Tomato by-products are usually fed to ruminants due to their high fibre content. They are not excellent feed ingredients, being less digestible than most major oil meal and protein sources. They can be bitter and should be used together with more palatable feeds. However, they can be a valuable and cost-effective source of protein, energy and fibre (Göhl, 1982 ; Caluya et al., 2003 ). In the Phillipines, Caluya et al., 2003 recommended including tomato pomace at up to 50% of the daily roughage requirement irrespective of whether it was fresh, dried or ensiled. The pomace should be given before the roughage or mixed (particularly when dry) thoroughly with chopped roughage.
Digestibility and energy values
In vivo OM digestibility of dried tomato pomace was estimated at 56% in sheep, using a balanced diet containing 34% pomace. In sacco rumen DM degradability was 48% (Abbeddou et al., 2011). A value of 62% for OM digestibility was obtained using the gas test method. Extremely wide estimates of ME have been obtained, depending on the method (in vitro , in sacco ) and equation used, ranging from 4.9 (Chumpawadee et al., 2007 ), 7 and 9 (Gasa et al., 1991 ; Abbeddou et al., 2011), to 11.8 MJ/kg DM (Aghajanzadeh-Golshani et al., 2010 ).
Protein value
In sacco protein degradability of dried tomato pomace in the rumen is quite high, from 65-70% (Chumpawadee, 2009 ; Abbeddou et al., 2011) to 76-78% (Ben Salem et al., 2008 ; Valizadeh et al., 2009 ). However, most of the protein is not digestible in the rumen but in the intestine (Gasa et al., 1988 ; Gasa et al., 1991 , Ventura et al., 2009 ), probably because an important fraction of this crude protein is acid-detergent insoluble (Weiss et al., 1997 ; Ventura et al., 2009 ).
Fresh or ensiled tomato pomace
Tomato pomace can be mixed with maize plant on a 50: 50 ratio basis and can be fed to ruminants (cattle, sheep, goats and buffaloes) as it is shown in the video below :
VIDEO
Fresh or ensiled tomato pomace can be used in ruminant diets mainly as a complementary roughage, especially during periods of forage scarcity. Wet pomace should preferably be ensiled with straw or other dry materials, and diets must remain properly balanced.
Dairy cows
Tomato pomace ensiled with whole maize plant at up to 12% of diet DM showed good preservation characteristics. Dairy cows fed this silage had the same DM intake, milk yield and milk composition as cows fed maize silage alone (Weiss et al., 1997 ). More recently, in China, 10% ensiled tomato pomace was used in diets for periparturient Holstein cows, replacing about 25-31% of maize silage. DM intake and apparent DM digestibility were slightly but significantly increased, while milk yield and major milk components were not significantly affected. Milk vitamin content and some antioxidant and immune indicators were also improved (Tuoxunjiang et al., 2020 ).
Dairy buffaloes
In Egypt, tomato pomace silage was included at about 25% of dietary DM in diets for lactating Egyptian buffaloes, mainly replacing clover forage rather than corn silage. DM intake was lower, and crude protein and crude fibre digestibility were reduced, but DM, NDF and ADF digestibility, as well as feed conversion ratio, were improved. Actual milk yield was not significantly affected, while 7% fat-corrected milk yield and milk fat percentage increased (Ebeid et al., 2015 ).
Dairy goats
In Iran, tomato pomace was included at 24% of diet DM in isoenergetic and isonitrogenous diets for lactating Saanen goats, replacing wheat bran. DM intake, milk yield, 4% fat-corrected milk and feed efficiency were not significantly affected. Tomato pomace improved the milk fatty acid profile by reducing saturated fatty acids and increasing monounsaturated fatty acids and CLA (Razzaghi et al., 2015 ).
Sheep
In lambs, fresh tomato pomace replaced more than 75% of poor-quality hay, resulting in higher OM intake and OM digestibility (Ojeda et al., 2001 ).
Fresh tomato pomace ensiled with 10% or 15% straw on a DM basis was well preserved. When offered as sole forage to 43 kg Awassi rams or 47 kg Segureña ewes for maintenance, intake was satisfactory and only small daily weight gains were observed (Denek et al., 2006 ; Barroso et al., 2008 ).
Ensiled tomato pomace can be fed to castrated lambs at up to 45% of diet DM and replace maize silage without modifying total DM intake. However, OM digestibility increased at up to 30% replacement but not beyond (Campos et al., 2007 ).
In Portugal, tomato pomace was used in mixed silages with potato, sweet potato or carrot wastes, wheat bran and alfalfa hay. These silages contained 350 g/kg tomato pomace and were included at 50% of dietary DM in diets for finishing lambs, corresponding to about 11% tomato pomace in dietary DM. They did not affect DM intake, average daily gain, feed conversion ratio, carcass traits, meat quality or in vitro methane production, while reducing feeding cost per kg live weight gain (Dentinho et al., 2023 ).
Dried tomato pomace
Dairy cows
In dairy cows in early lactation, dried tomato pomace included at 10% of diet DM did not affect DM intake, milk yield or milk composition (Safari et al., 2007 ). In multiparous dairy cows, dried tomato pomace was included at up to 32.5% of concentrate DM, replacing part of barley grain and whole cottonseed meal, without adverse effects on health, milk yield or DM intake (Belibasakis, 1990 ). This latter value refers to concentrate DM and should not be directly compared with inclusion levels expressed as total diet DM.
Dairy ewes
In Syria, dried tomato pomace was included at about 30% of diet DM in diets for lactating Awassi ewes, partially replacing concentrate. Tomato pomace reduced energy-corrected milk yield and milk protein yield, but increased milk fat percentage and partly improved the milk fatty acid profile by reducing saturated fatty acids and increasing monounsaturated fatty acids. Total CLA was unchanged and the n-6: n-3 ratio increased (Abbeddou et al., 2015 ).
Beef cattle and growing cattle
In beef heifers, dried tomato pomace completely replaced urea-treated straw, improving rumen digestion and feed efficiency. DM intake increased when tomato pomace replaced straw, but decreased slightly when pomace was fed alone (Yuangklang et al., 2006 ).
In Brahman-Thai steers, dried tomato pomace was included at 50% of diet DM in a total mixed ration without apparent problems. Diet DM intake was comparable to that obtained with other by-products, such as brewers grains, palm kernel meal and soybean meal, included at the same level (Chumpawadee et al., 2009 ).
In adult steers fed total mixed rations where dried tomato pomace replaced cassava chips at up to 11% of diet DM, there were no significant changes in DM intake or nutrient digestibility (Yuangklang et al., 2010a ). In two-year-old Brahman steers, replacing cassava by tomato pomace tended to reduce daily weight gain, but differences were not significant (Yuangklang et al., 2010b ).
Sheep
Dried tomato pomace can be used in growing and finishing sheep diets at moderate levels, generally around 10-20% of dietary DM, without major effects on intake or growth. Higher inclusion rates may reduce nutrient digestibility and should be used cautiously, especially when the diet is not properly balanced.
Young growing lambs fed a barley-based diet with 200 g/kg DM dried tomato pomace had similar N retention and growth performance to lambs fed a diet containing the same level of protein from soybean meal (Fondevila et al., 1994 ).
In growing lambs, feed blocks containing wheat bran, salt, minerals and 48% DM dried tomato pulp were used to partly replace concentrate in straw-based diets. Growth with the feed blocks was not significantly different from that of lambs fed straw and concentrate, although growth tended to decrease when the amount of concentrate offered decreased (Ben Salem et al., 2008 ).
In growing sheep, dried tomato pomace replacing 50 or 75% of sunflower meal protein significantly decreased DM, crude protein and crude fibre digestibility, and 12.5% was considered the maximum replacement rate for dietary protein (Mohamed et al., 1997 ).
In fattening lambs fed an alfalfa hay-based diet, dried tomato pomace included at 75% decreased OM digestibility, while daily weight gain was highest at 50% inclusion, which was proposed as the maximum recommended rate in that experiment (Ibrahem et al., 1983 ). However, such high levels should be used cautiously because of possible reductions in digestibility.
In Italy, dried tomato pomace offered ad libitum to finishing lambs represented about 11% of total DM intake and reduced concentrate intake by about 15%, without affecting total DM intake, average daily gain, feed conversion ratio, carcass weight or meat oxidative stability. It increased meat linoleic acid, γ-tocopherol and retinol (Valenti et al., 2018 ).
In Iran, tomato pomace powder included at 7.5 or 15% of dietary DM in diets for fattening lambs did not significantly affect feed intake, weight gain or feed conversion ratio, although effects on nutrient digestibility were variable (Mirzaei et al., 2025).
In Ethiopia, dried tomato pomace improved intake and growth in yearling Hararghe Highland male sheep initially weighing about 16.7 kg, and could replace concentrate under the trial conditions (Gebeyew et al., 2015).
In adult rams, a diet containing dried tomato pomace and alfalfa hay in a 1:1 ratio resulted in moderate digestibility of DM, OM and crude protein. Yeast supplementation improved digestibility, suggesting that diet balance and supplementation may be important when dried tomato pomace is used at high levels (Paryad et al., 2009 ).
Goats
In goats fed Napier grass ad libitum, dried tomato pomace replaced 25 to 100% of soybean meal offered at 1.5% BW without changing forage intake, concentrate intake or N utilization (Yuangklang et al., 2007 ).
Tomato seeds
Dairy cows
In the USA, whole tomato seeds were included at 1.1, 2.4 and 4.0% of diet DM in lactating dairy cows as a replacement for whole cottonseed. Dry matter intake and milk yield were not affected, but milk fat concentration and the apparent digestibility of crude protein and fatty acids decreased. Fecal fatty acid data suggested that part of the whole seeds passed through the digestive tract undigested, so processing may be important if tomato seeds are used as a source of fat or protein (Cassinerio et al., 2015 ).
Sheep
In the USA, dried whole tomato seeds were included at 0, 8, 16 and 24% of a basal forage diet for sheep and were found to be a digestible source of nutrients and energy. However, fibre and fatty acid digestibility decreased at higher inclusion levels, which suggests that high dietary levels should be used cautiously (Heguy et al., 2015 ).
