Gossypium spp.

Cotton

The husk is sometimes separated from the kernel before crushing, but often the whole seed is extracted for oil. Undecorticated oilcake is much richer in fibre and lower in protein. The term "Egyptian cotton cake" refers to the undecorticated cake of black seeds, and "Bombay cotton cake" is the term used for the undecorticated cake of white seeds. The cotton fibres of white seeds cover the whole surface and are very difficult to remove; if the cottonseed cake is broken, the fibres can be seen. 

For every ton of lint in seed cotton there are approximately 1.7 tons of cottonseed. One ton of seed yields about 200 kg of oil, 500 kg of cottonseed meal and 300 kg of hulls. The residual oil in hydraulic-press cake is usually between 4% and 8%, in screw-press cake between 3% and 5%, and in solvent-extracted meal less than 3%. 
 

GOSSYPOL. The seed embryo contains innumerable glands filled with a yellow pigment called gossypol. McDonald et al. (553) state that cotton seeds may contain from 0.3-20 g/kg DM of gossypol, and concentrations of 4-17 g/kg DM have been quoted for the kernels. Gossypol is a polyphenolic aldehyde which is an antioxidant and polymerisation inhibitor and is toxic to monogastric animals: pigs and rabbits are the most sensitive, whereas poultry are more tolerant. The general symptoms of gossypol toxicity are constipation, depressed appetite and loss of weight; death usually results from circulatory failure. Although acute toxicity is low, ingestion of a small amounts over a prolonged period can be lethal. It is important to distinguish between free (soluble in 70-30 v/v aqueous acetone) and bound gossypol since only the former is considered to be physiologically active. 

The free gossypol content of cottonseed meal decreases during processing and varies according to the methods used. In new seed, free gossypol accounts for 0.4-1.4% of the weight of the kernel. Screw pressed materials have 200-500 mg free gossypol/kg, pre- 

pressed solvent extracted meals 200-700 and solvent extracted 

1000-5000 mg/kg. Processing conditions have to be carefully controlled to prevent loss of protein quality owing to binding of gossypol to lysine at high temperatures. Fortunately the shearing effect of the screw press in the expeller process is an efficient gossypol inactivator at temperatures which do not reduce protein quality. 

It is generally considered that pig and poultry diets should not contain more than 100 mg free gossypol/kg and that inclusions of cottonseed meal should be between 50-100 kg/t of feed. Particular care is required with laying hens since comparatively low levels of the meal may cause an olive green discoloration of the yolk in storage. An associated pink discoloration of the albumen is now considered to be due to cyclopropenoids and not gossypol as was once thought. Treatment with ferrous sulphate can ameliorate the biological effects of gossypol; the amount of iron to be added is largely empirical. To reduce the effects of gossypol on growth, the following proportions of iron to free gossypol have been used: for cattle 1:1, for broilers 2:1, for layers 4:l and for pigs 1:1. 

Mature ruminant animals do not show ill-effects even when they consume large quantities of cottonseed meal but young cattle are much more susceptible to its toxic effects. 

USES 

COTTONSEED MEAL or COTTONSEED CAKE. 

Cottonseed meal is an excellent protein supplement for cattle. The limitations on effective utilization of this product in rations for swine and poultry are of minor significance for ruminant animals. 

Both decorticated and undecorticated cottonseed meal have a constipating effect on cattle, which is beneficial in feeds with a high molasses content. Calves are susceptible to the harmful effects of gossypol because of incomplete rumen development; hence it is recommended that concentrates for calves under five months of age contain no more than 10-15% cottonseed meal. 

Cottonseed meal has a relatively low rumen degradability and is therefore a good source of by-pass protein and especially useful in rations for milking cows. 

With Creole and crossbred village cows in Mauritius (normal milk yield 4-5 litres), Boodoo et al. (573) reported that producers obtained over 9 litres milk/day over 300 days with peak milk yield at 12 litres/day, by supplementing sugarcane tops and roadside grasses with 0.25 kg cottonseed cake/litre milk. The results were the same as those obtained with 0.5 kg/litre of commercial compound feed (17% CP). 

Cottonseed meal can be used safely and profitably in pig rations. Rations containing up to 0.01% free gossypol can be used without the addition of iron salts. On the basis of a typical analysis this means that the safe upper limit for a good screw-press or prepress solvent meal is about 20% and for direct solvent-extracted meal about 5%. Over these levels, iron must be added in a 1:1 weight ratio to free gossypol. 

Cottonseed meal can also be used in rations for growing chickens if the free gossypol does not exceed 0.03%. Below this level, iron (2:1 iron to free gossypol) will completely overcome the depressing effect. As cottonseed is low in lysine, it may be necessary to make up for this deficiency by adding lysine. Prepress solvent-extracted meal may be used in layer feed if the gossypol has been inactivated with iron (4:1 iron to free gossypol), if the free gossypol content is not above 0.4%. 

As determination of the amount of free gossypol in a meal requires laboratory facilities, ferrous sulphate may routinely be added to diets containing cottonseed meal. For instance, for layers 0.05% iron (corresponding to 0.25% ferrous sulphate septahydrate) can routinely be included in diets containing up to 10% cottonseed meal and up to 0.16% iron in rations containing greater amounts. Broilers cannot tolerate more than 0.07% iron in the diet. 

WHOLE COTTONSEED 

Whole cottonseed may be used as a feed for mature cattle, as is often done where proper milling equipment is not available. It is usually soaked in water and fed in small quantities as a supplement to green feed. 

Compared to the extracted meal, it has a lower protein content and a much higher oil content. High levels may cause scouring. The degradability characteristics of the protein should be similar. Delinting of FUZZY WHOLE COTTONSEED to DELINTED WHOLE COTTONSEED results in a higher protein and fat content and lower fibre content. 

Neill et al. (574) report the use of up to 20-30% WCS in intensive finishing rations for Brahman-cross steers. Although OM digestibility declined, intake was unaffected and LWG maintained 0.86 kg/day. They advise that WCS can be used without detriment to at least 20% in finishing diets, as a total feed during drought and for male animals (rams) without affecting libido. No evidence of gossypol toxicity was found but they suggest caution when feeding WCS to young stock. 

By treating with 5% ferrous sulphate solution, it can safely be included in small quantities in pig rations. 

COTTONSEED HULLS 

Cottonseed hulls are the parts of the cottonseed head that is left after the cotton and meal have been extracted and are normally considered to be a very low quality feed for ruminants. The results of two recent trials have shown that they 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 (567) 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 (567). 

Norbaev (568) reports problems of hepatosis associated with the feeding of cottonseed husks in Russia. Meat inspection of 1004 Karakul sheep slaughtered in Uzbekistan revealed hepatosis in 41%, cirrhosis in 10.7% and multiple abscesses of the liver in 3.7%. In a feeding experiment on 30 sheep, in which the daily ration comprised 2 kg cotton husks, 0.5 kg oatmeal and 0.2 kg lucerne hay. Liver disease developed within 2 months. Values for blood albumin and glucose were low. 

As cotton hulls are available at the mills where the meal is produced, mixtures of meal and hulls can be bought. An economical fattening ration for cattle is 20% meal and 80% hulls, together with 3-4 kg of grass daily and a mineral supplement. 

Various experiments with dairy cows cited by Coppock et al. (569) show that the roughage value of CSH is better than grass hays and nearly equal to high quality bermudagrass but inferior to mixed clover hay. There is no effect when CSH is substituted for corn or barley. There is some evidence that CSH fibre maintains milk and fat yield even when DM digestibility of the diet declines as a result of substitution of CSH for lucerne hay (570). In some diets, CSH may have a special value because of a stimulatory effect on feed intake, not through improvement in digestibility. 

Cottonseed hulls have frequently been included in complete diets for young, growing and lactating cattle. Replacement of rice bran with up to 20% CSH did not effect the milk yield or fat content of Murrah buffaloes (571). 

One novel application is reported by Yang et al. (572) of the feeding of cottonseed hulls to pigs in China, 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. 

COTTON WOOD 

Cotton wood is also used in some countries as a cattle fodder. Stems, branches and leaves can be ground, ensiled or hydrolysed with sodium hydroxide for feeding to beef cattle. 
 

					As % of dry matter
				DM	CP	CF	Ash	EE	NFE	Ca	P	Ref
Whole seeds, India				94.3	20.6	21.5	4.9	20.1	32.9			378
Whole seeds, Egypt				91.2	21.5	23.2	5.5	26.2	23.6			512
Bombay cotton cake				87.7	23.0	24.7	6.6	5.5	40.2			"
Egyptian cotton
cake				87.9	26.4	24.2	6.6	5.7	37.1			"
Oilcake with hulls,
mechanically extr-
acted, Israel				91.4	26.9	24.0	5.0	6.8	37.3	0.22	0.63	365
Oilcake with hulls,
mechanically extr-
acted, Uganda				88.0	26.2	25.6	6.2	5.7	36.3			69
Oilcake with hulls,
mechanically extr-
acted, Zimbabwe				94.5	30.5	7.9	7.0	7.6	47.0			499
Oilcake without
hulls, mechanically
extracted, Israel				92.3	47.7	12.5	6.6	5.4	27.8	0.22	1.34	365
Oil meal without
hulls, solvent
extracted, Iraq				94.3	40.3	15.7	6.8	0.6	36.6	0.31	1.11	182
Oil meal without
hulls, prepress
solvent extracted,
USA				89.9	46.1	15.1	7.1	0.7	31.0	0.17	1.36	452
Cottonseed hulls,
West Indies				86.2	13.9	30.0	3.6	8.8	43.7			191
Cotton wood,
Venezuela					5.3	64.9	8.1	0.9	20.8			537
							Digestibility (%)
					Animal		CP	CF	EE	NFE	ME	Ref
Seeds, Indian variety					Cattle		68.4	21.6	91.2	22.2	2.46	378
Seeds, Egyptian variety					Sheep		68.4	75.9	86.6	49.8	3.45	512
Bombay cotton cake					Sheep		77.2	20.3	93.8	53.7	2.13	"
Cake with hulls,
expressed					Sheep		75.0	38.0	95.0	66.0	2.59	365
Cake with hulls,
expressed					Cattle		72.0	57.0	91.3	80.4	3.02	499
Cake without hulls,
expressed					Sheep		83.0	45.0	97.0	74.0	3.06	365
Hulls					Sheep		0.0	49.0	78.0	43.0	1.74	"
					Nylon bag degradability
						a	b	c		12hr	48hr	Ref
						(%)	(%)	(/hour)		(%)	(%)
Whole cotton seed, Ghana					DM	21.2	53.0	0.0320			62.8	627
Cotton seed, Korea					DM	27.1	41.7	0.0398			60.6	"
Cotton hulls, Brazil					DM	2.8	51.0	0.0098			13.0	"
	[P (rumen degradability at time t) = a+b*(1-exp(-c*t))]
		Amino acid composition as % of crude protein
Oilcake											Ref	452
Arg	Cys	Gly	His	Ils	Leu	Lys	Met	Phe	Thr	Try	Tyr	Val
11.1	1.5	4.1	2.6	3.2	5.9	4.1	1.3	5.4	3.2	1.1	2.7	4.5

References

69, 182, 191, 365, 378, 400, 452, 499, 512, 537, 553, 567, 568, 569, 570, 571, 572, 573, 574, 627