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Cotton straw and cotton crop residues

Datasheet

Description
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Common names 

Cotton straw, cotton stalks, cotton stems, cotton wood, cotton sticks, cotton forage, cotton crop residues

Description 

The cotton harvest leaves several residues in the field, such as stalks, side branches, leaves, bolls, and seeds with adhering cotton lint (Wuren Huang et al., 2012). The amount of cotton crop residues, known under various names (e.g. cotton straw, cotton sticks, cotton wood) can range from 5 to 7 t/ha (Silanikove et al., 1986). As often happens with crop residues, the quality of the material is highly variable. For instance, cotton crop residues are usually dry but some varieties grown under irrigation contain about 30% green leafy foliage even at the time of last picking of cotton (Narasa Reddy et al., 1985). Cotton crop residues are abandoned as waste, but are often incinerated or ploughed into the soil as they may host insects that can infest the next cotton crop (El Saeidy, 2004; Wuren Huang et al., 2012; Silanikove et al., 1986). Cotton crop residues have been used as organic fertilizers for soil amendment and were shown to improve micro-organism activity and increase seedling growth (Wuren Huang et al., 2012). Cotton wood (the thicker stems) is used as firewood (Suttie, 2000). In Egypt, cotton stalks are transformed into briquettes for fire (El Saeidy, 2004). Cotton stalks, leaves and unripe bolls may be grazed or taken to the homestead, chopped and dried for winter feed (Suttie, 2000). Cotton crop residues are readily browsed by small ruminants. However, they should not be fed to livestock if pesticides residues in the plant are above the maximum residue levels (MRL) determined by national or supranational authorities (see Potential constraints on the "Nutritional aspects" tab).

Distribution 

Cotton crop residues are available next to cotton harvest and processing areas.

Processes 

Many processes have been tested to improve the nutritive value of cotton crop residues with varying results. Ammonia treatment and pelleting were shown to increase intake and nutrient digestibility in calves (Narasa Reddy et al., 1985). Pelleting or chopping increased intake in bulls (Flachowsky et al., 1981). Treatment with CaO or NaOH improved in vitro DM digestibility (Silanikove, 1994). Ozone treatment reduced by half the amount of lignin and increased in vitro OM digestibility by 100% (from 30% to 60%) but the effect of NH4OH treatment was less remarkable (Ben-Ghedalia et al., 1980). However, treatment with NH3 or NaOH failed to improve OM digestibility in sheep (Flachowsky et al., 1981).

Environmental impact 

In cotton-growing countries, cotton crop residues are considered as an ecological burden (Ben-Ghedalia et al., 1980).

Nutritional aspects
Nutritional attributes 

Cotton crop residues are a poor quality and fibrous by-product with a low crude protein content (4-10% DM) and high fibre content (NDF up to 80% DM, ADF > 60% DM, lignin 14-19% DM). However, high variability can be expected depending on the respective amounts of green leaves, dry leaves, stems, bolls and other parts in the specific sample.

Potential constraints 

Pesticides residues

The cotton plant is susceptible to many diseases, pests and weeds, thus large amounts of pesticides and herbicides are required throughout the growing season. Many of the chemicals used are labeled as “Do not feed to livestock any crop material that has had this chemical applied” (Buser, 2001). When cotton crop residues are intended for animal feeding, the crop should not be treated or the chemicals contained in the plant should remain below the MRL provided by national or supranational authorities. For example in Australia, 9 chemicals (Chlorpyrifos, Cypermethrin, Ethion, Dimethipin, Metolachlor, Parathion-methyl, Pirimicarb, Propaquizafop, Pyrithiobac-sodium) are listed as a potential danger to livestock and the corresponding MRLs are available in relevant Tables for feed commodities (APVMA, 2012). The MRL for cotton fodder provided by the Codex Alimentarius only deals with Indoxacarb, whose MRL is 20 mg/kg dry cotton fodder (Codex Alimentarius, 2013).

Ruminants 

Cotton crop residues are sometimes used to feed cattle and sheep, notably in cotton producing countries such as India and Egypt. These residues are of poor nutritive value. A low OM digestibility value (37%) has been reported in sheep, both for unprocessed cotton straw or after treatment with ammonia or NaOH (Flachowsky et al., 1981). A comparison between various crop residues found cotton crop residues to have a very poor DM degradability (7%), much lower than that of maize stover (37%) (Rao et al., 1995). For that reason, cotton crop residues are not used as a sole feed and various processes have been proposed, including mechanical processes (grinding, extrusion-pelleting), chemical treatments (NaOH, NH3, CaOH, ozone), and biological treatments (ensiling, treatment with fungi) in order to improve intake and nutritional value. However, the improved performance and revenue may not compensate the cost of these treatments. 

Cattle

Growing calves

Ground cotton straw included as the only roughage source (40%) in a complete diet with concentrate (60 %) was fed to growing young (6-9 months) crossbred calves (74 kg) for 180 days. The average DM intake of the diet was 108 g/kg W0.75 and the daily weight gain 627 g/d. When ground cotton straw was processed with an expander-extruder pelletizer before being included at the same level into the diet, both DM intake and daily weight gain increased: 113 g/kg W0.75 and 815 g/d respectively. When ground cotton straw was offered separately with concentrates, DM intake and daily weight gain (97 g/kg W0.75 and 465 g/d respectively) were lower than when cotton straw was included into the diet. The results indicated that the unprocessed cotton straw was less palatable and had a slower rate of passage through the rumen than the processed straw (Kirubanath et al., 2003).

When cotton straw was used as the sole roughage (45%) in a total mixed ration offered to calves (158 kg), pelleted cotton straw significantly increased DM and OM digestibility of the diet compared to ground material (53 and 54% vs. 50 and 51% respectively), but not the digestibility of the fibre fractions (NDF, ADF). Ground cotton straw treated with ammonia included (45%) in a complete diet significantly increased DM intake (2.7-2.8% of body weight) and daily weight gain (930-974 g/d) compared to untreated cotton straw (2.6% live weight and 796-878 g/d) (Narasa Reddy et al., 1985).

Gestating cows

Cotton crop residues can be grazed (cotton lint and leaves and to a lesser extent stalks) by dry gestating cows allowing them to maintain live weight and body condition score until the lint and leaves are fully consumed. When animals start to lose weight or body condition score, they have to be removed from the field. It can be assumed that about 0.4 ha can maintain dry cows for 30 to 40 days (Stewart, 2010).

Dairy buffaloes

In dairy buffaloes, expanded cotton straw fed for 180 days at 30% of a complete pelleted diet, in which it was the sole roughage, was compared to a conventional diet based on concentrate and sorghum straw. Dry matter intake and milk yield were similar but the diet containing expanded cotton straw gave the higher milk fat content (Nagalakshmi et al., 2004).

Sheep

Cotton straw (ground or as expanded-extruded pellets) was included (50%) in a complete diet with concentrates for sheep (28.3 kg) and compared to ground cotton straw offered separately with concentrates. Dry matter intake was higher with expanded extruded pellets (4.8% live weight), or when ground and mixed into the diet (3.9%), than when offered separately (3%) (Kishan Singh et al., 2003). Ensiling of cotton stalks treated with fungi (oyster mushroom Pleurotus ostreatus) increased the protein content, decreased fibre content and improved nutrient digestibility in rams (Hamza et al., 2006).

Nutritional tables
Tables of chemical composition and nutritional value 

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 75.7 31.2 40.0 97.7 3  
Crude protein % DM 6.4 2.3 3.5 9.6 7  
Crude fibre % DM 55.4 11.2 43.0 64.9 3  
NDF % DM 77.2 3.9 72.2 81.2 4  
ADF % DM 64.5 3.0 60.4 67.5 4  
Lignin % DM 16.8 1.9 14.1 18.7 5  
Ether extract % DM 1.7 1.0 0.7 3.0 7  
Ash % DM 7.6 2.5 4.2 11.1 7  
Gross energy MJ/kg DM 18.8         *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 8.9 1.5 6.7 10.2 4  
Phosphorus g/kg DM 2.9 2.6 1.2 6.7 4  
               
In vitro digestibility and solubility Unit Avg SD Min Max Nb  
OM digestibility, pepsin % 29.9   29.6 30.1 2  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 37.2       1  
Energy digestibility, ruminants % 34.0         *
DE ruminants MJ/kg DM 6.4         *
ME ruminants MJ/kg DM 5.1         *

The asterisk * indicates that the average value was obtained by an equation.

References

Ben-Ghedalia et al., 1980; Flachowsky et al., 1981; Grewal et al., 2003; Hamza et al., 2006; INFIC, 1978; Kirubanath et al., 2003; Silanikove et al., 1986; Silanikove, 1994

Last updated on 18/11/2013 00:34:53

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 27.3       1  
Crude protein % DM 12.2   12.1 12.3 2  
Crude fibre % DM 9.5   7.8 11.1 2  
ADF % DM 15.4       1  
Lignin % DM 6.5       1  
Ether extract % DM 9.5   9.3 9.7 2  
Ash % DM 9.1   3.8 14.4 2  
Gross energy MJ/kg DM 19.0         *
               
In vitro digestibility and solubility Unit Avg SD Min Max Nb  
OM digestibility, pepsin-cellulase % 64.7       1  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 89.7          

The asterisk * indicates that the average value was obtained by an equation.

References

CIRAD, 1991; Mecha et al., 1980

Last updated on 18/11/2013 00:31:34

References
References 
Datasheet citation 

Heuzé V., Tran G., Hassoun P., 2015. Cotton straw and cotton crop residues. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/744 Last updated on October 20, 2015, 14:59

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)
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