widely adopted feed enzyme technology.
Annison (1997) suggests that feed enzymes
have proved successful with broilers, for
the following reasons:
1.The digestive system of the chicken is
relatively simple which makes it susceptible
to digestive upsets that may be overcome
by specific feed enzymes.
2.Considerable research effort into the
additional enzyme activities required by
chickens and the composition of feed
ingredients has allowed nutritionists to
target dietary components which at present
either impair animal performance or are of
no nutritional value without enzymes.
3.Research into the effects of feed
enzymes in chickens can be done inexpen-
sively, compared with larger animals. The
favourable cost of research with chickens
means observations can be made based on
sound scientific principals in terms of
statistics, chemistry and physiology. Also,
experiments with broilers produce results
quickly which in turn speeds up develop-
ment of new products.
Many early experiments with broilers
looked at their response to enzymes from
day-old chicks for just 21 days and not the
whole growing period of 35–49 days.
Response to enzymes is much higher over
the 21-day period and does not truly reflect
their response from birth to slaughter.
Jeroch et al. (1995) completed a compre-
hensive review (1987–1995) of enzyme
preparations for broilers. Over this period,
there were 33 broiler experiments (from
Europe and Canada) which looked at the
effects of enzyme supplementation over the
whole growing period (Table 19.4). The rye
and triticale diets produced the greatest
weight gain and FCR response to enzymes,
followed by barley diets, with the smallest
improvement coming from enzyme-
supplemented wheat diets. Although the
magnitude of the improvement brought
about by enzymes was small, the improve-
ments are economically significant because
of the large numbers of birds produced on
each farm.
Broilers are particularly sensitive to
the water-soluble polysaccharide content
(mainly arabinoxyl) of cereals. The birds’
sensitivity to water-soluble polysaccharides
was detected when the apparent metaboliz-
able energy content of approximately
25% of Australian wheat was found to be
less than was predicted from proximate
analysis and gross energy determinations
(Rogel et al., 1987). Annison (1991)
showed that there is a negative correlation
between water-soluble polysaccharide
content (mainly arabinoxyl) and apparent
metabolizable energy content. Therefore,
any genetic or growing conditions which
favour water-soluble polysaccharide pro-
duction will reduce broiler performance. A
rapid, cheap and effective method is
required to measure soluble NSP, which
will allow enzyme supplementation to be
based on actual NSP content not typical
values.
Diets with high levels of pentosans or
-glucans can increase the digesta viscosity
which in turn increases the incidence
of sticky droppings. The addition of
pentosanase to rye-based diets (Pettersson
and Aman, 1988, 1989; Bedford et al., 1991)410 D.I. Officer
Table 19.4.Effect of enzyme supplementation of barley-, rye-, triticale- and wheat-based broiler diets on
final body weight and feed conversion ratio (FCR).
No. of Inclusion Improvement in Improvement
Cereal experiments (g kg^1 ) final weight (%)a in FCR (%)
Barley 11 350–700 3.5 (0–6) 3.6 (0–6)
Rye/triticale 11 155–600 4.6–7.5 (0.5–14) 3.2–4.6 (0.5–6.5)
Wheat 11 150–660 0.6–2.3 (3 to 7.5) 1.5–2.8 (1 to 6.5)
aMean response with a range of enzyme doses (range).
Summary of Jeroch et al. (1995) Table 3. Note: the rye experiment of Petterrson and Aman (1988) was
excluded from the table as an outlier with a 34% increase in final weight and 8% improvement in FCR.