Digestibility of energy, dry matter, protein, and fat and concentration of metabolizable energy in sunflower meal and sunflower expellers fed to growing pigs

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Sunflower meal (SFM) is a protein source that can be included in diets for pigs and other livestock species. In addition to providing amino acids, SFM also provide energy and other nutrients to diets, but because of the high concentration of fiber, SFM does not contain as much energy as other oilseed meals. The nutritive value of SFM depend on growing area, degree of de-hulling, and oil extraction process. Sunflower meal is obtained through a prepress-solvent extraction method, which yields a meal product with less than 3% fat. However, a double press procedure without solvent extraction may also be used to remove oil from the seeds, which results in generation of a co-product called sunflower expellers (SFE). Because the double-press procedure is less efficient in removing oil from the seeds, SFE contains between 6 and 10% oil. The concentration of fiber and protein also varies among different sources of SFM and SFE and is largely determined by the degree of de-hulling that takes place prior to oil extraction. Because the hulls are very high in fiber, there is a linear relationship between fiber concentration and the concentration of hulls in SFM and SFE, and there is a negative relationship between fiber and protein concentrations. However, data on the digestibility of nutrients and energy and concentrations of digestible energy (DE) and metabolizable energy (ME) in different sources of sunflower co-products are limited. Therefore, the objective of this research was to test the null hypothesis that there are no differences in the apparent total tract digestibility (ATTD) of dry matter, crude protein, fat, and gross energy and concentrations of DE and ME in SFM fed to growing pigs. The second objective was to test the null hypothesis that there are no difference in the ATTD of nutrients and energy concentrations between SFM and SFE fed to growing pigs.

 

Experimental design

Six sources of SFM and one source of SFE were procured from commercial suppliers. The SFM were obtained from the U.S. (2 sources), Ukraine (2 sources), Hungary, and Italy. A source of SFE from the U.S. was also used. A corn-based control diet and 7 diets containing corn and each source of sunflower co-products were formulated.

Sixty-four growing pigs with an average initial body weight of 31.5 kg were used. Pigs were housed individually in metabolism crates and urine and feces were collected for 4 days following 7 days of adaptation. There were 8 replicates per diet.

At the end of the animal work, diet and fecal samples were analyzed for gross energy, dry matter, crude protein and fat and urine was analyzed for gross energy. The ATTD of gross energy, crude protein and fat was calculated and concentrations of DE and ME were calculated as well. Data were analyzed using a model that compared data among the 6 sources of SFM. A contrast analysis was used to compare data for SFE and data for SFM. Results were considered significant at P ≤ 0.05 and considered a trend at P ≤ 0.10. The pig was the experimental unit for all analyses.

 

Results

Results indicated that the ATTD of gross energy and crude protein in SFE was less (P < 0.05) than in SFM, but the ATTD of fat in SFE was greater (P < 0.05) than in SFM (Table 1). No differences in DE and ME between SFM and SFE were observed. The ATTD of GE in SFM from Ukraine and Hungary was greater (P < 0.05) than in one of the sources from the U.S. and SFM from Italy. The ATTD of fat did not differ among SFM sources with the exception that the ATTD of fat in one of the U.S. sources was greater (P < 0.05) than in the other sources. Concentrations of DE and ME in one source from Ukraine and in SFM from Hungary was greater (P < 0.05) than in one of the U.S. sources and the SFM from Italy. No differences in DE and ME were observed among the 2 sources of SFM from the U.S. and one of the Ukraine sources.

Based on the results from the study it is concluded that the ATTD of gross energy and nutrients differed between SFM and SFE, but DE and ME did not differ between the 2 co-products. Among SFM sources, relatively small variations in the ATTD of GE, AEE, and CP were observed, but concentrations of DE and ME varied.

Table 1. ATTD of gross energy (GE), crude protein (CP), and fat and concentrations of DE and ME in 6 sources of sunflower meal (SFM) and 1 source of sunflower expellers (SFE) 1

a-cWithin a column, means without a common superscript differ (P < 0.05).

1 N = 8.