Male chicks are less desirable outputs of hatcheryproduction from layer lineage. There is flat information on the manipulation of the physiology of chicken to achieve reasonable profit in Yoruba ecotype chicken (YEC). Achievement of profitable sex ratio is important for planning and decision making. The objectives of this study were to determine the effects of: (i) artificial insemination on fertility, hatchability and morphometric characteristics in YEC; (ii) dietary palm kernel oil (PKO); and levels of estradiol and testosterone administration (i.m) on serum biochemistry, haematology, hormonal status, reproductive responses, egg characteristics and offspring sex ratio of YEC; and (iii) in-ovo estradiol and testosterone administration on sex ratio of YEC chicks.rnFour experiments were conducted. Experiment 1 investigated the effects of number of days post artificial insemination on fertility and hatchability in a completely randomized design; alternative methods on the percentile accuracy of sexing; sex on weekly body weights and morphometric measurements in YEC using a t-test. Experiment 2 examined the effects of dietary PKO (0, 1, 2, 3 and 4 percent) inclusion on serum biochemistry, haematology, hormonal status, reproductive responses and offspring sex ratio of YEC in a 2x5 factorial design. Experiment 3 evaluated the effects of estradiol and testosterone administration (i.m) on serum biochemistry, haematology, hormonal status, reproductive responses, egg characteristics and offspring sex ratio of YEC in a 2x2x5 factorial design. Experiment 4 investigated the in-ovo estradiol and testosterone administration (0, 1, 2, and 4IU) on hatchability and offspring sex ratio of YEC in a 2x4 factorial design. Data obtained were subjected to analysis of variance. Means were separated by the new Duncans multiple range test at p<0.05.rnThe findings of this study were that:rni. fertility was stable from day 1 to 12 except for a transient increase on day 6 and decrease from day 13 onwards;rnii. male chicks had longer (p<0.05) keel, shank and thigh length than female chicks at seventh and eighth weeks;rniii. dietary PKO; and levels of estradiol and testosterone administration (i.m) had no effect on serum biochemistry, haematology,hormone status and sex ratio in YEC; rniv. estradiol administration (i.m) resulted in lower feed per dozen egg (p<0.05) than testosterone administration;rnv. dietary 4% PKO decreased (p<0.05) feed intake, weight gain, feed per dozen egg, fertility and egg hatchability of YEC; andrnvi. in-ovo estradiol administration resulted in higher (p<0.05) hatchability and percentage female chicks than testosterone administration.rnrnThe study concluded that fertile eggs can be collected within day 1 and 12 after artificial insemination in YEC.Male chickscan be separated from femaleYEC from 7 weeks and above using body weight and morphometric traits.In-ovo estradiol administration increased hatchability and the percentage of female chicks hatched. In-ovo estradiol administration of up to 2 IU is therefore recommended for increased female chicks production in YEC.