Description and recommendations
Cottonseed hulls, cotton seed hulls, cotton hulls
Cottonseed hulls are the outer coverings of cotton seeds, and the by-product of the dehulling step of cottonseed oil extraction. After delinting, the hulls are separated from the kernel by screening. Cottonseed hulls are a fibrous product, primarily used to feed ruminants (Hall et al., 2000). Cottonseed hulls are used for feed in bulk or pellet form. They are sometimes mixed with cottonseed meal to create a higher density product that is easier to transport and handle (Blasi et al., 2002). Cottonseed hulls are one of the best roughages used to add bulk to diets rich in protein and energy, in order to reduce digestive upsets in ruminants (Lane, 2006). Cottonseed hulls are a valuable substrate for mushroom cultivation and the spent substrate can be fed to livestock (Bae et al., 2006; Miles et al., 2004; Yang et al., 1986). Cottonseed hulls have also numerous industrial uses such as plastic manufacture, oil drilling (mud additive) and furfural production (a solvent used in plastic and synthetic rubber production and in petroleum refining) (NCPA, 2011).
Cottonseed hulls are available at the mill where cottonseed oil and cottonseed meal are obtained. Due to their low density, they may be difficult to transport and are thus confined to a fairly restricted market radius (Blasi et al., 2002). They can be prepared in mixture with cottonseed meal. In the USA, the use of cottonseed hulls in pellets increased in the late 1990s (Coombs et al., 1996). The demand for hulls and the prices vary considerably with changes in the availability of other roughage feeds (NCPA, 2011).
Cottonseed hulls used in complete mixed rations for dairy cows were shown to reduce greenhouse gas (CH4) production (Bo et al., 2012).
Cottonseed hulls do not contain significant amounts of free gossypol: reported values are lower than 0.1% DM (Mujahid et al., 2000b; Noftsger et al., 2000), about ten times less than in the seed itself (see the Cotton seeds datasheet). Consequently, feeding animals with cottonseed hulls is less likely to result in negative effects due to gossypol. However, there has been several reports on the risk of feeding cottonseed hulls to livestock. When cottonseed hulls were fed to fattening lambs for a long period (8 months), it was found that gossypol accumulated in testis, liver, kidney, spleen and muscle (in order of decreasing content) (Tuerxhun et al., 2010). Meat inspection of 1004 Karakul sheep slaughtered in Uzbekistan in the late 1980s revealed hepatosis in 41% of the cases, cirrhosis in 11% and multiple abscesses of the liver in 4%. In a trial on 30 sheep fed 2 kg/d of cottonseed hulls, liver disease developed within 2 months and values for blood albumin and glucose were low (Norbaev, 1989). In pigs, several poisoning incidents (mortality up to 30%) have been reported in Russia in pig farms following the feeding of cottonseed meal and cottonseed hulls (Tishkov et al., 1988).
Cottonseed hulls contain condensed tannins (3-7% DM) mainly bound to protein and fibre (Yu et al., 1996). However, it seems that the condensed tannins of cottonseed hulls do not significantly reduce the rumen protein solubility (Yu et al., 1995a; Yu et al., 1995b).
Cottonseed hulls are a low-protein (3-9% DM), highly fibrous by-product (ADF 57-73% DM) mostly used for ruminant feeding.
Tables of chemical composition and nutritional value
Cottonseed hulls are used in ruminant feeding in areas of cotton growing. They are palatable compared to other fibrous by-products and have a stimulatory effect on feed intake in diets with limited fibre content. They were shown to increase intake compared to sunflower hulls and peanut hulls (Coppock et al., 1987).
Cottonseed hulls have been included at various levels (5 to 50%) into total mixed rations or complete feeds for lactating dairy cows (Klopfenstein et al., 1981; Blasi et al., 2002). When compared to other fibrous by-products (sunflower hulls, sugarcane bagasse) or forages (Bermuda grass, maize silage, sorghum silage or sugar cane silage), cottonseed hulls generally give the same or higher milk yield and higher milk fat content (Klopfenstein et al., 1981).
For dairy cows, cottonseed hulls are a valuable fibre source when introduced into diets with high starch content because they slightly increase diet intake and nitrogen retention (Beckman et al., 2005), improve starch digestion by increasing rumination, and reduce the amount of whole maize passing through the digestive tract (Blasi et al., 2002). They tend to increase the milk fat content without modifying the milk yield (Beckman et al., 2005). However, as cottonseed hulls have a low protein content, diets that include them must be carefully balanced in crude protein (particularly when high levels of hulls are used). Cottonseed hulls can be included into complete feeds in a pelleted or non-pelleted form without any difference in milk yield (Brown et al., 1977).
The following table summarizes several experiments in the USA:
|Increasing levels of pelleted cottonseed hulls in place of alfalfa hay cubes||5, 15 or 25%||No difference in milk yield (23-24.4 kg/d) and fat and protein content (2.9-3.2% and 2.7-2.9% respectively)||Brown et al., 1977|
|Comparison of two levels of cottonseed hulls in TMR||30 or 40%||Slight decrease of DM intake (20 kg vs 21 kg) and increase of milk fat content (3.2% vs 2.7%) at 40% level; same milk yield (22 kg/d)||Olson et al., 1975|
|Comparison of cottonseed hulls to maize silage in TMR||30%||Lower diet DM digestibility with cottonseed hulls (59 to 64%) but higher milk yield (23.4 to 20.5 kg/d)||Sargent et al., 1975|
|Comparison of two levels of cottonseed hulls into TMR based on maize grain and soybean meal||30 or 40%||No difference in DM intake (20 kg/d) or milk yield (19 kg/d); higher milk fat content with 40% cottonseed hulls (3.38 vs 3.16%)||Olson et al., 1974|
In Brazil, cottonseed hulls could replace up to half of Pennisetum purpureum silage (60% in the diet) in a complete diet for fattening steers, increasing the daily DM intake from 6.6 kg to 8.3 kg without altering DM digestibility (54-55.6%) (Chizzotti et al., 2005).
In India, feeding complete diets based on cottonseed hulls (60%) to crossbred calves improved growth rate, feed conversion efficiency and nutrient utilization over complete diets based on wheat straw. Flaking did not improve nutrient utilization and growth but increased bulk density, which may reduce the cost of handling, transportation and storage (Ramachandran et al., 2008).
In India, crossbred bulls fed cottonseed hulls at 50% (diet DM) or a mixture of cottonseed hulls (35%) and alfafa hay (15%) supplementing a diet based on chopped sorghum straw had higher nutrient digestibilities and DM intake than bulls fed a conventional diet (concentrate + straw) (Reddy et al., 1999).
In the USA, cottonseed hulls could be used as forage source (20 or 25%) instead of alfalfa hay in a complete diet for 325 kg fattening steers (Bartle et al., 1994) or 200 kg growing beef heifers (Hale et al., 1969) without change in daily weight gain of steers and heifers (1560 g/d and 670 g/d respectively), but with a higher DM intake (+ 0.8 kg/d and + 0.52 kg/d respectively). At a higher level (30%), DM intake increased (+ 0.5 kg/d) but daily weight gain decreased to 1445 g/d (Bartle et al., 1994). Adding molasses (9%) to cottonseed hulls into the growing beef heifer diets increased growth performance to 750 g/d (Hale et al., 1969). In another comparison between cottonseed hulls and alfalfa hay where steers were fed either feed at 8% (diet DM) for 103 days, steers fed cottonseed hulls had a lower average daily gain (1930 vs 2130 g/d) and showed a tendency to have fatter carcasses and a higher (less desirable) yield grade (Markham et al., 2002).
Replacement of rice bran with up to 20% cottonseed hulls did not effect the milk yield or fat content of Murrah buffaloes (Naidu et al., 1981).
Cottonseed hulls are capable of supporting moderate growth rates in sheep. When a small amount of by-pass protein was added to the diet of cottonseed hulls + urea + 50 g lucerne + vitamins/minerals, the growth rate of lambs exceeded 130 g/day and wool growth was increased from 6 to 9 g/day. Investigation of the rumens of these animals showed that protozoa were either eliminated or in very low population densities. This could be the reason why cottonseed hulls support such reasonable growth rates, even without supplementation with by-pass protein. Intake of cottonseed hulls by sheep is higher (c. 1 kg DM/day) than would be expected of a 40% digestible feed and this is possibly associated with a rapid breakdown of the indigestible material in the rumen (Davis et al., 1989).
In Benin, the full or 50% replacement of cottonseed meal with a 60:40 mixture of cottonseed meal and cottonseed hulls to supplement Guinea grass-based diets for fattening Djallonke sheep (1 year, 18 kg) for 60 days was found to give similar performance (carcass yield and characteristics) and resulted in a net profit (Alkoiret et al., 2007).
In China, cottonseed hulls could replace the fibre source in a complete diet for fattening 3 months old sheep, resulting in the same daily weight gain and better carcass characteristics after 8 months (Tuerxhun et al., 2010)
In China, pigs were offered cottonseed hulls after use as a growth medium for 4 harvests of mushrooms (Pleurotus sp.). The optimum dose was 10% of the diet mixed with concentrates, which gave the same growth rate and carcass quality as a control diet (Yang et al., 1986).
Cottonseed hulls can be assumed to be a suitable fibre source for rabbit feeding even though no direct experiment seems to have been reported in the literature (October 2013). This assumption is based on the safe utilisation in ruminant feeding up to 20% of the diet (see Ruminants). This position is reinforced by the negligible level of gossypol observed in the cottonseed hulls even for cotton varieties with a high level on gossypol in the kernel (Yu et al., 1993). The resistance of hulls to the development of mould contamination through Aspergillus flavus and subsequent very low risk of aflatoxins development is another positive point (Mayne et al., 1966). The high level of lignin in cottonseed hulls (18-20%) should be also considered as an advantage for the control of digestive health in the rabbit (Gidenne et al., 2010).
The digestible energy content of cottonseed hulls could be estimated using equations as 5.7 MJ/kg DM and the protein digestibility as about 22% (Lebas, 2013).
Tables of chemical composition and nutritional value
|Dry matter||% as fed||90.6||1.8||87.4||93.3||18|
|Crude protein||% DM||5.1||1.6||2.6||8.7||35|
|Crude fibre||% DM||53.0||7.5||35.0||64.8||21|
|Ether extract||% DM||3.2||1.9||1.0||8.1||16|
|Starch (polarimetry)||% DM||4.2||1|
|Gross energy||MJ/kg DM||19.8||0.4||18.3||19.8||3||*|
|Aspartic acid||% protein||19.7||1|
|Glutamic acid||% protein||8.3||1|
|Tannins, condensed (eq. catechin)||g/kg DM||51.5||51.0||52.0||2|
|Gossypol, free||mg/kg DM||430||191||160||680||12|
|Ruminant nutritive values||Unit||Avg||SD||Min||Max||Nb|
|OM digestibility, ruminants||%||42.9||7.2||36.9||50.9||3|
|Energy digestibility, ruminants||%||41.1||*|
|DE ruminants||MJ/kg DM||8.2||*|
|ME ruminants||MJ/kg DM||6.5||*|
|ME ruminants (gas production)||MJ/kg DM||6.6||6.1||7.1||2|
|ME ruminants (FAO, 1982)||MJ/kg DM||7.3||1|
|Nitrogen digestibility, ruminants||%||2.6||27.6||-30.9||36.4||4|
|Nitrogen degradability (effective, k=4%)||%||20||16||24||2||*|
|Nitrogen degradability (effective, k=6%)||%||16||13||20||2||*|
|Rabbit nutritive values||Unit||Avg||SD||Min||Max||Nb|
|DE rabbit||MJ/kg DM||5.7||*|
|Nitrogen digestibility, rabbit||%||22.0||*|
The asterisk * indicates that the average value was obtained by an equation.
AFZ, 2011; Alibes et al., 1990; Ashes et al., 1978; Beckman et al., 2005; Bhatti et al., 1995; Bo et al., 2012; Brown et al., 1977; Chizzotti et al., 2005; CIRAD, 1991; CIRAD, 2008; Garleb et al., 1988; Gartner et al., 1975; Göhl, 1970; Gowda et al., 2004; Hale et al., 1969; Henderson et al., 1984; Hsu et al., 1987; Krishna, 1985; Lirette et al., 1993; Mujahid et al., 2000; Neumark, 1970; Noftsger et al., 2000; Richard et al., 1989; Wheeler et al., 1979; Yu et al., 1995; Yu et al., 1995
Last updated on 19/11/2013 16:58:38
|Cottonseed hulls||Ella Liliane Mutuyimana / Kigali Farms, Rwanda||CC BY 3.0|
|Cottonseed hulls||Laurent Demuynck / Kigali Farms, Rwanda||CC BY 3.0|
|Bags of cottonseed hulls||Laurent Demuynck / Kigali Farms, Rwanda||CC BY 3.0|
|Cottonseed hulls for mushroom production||Laurent Demuynck / Kigali Farms, Rwanda||CC BY 3.0|