Relative Performance of Fattening Lambs on Raw and Processed Cottonseed Meal Incorporated Diets

In order to find the feasibility of feeding raw or processed cotton (Gossypium) seed meal (CSM), 30 male crossbred lambs were randomly assigned to 5 dietary treatments with 6 animals each. Lambs were fed each of the isonitrogenous and isocaloric concentrate mixtures containing 30% deoiled groundnut cake (DGNC) (reference diet), 40% raw, 45 minute cooked, 1% $Ca(OH)_2$ or iron (1 part free gossypol:0.3 parts iron) treated CSM (replacing about 50% nitrogen moiety of reference concentrate mixture). The concentrate mixture was fed to meet 80% of CP requirements (NRC, 1985) along with ad libitum maize (Zea mays) hay for 180 days. Incorporation of raw or processed CSM did not affect the palatability of diets as evidenced by higher (p<0.01) or comparable overall daily intakes of DM and protein (CP and Digestible CP) per kg $W^{0.75}$ by lambs in comparison to reference group. Intakes of DE and ME increased (p<0.01) due to inclusion $Ca(OH)_2$ treated CSM in diets, while the intakes were lower (p<0.01) on iron treated CSM based diet when compared with reference diet. The intakes of DM, CP, TDN, DE and ME by reference and experimental lambs were higher than the requirements stipulated by NRC (1985). The growth rate was highest (p<0.01) in lambs fed on diets with cooked CSM followed by those fed raw or $Ca(OH)_2$ treated CSM based diets. The growth of lambs fed on iron treated CSM diets was depressed (p<0.01) in comparison to that of other experimental lambs probably due to increased iron intake (889 mg/kg DM of diet) which was much higher than the toxic levels of 500 ppm (NRC, 1980). The lambs on various diets utilized DM with similar efficiency while the utilization of energy (TDN, DE and ME) was more efficient (p<0.01) when the diets contained raw or cooked CSM in comparison to that of reference diet. The lambs fed raw and $Ca(OH)_2$ treated CSM incorporated diets utilized DCP with higher (p<0.01) efficiency than the lambs fed reference diet. The feed cost per kg weight gain was lower (p<0.01) on raw, cooked and $Ca(OH)_2$ treated CSM based diets in comparison to reference diet. Cooking of CSM for 45 minutes further reduced the feed cost of weight gain.