Opuntia cladodes are a valuable forage for ruminants. They should be supplemented with sources of protein and fibre in a mixed diet. They should not be fed alone due to the risk of diarrhea and weight loss, though Opuntia -only diets have been reported (see Cattle below). They are rich in soluble carbohydrates, which makes the addition of molasses unecessary and helps to reduce the amount of cereal grain in the diet (Dubeux, 2011 ).
Cattle
Opuntia ficus-indica are used to feed cattle in intensive as well as extensive meat and dairy operations. While poor in terms of nutrients and fibre, Opuntia constitutes an important source of water in traditional production systems. There are reports of cattle being fed for 400 to 525 days exclusively on an Opuntia diet without watering, without serious side effects (Lopez-Garcia et al., 2001 ). However, cattle fed Opuntia had to be supplemented with copper, molybdenum and zinc (Felker, 2001 ). Cattle can consume 15 to 40 kg of fresh cladodes/day, and up to 90 kg if the cladodes are abundant and conditions are dry. Opuntia consumption depends on the availability of other feeds, and may decrease during the rainy season when grass is more plentiful (Lopez-Garcia et al., 2001 ).
Dairy cattle
The following videos show dairy cattle eating Opuntia in Brazil (Dubeux, 2011 ):
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Since the early 1900s, it has been known that Opuntia -based supplementation can increase not only milk production, but also the quality of butter in terms of consistency and storage life, as well as adding an attractive golden colour to the finished product (Lopez-Garcia et al., 2001 ).
However, it has also been reported that milk production in Holstein cows decreased when the amount of Opuntia increased in the diet. The optimal combination recommended to obtain a good balance between production costs and returns was 20 to 30% Opuntia (on a dry matter basis) supplemented with alfalfa hay, oats and sorghum (Lopez-Garcia et al., 2001 ). The inclusion of Opuntia forage resulted in a decrease in nutrient intake, NDF digestibility, total chewing time, feeding and rumination efficiencies, and water intake (Oliveira et al., 2007 ; Carvalho et al., 2005 ). Increasing the intake of Opuntia also caused significant changes in the milk profile (Oliveira et al., 2007 ).
There were no changes in feed intake, animal performances and apparent digestibility of nutrients when dairy cows were fed roughage supplemented with Opuntia ficus-indica (Silva et al., 2007 ). Feeding lactating cows on spineless cactus + urea advantageously replaced Bermuda grass hay and increased energy intake and milk production (Cavalcanti et al., 2006 ; Cavalcanti et al., 2008 ). However, the nutritive value of urea-treated Opuntia forage was lower than that of soybean meal (Melo et al., 2003 ), and it was necessary to maintain Bermuda grass hay in the diet when replacing corn by spineless cactus alone, in order to maintain microbial production (Oliveira et al., 2007 ).
Storage up to 16 days was shown to have no effect on the DM intake and milk production of dairy cows in Brazil (Santos et al., 1998 ).
Beef cattle
In Brazil it was concluded that 60% of the total energy requirements for beef cattle could be supplied by Opuntia . In Mexico, Opuntia has been successfully used to raise beef cattle receiving a supplement of maize stover, molasses and urea (Lopez-Garcia et al., 2001 ).
Sheep
Sheep can consume between 3 and 9 kg/day of Opuntia . They can browse around 3-5 kg/day of burnt and chopped Opuntia , but less if it is raw (Lopez-Garcia et al., 2001 ).
In Ethiopia, sheep were fed either 60% or 50% Opuntia ficus-indica forage mixed respectively with pasture or teff (Eragrostis tef ) straw. These diets supported a weight gain of 33 g/day and reduced water consumption to negligible quantities (Gebremariam et al., 2006 ; Tegegne et al., 2007 ). In Brazil, 50% Opuntia mixed with 50% dried grape residues gave good production results at a low cost (Barroso et al., 2006 ). Opuntia was able to replace feedstuffs such as barley, pangola hay (Digitaria eriantha Pennisetum purpureum Abidi et al., 2009 ; Lopes et al., 2008 ; Bispo et al., 2007 ). Supplementing sheep fed Atriplex nummularia with Opuntia resulted in better organic matter digestibility and nitrogen balance (Ben Salem et al., 2005 ). Opuntia gave the best dry matter intake, crude protein digestibility and metabolizable energy when sheep were provided an organic N source in the diet (soybean meal, or to a lesser extent Bermuda grass hay) (Misra et al., 2006 ; Ben Salem et al., 2002 ). Good results were also obtained with urea-ammoniated Opuntia (Lopes et al., 2008 ).
In Southern Africa, sheep fed Opuntia alone survived for 500 days. However, a supplement of bone meal, common salt and urea (1:1:1) was recommended. Cactus meal can also be supplemented with 6.5% fish meal. Alfalfa, either meal or hay (100 g to 200 g), is the most valuable supplement for cactus meal ad libitum . Other legume hays may also be useful, provided that they are reasonably high in protein (De Cock, 2001 ).
Goats
The following videos show goats eating Opuntia in small and large farms in Brazil (Dubeux, 2011 ):
VIDEO VIDEO VIDEO
Opuntia is palatable to goats. Daily consumption ranges from 3 to 9 kg/day in the open field, and up to 11 kg when they are housed (Lopez-Garcia et al., 2001 ).
In Tunisia, feeding goat kids with Opuntia had positive effect on meat quality and especially on fatty acid composition (Atti et al., 2006 ). In Brazil, Opuntia replaced corn meal in the diet of dairy goat diets without altering milk production. Milk fat content decreased when the level of Opuntia increased and water intake was considerably reduced (Costa et al., 2009 ). A 15% (DM basis) dietary level of inclusion of Bermuda grass (Tifton hybrid) hay was recommended in order to maximise performance from an Opuntia -based diet (Vieira et al., 2008 ). In Chile, Opuntia replaced up to 30% of the alfalfa hay ration without significantly affecting consumption, live-weight and milk production. The presence of Opuntia cladodes in the ration of goats in the suckling period induced a higher intake and an increase in milk production (Azocar, 2001 ).
