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Whole Cottonseed & Gossypol

Gossypol is a yellow-green polyphenolic compound found in the pigment glands of cottonseed which is toxic to animals. Ruminants are able to detoxify the free gossypol in the rumen to a certain extent however over-consumptions, irregular feeding and lack of substantial roughage in the diet can affect the ability of the animal to detoxify gossypol and the animal may suffer from toxicity as a result. Gossypol toxicity induces a disease syndrome in young, immature ruminants characterised by weakness, anorexia, poor growth and inanition that may resemble parasitic nutritional or infectious diseases. These clinical signs may appear in animals that have ingested gossypol from several weeks to four months. Following these initial signs, the affected animals may appear "pot-bellied" and convulse just prior to death. Deaths are often caused by pulmonary edema and heart failure (Bailey, Smith & Coppock 1996). It has also been known to have varying effects on fertility in male ruminants, especially bulls.

Free gossypol levels in whole cottonseed generally range from 0.55% - 1.6% in Australian varieties of cotton (Blackwood 2007). It is important to obtain a gossypol analysis of the whole cottonseed you intend to use as a drought feed so correct dosages can be fed to reduce the risks of gossypol toxicity.

Which livestock does it effect and how?

Bulls and rams:

Excess gossypol in the diets of bulls can cause reduced spermatogenesis and impaired sperm motility. Reduced sperm motility is associated with morphological aberrations of the sperm mid-piece. It has also been shows to damage the spermatogenic epithelium (Adams et.al 1998). Research states that young developing bulls (6-14 months of age) fed as little as 1.6g/day of free gossypol intake reduced sperm quality and damaged sperm producing tissues. Whole cottonseed in the diets of bulls has been found to reduce semen quality when compared to diets containing no gossypol. Effects were seen in immature, detached sperm heads and a decrease in the number and mobility of spermatozoa. It has been observed that it can take up to 6 weeks after gossypol is removed from the diet for semen to return to normal. Due to this, feeding whole cottonseed to bulls may have an effect on fertility at joining.

Experiments conducted on the effects of gossypol and cottonseed products on the reproductive performance of rams showed that there was extensive damage to the germinal epithelium in both rams and bulls fed diets containing gossypol (Randel, Chase & Wyse 1992). Toxicity in the rams was shown through a reduction in ejaculate volume, total sperm output, total functioning sperm fraction and serum concentrations of testosterone. Increased gossypol in the diet was also found to dramatically increase the percentages of total abnormal sperm, abnormal-head sperm and abnormal-tail sperm which ultimately could affect the sperms ability to fertilise the ova (El-Mokadem et.al 2012). These studies concluded that producers should severely limit the free gossypol intake of male ruminants to reduce any risks of impaired sperm cell development and functioning

There are currently no ?safe?۪ guidelines for how much gossypol can be fed to bulls and rams without affecting semen quality therefore it should be excluded from the diet for male ruminants for at least two months before joining and during the joining period. If your bulls are being fed whole cottonseed, it is highly recommended that no more than 0.5kg per head per day is fed to reduce any risks (Blackwood 2007) and no more than 50g per head per day for rams.

Cows and ewes:

The literature generally states that female ruminants appear to be more resistant to gossypol when compared to males. In vitro studies have shown some inhibition of embryonic development and ovarian steroidogenesis. In commercial operations it appears unlikely that gossypol intake affects reproduction in females (Adams et.al 1998). Research states that no more than 20-25g of free gossypol should be fed to cows, therefore assuming the whole cottonseed contains 1% free gossypol daily intakes of whole cottonseed should not exceed 2-2.5kg per head.

Calves and lambs:

Studies conducted on the effect of free gossypol on pre-ruminant male calves found that the calves exhibited dysponea, coughing and preferred a recumbent posture when fed diets for 90 days containing 400-800mg free gossypol. Severe inter mandibular swelling and jaundice was also noted and one of 12 calves fed 400mg of gossypol per kg of cottonseed and 4 of 12 calves fed 800mg/kg of gossypol died due to circulatory failure (Alexander et.al 2009).

As a result, calves less than 4 months of age (or less than 140kg) should not be fed whole cottonseed as only 10g/day of whole cottonseed would supply a toxic level of gossypol. Do not feed to calves that do not have a fully developed rumen i.e. less than 4 months of age. Calves that are from 5-12 months of age will have a functioning rumen however in drought conditions they should not be fed more than 2kg per head per day if they are under 200kg liveweight (Blackwood 2007).

The effects of gossypol toxicity on lambs has been tested on eight week old lambs were dosed orally with gelatine capsules containing 0, 45, 136 or 409mg free gossypol/animal for 30 days in order to study clinical and pathological effects of the feeding. All lambs at the highest dosage level died between day 19-30 of the experiment with sudden death or chronic dyspnoea. Lambs in the other groups survived and most of them appeared healthy and had satisfactory weight gains however at necropsy, many of the treated lambs had macroscopic lesions. They also showed excessive pericardial and thoracic fluid, heat degenerations, generalised icterus and oedematous lungs (Alexander et.al 2009).

Therefore, lambs less than 5 months of age should not be fed whole cottonseed as even though they may not appear to be affected externally it could cause significant damage to internal organs over time. It is suggested that weaners over 5 months of age should be fed no more than 100g per day (Riverina 2013).

How much to feed in drought situation?

When feeding WCS as a drought feed there must be plenty of roughage available to support a 70:30 roughage to WCS ratio and diets consisting of only roughage and WCS should not exceed 2.5kg/head/day for adult stock. WCS should never be fed when there is no roughage available (Blackwood 2007).

Risks associated with gossypol toxicity can be increased in livestock where feeding is inconsistent from day-to-day. It can be very labour intensive to put feed out every day so in the past it has been recommended that producers feed out 6kg/head one day which is supposed to work out as the equivalent of 2kg per head per day for three days. This simply means that the livestock will consume the whole 6kg on day one and be at a very high risk of gossypol toxicity or fatty liver. If the maximum level of free gossypol is approximately 20g/day for adult cows then she only needs 2kg of whole cottonseed per day at 1% free gossypol. Therefore, by putting out 6kg in one day, there is a high chance that the cow will consume thrice the maximum limit in one day and be at risk of suffering from gossypol toxicity.

Alternative feeds:

Top Country manufactures several production rations which may be an option for you to consider if the season continues to be dry and pasture quality continues to decline. They are suitable as weaner rations (dependant on weight range), for spike feeding heifers and bulls prior to joining and even as drought feeds for maintaining condition on poor quality feed. These rations combine slow breakdown protein meals (cottonseed meal and copra meal) with varying amounts of grain and a balance of vitamins and trace minerals. Top Country has three different production rations; Top Production, Top Grower and Top Background. The table below compares the nutritional value of each of these rations to whole cottonseed. Each of these production rations are very safe and can be fed in a variety of situations at restricted intakes or fed ad-lib without the risk of gossypol toxicity.

ME/kg DM

PROTEIN %

CALCIUM %

PHOSPHORUS %

FAT %

STARCH %

CRUDE FIBRE %

NDF %

WHOLE COTTONSEED

13.0

21.0

0.14

0.60

17.0

1.0

24.0

40.0

TOP PRODUCTION

10.2

40.0

1.8

1.0

6.6

13.2

8.7

22.0

TOP GROWER

10.8

28.4

1.8

1.0

6.4

19.2

9.9

23.7

TOP BACKGROUND

11.0

22.0

1.9

1.0

4.0

31.6

10.2

24.9

Top Production is a self-limiting production ration which combines slow breakdown protein meals with a low inclusion of grain (approximately 15%). This ration is designed to assist with achieving higher weight gains on dry standing feed and works by improving the rumen function so that the mature feed can be broken down quicker and more completely. Top Production contains 2.5% urea for cattle and 1% urea for sheep and consumptions are restricted to 0.5% body weight per head per day. For example, a 500kg cow will consume approximately 2.5kg per day. Top Production works best when there is a good amount of dry feed available in the paddock due to the high inclusion of protein in the ration. There is not enough grain in this ration to provide weight gains on the ration alone, therefore it must be used in conjunction with dry feed (same theory as a dry lick).

Top Grower is another production ration which may be more suitable as the dry feed continues to deteriorate over the next few months if it doesn?۪t rain. Top Grower contains approximately 25% grain in combination with slow breakdown protein meals to achieve higher weight gains and improve digestion efficiency of dry pasture. This product contains 1% urea and consumptions are targeted between 0.5-0.7% body weight. Generally consumptions on dry feed would be restricted to about 0.7% body weight, therefore a 500kg cow would consume up to 3.5kg per day if consuming this product ad-lib. Daily gains for cattle on grower will vary depending on consumptions so they could range from 500g (at 0.5% BW consumption) to 700g (at 0.7-1.0% BW consumptions) on top of any gains from the pasture alone. If your dry feed is getting critically low, Top Grower may be a more suitable option for your livestock as it contains enough grain to support production when fed on its own.

Top Background is again based on slow breakdown protein meals as well as a 40% grain inclusion to achieve higher weight gains on both green and dry pastures. Intakes are generally restricted to 0.5% body weight per head per day on green feed so livetsock can consume up to 1.0% BW on dry feed. Gains for cattle can be up to 0.8kg per head per day on top of their gains from the pasture.

If you are interested in discussing any of Top Country?۪s production rations further or would like to obtain a quote please don?۪t hesitate to contact one of our qualified nutritionists today!

References:

Adams, AL, Staples, CR, Van Horn, HH & Thatcher, WW 1998, ?Effects of gossypol from whole cottonseed on lactation and reproductive performance of dairy cows?۝, Dairy and Poultry Sciences Department, University of Florida

Alexander, J, Benford, D, Cockburn, A, Cravedi, JP, Dogliotti, E, Di Domenico, D, Fernandez-Cruz, ML, Furst, P, Fink-Gremmels, J, Galli, CL, Grandjean, P, Gzyl, J, Heinemeyer, G, Johansson, N, Mutti, A, Schlatter, J, Van Leeuwen, R, Van Peteghem, C & Verger, P 2009, ?Scientific Opinion- Gossypol as undesirable substance in animal feed?۝, The EFSA Jorunal, vol. 908, pp. 1-55

Bailey, EM, Smith, CW & Coppock, CE 1996, ?Gossypol?۝, The Texas Agricultural Experiment Station, Texas

Blackwood, I 2007, ?White cottonseed ? a supplementary feed for beef cattle?۝, NSW Department of Primary Industries and Fisheries

El-Mokadem, MY, Taha, TA, Samak, MA & Yassen, AM 2012, ?Alleviation of reproductive toxicity of gossypol using selenium supplementation in rams?۝, Animal Production Department, Faculty of Agriculture, Alexandria University, Egypt

Randel, RD, Chase, CC & Wyse, SJ 1992, ?Effects of Gossypol and Cottonseed Products on Reproduction of Mammals?۝, Journal of Animal Science, vol 70, pp. 1628-1638

Riverina 2013, Whole Cottonseed, http://www.riverina.com.au/website/animal/whole_cottonseed.htm?y=0, Updated April 2013

Author: Susie Doyle

Tags: pregnancy rates toxicities safe levels Gossipol whole cottonseed

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