What is it to become, filly or colt?

Natural choice of foal gender in horse-breeding

With this longer-term study we want to find out, if breeders can influence the future foals gende at the time of covering and so put to use the natural choice of the foal gender.

Breeders of every horse breed are invited to join; the more foals we evaluate, the more accurate and safe our results will be!

read more > overview.pdf!

Study Reports 2013 ( 31.May 2013)

Reductionary diet (chance for a filly was 32:1) :  2 fillies, 1 colt

Fattening diet (chance for a colt was 4:1)   3 colts

Our Lille Ged's foal falls out of a clean category: desired had been a filly, but accidentally the reductionary diet had been changed to a fattening diet after the first covering period >  this led to an early abortion and a covering under probably still fattening diet; here a colt might have been more probable than the resulting filly!


20% fillies  > pdf

Overview  > pdf

Cover letter > pdf

Report on Lilles's diet in 2011 > pdf

Report in Lille's diet in 2012 > pdf  

Form Breeding Report  > pdf

Form Foaling report > pdf

Table of Data  > ods  (Open Office)  or  > xlsx    (Excel)

Body Condition Score > pdf

NZ study (1) >  pdf

NZ study text > pdf

Variations in Birth/Sex Ratio (2)  >pdf

Trivers Willard (3) > pdf