X. Zhang et al., Body weight and semen production of broiler breeder males as influenced bycrude protein levels and feeding regimens during rearing, POULTRY SCI, 78(2), 1999, pp. 190-196
An appropriate dietary CP level and feeding regimen during rearing is consi
dered important for controlling BW and improving semen production in broile
r breeder males. A total of 640 day-old broiler breeder male chicks of two
commercial strains (A and B) received treatments of a factorial arrangement
of two CP levels (12 and 16%) of corn-soybean grower diets and two feeding
regimens [changing feed to a grower diet from the standard broiler starter
at 0.45 and 0.68 kg BW and then skip-a-day feeding]. Four- to 28-wk BW dif
fered between CP levels during rearing, with heavier BW on the 16% CP diet
than on the 12% CP diet in spite of isocaloric feed intake. Strains did not
show a significant difference in BW prior to 40 wk of age. Feed restrictio
n initiated at 0.45 or 0.68 kg BW had no effect in controlling BW after 4 w
k of age. Uniformity of BW did not differ between CP levels. Semen volume w
as greater on the 12% than on the 16% CP diet from 28 to 36 wk of age. Seme
n concentration was not affected by CP levels, feeding regimens, or strains
. Spermatozoa per ejaculate from 28 to 52 wk of age was correlated negative
ly with 8- to 20-wk BW. This negative relationship was attenuated with age,
until at Week 46 or later spermatozoa per ejaculate was associated positiv
ely with BW after sexual maturity. No difference in percentage of males in
semen production was noted between strains, CP levels, or feeding regimens.
in brief, diet changes at 0.45 or 0.68 kg BW were not important in improvi
ng semen production, whereas the low CP diet (12%) had advantages in semen
production over the high CP diet (16%). A negative relationship existed bet
ween semen production and BW during rearing; however, continued BW gain aft
er sexual maturity was necessary to optimize semen production, especially d
uring the late breeding period.