Fodder beet is well appreciated for its palatability and is often used to replace cereal grains as a source of energy. It is a fresh forage, highly valuable for winter feeding, with a positive effect on the health status of the animals (Chenais, 1994a; Dulphy et al., 2000; ADBFM, 2009).
Risk of acidosis
Due to the large amount of fermentable carbohydrates and low contents of fibre, protein and mineral matter (which results in a weak buffering capacity), feeding fodder beet may cause acidosis though the risk is low. Dry matter intake should not exceed 0.8% LW (Dulphy et al., 2000; Enemark et al., 2002). They should be included progressively in the diet in order to acclimatize the rumen flora to a sucrose-rich feed. A fodder beet-based diet should be balanced with fibrous forages such as hay (ADBFM, 2009). Ketosis can also result from feeding excessive amounts of fodder beet (Dulphy et al., 2000).
The fill value of a low-DM fodder beet is lower or comparable to that of fresh grass, silage or hay, while the fill value of high-DM fodder beets is even lower and comparable to that of concentrate feeds (INRA, 2007).
Digestibility and energy value
Fodder beet is highly digestible: OM digestibility is in the 87-90% range (Dulphy et al., 2000), although a value of 96% has been reported (Sabri et al., 1988). The values for lactation NE are about 7.9-8.2 MJ/kg DM (INRA, 2007; Donosa, 2010), similar or higher than those of cereal grains. However, a DM intake of fodder beet higher than 0.5% LW slightly depresses digestibility and the energy value, the lactation NE dropping to 7.1 MJ/kg DM. Roots that have been insufficiently cleaned contain large amounts of mineral matter that decrease their energy value (Dulphy et al., 2000).
An in vitro study concluded that the larger amounts of substrate fermented with fodder beet have a potential to supply more energy for microbial synthesis than a barley/oat grain mixture or raw potatoes. The replacement of a barley/oat grain mix by fodder beet did not result in a decreased supply of glucogenic substrates, and fodder beet facilitated microbial growth (Eriksson et al., 2004b; Eriksson et al., 2004c).
The protein content of fodder beet is low and beet protein is quite soluble (N effective degradability of 85%) (INRA, 2007). Nitrogen supplementation is therefore necessary (Dulphy et al., 2000). Fodder beet can help to control an excess of dietary protein. Supplementing dairy cows fed alfalfa/grass silage with fodder beet resulted in a lower concentration of milk urea and in a lower urea:creatinine ratio in the urine (Eriksson et al., 2009).
Fodder beets are valuable for dairy cows. Lactating dairy cows can be fed with 20 kg/d of fresh fodder beets (about 3-4 kg DM). A 1-week transition with 1 kg (DM) of fodder beets is recommended (ADBFM, 2009). Diets with 3 or 6 kg (DM) of fodder beets can support a milk production of 30 kg/d (Dulphy et al., 2000).
Many studies have reported that the inclusion of fodder beets increases the fat and the protein contents of milk. This effect is particularly notable with diets based on forages such as grass silage and hay that tend to give low milk fat and protein. The effect is small when fodder beets are included at less than 0.8% LW (DM basis) in the diet, and insignificant when fodder beets supplement maize silage (Dulphy et al., 2000). In lactating cows, the inclusion of fodder beet in the diet reduced silage DM intake but resulted in an increase in total DM intake and estimated ME intake. It had no significant effect on milk yield, though it increased milk protein content and milk energy output. However, milk energy output expressed as a proportion of ME intake was significantly reduced (Ferris et al., 2003). Fodder beets tended to decrease the milk yield and the energy corrected milk yield was lower whereas the composition of the milk was unaffected compared to a total mixed ration with barley (Mogensen et al., 2003).
The milk of dairy cows fed on hay and fodder beet roots basal diet has generally high undesirable saturated fatty acid content (Collomb et al., 2004). Milk fatty acid profile could be enhanced by supplementation of basal diet (hay ad libitum and 15 kg fodder beet roots) with either 1 kg ground rapeseed, or 1.4 kg ground linseed, or 1 or 1.4 kg ground sunflowerseed (Collomb et al., 2004).
Fodder beet can be associated with potatoes. However, in lactating cows, compared with barley, a mix of fodder beet and potatoes (80:20) appeared to reduce silage intake, relative to the control diet, and decreased milk production by a magnitude corresponding to the resulting lower intake of ME (Eriksson et al., 2004a).
Suckler cows can be given 30-40 kg/d of fresh fodder beet (4-6 kg DM) but the amount should not exceed 10% LW (ADBFM, 2009).
Lactating ewes can eat 4-7 kg/d of fresh roots (0.6-1 kg DM) though the precise amount depends on the animal requirements. A four-week adaptation period (with 1 root per day) is recommended. Older ewes should be fed chopped roots (ADBFM, 2009).
Lactating goats can be fed 4-5 kg/d of fresh fodder beet (0.6-0.75 kg DM). Gestating animals can eat 1 kg/d of fresh roots (ADBFM, 2009).
Fodder beet in organic farming
Like other root crops, fodder beet might be of good value in organic dairy farming, assisting with energy supply as well as nitrogen balance. It could also be beneficial by reducing the amount of potential human food used in animal feeding (Eriksson, 2000).
Fodder beet in the tropics
Fodder beet is a relatively uncommon crop in tropical and subtropical countries, but it could be useful in periods of feed scarcity. In Sudan, a trial comparing fodder beet (a mixture roots and tops) and sorghum forage concluded that fodder beet had a higher nutritive value (lower crude fibre, higher protein and ME), which was reflected in the lower DM intake and equal or superior milk yields by cows fed on beet roots without any adverse effects. Feeding cost was also much lower (Khogali et al., 2011).