Data sheets: Rye

Introduction

Rye (Secale cereale) is an annual or biennial monocot plant in the grass family that is very resistant to winter conditions. It is grown mainly for grain production in areas where the climate and soil are unfavorable for other cereals, or as a winter crop where temperatures are too low for winter wheat (Europe and North America). Although its cultivation is small (<1% of the total cereal grains produced worldwide), the selection and improvement of varieties that are rustic, but productive in dry areas with poor soils, make it an interesting alternative for cereal production for animal feed in the context of climate change. This is because its characteristics and cultivation needs (water, fertilizers, and phytosanitary treatments) make it a more sustainable cereal (lower CO₂ equivalent- approximately 10% lower than wheat and >50% lower than corn, respectively). Traditionally, its main limitation as an animal feed grain has been the presence of very stable alkaloids (ergotamine, ergocristine, ergometrine, ergotoxine, dihydroergotamine, ergoline, and lysergic acid amides) associated with ergot contamination produced by the fungus Claviceps purpurea, although there are now improved varieties that are resistant to the fungus.

The grain is composed of about 12% pericarp (external and internal layers), 11% aleurone layer, 4% germ, and 73% endosperm. The bran fraction (pericarp and aleurone layer) is where rye differs most from cereals such as wheat (with an even greater difference from corn that has 10 times less) since it presents a higher proportion of fructo-oligosaccharides (+2%), beta-glucans (+1.4%), arabinoxylans (+1.5%) and lignin (+0.6%) although it has a lower concentration of cellulose (-0.5%), which confer characteristics at the fermentation and degradation level that are beneficial to aspects of intestinal health. In addition, these outer layers present phenolic compounds, lignans, and alkylresorcinols that, together with the fractions described above, can contribute at the intestinal level as antioxidants, antimicrobials, and antiparasitics. In any case, both alkaloids and phenolic compounds can affect feed acceptance at high inclusion levels, although recent studies have not observed effects on production yields at high inclusion levels either in nursery or finishing pigs. Like most cereals, the endosperm is mealy with an average starch content of 55%.

The presence of pentosans, mainly associated with the pericarp or bran (NDF content around 11%), does not negatively impact digesta viscosity in piglets and has even less of an impact in adult pigs, compared to other commonly used cereals such as wheat or barley. In any case, the soluble xylan and arabinoxylan content is much higher (a differential characteristic) than in the other commonly used cereals (>rice >naked oats >corn-sorghum >barley >wheat >triticale). The rye grain is rich in lysine although, due to its limited protein content compared to other cereals typically high in energy such as wheat, the total percentage of lysine ends up being very similar. On the other hand, it is unbalanced in sulfur amino acids since its concentration is 5-8% lower than that of wheat. Finally, the inclusion of rye in swine diets can improve the efficiency of the manufacturing process (Mt/h) and the pellet quality, since the water retention capacity of the soluble fibrous fractions it contains facilitates the pelleting process.

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 evaluation system shows the range of values (minimum and maximum) resulting from the integration of 2 different classifications that this evaluation system considers basically according to the origin and production area (Spanish Rye, German Rye, as a representation of imported rye produced in Central and Eastern Europe, which according to market availability is complementary to spanish production).

Unlike the rest of the tables, FEDNA is the only evaluation system that differentiates between two qualities of rye, classified basically according to moisture content and with slightly differing protein, fat, and starch contents, while CVB, INRA, and NRC consider only one rye quality with intermediate values, with NRC having the closest value to the spanish produced FEDNA rye (89.4% DM) and CVB in the low range (87% DM), equating with the values given by INRA, FEDNA for German (European) rye, and BRAZIL that present moisture contents between 2.5-3 percent. The protein content ranges >2.5 percent between the different rating systems with a minimum of 9% for INRA rye, having the lowest protein content, and NRC having the highest (11.7%). These differences can be associated with the type of varieties typically grown, the degree of selection pressure, and the growing conditions, with the typical rye producing regions (Central Europe and North America including Canada) showing the best results in terms of protein, with the exception of CVB. In any case, if the more extreme values for protein and starch proposed by NRC and BRAZIL are not considered, there is hardly any relationship between protein and starch content.

The small variation in starch content has little impact on the estimation of NE content. Unlike other high energy cereals such as corn, a clear contribution from the fibrous fraction in terms of energy is observed which, together with the small contribution of fat content due to its low variability (<1 percent), is determinant in explaining the 110 kcal/kg difference in NE (although <4.5%) observed between the different more extreme evaluation systems (2470 kcal/kg; FEDNA (spanish national rye) vs. 2360 kcal/kg; INRA). Once again, it can be considered that this small variation could be attributable to the cultivation of improved varieties and hybrids in which the composition of the fibrous fraction (non-starch polysaccharides- NSP), the aforementioned pentoses (soluble xylans and arabinoxylans) and hexoses (mostly fructans), although not digestible by endogenous enzymes, may have a greater fermentation capacity.

In terms of total amino acids, taking lysine as a reference, no major differences are observed and these differences in terms of total lysine content can be compensated by the 2.5 points of variation in protein content observed between evaluation systems. The values for the rest of the total amino acids are quite proportional to lysine, with the exception of sulfur amino acids (methionine and cysteine), branched amino acids (valine and isoleucine), and tryptophan, with values penalized by NRC with respect to the average of the rest of the evaluation systems considered (-65%, -13% and -15%, respectively). The digestibility coefficient of protein and lysine presents a range between 69-77.5%, with an average value of 72%, but basically attributable to the maximum value of 77% presented only by BRAZIL (but the lowest for lysine) being the lowest value for NRC.

Recent findings

1. The apparent ileal digestibility and the apparent total tract digestibility of carbohydrates and energy in hybrid rye are different from some other cereal grains when fed to growing pigs.

An experiment was conducted to determine the apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of energy, starch, and total dietary fiber (TDF) in two varieties of hybrid rye and compare these values with values obtained for barley, wheat, corn, and sorghum. Results indicated that the metabolizable energy (ME) on a dry matter (DM) basis was greatest in corn and wheat (3,732 and 3,641 kcal/kg DM), and least in barley (3,342 kcal/kg DM), whereas the two hybrid ryes contained 3,499 and 3,459 kcal/kg DM, respectively. The ME values in hybrid rye were not different from values determined for barley and sorghum (3,573 kcal/kg DM). The AID of TDF was less than 35% for all cereal grains, but the ATTD of TDF was greater (P < 0.05) in the two hybrid ryes (68% and 70%) than in the other ingredients (56% to 58%). In conclusion, feeding hybrid rye to pigs resulted in reduced pre-cecal absorption of energy compared with wheat, corn, and sorghum, but because hindgut fermentation of fiber was greater in hybrid rye than in other cereal grains, the content of ME in hybrid rye was not different from barley and sorghum but less than in corn and wheat.

2. Phosphorus digestibility and metabolisable energy concentrations of contemporary wheat, barley, rye and triticale genotypes fed to growing pigs

This study was conducted to determine apparent total tract digestibility (ATTD) of phosphorus (P) and metabolisable energy (ME) concentrations for pigs of 32 different genotypes (n = 8 per grain species) of barley, rye, triticale and wheat. All genotypes were grown at the same location under the same field conditions and were fed to growing castrated crossbred pigs using a series of duplicate 3 × 3 Latin square designs. The mean ATTD of P was greater for wheat than for triticale, rye or barley (59.4%, 50.4%, 44.9% and 44.4%, respectively, for the mean of each grain species). Within-grain species differences among genotypes were obtained for ATTD of P of barley and triticale. The concentrations of ME of triticale and wheat were higher than that of barley and rye (16.1 and 16.2 vs. 14.9 and 14.8 MJ ME/kg DM, respectively). Differences in ME concentration among genotypes within a grain species were found for barley, triticale and wheat. No differences were found for rye.

3. Apparent and standardized ileal digestibility of AA and starch in hybrid rye, barley, wheat, and corn fed to growing pigs

An experiment was conducted to determine the apparent ileal digestibility (AID) of AA and starch and the standardized ileal digestibility (SID) of AA in three varieties of hybrid rye and in one source of barley, wheat, and corn. The AID of starch was greater in wheat and corn than in barley or hybrid rye, but all grains had AID values for starch that were above 95%. Wheat and barley contained more CP and indispensable AA than hybrid rye, but hybrid rye contained more indispensable AA compared with corn. The SID of CP and all indispensable AA was greater in barley, wheat, and corn than in the three varieties of rye. However, because of the greater concentration of AA in hybrid rye than in corn, the quantities of standardized ileal digestible CP and AA were not different between corn and hybrid rye. In conclusion, hybrid rye has greater concentrations of most AA than corn, but the digestibility of AA in rye is less than in other cereal grains.

4. Feed additive blends fed to nursery pigs challenged with Salmonella

Salmonella in pigs is a concern for human foodborne salmonellosis. Dietary fungal fermented products, coated butyrate, and organic acids (OAs) may be promising control strategies. The objectives of this study were (i) to evaluate in vitro binding affinity of Salmonella enterica serovar Typhimurium (S. Typh) and Enteritidis (S. Ent), and enterotoxigenic Escherichia coli (ETEC) F4 or F18 to mannan-rich hydrolyzed copra meal (MCM) and fermented rye (FR) with Agaricus subrufescens; and (ii) to assess MCM and Fermented Rye efficacy to control in vivo S. Typh shedding when combined with OAs and compared with coated butyrate strategy. In conclusion, Fermented Rye and MCM show in vitro-binding affinity to Salmonella enterica serovars Typh and Ent. Feeding Fermented Rye or MCM combined with OA to nursery pigs reduces the peak and averages S. Typh shedding compared with control. Fermented rye with OA tends to improve pig performance after S. Typh challenge

5. Increasing hybrid rye level substituting wheat grain with or without enzyme on growth performance and carcass traits of growing-finishing barrows and gilts

New European, fall-planted hybrid rye grown in western Canada is more resistant to ergot and fusarium and has lower content of anti-nutritional factors than common rye. We evaluated the effect of feeding increasing hybrid rye level substituting wheat grain and non-starch polysaccharide (NSP) enzyme inclusion in diets fed to growing-finishing pigs raised under western Canadian commercial conditions. In conclusion, fall-planted hybrid rye can completely replace wheat grain in grower-finisher pig diets without affecting feed efficiency, feed cost per pig or feed cost per kilogram BW gain. Inclusion of NSP enzyme would be recommended for diets including high rye levels to improve feed efficiency and ADG.

References

FEDNA: http://www.fundacionfedna.org/
FND. CVB Feed Table 2019. 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.