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%) in total mixed rations and 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 sugarcane silage), cottonseed hulls generally give similar or higher milk yield, and higher milk fat content (Klopfenstein et al., 1981).
For dairy cows, cottonseed hulls are a valuable source of fibre when introduced in diets with high starch content because they slightly increase 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 reducing milk yield (Beckman et al., 2005). However, as cottonseed hulls are low in protein, a supplement may be necessary to balance the diet, 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 vs. 64%) but higher milk yield (23.4 vs. 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 replaced up to half of the 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 compared to 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, a diet based on chopped sorghum straw, fed to crossbred bulls, and supplemented with cottonseed hulls, at 50% (diet DM) or a mixture of cottonseed hulls (35%) and alfafa hay (15%), resulted in a greater DM intake and was more digestible than a conventional diet (concentrate + straw) (Reddy et al., 1999).
In the USA, cottonseed hulls were used as a forage source (20 or 25%) instead of alfalfa hay in a complete diet for 325 kg fattening steers (Bartle et al., 1994), and 200 kg growing beef heifers (Hale et al., 1969). In both trials cottonseed hulls did not affect the daily weight gain of the steers and heifers (1560 g/d and 670 g/d respectively), but increased DM intake (+ 0.8 kg/d and + 0.52 kg/d respectively). At a higher level (30% cottonseed hulls), 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 diet of growing beef heifer 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% of the diet DM for 103 days, those fed cottonseed hulls had a lower average daily gain (1930 vs. 2130 g/d) and showed a tendency to have fatter carcasses and a worse carcass classification (Markham et al., 2002).
Replacement of rice bran with up to 20% cottonseed hulls did not affect the milk yield or milk fat content of Murrah buffaloes (Naidu et al., 1981).
Cottonseed hulls are capable of supporting moderate growth rates in sheep. With lambs, a diet of cottonseed hulls + urea + 50 g lucerne + vitamins/minerals resulted in a growth rate of 75 g/d and a whool growth of 6.1 g/d. When a small amount of by-pass protein was added to this diet, the growth rate of lambs exceeded 130 g/day and wool growth was increased 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 explain why cottonseed hulls support adequate growth rates, even without supplementation with by-pass protein. Intake of cottonseed hulls by sheep was higher (1 kg DM/day) than would be expected of feed with a digestibility of about 40%, possibly associated with a rapid breakdown of the indigestible material in the rumen (Davis et al., 1989).
In Benin, replacement of all or 50% of the cottonseed meal with a 60:40 cottonseed meal and cottonseed hulls mix to supplement Guinea grass-based diets, for fattening Djallonke sheep (1 year, 18 kg LW) for 60 days, had no effect on carcass yield and characteristics, but resulted in a net profit (Alkoiret et al., 2007).
In China, when cottonseed hulls replaced the traditional fibre source, in a complete diet for fattening sheep from three months of age, until slaughter at eight months, daily weight gain was unaffected and carcass characteristics improved (Tuerxhun et al., 2010).