Department of Animal
Science, Faculty of Agriculture, Ferdowsi
University
of Mashhad, Mashhad, Iran
|
The effects of pistachio
by-products aqua extract (PBE) on growth performance and retention of
dietary nitrogen (N) were investigated in finishing lambs fed diets
containing 11.3% DM (low protein; LP) or 13.9% DM (high protein; HP)
crude protein. Two groups (n = 10) of Baluchi ram lambs (4-5 months old,
26.25±3.30 kg initial BW) were allotted to LP and HP treatments. In each
group, one half of the lambs received experimental diets mixed with 500
ml liquid fresh PBE per kg DM of diet. Thus, four experimental diets
were tested: LP diet without PBE supplementation; LP-PEB, LP diet with
PBE supplementation; LP+PBE, HP diet without PBE supplementation; HP-PBE
and HP diet with PBE supplementation; HP+PBE. Feed intake, average daily
gain (ADG) and feed conversion ratio (FCR) were recorded for a 50 d
experimental period. Plasma urea (PUN) and ruminal NH3-N
concentrations were measured at 0, 2 and 4 h after morning feeding on
the 35th d of the experiment. Apparent total tract
digestibility of DM, organic matter (OM) and N as well as urinary losses and retention of N
were also determined for 5 days at the end of the experiment. Although
there was a tendency for feed intake to be lower (P=0.102) in LP
compared with HP fed lambs, the dietary CP level had no effect on ADG
and FCR. In contrast, PBE supplementation improved both growth rate
(P=0.021) and FCR (P=0.104) of lambs. The urinary losses of N and also
PUN and ruminal NH3-N concentrations at h 2 and 4 after
feeding were decreased and the retention of N was increased by PBE
supplementation of diets. However, these effects of PBE were only
significant in the lambs fed HP diet. The concentrations of PUN (0 and 4
h after feeding) and ruminal NH3-N (4 h after feeding) were
affected positively by dietary CP level. Although the lambs feeding on
the LP diet retained a higher percentage of N intake or N digested, no
difference in daily N retained was observed between LP and HP fed lambs.
The experimental treatments had no effect on DM, OM
and N apparent digestibility. Our results indicated that the low
concentration of PBE tannins have a protein-sparing potential depend on
dietary CP density, thereby improving growth performance and N retention
in finishing lambs.
|