A common belief among practical breeders is that the male in multiparous species affects the number at a birth. This belief has even permeated scientific writing; many biologist apparently taking the supposed observation at face value, while others have sought biometrical proof in the various accumulations of the data regarding fertility inheritance found in biological records

Wentworth, Edward N.

University of Northern Iowa

Proceedings of the Iowa Academy of Science Volume 24 Annual Issue Article 46 1917 The Influence of the Male on Litter Sizes Edward N. Wentworth Kansas Agricultural College Let us know how access to this document benefits you Copyright ©1917 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Wentworth, Edward N. (1917) "The Influence of the Male on Litter Sizes," Proceedings of the Iowa Academy of Science, 24(1), 305-308. Available at: https://scholarworks.uni.edu/pias/vol24/iss1/46 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. TII.E INFLUENCE OF TIIE JIALI<J OX Ll'l"l'ER SIZES.1 EDWARD N". 'VE:-.ITWORTH. A coni'mon belief among· practical breeders is that the male in multi;rnrous spel'ies affec·ts the number at a. birth. This be-lief has even permeatecl scientific writing; mauy biologists ap-parently taking the snpposed observation at fa.ce value. while others have sought bionwtrirnl proof in the various accumula-tions of the data regarding fertility inheritanec found in bio-logical records. Tims Ewart reports the case of a long-haired Skye terrier hitch that mu; infertile to two males of her race and was the dam of onp m•akly pup to the service of a third, whieh produced four strmig· pupR to a vigorouR W eRt Highland terrier. Harris. in some calenlations made on litter frequencies reported by Wentworth all(l Anhel, ealls attPntion to the fact that there is a statisticall,\· significant correlation between the size of litter in which boars arr produced and the size of litters in which their daughtPrs arr procluced, while he discovers the same thing in data reportecl on Shropshire sheep studied by Rietz arnl Roberts. Several otlwr series of statistics show sim-ilar characteristies, altl1ough thl',\' are not as exh'nsive as those disc·ussed. From purely logical gronncls it is difficult to conceive ,11>·hy the male should affect thr number per litter. It would seem obvious that among the millions nf sperin cells in each seminal discharge of the male there would he suffic'.icnt gametes not only to fertilize the relatively fe\\· om released hy the female, but also to reach them in time to form an effective union. Theoreti-cally there seem to be only three ways possible in which there might be differences between males. First, the· male although functional to a certain clPgree. might produce such weak cells that their vitality woulcl be exhausted before they could reach the ova .. Second, even though they reach the ova, they might not form strongly viable zygotes. a condition which is frequently found in multiparous animals. Hammond reports that in swine there are normally several fertilized ova which atrophy during the gestation period, although h<' seems unable to determine the 'Paper No. 7 from tl1e Laboratory of Animal Technology, Kansas State Agricultural College. 20 1Wentworth: The Influence of the Male on Litter SizesPublished by UNI ScholarWorks, 1917366 IOWA ACADEMY OF SClENCJ<J VoL. XXIY, 1917 cause. 'l'here is a possibility that one cause for atrophy might be inherent in the sperm. Third, it is possi\1le that there may be an influence of the spPr111 011 the egg similar to that which causes duplicate twins. This is difficult to prove. Recognizing that there m·p thn'c such. classes of possibilities. all of which were impossiblP to tl',.;t with data thP iHiter had at hand, an examination of a .large amount of ne\\- material was made with the view of diseow1·i11g whether such eonditions cx-.isted inherently in all cases. Southdown sherp and Chester \Vhite hogs wrre chosen for this pnrposr, as iYe1l as a frw rec•ords on Collie dogs. In Southdown prdigrt'l'S 1H'gn11 from single births the av,crag1~ progenie'! were of course decirledly lower than in those begun from multiple births, since then' wrre only sewn possible matings on each pedigree blank (the great-grandpa rental genrration lw-ing the last). :F'nrthrrtllOl'(', in many casrs thr Rirc>, grand-parents, or great-gramlparPnts. wrrc importrd, ·with few data obtainable as to birth rank. This g·avc considerable statistical weig:J1t to the mating from which the pedigree started. Henee the results from Southdom1 pedigrees brgun with multiple births are presented separatel.\·. 'l'hr data for each Hl'(' presented in 'l'able> I and II. TABLE I. BREEDING PERFORMANCE OF SOUTHDOWN MALES IN PFJDI· GREES STARTED FROM SINGLE BIRTHS. Birth Rank of Sire :>iumber Cases 1------------------------------ 2811 2------------------------------ 886 3______________________________ 18 TABLE II. Birth Rank of Progeny 1.2864±.00!i9 1.2776±.0103 1.3888±.0775 BREEDING PERFORMA!><CE OF SOUTHDOWN MALES IN PEDf-GREES STARTED FROM TWIN BIRTHS. Birth Rank of Sire 1 _____________________________ _ 2 _____________________________ _ 3 _____________________________ _ ~umber Cases 4120 1165 26 Birth Rl1nk of Progeny 1.5296±.0054 1.5682±.0072 1.6154±.0644 2Proceedings of the Iowa Academy of Science, Vol. 24 [1917], No. 1, Art. 46https://scholarworks.uni.edu/pias/vol24/iss1/46lNFLUENCE OF THE MALE ON LITTER SIZES 307 In '!'able I the differen('es het\reen sires of different birth rank as far as breeding 11 nalities arc concPrned, are in no case signifi-cant, if the eonvcntional ratio of the «onstant being at least three timer,; its probable error is assumed. Jn Table II, the dif-ference bet\n·en single . .; arul twins, .0:~86 ± .omn is possibly signifi-cant, the oth<·rs are 11ot. Since five out of six such constants are wit significant. it is doubtful if the sixth one is, even though the chames o! its hei11g significant are approximately 216 to 1. Of Chest1·r ·white hogs the following statistics were colleC'ted. TABLE IlI. BREEDJNG PERFORMANCE OF CHESTER WHITE BOARS 01<' DIFFERENT BlRTH HANK. Birth Hank of Sire :\'umber Cai;f's 5------------------------------ 2 6______________________________ 7 7______________________________ 31 g ______________________________ · 65 9______________________________ 112 lf)______________________________ 100 11______________________________ 54 12______________________________ 30 13______________________________ 11 14______________________________ 2 15______________________________ 1 Birth Hank of Progeny 8.0000±.4 7 69 7.2857±.3531 7.9644±.2061 S.3235±.1889 8.1447±.1473 7.8623±.1542 7.9466±.1894 8.1121±.2013 7.6524±.28177 9.0000±.4 769 8.0000 Tn i10 ta,.;(' in 'l'ablc III is the' diffrrenee between an~- hYo types of sirp,.; statistically significant. Table lV shows the results obtained from a few records on Collies. The figures are not comparable statistically. hut since the evidcnee is the same as in the prcvions cases. the data are present.('( l. TABLE IV. EFFECT OF BIRTH RANK OF SIRE IX COLLIES ON NUMBER OF PUPS PER LITTER. lhrth Hank of Sire ~umber Cases 4______________________________ 3 5______________________________ 7 6------------------------------ 7 '------------------------------ 4 8------------------------------ 2 Average Number Progeny 5.3333±.1836 5.5714±.2304 5.7142±.1805 5.7500±.2500 . 5.0000±.4769 3Wentworth: The Influence of the Male on Litter SizesPublished by UNI ScholarWorks, 1917308 IOWA ACADEMY OF SCIENCE VoL. XXIV, 1917 Whih' these numbers arc hy no means large enough to be conclusive, yet in the face of the conflicting evidence from other sources it would seem that the male has no significant effect upon the litter number. Such conclusion seems just on logical grounds in spite of the possibilities suggested earlier in the paper, and until more definite evidcnee is adduced it seems only reasonable to conclude that the femah• dPtermines the number at a birth. KANSAS AGRICULTCRAL. COLLEGE. LITERATURE CITED. EWART, J. C., The Breeding and Origin of Domestic Animals: 27th Report Bureau of Animal Industry, pp. 125-186, 1910. HARRIS, J. A., Variation, Correlation, and Inheritance of Fertility in the Mammals: American Naturalist, Vol. 50, pp. 626-636, 1916 . . RIETZ, H. L., and ROBERTS, E., Degree of Resemblance of Parents and Offspring with Reference to Birth as Twins for Registered Shropshire Sheep: Journal of Agricultural Research, Vol. 4, pp. 479-510, 1915. WENTWORTH, E. N., and AUBEL, C. E., Inheritance of Fertility in Swine: Journal of Agricultural Research, Vol. 5, pp. 1145-1160, 1916. 4Proceedings of the Iowa Academy of Science, Vol. 24 [1917], No. 1, Art. 46https://scholarworks.uni.edu/pias/vol24/iss1/46

The Influence of the Male on Litter Sizes

https://scholarworks.uni.edu/cgi/viewcontent.cgi?article=6489&context=pias

The Influence of the Male on Litter Sizes

Abstract

Similar works

Full text

Available Versions

University of Northern Iowa