Laying Hens fed a Corn-Sunflower Meal Diet Supplemented

The benefits of adding enzymes to better utilize b-glucans by poultry was first observed in the early 1960s (Leslie, 1995). In 1971 Nelson et al. demonstrated the beneficial effect on phosphorus availability of adding phytase to broiler diets. However, it took nearly 20 years before phytase production became economically feasible (van der Klis et al., 1997). Only in recent years has the use of exogenous enzymes to increase phosphorus, protein or energy digestibility of poultry feeds gotten widespread attention by researchers (Pack and Bedford, 1997).

Addition of enzymes to diets containing soybean meal as a protein source has been shown to produce not only direct benefits (increase in body weight gain, improved feed conversion, reduction in feed costs), but also indirect benefits in broiler production such as reduced variability in bird body weight, improved litter quality and reduction in nitrogen released into the environment (Dale, 1997) . However, a comparatively small amount of information in this area is available regarding egg producing birds; and it has been suggested that less response to exogenous enzymes could be expected from layers due to their more mature digestive system (Considine, 1997).

The international limitations imposed on utilization of meat meals in diets fed to food animals together with the increasing demand for soybean meal may create a necessity to search for other protein sources to economically balance compound feeds. In this regard it is important to note that sunflower is one of the largest oil crops in the world. In addition, the isonutritive replacement of soybean meal by sunflower meal in poultry diets has been shown to have no negative effects on either broiler or layer performance (Schang and Azcona, 1994). However, it is well known that the lysine or energy content of sunflower meal may limit its level of inclusion in poultry feeds.

In view of these considerations it was the purpose of this work to evaluate the performance of laying hens fed diets containing sunflower meal and Allzyme Vegpro.

MATERIALS AND METHODS

Two hundred and seventy (270) ISA Brown laying hens were assigned to three experimental diets at 48 weeks of age. Hens in one group received the standard corn/soybean meal diet while those in the second and third groups received corn/sunflower meal diets. Allzyme Vegpro, an enzyme formulated to increase digestibility of protein meals, was added to the diet fed the third group at 1 kg per tonne.

The sunflower meal used in this experiment was commercially recognized as a ‘low fiber’ type having 14.7% of crude fiber. Regular sunflower meal would have an average fiber content of 18–21%. Analytical values of each ingredient were used in formulation of the experimental diets (Tables 1 and 2). True metabolizable energy and amino acid availability of feedingstuffs were measured using the procedure of Sibbald (1979).

Diets were formulated to be iso-nutritive following the breeder recommendations for feed consumption of 115 g/hen/day. In formulating the diet to which Vegpro was added, the values for energy, protein and total and digestible amino acid observed for sunflower meal were increased by 7%.

Table 1. Nutrient composition of the corn, soybean and sunflower meals used in this experiement (as fed basis).

Performance of Laying Hens fed a Corn-Sunflower Meal Diet Supplemented with Enzymes - Image 1

Each treatment had five replicates of 18 hens with similar levels of production at the beginning of the trial. Layers were housed in 30 × 45 cm cages at a rate of three birds per cage.Water and feed (mash) were provided ad libitum.

The experiment consisted of three 28 day periods and lasted 84 days. Egg production by replicate was recorded daily. Once a week feed consumption was determined and feed conversion rate calculated. Eggs produced over 5 days and 18 hens per treatment were weighed each 28 days. At the end of the trial egg shell strength (mg/cm₂), Haugh Units and yolk pigmentation (Roche score) were measured on samples of 20 eggs per treatment.

Table 2. Composition of the experimental diets.

Performance of Laying Hens fed a Corn-Sunflower Meal Diet Supplemented with Enzymes - Image 2

Performance of Laying Hens fed a Corn-Sunflower Meal Diet Supplemented with Enzymes - Image 2

The percentage of dirty eggs was measured at the end of the first experimental period.

The data were analyzed by analysis of variance (Steel and Torrie, 1960). Main effects were tested for statistical significance (P<0.05) using the error mean square and significant differences among treatments were determined using Duncan’s multiple range test.

RESULTS AND DISCUSSION

In general, replacement of soybean meal with sunflower meal reduced all production parameters with differences significantly lower for egg-mass and egg production (Table 3). In terms of internal and external egg quality parameters (pigmentation score, Haugh units and shell strength), no significant differences were observed among treatments. Considine (1997) observed similar results when feeding hens several diets formulated to contain either 14, 16 or 19% protein. His data showed that egg production and feed intake were significantly higher for hens receiving soybean meal-based diets in comparison to those fed diets including distiller’s dry grains, sunflower meal or peas. Considering that an amino acid might be limiting layer performance, tryptophan was added to a second batch of the corn/sunflower meal diet (to reach 0.22%) in the present study. However, no improvement in egg production was observed in response.

Table 3. Effect of diet on layer production and egg quality parameters.

Performance of Laying Hens fed a Corn-Sunflower Meal Diet Supplemented with Enzymes - Image 3

Performance of Laying Hens fed a Corn-Sunflower Meal Diet Supplemented with Enzymes - Image 3

The lack of difference in performance between the two sunflower mealbased diets would confirm the hypothesis that Vegpro increases both protein and energy availability of sunflower meal. This observation is also in agreement with results previously reported by Considine (1997) who found an increase in egg production when Vegpro was added to diets containing a combination of wheat, sunflower meal and distiller’s dry grains. Brake (1992) also demonstrated that supplementation of corn/soybean meal diets with a-galactosidase increased egg production and further suggested that enzymes would not only increase available energy of legumes but would also help in alleviating digestive disorders associated with these carbohydrates.

The presence of non-starch polysaccharides (NSPs) can depress nutrient digestibility mainly due to an increase in digesta viscosity (Feord, 1997). The high content (28% of dry matter) and low digestibility (17%) of NSPs reported (Charlton, 1996) in sunflower may also be the cause of sticky droppings and dirty eggs. However, in this experiment use of sunflower meal did not increase the amount of dirty eggs. Although variability was high, these data also indicated that the addition of Vegpro to a sunflower meal-based diet reduced the amount of eggs with black stains.

Low fiber sunflower meal represents a suitable protein source for feeding broilers and turkeys (Schang and Azcona, 1994). However, some limitations in terms of energy availability and lysine could limit its level of inclusion in poultry diets. The results of this experiment demonstrate that the use of Vegpro would improve sunflower meal nutrient digestibility, providing the feed industry with an economical alternative ingredient for poultry diets.

REFERENCES

Brake, J. 1992. Production of broiler breeders increases when fed diets containing commercial enzyme preparations – possible method to improve performance in hot climates. In Proc. XIX World Poultry Congress, Amsterdam, The Netherlands. pp. 416–419.

Dale, N. 1997. Alternative feed ingredient strategies for poultry. Feed and Grain 36:1 22–25.

Charlton, P. 1996. Expanding enzyme applications: Higher amino acid and energy values for vegetable proteins. In: Biotechnology in the Feed Industry. Proceedings of the 12th Annual Symposium (T.P. Lyons and K.A. Jacques, eds). Nottingham University Press, Loughborough, Leics, UK. pp. 317–326.

Considine, M. 1997. The response of ISA Brown Layers to the addition of AllzymeVegpro in diets containing vegetable protein supplements. Proceedings of World’s Poultry Science Association, August 24–28, Faaborg, Denmark. pp. 478–479.

Feord, J. 1997. Boosting digestibility: The use of enzymes in cereal-based dry dog food. Petfood Industry 39: 22–30.

Leslie, A.J. 1995. Future potential for cereal enzymes. Proceedings of the International Launch of Allzyme Vegpro. Alltech, Inc. USA.

Pack, M. and M. Bedford. 1997. Feed enzymes for corn and soybean broiler diets. World Poultry 13:87–93.

Schang, M.J. and J.O. Azcona. 1994. Biochemical characterization of SUNECO in poultry. Oleaginosa Moreno Hermanos, Bahia Blanca, Argentina, p. 26.

Sibbald, I.R. 1979.Abioassay for available amino acids and true metabolizable energy in feedingstuffs. Poultry Science. 58:668–673.

Steel, R.D. and J.H. Torrie. 1960. Principles and Procedures of Statistics. 2nd edition. McGraw-Hill Book Co., New York, NY.

van der Klis, J.D., H.A.J. Versteegh, P.C.M. Simons and A.K. Kies. 1997. The efficacy of phytase in corn-soybean meal-based diets for laying hens. Poultry Science. 76:1531–1534.

Authors: M.J. SCHANG and J.O. AZCONA
INTA – Estación Experimental, Pergamino, Buenos Aires, Argentina.