4. Studies Involving Pea-based Rations and Poultry
The level of nutrients provided by peas is well suited
to the requirements of laying hens and studies quoted elsewhere
in this review suggest that the digestive physiology of the adult
bird will allow optimum utilization of this feedstuff. Recent
North American trials indicated moderate quantities of peas were
suitable for use in the diets of young birds, but that hens could
achieve excellent performance at higher dietary levels (Table
4). A European study indicated performance was not affected by
350 g kg-1 dietary wrinkled (assumed) peas, but that daily egg
production declined significantly from week 3 (98%) to week 8
(90%) at a 500 g kg-1 inclusion rate. As seen by other authors
(Ivusic et al. 1994 {23}, Ivusic 1989 {97}), average egg
weight increased with dietary pea concentration (Castanon and
Perez-Lanzac 1990{80}). These observations may have been affected
by the authors' failure to supplement the diets with methionine.
Another trial indicated that 375g kg-1 peas sustained production
equivalent to a fishmeal control, but reduced egg size; however,
the oat-based diets contained only 2400 kcal kg-1, making the
data unapplicable to modern laying strains (Davidson 1980{144}).
Further work is needed to corroborate the studies shown below.
| Table 4 . Results from North American studies involving the use of peas in diets for laying hens and chicks. | ||
| Reference | Treatment | Effect |
| Guenter et al., 1992 as in {9} | 0 vs. 230, 460 or 680 g kg-1 peas in 19% CP diets for age chicks. | Gain was significantly reduced at 460 and 680 g kg-1 dietary peas; FE declined significantly at all pea levels (P<0.01). |
| Ivusic et al., 1994 {23} | 0, 148, 296, 445 or 590 g kg-1 peas were added to SCWL layer diets from 22 to 58 weeks of age. | Performance was equivalent to the corn-soy control, except 590 g kg-1 peas reduced shell quality; at 500 g kg-1 peas the increased proportion of large eggs approached significance (P<0.06). Pea diets reduced yolk color . |
| Ivusic et al., 1989{97} | Corn-soy control vs. 590 g kg-1 pea diets supplemented with soybean oil, yeast culture, choline, biotin and combinations thereof in SCWL layer diets from 38 to 70 weeks of age. | Pea diets increased the proportion of large, extra large and jumbo eggs, an effect accompanied by reduced shell quality (P<0.05). |
A high crude fibre level in peas (9.9% DM) was implicated
in reduced pea ME levels for birds in-lay (2806kcal kg-1 DM; Askbrant
and Hakansson 1984{128}). However, antinutritive effects of viscous
polysaccharides in the barley, oat (320g kg-1 each) and wheat
(100g kg-1) components of the diet may have been attributed to
low pea ME. Another study found pea AMEn values were 4.6% higher
in test diets containing maize versus wheat, but attributed this
effect to the higher dietary lipid content of the maize diet (Carré
et al. 1987 {118}). It is possible that viscous polysaccharides
in the small-seeded cereals exacerbated the alleged inhibitory
effect of pea cotyledon structure on digestibility.
A few recent studies have documented the performance
of broilers consuming pea-based diets (Table 5). While results
are somewhat inconsistant, it is obvious that broilers respond
well to moderate levels of peas in both starter and grower rations.
Brenes et al.(1993, {37}) indicated that the addition
of peas did not affect the performance of young broilers consuming
corn-SBM diets. Other workers (Igbasan and Guenter 1996{10, 11})
observed reductions in gain and feed conversion (FC) with pea
levels 400g kg-1 or greater, but only FC was affected at 230g
kg-1 peas (Guenter et al. 1992 in Castell et al. 1996{9}).
A pea/ whole canola blend caused slight reductions in gain and
FC, but whether this effect was due to either or both feed ingredients
wasn't determined (Fasina and Campbell 1997{305}).
| Table 5. Canadian studies on the effects of peas in broiler diets. | ||
| Reference | Treatment | Effect vs. control |
| Castell et al.1996 {9} | 0, 230, 460, 680 g kg-1 peas in diets for chicks 1-21d of age. | 230 g kg-1 reduced FC (2.29 vs. 2.22; P< 0.01); 460 and 680 g kg-1 reduced all performance criteria (P<0.01) |
| Igbasan & Guenter, 1996 {10} | 0 vs. 400 g kg-1 yellow-, green- or brown-seeded peas in wheat-soy diets for broiler chicks 3-17 d of age. | Brown peas reduced weight gain (P<0.05) and all of the pea diets reduced FC (P<0.05). |
| Brenes et al.{37} | 0 vs. 500 g kg-1 Trapper or Maple peas in the corn-soy diets of broiler chicks 10-17 days old. | Weight gain, feed consumption and FC did not differ between diets (P>0.05). |
| Igbasan & Guenter 1996 {11} | 0 or 450 g kg-1 yellow (YPC) or green (GPC) pea chips in corn-soy diets of broiler chicks 5-19 days old. | Relative to the control, YPC and GPC diets had reduced weight gains (441, 361, 366 g, resp.) and FC (1.47, 1.58, 1.69 g, resp) (P<0.05). |
| Fasina & Campbell 1997 {8} | Pea/whole canola blend (1:1) added at 0, 100, 200 and 300 g kg-1 to wheat-soy starter (0-20 d) and grower (21-40 d of age) diets of broiler chicks. | Inclusion of the pea/whole canola blend reduced gain (2.03, 1.95, 1.94 and 1.92) and FC (1.87, 1.98, 1.97, 1.95, resp.) for all diets relative to the control (P<0.05). |
High dietary levels of peas did not support broiler performance equivalent to controls (Table 5) but this may not accurately reflect the nutrient value of peas. Young birds digested only 79% of pea amino acids on average, and values for lysine and methionine were only 80 and 60%, respectively (Table 2). Therefore, diet formulation on the basis of available amino acids may have enhanced the performance of birds consuming the higher inclusion levels of peas. A European study formulated diets on an available amino acid basis (1.25, 0.82, 0.7 and 0.2% available lysine, methionine, threonine and tryptophan). Broilers consuming the pea-based diet (300 g kg-1) had higher weight gains (43.4 vs. 41.7 g day -1) but poorer FC (1.60 vs. 1.58 g gain g-1 feed) than the casein-based control (Huisman et al. 1990{77}).
European studies supported the use of peas at 300g
kg-1 diet in broiler diets (Wurzner et al. 1988{107}).
Brenes et al. 1989 {87}) even indicated that levels of
600 and 800g kg-1 peas improved performance over corn-soy isolate
diets; however, the latter trial added oil only to the pea diets,
and this may have adversely affected consumption of the unpelleted
(inferred) control
The 'Miranda' variety of pea replaced SBM as the sole protein source in starter, developer and breeder rations fed to ISA Vedette dwarf broiler breeder hens. Performance was measured to 45 weeks of age and indicated weight gain, hen-day egg production, egg weight, fertility and hatchability of pea-based diets was equivalent to the corn-SBM control (Kill and Savage 1992{45}).
The semen quality and reproductive performance of
broiler breeder cockerels fed corn-SBM or corn-yellow pea diets
were similar for both caged and floor pen environments. High
(16% CP, 2850 kcal kg-1) and low (7% CP, 2400 kcal kg-1) density
pea diets supported fertility and hatchability equivalent to diets
containing SBM (Rakphongphairoj and Savage 1988{104}; Bootwalla
et al. 1988{110}).
The single reference available indicated that peas
were an excellent protein source for all stages of turkey rations.
Nicholas Large White turkeys were fed 250 (0-4 weeks), 300 (4-8weeks),
350 (8-12 weeks), 500 (12-16 weeks) and 550 g kg-1 (16-20 weeks
- toms only) peas in methionine-supplemented diets with (CSP+F)
and without (CSP-F) added fat. In two separate trials, CSP+F
supported growth and FC equal or superior to the corn-SBM control.
The CSP-F rations contained 50 (starter) to approximately 140
kcal kg-1 (finisher) less energy, but only FC was inferior to
CSP+F and corn-SBM rations (Savage et al. 1986{125}).
Geese are noted for their ability to utilize dietary
fibre. An experiment in which White Italian geese (3-8 weeks
of age) were fed rations containing 200 g kg-1 peas indicated
digestibility of neutral detergent fibre, acid detergent fibre,
cellulose and hemicellulose was 41.7, 17.6, 20.9 and 53.8%, respectively
(Jamroz et al. 1992{187}). The growth performance (63.4
g day-1) of geese consuming pea diets was among the highest measured
in the study (Wiliczkiewicz et al. 1992{47}).