Data sheets: Sugar beet pulp

Introduction

Sugar beet pulp is a co-product of the sugar industry. Pulp is the fibrous fraction (50% of the total) obtained after extracting the glucose syrup at high temperatures (60-70ºC). This fibrous fraction is basically composed of the cell walls of the beet skin and pulp and has a sugar content of 2-4%. In animal feed, this wet fraction can either be used directly, pressed (27% dry matter; 21% of the total), or dried and granulated (90% dry matter, 5% of the total), the latter being the most common presentation and form of storage. Generally, a small fraction of molasses (about 3%) obtained in the extraction process itself is reintroduced to facilitate the pelleting process. This slightly increases the energy value and palatability. Granulated pulp has a moisture content of 8.0-12%, ash content of 4.0-5.0%, crude protein of 7.0-8.9%, crude fat of 0.5-0.6%, crude fiber content of 15.0-20.0%, and neutral detergent fiber (NDF) of 40-50%. The NDF content of sugar beet pulp can vary depending on factors such as the degree of fiber extraction, drying methods, and the efficiency of the fiber separation processes during sugar production.

Granulated beet pulp is usually presented in pellets 6-10 mm in diameter, which forces pig feed mills to grind it, modifying the particle size and functionality of the fibrous fraction contained in the ingredient (this can affect the expected functionality depending on the age and digestive ability of the pig). The fibrous fraction consists mainly of cellulose, hemicellulose, and pectins, which are hydrolyzed and metabolized more slowly than starch and sugar. It is worth noting that sugar beet pectin contains a high level of ferulic acid. Ferulic acids, categorized as phenolic compounds, are considered bi-functional, a potentially nutritional element for both the organism and its microbiota. Oxidative enzymes can oxidize the ferulic acid groups to form a variety of dehydrodiferulates, dehydrotriferulates, and probably larger products with gelling properties that can modify gut rheology.

The pulp, depending on its particle size, is more rapidly hydrolyzed into pectin-derived oligosaccharides. These oligosaccharides are composed of partially acetylated rhamnogalacturonan and partially methylated/acetylated homogalacturonan which are completely fermented by fecal microbiota. Therefore, the final value of beet pulp in swine goes beyond its nutritional value, with the functionality of the fibrous fraction being the most interesting at both the rheological level as a substrate for the commensal microbiota, making it attractive in different phases of the swine production cycle.

Comparative study of nutritional values

The systems used in the comparison are FEDNA (Spain), CVB (the Netherlands), INRA (France), NRC (USA), and ROSTAGNO (Brazil).

¹ Among the evaluation systems studied, FEDNA and NRC consider only one category for dehydrated beet pulp. However, CVB and INRA consider more than one category based on the technological treatment of reintroducing molasses from the extraction process to improve the efficiency of the process and the quality of the final granules. Beet pulp is not included in BRAZIL's tables of evaluated ingredients because the country is neither a producer nor an importer of sugar beets.

Dehydrated beet pulp in pellet form is a common ingredient in most pig feed mills. It is a typical ingredient in gestation diets and the transition to lactation, but it is also common in young piglet diets, although the level of inclusion varies greatly between countries and feed types, closely linked to the fermentation and utilization of the degradation of the fibrous fraction, but also its rheological properties of the digesta and modulation of transit.

Beet pulp is primarily a fibrous ingredient and is considered in swine feed formulation due to its impact and functionality. The average crude fiber value is 16.2% ± 2.01; however, the variability is high (CV > 10%) due to the technological process and the degree to which molasses from the extraction process is reincorporated at the time of granulating, which CVB takes into account. If the range of molasses reincorporation is not considered, the mean crude fiber content is 17.5% ± 0.48 (CV = 2.73%). As a fibrous ingredient, the mean protein value of the different selected evaluation systems is low at 8.9% ± 0.85. For CVB, a linear response of increased protein content from 7.5% to 10.2% is observed, which is directly related to the reincorporation of molasses. However, INRA and CVB, in their version with lower sugar concentration, are the systems with the lowest protein content (CP < 9.0%). While CVB (intermediate sugar incorporation), NRC, and FEDNA, respectively present very similar values (9.3% ± 0.32; CV = 3.44%). The fat content values for most of the studied evaluation systems are very similar (FEDNA, NRC, CVB, and INRA), indicating that processing has no impact and fat is not reincorporated during processing.

The range of dry matter proposed is very stable across the different evaluation systems, presenting very little variation among them (89.5% ± 1.19; CV = 1.33%). The sugar content on the other hand (mainly lactose within this category) is much more variable (11.5% ± 6.28; CV = 55.5%), which can also condition the formulation process or the result if this variability is not taken into account. The basic sugar level contemplated by most of the evaluation systems (FEDNA, INRA, and CVB) is 6.5% ± 0.42; CV = 6.4%. NRC does not evaluate sugar content for beet pulp and yet both INRA and CVB clearly consider molasses re-incorporation levels, giving increases in sugar content of 2 (INRA) and 6, 12, and 15 (CVB) percentage points, respectively.

Apart from being a fibrous ingredient, the contribution to the energy value by degradation and fermentation of the fiber correspond to mean NE values of 1872 Kcal/kg ±345 and 1943 Kcal/kg ±249 for growing and adult animals respectively. The large variability (CV >10%) in terms of kcal/kg that can affect the final NE content of the formulation and the intake regulation (>150 kcal) is mainly explained by the differential content in sugars derived from the reincorporation of molasses to facilitate the pelleting process (R2 = 0.78). However, CVB attributes high NE values even to ingredients with low sugar content, assuming a greater contribution from fiber degradation rather than sugar when sugar content is <10%.

The variation and observed response to protein content associated with processing and re-incorporation of sugars (molasses) is not consistent with the amino acid (AA) content, specifically with lysine as a reference. It shows an inversely proportional relationship between AA content and sugar content (R2 = 0.99, excluding INRA with high sugar content, which also overestimates AA with values well above the average), with the CV for all AA being <1%. However, this behavior is not the same for all amino acids. The sulfur-containing AA do not present a correlation (R2 < 0.10) and the branched ones (Ile and Val) present negative correlations lower than lysine (R2 < 0.65), while threonine and tryptophan present high correlations (R2 < 0.90). The presented digestibility coefficient for protein and lysine ranges between 50-55% and is very similar across the evaluation systems studied. It is important to highlight that on average the Ca value is similar to many of the cereals used in animal feed (0.81% ±0.09) if we exclude the values provided by the INRA system, which presents a Ca content 70% higher than the average of the rest of the evaluation systems (FEDNA, NRC, and CVB), however, the variability is high (CV>10%), making it important to consider this variability in the mineral content.

Recent findings

1. Influence of fiber type and carbohydrase supplementation on nutrient digestibility, energy and nitrogen balance, and physiology of sows at mid and late gestation

This present study evaluated the effects and mechanisms of supplementing multicarbohydrases to gestating sow diets containing either corn-dried distiller grains or sugar beet pulp fibrous co-products. Significant energy, dry matter, and fiber digestibility enhancements with carbohydrase supplementation were observed, irrespective of adaptation time. However, the interaction between enzyme supplementation and fiber type led to distinct immune marker responses. Sows in late gestation have greater nutrient and energy digestibility and altered nitrogen balance relative to day 50 of gestation. These findings highlight the potential benefits of incorporating carbohydrases into gestating sow diets to improve nutrient utilization and metabolic efficiency. Moreover, the study underscores the complex interplay between enzyme supplementation, adaptation time, dietary fiber characteristics, and immune responses, offering valuable insights into the underlying mechanisms governing sow physiology during gestation and the influence of enzyme supplementation.

2. Influence of fiber-rich coproducts on nutrient and energy digestibility and utilization in sows

Coproducts from the food and agricultural industries have the potential to partly substitute grain in diets for empty nonlactating sows. Many coproducts are high in fiber and with diverse fiber composition. Some are easily fermented, while others are more resistant to fermentation giving rise to a large variation in the total tract digestibility and utilization of nutrients and energy. How well fiber-rich coproducts are digested and utilized is poorly understood in sows, but it is important to ensure an optimal energy and protein composition of the feed depending on the physiological stage of the sow. This study aimed to increase knowledge on the digestibility and utilization of six fiber-rich coproducts potentially to be included in the sow’s feed. We found pea hulls and sugar beet pulp suitable as grain replacers due to their high total tract digestibility and no negative effects on energy and protein utilization. Potato pulp and brewers' spent grain were also well suited. However, caution should be taken in balancing diets because of increased fecal and urine nitrogen output, which will increase environmental impact. Seed and pectin residues primarily serve as gut fill.

3. Influence of sugar beet pulp supplementation on pigs' health and production quality

The present work studied the effect of sugar beet pulp (SBP) supplementation in the diet on pork quality by examining the effect of an SBP-supplemented (3%) diet (TG-I group) on 300 Large White/Norwegian Landrace pigs in terms of growth performance, blood parameters, microbial profiling of feces, carcass parameters, and meat quality, including the profiles of biogenic amines, fatty acids, and volatile compounds. After 163 days of the experiment, TG-I pigs had a significantly lower average daily gain and feed conversion ratio than pigs in the control group, as well as a significantly higher percentage of carcasses in the S and KN classes and a lower percentage in the E and U classes. Feces of TG-I contained significantly more bacteria that are considered probiotic. Significant differences were found in most of the blood parameters, fatty acids, volatile compounds profile, and emotional responses between the two groups. Higher drip loss, protein content, and redness as well as lower cooking loss, intramuscular fat content, and lightness were observed in the meat of TG-I. Most of the sensory properties, as well as overall acceptability, were rated higher for the meat of TG-I. It was concluded that a diet containing 3% of SBP could be beneficial for the improvement of pigs' gut health and pork quality.

4. Increased feed supply and dietary fiber from sugar beet pulp improved energy retention in gestating sows

Feeding sows sugar beet pulp (SBP) has many known benefits, for example, increased satiety, and it is a highly fermentable fiber source for sows. This study investigates how efficient sows utilize energy for fat and protein retention in response to increased SBP inclusion in the diet. After a demanding lactation, sows need to restore body fat and concomitantly avoid excessive protein retention, which increases energy demand for maintenance and risk of locomotory problems. The hypothesis in this study was that energy from fermented fibers is more efficient for fat retention than dietary starch. In the study, sows had numerically greater fat retention when fed high concentrations of fiber from SBP, but, concomitantly, sows unintendedly also increased their protein retention, which in turn increased their live weight substantially. Sows were fed one of three feeding strategies depending on the body condition score (lean, medium, or fat) in early gestation, and backfat was efficiently restored in most sows within a month. To conclude, gestating sows have a high capability to utilize energy from fermented fiber, but sows prefer to retain protein rather than fat, which needs to be addressed in the nutrition of modern genotype sows.

References

FAOSTAT: http://www.fao.org/faostat/es/#data/QC

http://www.mapama.gob.es/es/agricultura/temas/producciones-agricolas/cultivos-herbaceos/cereales/

FEDNA: http://www.fundacionfedna.org/

Rostagno, H,S, 2017, TABLAS BRASILEÑAS PARA AVES Y CERDOS, Composición de Alimentos y Requerimientos Nutricionales, 4° Ed,

Sauvant D, Perez, J, and Tran G, 2004, Tablas de composición y de valor nutritivo de las materias primas destinadas a los animales de inters ganedor, INRA, https://www,indexmundi,com/agriculture/