage units (P < .001). Thus, adipose tissue from Brahman and Hereford purebred and crossbred calves became markedly more unsaturated early postweaning; this change was less dramatic in the purebred Hereford calves.
本研究的目的是比较不同生长阶段的普通牛和瘤牛所产犊牛的脂肪酸组成。将海福特牛（H）和婆罗门牛（B）胚胎移植到海福特牛或婆罗门牛母牛（n = 58）体内，以生产纯种婆罗门牛（BB）、纯种海福特牛（HH）、海福特牛×婆罗门牛（HB）和婆罗门牛×海福特牛（BH）后代。犊牛在2至3周龄时去势。断奶前（210日龄），犊牛饲喂天然牧草。断奶后，犊牛在干栏舍中饲喂精料日粮。通过活检在两个时间点采集脂肪组织：断奶时采食牧草期间以及断奶后3个月开始采食饲料时。第三个样本是在屠宰时（约430日龄）从育肥牛中采集的。活检和死后采集的样本均取自肛周区域。每个样本的脂肪酸组成通过重复测量的归一化百分比面积均值来确定。一般来说，BB犊牛生长最慢，BH阉牛生长最快（P < 0.05）。BH阉牛的胴体日增重分别比H系阉牛和BB阉牛重15%和20%（P < 0.05）。来自婆罗门牛父本或母本的犊牛的脂肪组织样本的饱和度低于来自海福特牛父本或母本的犊牛的样本（P < 0.05）。不饱和度差异主要归因于单不饱和脂肪酸（MUFA）的百分比。随着犊牛年龄增长，MUFA显著增加，多不饱和脂肪酸略有增加（由于18:2和18:3呈反向、近乎成比例变化），饱和脂肪酸减少10个百分点（P < 0.001）。因此，婆罗门牛和海福特牛纯种及杂交犊牛的脂肪组织在断奶后早期明显变得更不饱和；这种变化在纯种海福特牛犊牛中不太明显。
