Effect of substituting soybean for sieved sunflower meal in broiler diet: influence on growth performance

Sunflower (Helianthus annus) is high oil-yielding seed crop, that well adapts to a wide range of climatic and soil conditions. Sunflower meal (SFM), a by-product of sunflower oil extraction, is available in considerable quantities for use in animal feeds (Mushtaq et al. 2009). The low metabolizable energy of sunflower meal and its deficient utilization by non-ruminant animals are directly related to its high fibre content, resulting in worse live performance (Furlan et al., 2001). However, previous studies reported that SFM could be included up to 175 g/kg of diet without adversely affecting the broiler performance provided diet was supplemented with lysine. Moreover, no effects on weight gain, feed consumption and efficiency were reported when SFM was included up to 200 g/kg of diet (Selvaraj & Purushothaman, 2004). In countries where soybean meal (SBM) is not cultivated, the SFM may be an economical feed ingredient for poultry diets. Efficient and economically viable technological solutions, as the sieving procedure, for the production of sunflower meal with high content of crude proteins (>38%), and low levels of fibre (<14%) have been identified throughout the world (Levic et al. 1992; Sdredanivic et al. 2006). Therefore, the objective of this study was to determine the possible beneficial effects of dietary substitution of soybean meal by sieved sunflower meal on broiler growth performance.

A growth trial with 200 day-old Hubbard strain broiler chicks was conducted from 14 to 49 d of age and involving two dietary treatments. Broilers, from a commercial hatchery, were raised in a conventional environment and fed ad libitum a common starter diet until 14 d of age. On day 14, birds were individually weighed and randomly divided among 20 pens in a commercial poultry facility located in Province of Bari, Italy. Each diet (treatment) was replicated ten times, with each replicate comprising one pen of ten birds. From 14 d to slaughtering age (49 d) birds were fed two wheat middlings (WM) based diets containing soybean meal (WM-SBM) sunflower meal (WM-SFM) as main protein source, respectively. The WM and SFM were previously sieved to separate the fibrous component to obtain a raw ingredients with a low fibre content. Feed (pelleted form) and water were provided ad libitum. Randomized samples from each diets were collected for proximate analysis by the procedure described by AOAC (2000). Body weight (BW) and feed intake (FI) were measured every week. Body weight gain was calculated on weekly basis throughout the experimental period of 49 d of age. The consumed amounts of feed were recorded every week and daily feed intake was mined calculated at the end of the trial. Feed efficiency was calculated using the following ratio FI:BW. Ingredient and chemical composition of the diets are shown in Chart 1. A completely randomized design was used with two treatments and ten replicates (pens) per treatment. Data were statistically analyzed by the general linear model procedure of SAS (2001).

Chart 1. Ingredient and chemical analysis of diets

The effect of experimental diets on live body weight, weight gain, feed intake and feed efficiency are reported in Chart 2. The birds'''' mortality during the whole experiment was very low (~1%), and it was not related to the experimental treatments. Live body weight of broilers at the end of trial (49 days of age) was not significantly influenced by substitution of soybean with sunflower meal in diet (P = 0.023). The level of sunflower by-product (172 g/kg of diet) did not show negative effects on broiler weight gain among groups. Sieved sunflower meal at the our level of substitution increased the feed consumption of broilers during the experimental period (108.5 vs. 109.2). In fact, the experimental treatment containing SFM did not reduce feed intake in comparison to the control group diet containing SBM (P = 0.095). As consequence, the feed efficiency of broilers resulted not significantly affected (P = 0.062) by experimental treatments for the whole trial period (1.97 vs. 2.02). Our findings indicate furthermore that replacing corn with durum wheat-middlings reduces the use of soybean meal up 172 g/kg in diets for broiler chickens, reducing also the cost of feed production in countries where soybean meal production results adverse.

Chart 2. Growth performance of broiler chicks

Data obtained in this experiment is supportive of the utilization of sieved sunflower meal in poultry rations. The use of this alternative sunflower by-product in diet, without any negative effects in broiler''''s growth performance, offers a viable option to help counteract the current constraints of soybean meal.

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