Sorghum bran is available in peri-urban areas in some African countries (Boitumelo, 1993). In Botswana, sorghum bran included at up to 25% in the diet of crossbred cattle was found to be a suitable by-product, able to improve the nutritive value of the diet in both the dry and the wet season (Boitumelo, 1993; Kiflewahid, 1988). Sorghum bran fed at 1 kg per kg milk with a basal diet of sorghum stover met the requirements of a cow (450 kg, 5 kg milk/day) suckling a calf (Mahabile et al., 2000).
Sorghum distillers’ grains
Most of the trials with sorghum distillers' grains have been carried out in the United States with feedlot steers and dairy cattle. The overall conclusion is that sorghum distillers’ grains have a nutritive value higher than that of maize grain for finishing beef cattle and lactating dairy cows, notably due to the higher content in protein and lipids (Al-Suwaiegh et al., 2002; Klopfenstein et al., 2008). They can be included at 15-30% in beef cattle diets (Al-Suwaiegh et al., 2002; Klopfenstein et al., 2008; May et al., 2010; Wood et al., 2011). Inclusion levels of 15% (Al-Suwaiegh et al., 2002) and 30% (Chiou et al., 1999) have been proposed for dairy cattle. An additional benefit of sorghum distillers is that their lower starch content reduces the incidence of acidosis when they substitute for grains (Al-Suwaiegh et al., 2002; Lodge et al., 1997). The OM digestibility of sorghum distillers is quite high, in the 74-81% range (Lodge et al., 1997), though a much lower value (45%) has been observed for a sample with a high lignin content (more than 25% DM) (Cavani et al., 1990). Wet distillers' grains are a good source of undegradable protein (Chiou et al., 1999). They can be fed in combination with urea and this mixture has a protein efficiency close to that of soybean meal (Waller et al., 1980).
When compared to corn distillers, sorghum distillers have a slightly lower or comparable feeding value (Al-Suwaiegh et al., 2002; Klopfenstein et al., 2008; May et al., 2010; Wood et al., 2011). In crossbred yearlings steers, wet or dried sorghum distillers’ grains included at 15% (diet DM) had no effect on meat quality (color, fatty acid profiles, lipid oxidation, tenderness and sensory attributes of the strip loins) compared to wet or dried corn distillers (Gill et al., 2008). Carcass characteristics of finishing yearling steers were similar with wet or dried corn distillers or sorghum distillers included at 30% (diet DM), but hot carcass weight was higher with distillers’-based diets than with rolled maize-based diets (Al-Suwaiegh et al., 2002). Sorghum dried distillers grains plus solubles can be included at 20% (diet DM), similar to corn DDGS, in grower and finisher diets, without negatively affecting overall growth or carcass traits. However, feeding sorghum distillers may reduce performance when maize silage based diets are fed, resulting in earlier fattening at a lighter body weight (Wood et al., 2011).
It should be noted that experimental results are not always consistent, due to variations in processes and extent of heat damage (Cavani et al., 1990). For instance, the inclusion of 15% sorghum wet distillers’ grain plus solubles in finishing diets decreased feed efficiency and in vitro DM digestibility when compared to maize-based diets (Leibovich et al., 2009). Sorghum distillers' dried grains with solubles improved the health status of shipping-stressed calves, but depressed performance when compared to a mixture of soybean meal and blood meal (Koevering et al., 1992). In particular, there may be differences between dry and wet sorghum distillers, and the feeding value may depend on the absence or presence of solubles (Lodge et al., 1997). The form (wet or dry) of sorghum distillers's grain did not affect DM intake, rumen pH, volatile fatty acids, and in situ digestion kinetics of NDF from distillers’ grains when fistulated cows were fed 15% distillers’ grains (Al-Suwaiegh et al., 2002). The input of water from fresh distillers’ grains (up to 30% of the diet) may reduce DM intake in dairy cows, but it has a positive effect on fibre digestion as it slows down the rate of passage through the rumen (Chiou et al., 1999). In a digestibility trial with lambs, dried sorghum distillers’ grains with solubles had a lower OM digestibility than wet distillers without solubles, which could be due to the possibly higher rate of passage of the smaller dried grains (Lodge et al., 1997). In finishing crossbred yearling steers, adding solubles to wet sorghum distillers (40% diet DM) did not modify feed efficiency and daily gain (Lodge et al., 1997).
In Taiwan, a maize-sorghum distillers’ grain silage fed with a concentrate to growing goats gave the same performance as alfalfa pellets but was more cost-effective (Su Ankuo et al., 2001).
Sorghum wine residue
When available, sorghum wine residue can replace the concentrate for growing goats (Hsieh Weinchang et al., 2002).
Sorghum gluten feed
Sorghum gluten feed can replace up to 30-50% of the grain in cattle diets (Göhl, 1982; Riggs, 1958).
Sorghum gluten meal
Sorghum gluten meal can replace equal amounts of cottonseed meal in cattle fattening rations (Riggs, 1958).