PHYSIOLOGICAL AND REPRODUCTIVE RESPONSES OF YORUBA ECOTYPE CHICKENS TO DIETARY AND HORMONAL MANIPULATIONS
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Date
2018
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Abstract
Male chicks are less desirable outputs of hatchery production 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.
Four 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 4 IU) 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.
The findings of this study were that:
i. fertility was stable from day 1 to 12 except for a transient increase on day 6 and
decrease from day 13 onwards;
ii. male chicks had longer (p<0.05) keel, shank and thigh length than female chicks
at seventh and eighth weeks;
iii. 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;
iv. estradiol administration (i.m) resulted in lower feed per dozen egg (p<0.05) than
testosterone administration;
v. dietary 4% PKO decreased (p<0.05) feed intake, weight gain, feed per dozen egg,
fertility and egg hatchability of YEC; and
vi. in-ovo estradiol administration resulted in higher (p<0.05) hatchability and
percentage female chicks than testosterone administration.
The study concluded that fertile eggs can be collected within day 1 and 12 after artificial
insemination in YEC. Male chicks can be separated from female YEC 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.