A. Brosh et al., EFFECTS OF SOURCE AND CONTENT OF ASH IN POULTRY LITTER USED IN DIETS FOR BEEF-CATTLE, Journal of Agricultural Science, 131, 1998, pp. 87-95
Two experiments were carried out in order to study the effect of the a
sh content of poultry litter (PL) on its nutritional value. In Expt 1,
broiler PL was incorporated in the proportions of 30 and 45 % into di
ets based on wheat straw supplemented with 20% maize grain. The PL was
either fresh (containing 19% ash) or had been heated in a stack (givi
ng 26% ash). There were also two additional diets containing 45% fresh
PL to which either ground limestone or wood ash had been added to pro
vide the same ash content as the diets containing 45 % stored, high as
h FL. An in vivo digestibility and nitrogen balance trial was carried
out. Storing the FL, which resulted in heating and an increase in ash
content, reduced dry matter intake significantly. The largest and most
significant effect on the digestibility of dry matter, organic matter
and crude protein can be ascribed to the freshness of the FL. Stored,
heated PL had a highly negative effect on crude protein digestibility
and on nitrogen retention. No negative effect of adding extrinsic ash
was recorded. In Expt 2, the nutritional value of layer PL (LPL), com
pared with that of broiler PL (BPL), was examined using ten beef cows
before and after calving. The diet was composed of 45% FL, 35% wheat s
traw (WS) and 20% maize grain. Daily dry matter intakes were 12.7 and
16.2 g/kg liveweight (LW) before calving and 15.5 and 22.8 g/kg LW aft
er calving, for cows fed LPL and BPL, respectively. Owing to the combi
ned effect of the lower dry matter intake, lower gross energy content
and lower digestibility of LPL, the digestible energy intake of BPL di
ets was almost three-fold, and nitrogen absorption (g/kg LW0.75) on th
e BPL was 2.4-fold higher than on the LPL diets. Because the ash intak
e of both diets was similar, it is suggested that the main inhibiting
factor of intake after calving was the rumen's ability to mobilize the
large amounts of ash-rich complexes of ash and organic matter to the
reticular omasal orifice and, consequently, out of the rumen.