1963-Voice Of The Tennessee Walking Horse 1963 March Voice | Page 17

15 Voice of the Tennessee Walking Horse Why Full Sisters Differ: A Billion Reasons Dr. E.: My question is this: I have two mares that are full sisters, but they are quite unalike. They differ in size, temperament, conformation, and in almost every conceivable character. Why is this so? J-J- Dear J.J.: Parents sometimes transmit to one offspring much better inheritance than they do to another, simply as a result of chance differences in the genes that go to different sperm and eggs at the time they are formed. It's this way: In the body cells of an animal, there are a number of pairs of bundles, called chromosomes. In turn, the chromosomes carry pairs of minute particles, called genes, which are the basic hereditary ma­ terial. The nucleus of each body cell of horses contains 30 pairs of chromo­ somes, or a total of 60; whereas there are thousands of pairs of genes. When a sex cell (a sperm or an egg) is formed, only one chromosome and one gene of each pair goes into it. Then when mating and fertilization occur the single chromosomes from the germ cell of each parent unite to form new pairs, and the chromosomes and genes are again present in dupli­ cate in the body cells of the embryo. Billion Possible Samples Thus, with all possible combina­ tions of 30 pairs of chromosomes (the specie number in horses) and the genes that they bear, the total possible kinds of samples which are capable of being transmitted are 1,073,741, 904 kinds of sperm and 1,073,741,904 kinds of eggs. Thus, any stallion or mare can transmit over one billion different samples of its own inheri­ tance; and the combination from both pa rents makes possible one billion times one billion genetically different offspring. It is not strange, therefore, that full sisters (except identical twins from a single egg split after fertilization) are so differ­ ent. Actually, we can marvel that they bear as much resemblance to each other as they do. Because of this situation, the mat­ ing of a mare with a fine track rec­ Kent mare dropped a fuzzy-haired colt. With such an unpretentious background—a crippled dam and an incorrigible sire—no wonder Jonas Seely smiled when his poor hired man, Bill Rysdyk, cast a wistful glance at the colt. Soon a horse trade, an offer of S125, on credit from his penniless hired man; and proud new owner Bill Rysdyk led his crippled The Story of Hambletonian 10 mare and her colt down the road. Whatever may be said of Hamble­ Hambletonian 10 was trained for a tonian 10—patriarch of the Standard- few weeks, at which time he trotted bred breed of horses—he was the re­ the mile in 2:48. It was claimed that sult of a chance mating; one of na­ in stud condition he could trot a ture’s secrets for which there is no 2:20 dip. But he was placed in service breeding formula. In fact, had senti- as a two-year-old, never to race in competition. So famous did Hambletonian 10 By Dr. M. E. Ensmiger become by virtue of the speed of his Clovis, Calif. get that his service fee was upped to S500—comparable to a SI0,000 stud fee today. During his 21 years in ment not caused the acquisition of stud, he sired 1,321 foals. Today, 99 a crippled mare, had an evil-tempered per cent of all racing Standardbreds old stallion been sold to a fish peddler trace directly to Hambletonian 10, a year earlier, and had a hired man and most harness horses show cross not had an eye for superior horse after cross to him. flesh, the Standardbred breed might never have been born. While delivering cattle to Charles Kent, a New York slaughterer, Jonas ‘HIalLing