Efficiency of soya bean meal replacement by rapeseed meal and/or canola seeds in commercial layer diets

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  • Researchers have been invested in finding solutions for poultry feeding which support high layer performance at lower feeding costs.
  • Soya bean meal is the main source of vegetal protein used in poultry feeding because of its high protein level (44% non-dehulled and 46 to 50% dehulled), balanced composition of essential amino acids and because it has the highest lysine digestibility (91%) of all the available protein sources.
  • Rapeseed meal and/or canola seeds are potential alternative vegetal sources for poultry feeding, allowing cutting the feeding cost, provided the compound feed was formulated adequately.
  • Many studies conducted during the previous decades have shown that the addition of enzymatic preparations has improved the efficiency of rapeseed meal nutrient utilisation. However, rapeseed meal has a higher vitamin content (choline, biotin and folic acid) than soya bean meal.
  • The trials for rapeseed meal (experiment 1) and canola seeds (experiment 2) utilisation were conducted on 432 Roso SL 2000 commercial layers supplied by SC Avicola Bucuresti SA.

Researchers have been invested in finding solutions for poultry feeding which support high layer performance at lower feeding costs.

Poultry feeding uses two main types of ingredients: cereal grains and vegetal industrial by-products. Maize is the most important feed ingredient due to its high nutrient levels, which provide high energy input. Maize protein has a low biological value, however, because two of the amino acids essential to non-ruminant feeding, lysine and tryptophan, are at very low levels. Hence, the need arose to supplement compound feed formulations with ingredients of high biological value.

Soya bean meal is the main source of vegetal protein used in poultry feeding because of its high protein level (44% non-dehulled and 46 to 50% dehulled), balanced composition of essential amino acids and because it has the highest lysine digestibility (91%) of all the available protein sources.

The compound feed industry uses partially defatted and full-fat soya bean meal. Although regarded as a strategic feed ingredient in many countries in Europe and Asia, soya bean meal is imported, hence the need to find alternative vegetal protein sources.

Rapeseed meal and/or canola seeds are potential alternative vegetal sources for poultry feeding, allowing cutting the feeding cost, provided the compound feed was formulated adequately.

Read more about the planning for an efficient layer system.

The rapeseed meal made from whole seeds contains approximately 40% crude protein (on a dry matter or DM basis). Rapeseed meal protein is less digestible than that of soya bean meal (72 versus 88%), but the amino acids balance is similar or even better than in soya bean meal (for the sulphur amino acids) (Summers et al., cited by Koreleski, 1993). Considering the high level of insoluble polyosides and tannins from the teguments, the metabolisable energy is quite low and is one of the problems of this meal, in addition to the presence of glucosinolates.

Many studies conducted during the previous decades (Cowan et al., 1994; Khattak et al., 1996; Miles, 2002) have shown that the addition of enzymatic preparations has improved the efficiency of rapeseed meal nutrient utilisation. However, rapeseed meal has a higher vitamin content (choline, biotin and folic acid) than soya bean meal (Bell, 1984 cited by Koreleski, 1993).

Experiments conducted on broilers in the National Research Development Institute for Animal Biology and Nutrition (IBNA) have shown that rapeseed can be used in compound feed formulations for broilers, replacing up to 25% of soya bean meal without affecting broiler performance. Compound feed supplemented with the enzyme complex Kemzyme VP Dry (beta-glucanase, endo-beta-glucanase, alpha-amylase, bacillolysine and endo beta-xylanase) did not significantly influence broiler performance (Vasile et al., 2005).

Canola is a rapeseed variety with superior nutrition, containing 20 to 22% crude protein and 40 to 42% fat, low levels of glucosinolates and erucic acid (Swick and Tan, 1997). Compared to soya bean meal, canola has a higher level of calcium and phosphorus, but around 65% of the phosphorus is phytates and thus unavailable. The sulphur content also is higher than in the soya bean meal (1,1 versus 0,4%), which may cause leg defects (Larbier and Leclercq, 1994; Charlton, 1997).

Material and methods

The trials for rapeseed meal (experiment 1) and canola seeds (experiment 2) utilisation were conducted on 432 Roso SL 2000 commercial layers supplied by SC Avicola Bucuresti SA. The layers, between the ages of 40 to 47 and 51 to 58 weeks, were assigned to three groups for each experiment as follows: a control (C) group and two experimental (E) variants with 24 replicates each (one replicate in a cage with three layers).

Each experiment used three compound feed formulations: a maize and soya bean meal-based control diet, and two experimental diets in which 52,38 and 72,86% of the soya bean meal was replaced by rapeseed meal. This replaced 34,32 and 45,74% of the dietary crude protein, respectively, in experiment 1; 18,31 and 30,32% of the soya bean meal was replaced by canola seeds, which replaced 17,40 and 22,45% of the dietary crude protein, respectively, in experiment 2.

All diets were isocaloric and isoprotein, and had similar levels of sulphur amino acids, calcium and available phosphorus, and agreed with the feeding requirements recommended for the intensive rearing of commercial layers.

The rapeseed meal had the following chemical composition: 90% DM; 34,45% crude protein; 2,60% ether extractives; 11% crude fibre; 7% ash; and 1 790 kcal/kg metabolisable energy. The canola seeds had the following chemical composition: 93,18% DM; 17,42% crude protein; 40,58% ether extractives; 9,17% crude fibre; 9,02% ash; and 3 900 kcal/kg metabolisable energy. All analyses were performed within IBNA specifications.

Read more about egg production in a layer system.

The layers were kept in a two-tier battery, with free access to feed and water. Throughout the experimental period, light was provided by light bulbs using a 16-hour regimen (between 04:30 and 20:30).

Production parameters that were monitored included laying percentage (monitored daily); average egg weight (determined by weighing all eggs for four consecutive days, at the end of each four week period); proportion of egg components including yolk, white and eggshell (determined by weighing all eggs produced daily, for one week at the end of the experiment); feed intake (recorded daily for each replicate separately, calculated per layer per day); and live layer weight (determined by individual weighing of the layers at the beginning and end of the experiment).

At the end of the experiment, we calculated:

  • Egg mass production (grams of egg/layer/day).
  • Feed conversion into eggs (grams of feed/grams of egg).
  • Feeding cost (economic efficiency, %).

The eggs with abnormal morphology or shell defaults (broken or cracked shells, shell-less eggs, deformed eggs) and mortalities were monitored daily. The experimental data were processed statistically by variance analysis using the Fisher test. The Student’s t-test was used to evaluate the significance of differences between experimental groups. Differences were considered statistically significant
for P < 0,05.

Results and discussion

Experiment 1

The statistical calculation of the data on the laying percentage, egg weight, production of egg mass, feed conversion into eggs and egg component indices (Table 1) have shown no significant differences between the groups up to 52,38% soya bean meal replacement by rapeseed meal. The resulting average values are similar to those of the control group (P > 0,05). Exceeding this level of replacement significantly depressed layer performance (P < 0,05).

Experiment 2

Table 2 contains the experimental data which shows no significant differences from the group where 30,32% of the soya bean meal was replaced by canola seeds, the average values being similar to those of the control group (P > 0,05). These results agree with the data of Elwinger and Saeterby, 1986; Leeson et al., 1987; Rachwal et al., 1989; Smulikowska and Buraczewski, 1991; Zglobica and Wezyk, 1991 cited by Koreleski 1993, reporting that a 25% replacement of soya bean meal by canola seeds in protein and energy-balanced diets did not affect layer performance, nutrient deposition and bone mineralisation.

The experimental results show that rapeseed meal and/or canola seeds can be used as a potential alternative to sources of vegetal protein for commercial layer diets. Rapeseed meal can be used up to a level of 15% in the compound feed. The formulation for commercial layers replaces up to 50% of soya bean meal. Canola seeds can be used up to a level of 20% in the compound feed formulation replacing 25 to 30% of the dietary soya bean meal, without significantly affecting laying performance and egg quality. – Georgeta Ciurescu, National Research Development Institute for Animal Biology and Nutrition, Balotesti, Romania

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