Data sheets: Sunflower meal

Introduction

The sunflower (Helianthus annuus L.) is an annual herbaceous plant of the Asteraceae family that has a compound inflorescence about 15-30 cm in diameter and produces seeds known as sunflower seeds. The sunflower seeds are actually a fruit with a hull about 20 mm long and 15 mm wide that contains an oleaginous seed inside. There are two types of sunflower: those with high oleaginous aptitude (40% oil) and low oleaginous aptitude (<30% oil) but, because they are of interest to the oil extraction industry, >90% of the seed production is of the high oleaginous type since they produce oil of high nutritional value. As a co-product of oil extraction, sunflower meals or cakes are obtained, which are a good source of protein for animal feed.

The quality of sunflower meal is highly variable and depends mainly on the type and the extraction process used. It must be noted that the hull represents >25% of the fruit, which hinders both the extraction yield and the final quality of the meal, so in many cases a dehulling is done prior to extraction. The whole seeds are crushed and then about 10-12% of the fibrous fraction of the hull is separated by physical or pneumatic methods. The partially dehulled seed fraction is pressurized by expeller pressing resulting in an extraction cake with up to 15% oil content. But in many cases the process continues with solvent extraction to improve the oil extraction yield, resulting in a final meal with <2% fat content and higher protein concentration. Solvent extraction does not disqualify the use of sunflower meal in swine feed except for EU organic production, where its use is prohibited.

Like other vegetable protein sources, its value for use in swine feed depends on its quality and protein content, which determine the different categories on the market. Indirectly, the fiber and fat content also determine the quality of the product and affect the appearance and color of the ingredient, so that one can see at a glance a gradation from gray to black depending on the amount of hull contained in the meal. It is an ingredient with lower protein content than soybean meal and it is more fibrous, but it has a good amino acid profile for pigs (although poor in lysine, the content of sulfur, tryptophan, and arginine is interesting) and, despite its fiber content, it is palatable. Although it is mainly recommended for finishing pigs and sows in gestation and lactation, very good quality meals could also be considered for nursery piglets.

Comparative study of nutritional values

The systems used in the comparison are: FEDNA (Spain), CVB (the Netherlands), INRA (France), NRC (United States), and Brasil (Brazil).

¹The FEDNA, CVB, INRA, and NRC evaluation systems present the range of values (minimum and maximum) resulting from the integration of the different classifications that these evaluation systems consider basically according to the protein content, which differs mainly by the type of processing and fat extraction system and the residual amount of fat and fiber in the meal, with CVB and FEDNA having the largest number of product categories associated with these variables.

²The evaluation system BRASIL presents only the average figure since this system considers only one quality as the average value for this protein concentrate.

(*) The range in EE for meals physically extracted or expeller meals varies between 9.1% and 8.5% for protein concentrations of 31% and 34%, respectively (intermediate values to the range presented in the table). As shown in the text, it should be noted that the higher energy values are also due to the residual fat content of the meals (FEDNA).

For sunflower meals, as for the rest of the vegetable protein concentrates obtained from extraction, with the exception of soybean products, the range of qualities considered by most evaluation systems is very wide and depends on the extraction system and process and capacity to extract the oil. Moreover, in the case of sunflower meal, the variability is increased depending on whether or not dehulling is considered and the efficiency of removing the hulls before extraction.

With the exception of BRAZIL, which only considers a single average quality, the rest of the systems present several categories. CVB and FEDNA differentiate according to the extraction method: physical, or physical + solvents, with several qualities within each category. On the other hand, INRA and NRC classify according to fiber content or, in other words, according to whether or not it is considered dehulled, although NRC clearly stands out for its low residual fat content as it considers solvent extraction as the only processing method.

In this review, the maximum and minimum values have been chosen to coincide with the extremes used commercially and are shown in the table of the evaluation systems.

Contrary to other vegetable protein concentrates derived from extraction processes, the protein content is directly determined by the level of fiber (and basically dependent on the degree of efficiency of the dehulling stage, which is often not able to remove more than 8-10% of the hull), so the final fiber content between products is very variable (CV~21%). This remaining hull determines the quality of sunflower meal, acting as a dilution factor and determining the final protein content in the marketed meals and cakes (R² = -0.90 physical and - 0.82 physical + solvents). However, only for physical extraction or expeller (but not physical + solvents) the residual fat content acts as a dilution factor and is what determines (after fiber content) the final protein concentration in marketed meals from this extraction system (R² = -0.88).

With the exception of INRA and FEDNA, which give a lower than average protein digestibility coefficient (-5% to -10%) for those meals with higher fiber content, the rest of the systems FEDNA, CVB, INRA, and NRC present very similar digestibility coefficients (mean=80%; (CV~1.2%), the large differences within each system, mainly for FEDNA and CVB, are related to the physical extraction system.

NRC gives a lower value for net energy (NE), (between -450 with respect to the mean and -1015 kcal/kg than the most extreme evaluations), which is basically explained by the presence of hull. The NE value for the rest of the systems is very similar and clearly dependent on the extraction system and its efficiency, indicating a clear positive relationship between the fat content and the NE value (R² >0.65). It should be noted that the difference between those meals obtained from very efficient extraction systems with residual fat levels <2% clearly presents a differential of almost -575kcal EN/kg with respect to the rest (-31%). In general terms, the estimation of the NE value is basically determined by the content of hull (fiber depending on the degree of dehulling) together with the residual fat content in the meal depending on the extraction system and its efficiency.

The starch content, considered null for INRA or almost negligible for FEDNA and NRC (~ 2%), is variable and increases up to >4.5% for CVB and BRAZIL, resulting in a large overall variability (CV>40%), although with a negligible impact on the energy content, as well as the sugar content.

Regarding total amino acids, the deficiency in lysine stands out, but there is good content of total sulfur amino acids and arginine with respect to protein, but regardless of the total value, it can be observed that there are no major differences between the different systems (CV<2%) regardless of the protein content of the meals (considering a CP range between ~20 and ~40%).The amino acid digestibility coefficient is more variable between extraction systems than between evaluation systems for the same extraction system, although the mean is similar for all AA, the variability is greater for physical extraction + solvents than for physical extrusion or expeller (basically FEDNA and CVB) with CVs of 2.7% and 1.3%, respectively.

Recent findings

1. Net Energy of high-protein sunflower meal fed to growing pigs and effect of dietary phosphorus on measured values of NE.

The present study was conducted to determine the energy values of high-protein sunflower meal (HP-SFM). The NE of HP-SFM determined was 2062 kcal/kg and 2151 kcal/kg respectively, depending on P-deficient or P-adequate basal. Although no differences were observed in energy values, the amount of P in basal diet might affect energy balance by modifying N utilization, thus, a diet containing an adequate amount of P is a more suitable basal diet when the difference method is used for calculation of NE in a feed ingredient like sunflower meal with high CP content.

2. Net energy content of rice bran, corn germ meal, corn gluten feed, peanut meal, and sunflower meal in growing pigs.

The present experiment was conducted to determine the net energy (NE) content of different feed ingredients for growing pigs using indirect calorimetry. The feed ingredients under study were: full-fat rice bran (FFRB), corn germ meal (CGM), corn gluten feed (CGF), solvent-extracted peanut meal (PNM), and dehulled sunflower meal (SFM). The observed NE values were highest for FFRB and PNM and the lowest in the corn co-products and SFM.

3. Effects of dietary fibre level and body weight of pigs on nutrient digestibility and available energy in high-fibre diet based on wheat bran or sunflower meal.

The objectives of this study were to investigate the effect of body weight (BW) on available energy in fibre-rich diets containing two NDF levels; and to evaluate the effect of fibre type and NDF level on AA digestibility by using combination high or low protein diets in combination with wheat bran or sunflower meal. The addition of sunflower meal increased the standardized ileal digestibility (SID) of Met. In conclusion, diets rich in fibre had different nutritional values at different pig weight stages. The AA digestibility depends mainly on chemical composition of diets.

4. Fermentation of rapeseed meal, sunflower meal and faba beans in combination with wheat bran increases solubility of protein and phosphorus.

The present work studied the solubilization of protein, N and P when increasing ratios of wheat bran were fermented with rapeseed meal (RSM), sunflower meal (SFM), faba beans (FB) or a combination of these (RSM/SFM/FB). The main findings were that fermentation of RSM, SFM, FB and RSM/SFM/FB without or with wheat bran uncovers a potential for increased protein and P digestibility and thereby reduced N and P excretion from pigs in the feed ingredients evaluated.

5. Amino acid digestibility of plant protein feed ingredients for growing pigs.

The present work was conducted to determine the N and AA digestibility of different protein sources (potato protein concentrate, soy protein concentrate, soy protein isolate, linseed meal, sunflower meal, cottonseed meal, canola meal, and camelina meal) fed to growing pigs. The apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of N for potato concentrate, soy concentrate, and soy isolate were similar and greater than that for linseed meal. The AID and SID of N and all AA were greatest for sunflower meal, and canola meal had similar AID and SID of N, Met, Thr, Leu, and Val. The AID and SID of all essential AA, except for Met and Trp, were lowest for sunflower meal. Cottonseed meal had lower AID and SID for Lys, Ile, Leu, Met, Thr, and Val compared with the other protein sources. Therefore it was concluded that the digestibility of N and AA varies greatly among oilseed meals.

References

FEDNA: http://www.fundacionfedna.org/
FND. CVB Feed Table 2016. http://www.cvbdiervoeding.nl
INRA. Sauvant D, Perez, J, y Tran G, 2004, Tables de composition et de valeur nutritive des matières premières destinées aux animaux d'élevage.
NRC 1982. United States-Canadian Tables of Feed Composition: Nutritional Data for United States and Canadian Feeds, Third Revision.
Rostagno, H,S, 2017, Tablas Brasileñas para aves y cerdos, Composición de Alimentos y Requerimientos Nutricionales, 4° Ed.