Bennett G L
Roman L. Hruska U.S. Meat Anim. Res. Center, U.S. Department of Agriculture Clay Center, NE 68933.
J Anim Sci. 1987 Dec;65(6):1471-6. doi: 10.2527/jas1987.6561471x.
Periodic rotational crosses differ from conventional rotations by using sire breeds an unequal number of generations but in a regular sequence. Formulas for breed composition and heterosis in offspring from periodic rotations at equilibrium averaged over all generations of a cycle and for each generation of the cycle are presented. Coefficients of squares and products of breed differences and heterosis used to calculate inter-generational variance are also derived. Several specific periodic rotations utilizing a range of breed proportions were found to use from 70 to 95% as much heterosis as conventional rotations using the same number of breeds equally. Estimates of swine and cattle additive breed and heterosis effects taken from the literature were applied to the formulas. In both the swine and cattle examples, periodic rotations were found that equaled or exceeded the conventional rotations using the same number of breeds and also had lower inter-generational variance.
周期性轮回杂交与传统轮回杂交不同，它使用的父本品种代数不相等，但按固定顺序进行。文中给出了在一个周期的所有世代平均以及每个世代的平衡状态下，周期性轮回杂交后代的品种组成和杂种优势的公式。还推导了用于计算代际方差的品种差异和杂种优势的平方和乘积系数。研究发现，几种特定的周期性轮回杂交，在使用相同数量品种的情况下，杂种优势的利用程度为传统轮回杂交的70%至95%。将从文献中获取的猪和牛的加性品种和杂种优势效应估计值应用于这些公式。在猪和牛的例子中，都发现了一些周期性轮回杂交，其杂种优势等于或超过使用相同数量品种的传统轮回杂交，并且代际方差更低。
