Comparison of the nutritive value and fatty acid profile of the green pruning residues of six grapevine (Vitis vinifera L.) cultivars

P G Peiretti, G Masoero¹ and S Tassone²

Institute of Sciences of Food Production, National Research Council, Grugliasco, Italy
piergiorgio.peiretti@ispa.cnr.it
¹ Academy of Agriculture of Torino, Torino, Italy
² Department of Agriculture, Forestry and Food Sciences, University of Torino, Grugliasco, Italy

Abstract

Interest in the green pruning residues of grapevine (GPR), harvested in spring, as a feedstuff has been increasing due to its nutritive value. The aim of this study was to investigate the differences between six cultivars of red Vitis vinifera (Nebbiolo, Barbera, Syrah, Grenache, Pinot Noir and Cabernet Sauvignon) as far as the chemical composition, gross energy, in vitro apparent digestibility (DMD) and fatty acid (FA) profile of their GPR are concerned.

There are not significant differences among cultivars in terms of dry matter (DM), crude protein and lipid contents. Whereas there are significant differences among cultivars in terms of ash, neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin contents ranged from 54 to 70, 495 to 542, 375 to 425, and 91 to 142 g/kg DM, respectively. Moreover, the cell wall contents (NDF, ADF and lignin) of the GPR were negatively correlated to the DMD, which ranged from 449 to 544 g/kg DM. The FA profile of the GPR was characterized by a low content of saturated FAs and a high content of polyunsaturated FAs (PUFA); among the latter, α-linolenic acid and linoleic acid ranged from 356 to 419 and 228 to 312 g/kg of the total FAs, respectively. Linoleic acid was found to differ significantly for the six cultivars, and the highest value was found in the GPR of the Pinot Noir.

Thus, GPR may have a good potential nutritive value and an interesting PUFA content for small ruminants.

Key words: by-product, chemical composition, digestibility, fibrous content, ruminant

Introduction

Several wine production by-products have been studied as sources of natural bioactive compounds. They have been found to be potentially safe and have therefore been proposed as health promoters (Teixeira et al 2014). Moure et al (2001) reported that certain by-products of grape processing, such as seeds and peels, are promising sources of natural antioxidants. The rich and varied chemical composition of these by-products has led to a considerable interest in grape pomace as a promising source of compounds that show good nutritional properties for ruminants (Abarghuei et al 2010; Bahrami et al 2010; Basalan et al 2011; Baumgärtel et al 2007; Besharati and Taghizadeh 2009; Bravo and Saura-Calixto 1998; Deng et al 2011; Pirmohammadi et al 2007a; Romero et al 2000; Spanghero et al 2009; Zalikarenab et al 2007). Other studies have assessed the effects of ensiling on the nutrient utilization of grape pomace in ruminants (Alipour and Rouzbehan 2007; Pirmohammadi et al 2007b; Rebolé and Alvira 1986; Rebolé et al 1988; Santos et al 2014; Winkler et al 2015).

Grapevine (Vitis vinifera L.) pruning is the most important operation that growers perform on the plants during spring, and it generates an abundant residue, which is usually left in the fields. Viticulture produces large quantities of these green residues, which represent a management issue from an economic point of view, but which could constitute a source of alternative feedstuff for ruminants, and in particular for sheep. Gurbuz (2007) determined the potential value of the leaves of four Turkish grapevine cultivars (Ak, Kabarcık, Kıbrıs and Mahrabası), considering their chemical composition, in situ DM and crude protein (CP) degradation, and in vitro gas production. Kok et al (2007) studied the forage and nutritive values of grapevine leaves plus the summer lateral shoots of four cultivars (Cabernet Sauvignon, Merlot, Sauvignon Blanc and Sémillon) at grape harvest and at two post-harvest dates.

However, very little information is available in literature about the fatty acid (FA) content of grapevine by-products (Hussein and Abdrabba 2015). Grape seeds are also a source of healthy FAs and dietary fibre, according to Cao and Ito (2003).

The aim of this study was to investigate the differences in the chemical composition, gross energy, in vitro apparent digestibility (DMD) and FA profile of the green pruning residues of grapevine (GPR) taken from six cultivars of red Vitis vinifera.

Materials and methods

Plant material and environmental conditions

The trials were carried out in the western Po Valley (Italy) in June 2016. The GPR of six cultivars of red Vitis vinifera (Nebbiolo, Barbera, Syrah, Grenache, Pinot Noir and Cabernet Sauvignon) were cut for each cultivar, with edging shears, on three plots randomly located in an experimental field at an altitude of 290 m above sea level (45°06′50″N 7°59′13″E). Sampling was only conducted in favorable weather conditions and after the disappearance of dew.

Chemical analysis

An aliquot of 200 g of each collected GPR sample was used to determine the DM, in duplicate, in a forced draft air oven at 105 °C overnight. Another aliquot of 200 g was immediately refrigerated, freeze-dried, and then brought to air temperature, ground in a Cyclotec mill (Tecator, Herndon, VA, USA) to pass through a 1-mm screen, and then stored for other analyses using the methods of the Association of Official Analysis Chemists (1990) for CP (AOAC method 955.04) and ash (AOAC method 942.05). Neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin were determined using an Ankom 200 Fibre Analyser (Ankom Technology Corp., Macedon, NY, USA), according to the Van Soest et al (1991) method. The NDF of the samples was analyzed without sodium sulfite or α–amylase. Gross energy (GE) was determined using an adiabatic calorimeter bomb (IKA C7000, Staufen, Germany), according to Meineri and Peiretti (2005). The lipid content was quantified according to Peiretti et al (2013). All the analyses were performed in duplicate.

In vitro digestibility

The GPR samples were also analyzed to determine their DMD, using a Daisy II Incubator (Ankom Technology Corp., Fairport, NY, USA), according to Robinson et al (1999). Freeze-dried samples (0.25 ± 0.01 g) were double-weighed in F57 Ankom bags, with a pore size of 25 µm, heat-sealed and then placed into an incubation jar. Each jar was a glass recipient with a plastic lid provided with a single-way valve, which prevented the accumulation of fermentation gases, and was filled with 2 l buffered rumen fluid, in an anaerobic condition. The jar was then introduced into the incubator. The rumen liquor was collected, at a slaughterhouse, from the rumen content of cattle fed a fibre-rich diet (Spanghero et al 2010). The heat (39°C) and agitation were maintained constant and uniform in the controlled chamber by means of continuous rotation. After 48 h of incubation, the jars were emptied and the bags were rinsed gently. DMD was calculated using the following equation:

DMD (g/kg DM)= DMwt_ante- DMwt_post/ DMwt _ante * 1000

where DMwt_ante is the DM weight before the incubation and DMwt _post is the DM weight after the incubation.

Fatty acid analysis

FA analysis was performed on freeze-dried GPR (2 g), according to the method described by Peiretti et al (2013). The FA methyl esters in hexane were injected into a gas chromatograph (GC 1000 DPC; Dani Instruments S.p.A., Cologno Monzese, Italy), equipped with a flame ionisation detector, a programmed temperature vaporizing injection port and a Supelcowax-10 fused silica column (60 m × 0.32 mm, 0.25 μm). The peak area was measured using a Dani DDS 1000 Data Station. Each peak was identified according to pure methyl ester standards (Supelco and Restek Corporation, Bellefonte, PA), and the data were expressed as relative values. The FA content was expressed as g/kg of total FAs.

Statistical analysis

The variability in the chemical composition, the digestibility and the FA profile of the samples were analyzed, to establish their statistical significance, by means of an analysis of variance (ANOVA), using SPSS version 11.5.1 for Windows (SPSS Inc., Chicago, IL, USA) to test the effect of the cultivars. Multiple comparisons of the means were conducted using a Post Hoc (Tukey test) procedure to establish any differences among locations. Differences were considered significant at the p <0.05 level.

Results and discussion

Chemical composition

To the best of the authors’ knowledge, this is the first work that has studied the differences in the chemical composition, gross energy, DMD and FA profile of the green pruning residues of grapevine cultivars. The DM, CP and lipid contents of the GPR did not differ significantly among cultivars (Table 1), whereas ash, NDF, ADF and lignin contents of the GPR were significantly different, and ranged from 54 to 70, from 495 to 542, from 375 to 425, and from 91 to 142 g/kg DM, respectively. Kok et al (2007) reported lower nutritive values of shoot and leaf residues from the annual pruning of 4 cultivars, including Cabernet Sauvignon (CP 45 g/kg, NDF 325 g/kg, and ADF 248 g/kg).

The lipid content of the GPR ranged from 9 g/kg DM in Pinot Noir to 14 g/kg DM in the Grenache cultivar. Maier et al (2008) found that the total oil contents ranged from 29 to 43 g/kg for pressed seed residues and from 76 to 160 g/kg for grapevine seeds. Yi et al (2009) analyzed grape pomace powders, and found a lipid content of 68 g/kg for Royal Rouge and 73 g/kg for a Cabernet Sauvignon cultivar.

In vitro digestibility

The apparent digestibility of the DM of the GPR is shown in Table 1. In the present study, relatively high values, ranging from 449 (Nebbiolo) to 544 g/kg DM (Barbera), were observed for all the cultivars. The DMD was similar for Sirah, Grenache, Cabernet Sauvignon and Pinot Noir As described in figure 1, DMD was correlated to the fibre fractions. Higher NDF, ADF and lignin corresponded to lower digestibility, in agreement with the results of Baumgärtel et al (2007).

All the digestibility values were higher than the average DMD reported by Feedipedia (Heuzé et al 2017) for grape branches and leaves However, very few studies have been conducted on the digestibility of grapevine pruning residues. Rebolé and Alvira (1986) determined the in vitro digestibility of fresh vine branches with their leaves, according to the Tilley and Terry (1963) method, and reported an average value of 427 g/kg.

Figure 1. Correlation between the cell wall contents (NDF, ADF and lignin) and in vitro apparent digestibility (DMD) of the pruning residues of grapevine

As the storage of fresh GP is difficult, because of its water content, Rebolé et al (1988) studied the digestibility of ensiled vine branches and leaves and found a reduction in DMD compared to the digestibility of fresh by-products. Some authors have analysed the vine leaves of Vitis vinifera. Kamalak (2005) reported DMD values, determined by means of Tilley and Terry’s method (1963), which ranged from 598 to 753 g/kg. Instead, Romero et al (2000) found a lower in vivo digestibility (422 g/kg), due to a high tannin content and a low digestibility of protein. Bersharati and Taghizadeh (2009) found an in situ DMD of dried grape by-products (grape cluster stems and rejected raisins) of 638 g/kg. Basalan et al (2011) determined in vitro digestibility using an Ankom Daisy Incubator, and the DMD value of the stalk was found to be 292 g/kg at 48 h.

The other data on the digestibility of grape by-products mainly refer to grape pomace. Winkler et al (2015) reported higher values in ensiled pomaces than in dried grape ones. On the other hand, some authors (Spanghero et al 2009; Pirmohammadi et al 2007b) found a reduction in digestibility due to ensilage. However, it has also been found that the digestibility of ensiled grape pomace can be increased by adding polyethylene glycol (Alipour and Rouzbehan 2007).

Trials on animals have shown that adding dried grape pomaces to ruminant diets has no negative effects on performance, and could be a good source of fibre (Bahrami et al 2010; Zalikarenab et al 2007).

Fatty acid

The FA profile of the GPR (Table 2) was characterized by a low content of saturated FAs (SFA) and a high content of polyunsaturated FAs (PUFA), and of the latter, α-linolenic acid and linoleic acid ranged from 356 to 419 and 228 to 312 g/kg of total FAs, respectively. The content of linoleic acid differed significantly over the six cultivars, and the highest value was found in the GPR of the Pinot Noir cultivar.

Chitarrini et al (2017) highlighted the role of some FAs in response to abiotic stress, such as mechanical wounding of grapevine leaves (Bianca cultivar), and reported an increase in linoleic acid, α-linolenic acid and oleic + cisvaccenic acid during the first 12 h after injury.

Miele et al (1993) determined the FA composition of different lipid fractions of leaves, pericarps, skins, musts, and seeds of Vitis vinifera (Cabernet Sauvignon cultivar) collected at grape maturity. They found that α-linolenic acid was the most abundant acid in leaves, pericarps and skins, while linoleic acid was predominant in seeds. The unsaturated FA/SFA ratio was found to vary according to the lipid fraction and the tissue, and it decreased from seeds to leaves, pericarps and skins.

Santos et al (2011) determined the FA profile of the pulp, peel and seeds of Vitis vinifera (Benitaka and Brazil cultivars), and detected a total of twelve FAs in peels, eleven FAs in seeds and nine FAs in pulps. The main FAs were: linoleic, palmitic and oleic acid in the peels, linoleic, palmitic and α-linolenic acid in the pulp, linoleic, oleic and palmitic acid in the seeds, respectively. Hussein and Abdrabba (2015) found that the FA composition of the seeds of red grapes (Sultana cultivar) had a high PUFA content, and linoleic acid in particular (553 g/kg total FA), and this was followed by oleic acid (258 g/kg total FA), while palmitic acid was the dominant SFA (119 g/kg total FA). Lachman et al (2015) evaluated the FA composition in the seed of different grapevine cultivars, and reported that linoleic acid was the most abundant FA in all the analysed grape seed oils, contributing with between 68 and 78 g/100 g oil, while α-linolenic acid was only present in small traces, that is, from 0.29 to 0.77 g/100 g oil. Yi et al (2009) determined the FA composition of grape pomace powder (Cabernet Sauvignon and Royal Rouge cultivars) and found differences in the linoleic and α-linolenic acid contents, SFA, cis monounsaturated FA (MUFA) and n-6 PUFA; they also found a ratio of n-6/n-3 for the two cultivars.

Ju et al (2016) detected a total of sixteen FAs in grape skins (Pinot Noir cultivar). The main SFAs were palmitic, stearic, behenic and arachidic acid, and the main unsaturated FAs were linoleic, oleic and palmitoleic acid; α-linolenic acid was not detected.

Santos et al (2014) studied the effect of incorporating grape residue silage (at 0, 50, 75, or 100 g/kg of DM) in a diet containing soybean oil on the milk FA and antioxidant composition of lactating dairy cows. They reported an FA profile of grape residue silage that was characterized by five main FAs: linoleic (612 g/kg of the total FAs), oleic (192 g/kg of the total FAs), palmitic (125 g/kg of the total FAs), stearic (44 g/kg of the total FAs), and α-linolenic acid (41 g/kg of the total FAs). They reported that the supplementation had no effect on the total polyphenol and flavonoid concentrations in milk, while the PUFA/SFA ratio increased in milk fat as the grape residue silage was increased.

Conclusions

• This study has confirmed that GPR may have a fairly good potential nutritive value and an interesting content of PUFA for small ruminants.
  
  
• However, further studies are still needed, and ruminant feeding tests should be carried out to assess the palatability and intake of GPR and to determine the effect of supplementation of this by-product on the growth performance of ruminants.

Acknowledgments

The authors thank Mrs M. Jones for the linguistic revision of the manuscript and Mr. T. Strano (Department of Agriculture, Forestry and Food Sciences, University of Torino) for the helpful collaboration in the field operations.

References

Abarghuei M J, Rouzbehan Y, Alipour D 2010 The influence of the grape pomace on the ruminal parameters of sheep. Livestock Science, 132:73–79. http://ac.els-cdn.com/S1871141310001794/1-s2.0-S1871141310001794-main.pdf?_tid=6fb1bb3c-96df-11e7-b951-00000aab0f02&acdnat=1505127385_0e709ae6b2457c9f8adcade4a0ce6dd7

Alipour D and Rouzbehan Y 2007 Effects of ensiling grape pomace and addition of polyethylene glycol on in vitro gas production and microbial biomass yield. Animal Feed Science and Technology, 137: 138–149. http://ac.els-cdn.com/S0377840106003932/1-s2.0-S0377840106003932-main.pdf?_tid=8728b806-96df-11e7-b993-00000aab0f6c&acdnat=1505127424_7a5146a870e3e48503aa9091c9217948

AOAC (Association of Official Analytical Chemists) 1990 Official Method of Analysis. 15th edition. Washington, DC, USA

Bahrami Y, Foroozandeh A D, Zamani F, Modarresi M, Eghbal-Saeid S and Chekani-Azar S 2010 Effect of diet with varying levels of dried grape pomace on dry matter digestibility and growth performance of male lambs. Journal of Animal and Plant Sciences, 6: 605–610. http://m.elewa.org/JAPS/2010/6.1/7.pdf

Basalan M, Gungor T, Owens F N and Yalcinkaya I 2011 Nutrient content and in vitro digestibility of Turkish grape pomaces. Animal Feed Science and Technology, 169: 194–198. http://ac.els-cdn.com/S037784011100318X/1-s2.0-S037784011100318X-main.pdf?_tid=9e846cb6-96df-11e7-a890-00000aab0f27&acdnat=1505127464_93a73bc700fbd0bee1cab00fbcbf6c7f

Baumgärtel T, Kluth H, Epperlein K and Rodehutscord M 2007 A note on digestibility and energy value for sheep of different grape pomace. Small Ruminant Research, 67: 302–306. http://ac.els-cdn.com/S0921448805004694/1-s2.0-S0921448805004694-main.pdf?_tid=b43ce4fc-96df-11e7-b0a3-00000aacb362&acdnat=1505127500_d0f799c8a5c1684f0df0b19909789f7b

Besharati M and Taghizadeh A 2009 Evaluation of dried grape by-product as a tanniniferous tropical feedstuff. Animal Feed Science and Technology, 152: 198–203. http://ac.els-cdn.com/S0377840109001357/1-s2.0-S0377840109001357-main.pdf?_tid=dc9f379c-96df-11e7-ab14-00000aacb362&acdnat=1505127568_e26754443d369f7fdd09d212c9cb3d78

Bravo L and Saura-Calixto F 1998 Characterization of dietary fiber and the in vitro indigestible fraction of grape pomace. American Journal of Enology and Viticulture, 49: 135–141.

Cao X and Ito Y 2003 Supercritical fluid extraction of grape seed oil and subsequent separation of free fatty acids by high-speed counter-current chromatography. Journal of Chromatography A, 1021: 117–124. http://ac.els-cdn.com/S002196730301642X/1-s2.0-S002196730301642X-main.pdf?_tid=13e2ac16-96e0-11e7-b95a-00000aacb35d&acdnat=1505127661_851e644c32f9bda836af05b8ed6e0347

Chitarrini G, Zulini L, Masuero D and Vrhovsek U 2017 Lipid, phenol and carotenoid changes in ‘Bianca’ grapevine leaves after mechanical wounding: a case study. Protoplasma. Published online March 21, 2017. DOI 10.1007/s00709-017-1100-5 http://www.readcube.com/articles/10.1007/s00709-017-1100-5

Deng Q, Penner M H and Zhao Y 2011 Chemical composition of dietary fiber and polyphenols of five different varieties of wine grape pomace skins. Food Research International, 44: 2712–2720. http://ac.els-cdn.com/S0963996911003425/1-s2.0-S0963996911003425-main.pdf?_tid=3b91fe42-96e0-11e7-af53-00000aab0f6b&acdnat=1505127727_c03f5d288a270031772cc72755375c56

Gurbuz Y 2007 Determination of nutritive value of leaves of several Vitis vinifera varieties as a source of alternative feedstuff for sheep using in vitro and in situ measurements. Small Ruminant Research, 71: 59–66. http://ac.els-cdn.com/S0921448806001192/1-s2.0-S0921448806001192-main.pdf?_tid=50fcd860-96e0-11e7-bfbd-00000aacb360&acdnat=1505127763_e08813f1bb2cc13c5a2864adb012b58f

Heuzé V, Thiollet H and Tran G 2017 Grape leaves and vine shoots. Feedipedia, a programme by INRA, CIRAD AFZ and FAO. Retrieved September 6, 2017, from http://www.feedipedia.org/node/512

Hussein S and Abdrabba S 2015 Physico-chemical characteristics, fatty acid, composition of grape seed oil and phenolic compounds of whole seeds, seeds and leaves of red grape in Libya. International Journal of Applied Science and Mathematics, 2: 2394–2894. https://www.ijasm.org/administrator/components/com_jresearch/files/publications/IJASM_79_Final.pdf

Kamalak A 2005 Chemical composition and in vitro dry matter digestibility of leaves of Vitis vinifera. Livestock Research for Rural Development, Volume 17, Article #3. http://www.lrrd.org/lrrd17/1/kama17003.htm

Kok D, Ates E, Korkutal I and Bahar E 2007 Forage and nutritive value of the pruning residues (leaves plus summer lateral shoots) of four grapevine (Vitis vinifera L.) cultivars at grape harvest and two post-harvest dates. Spanish Journal of Agricultural Research, 5: 517–521.

Ju Y, Zeng J, Zhu M, Lv X, Wang T, Zhang Z, Li H and Fang Y 2016 The effects of a plant growth regulator, leaf removal, bagging, and harvest time on the lipoxygenase activity and fatty acid composition of pinot noir grapevines. Pakistan Journal of Botany, 48: 1431–1438. https://www.pakbs.org/pjbot/PDFs/48(4)/15.pdf

Lachman J, Hejtmánková A, Táborský J, Kotíková Z, Pivec V, Střalková R, Vollmannová A, Bojňanská T and Dědina M 2015 Evaluation of oil content and fatty acid composition in the seed of grapevine varieties. LWT - Food Science and Technology, 63: 620–625.

Maier T, Schieber A, Kammerer D R and Carle R 2008 Residues of grape (Vitis vinifera L.) seed oil production as a valuable source of phenolic antioxidants. Food Chemistry, 112: 551–559.

Meineri G and Peiretti P G 2005 Determination of gross energy of silages. Italian Journal of Animal Science, 4: 147–149. http://www.tandfonline.com/doi/pdf/10.4081/ijas.2005.2s.147?needAccess=true

Miele A, Bouard J and Bertrand A 1993 Fatty acids from lipid fractions of leaves and different tissues of Cabernet Sauvignon grapes. American Journal of Enology and Viticulture, 44: 180−186.

Moure A, Cruz J M, Franco D, Domı́nguez J M, Sineiro J, Domı́nguez H, Núñez M J and Parajó J C 2001 Natural antioxidants from residual sources. Food Chemistry, 72: 145–171.

Peiretti P G, Gai F, and Tassone S 2013 Fatty acid profile and nutritive value of quinoa ( Chenopodium quinoa Willd.) seeds and plants at different growth stages. Animal Feed Science and Technology, 183: 56–61.

Pirmohammadi R, Hamidi O and Mohsenpur-Azari A 2007a Effects of polyethylene glycol (PEG) addition on composition, degradability and digestibility of white grape pomace. Journal of Animal and Veterinary Advances, 6: 1135–1139. http://docsdrive.com/pdfs/medwelljournals/javaa/2007/1135-1139.pdf

Pirmohammadi R, Golgasemgarebagh A and Mohsenpur-Azari A 2007b Effects of ensiling and drying of white grape pomace on chemical composition, degradability and digestibility for ruminants. Journal of Animal and Veterinary Advances, 6: 1079–1082. http://docsdrive.com/pdfs/medwelljournals/javaa/2007/1079-1082.pdf

Rebolé A and Alvira P 1986 Composition of vine-branches with leaves of Vitis vinifera L. fresh and ensiled using different additives (previous results). Animal Feed Science and Technology, 16: 89–97.

Rebolé A, Alvira P and González G 1988 . Digestibility in vivo of ensiled grapevines (branches and leaves): influence of the system of analysis in the detergent fibre scheme on the prediction of digestibility. Animal Feed Science and Technology, 22: 173–177.

Robinson P H, Campbell M and Fadel J G 1999 Influence of storage time and temperature on in vitro digestion of neutral detergent fibre at 48 h, and comparison to 48 h in sacco neutral detergent fibre digestion. Animal Feed Science and Technology, 80: 257–266.

Romero M J, Madrid J, Hernandez F and Ceron J J 2000 . Digestibility and voluntary intake of vine leaves (Vitis vinifera L.) by sheep. Small Ruminant Research, 38: 191–195.

Santos L P, Morais D R, Souza N E, Cottica S M, Boroski M and Visentainer J V 2011 Phenolic compounds and fatty acids in different parts of Vitis labrusca and V. vinifera grapes. Food Research International, 44: 1414–1418.

Santos N W, Santos G T D, Silva-Kazama D C, Grande P A, Pintro P M, De Marchi F E, Jobim C C and Petit H V 2014 Production, composition and antioxidants in milk of dairy cows fed diets containing soybean oil and grape residue silage. Livestock Science, 159: 37–45.

Spanghero M, Salem A Z M and Robinson P H 2009 Chemical composition, including secondary metabolites, and rumen fermentability of seeds and pulp of Californian (USA) and Italian grape pomaces. Animal Feed Science and Technology, 152: 243–255.

Spanghero M, Berzaghi P, Fortina R, Masoero F, Rapetti L, Zanfi C, Tassone S, Gallo A, Colombini S and Ferlito C 2010 Precision and accuracy of in vitro digestion of neutral detergent fiber and predicted net energy of lactation content of fibrous feeds. Journal of Dairy Science, 93: 4855–4859. https://doi.org/10.3168/jds.2010-3098

Teixeira A, Baenas N, Dominguez-Perles R, Barros A, Rosa E, Moreno D A and Garcia-Viguera C 2014 Natural bioactive compounds from winery by-products as health promoters: a review. International Journal of Molecular Sciences, 15: 15638–15678. http://www.mdpi.com/1422-0067/15/9/15638/htm

Tilley J M A and Terry R A 1963 A two stage technique for in vitro digestion of forage crops. Journal of the British Grassland Society, 18: 104–111.

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science, 74: 3583–3591. https://doi.org/10.3168/jds.S0022-0302(91)78551-2

Winkler A, Weber F, Ringseis R, Eder K and, Dusel G 2015 Determination of polyphenol and crude nutrient content and nutrient digestibility of dried and ensiled white and red grape pomace cultivars. Archives of Animal Nutrition, 69: 187–200.

Zalikarenab L, Pirmohammadi R and Teimuriyansari A 2007 Chemical composition and digestibility of dried white and red grape pomace for ruminants. Journal of Animal and Veterinary Advances, 6: 1107–1111. http://docsdrive.com/pdfs/medwelljournals/javaa/2007/1107-1111.pdf

Yi C, Shi J, Kramer J, Xue S, Jiang Y, Zhang M, Mad Y and Pohorly J 2009 Fatty acid composition and phenolic antioxidants of winemaking pomace powder. Food Chemistry, 114: 570−576.

Received 9 September 2017; Accepted 13 September 2017; Published 3 October 2017

Go to top