(Coturnix coturnix japonica) during rearing and laying periods - IBNA

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M. M. Nagharchi et al.
whey). It is also evidenced that the best feed conversion ratio in this period was
presented by the broilers fed the diet with prebiotic. At the end of experiment,
results about nutrient digestibility shown that treatments significantly affected
on protein and fat digestibility (P>0.05). Significantly differences were
observed in treatment that consumed the feed containing prebiotic (P>0.05),
specially about T6 (3% fermented whey) that have had highest digestibility for
both fat and protein in faecal and ileum. In all treatment that was fed with whey,
nutrient digestibility in faecal was higher than basal diet (P>0.05).
DISCUSSIONS
The addition of whey as a prebiotic to diets may influence broiler weight
gain (Jones & Ricke, 2005). However, the main objective of using these
compounds in broiler diets is to improve their feed conversion ratio (Dibner &
Richards, 2005), as was observed in this study. The mechanism that explains the
action of prebiotics is focused on gastrointestinal tract, as most of these
products are not absorbed, and are not efficient as growth promoters in germfree
animals (Coates et al., 1955; Coates et al., 1963). Therefore, it maybe
speculated that there is a strong interaction between prebiotics and the intestinal
micro flora. The improvement in performance (feed conversion ratio) of birds
fed with diets containing the tested prebiotic shows that the use of these
products is a feasible alternative to antibiotics used as growth promoters.
Similar results were also found by Maiorka et al. (2001), Pelicano et al. (2004),
and Pelícia et al. (2004). Wolf et al (1998) hypothesized that when a
fermentable carbohydrate reached the hind gut, the bacterial mass in the hind
gut increased due to increased energy (the prebiotic ) reaching the hind gut.
When carbohydrate are limited in the hind gut, bacteria increase fermentation of
amino acids to short-chain fatty acids and ammonia to obtain energy (Russell et
al., 1991); however, when energy is sufficient, the luminal concentration of
nitrogenous compounds decreases and the concentration of fecal nitrogen
(bacterial mass) increases (Cummings et al 1987). The latter caused a decrease
in amino acid digestibility, particularly when high levels of an oligosaccharide
were fed. On the other hand, Xu et al (2003), evaluated the effect of a prebiotic
in the name of fructooligosaccharids (FOS), on small intestinal digestive
enzyme activity of total protease, amylase, and lipase in 49-d-old broilers and
fund that these enzymes activity were improved by 27, 75 and 32%
respectively, compared with unsupplemented broilers when FOS was
supplemented at 4 g/kg. thus, the improvement in protein and fat digestibility in
current study may have been due to increase in proteolytic and lipase activity in
the small intestine. Positive effects of oligosaccharides (prebiotic) on nutrient
digestibility were observed by Wu et al. (1999) and Batal & Parsons, (2002).
There are some hypothetical mechanisms that can explain the improved nutrient
digestibility in fermented whey fed chickens. One of these mechanisms is the
acidifying effect of the fermented whey in the interior part of the