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
||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)