The influence of dietary nutrient concentration on performance
and the growth of fat depots, breast
meat and leg muscles was examined in five groups of male broiler chickens
fed ad libitum with
combinations of high (H), commercial (C) or low (L) energy and nutrient
concentration in starter and
finisher diets. Diets were changed from starter to finisher at 3 weeks
of age giving 200 birds on each
of five treatments: HH, HL, CC, LH and LL. Ten birds per treatment were
slaughtered at weekly
intervals from 0 to 70 days. Five of these were dissected into component
lean tissues of breast muscles
(white meat) and thigh+leg muscles (dark meat) and fat depots, and the
other five carcasses were
minced for chemical analyses. Data were analysed by fitting Gompertz functions
to each component.Analysis of body weight, carcass components and feed intake revealed
that at 70 days birds on LH
approached similar liveweights to those on HH with lower overall food intakes,
comparable feed
conversion ratios but slightly greater fat depots. The HL birds had less
fat but achieved specific
weights over longer periods of time with greater feed intakes and poorer
feed conversion ratios.
Content of white and dark meat was always greater in HH birds, with differences
between treatments
being greater for white meat.Decisions on which conditions are most appropriate will be influenced
by time taken to reach
specific liveweights if whole birds are marketed, or the rate of growth
of individual portions if further
processing is considered, together with feed conversion efficiency and
the relative costs of diets
varying in energy and nutrient concentration.
Arabinoxylooligosaccharides from Wheat Bran Inhibit Salmonella Colonization in Broiler Chickens