Summary. lneffectiveness of post-hatching overfeeding in modifying the subsequent appetite, weight gain and body composition of the chicken.The effects of post-hatching overfeeding were studied in the chicken. Hubbard and Leghorn chickens were force-fed daily from 0 to 9 days of age by a factor of 1.5 times the food intake of the ad libitum-fed group, then 1.2 times that intake from 10 to 15 days. Thereafter, they were refed ad libitum. As might be expected, body weights were increased at the end of the forced-feeding period in overfed chickens of both breeds. Liver weight and malic enzyme activity and the size of adipocytes isolated from subcutaneous and gizzard adipose tissues (only measured in the Leghorn breed) were also increased by overfeeding. After Introduction.