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Abstract:The value of cotton seed cake as a source of crude protein in sheep diets was studied. The cotton seed cake was incorporated into diets at levels of 0, 15 and 30 YO after replacement of soya bean meal and was fed adlibitum to growing lambs.The diets were formulated to be isonitrogenous and isocaloric. Sixteen lambs (8 male and 8 female) having an average liveweight of approximately 13.6 kg were used in each treatment.After being fed for 62 days and having reached a liveweight of approximately 26.7 kg, five male lambs from each treatment were slaughtered and carcass data were collected. Results of the growth trial showed that there were no significant differences in feedlot performance or carcass analysis among the lambs fed these diets. The dressing percentage was slightly higher (P > 0.05) for lambs fed the 15 YO cotton seed cake compared with the 30% cotton seed cake and control diets. However, the final weights were substantially higher ( P < 0,001) and live average daily gains and feed intakes were all higher (P < 0.10) for male animals.It was concluded that cotton seed cake is an acceptable feed ingredient for growing sheep and can satisfactorily replace soya bean meal as a source of protein in ruminant diets, a feedstuff locally produced in Greece and substantially cheaper than the imported soya bean meal.

Two in vivo digestion trials were conducted to evaluate the effects of diet's crude protein (CP) level, N degradability, and non-forage fibre source (NFFS) on nutrient digestibility and energy value of sheep rations. In each trial, rams were fed four isocaloric and isofibrous rations, differing in main protein and/or NFFS source. At the first trial, mean CP/metabolizable energy (ME) ratio of the diets was 17 g/MJ ME and at the second trial, 13 g/MJ ME. At both trials, the first ration contained cotton seed cake (CSC) and wheat bran (WB), the second CSC and corn gluten feed (CGF), the third corn gluten meal (CGM) and WB and the fourth CGM and CGF. Data of both trials were analysed in common as 2 x 2 x 2 factorial experimental design. Low N degradability (CGM) had positive effect on CP, neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility of the ration. Those results suggest that an increase in rumen undegradable protein (RUP) content does not negatively affect nutrient digestibility of sheep rations. Corn gluten feed significantly elevated crude fibre (CF) digestibility, in comparison with WB. Rations having high CP/ME ratio had higher digestibility of CP in comparison with those having low CP/ME ratio; the opposite was true for ether extract, CF, NDF and ADF digestibilities. CP level x N degradability interaction negatively affected energy value of the rations that had high CP level and high N degradability. Former suggest that when CP content is high then N degradability should be low otherwise ration's ME is negatively affected. CP digestibility and coefficient q of the rations containing WB and having high N degradability (N degradability x NFFS interaction) were the lowest suggesting that the combination of CSC and WB negatively affected CP digestibility and energy value of the ration. This could be explained by a reduced microbial CP synthesis, or lower RUP digestibility or both.

The effect of gossypol content of cottonseed cake given as a source of CP in lamb (n = 8) rations was examined on the following blood parameters: plasma total protein, albumin, globulins, urea, glucose, hematocrit, hemoglobin, and mean corpuscular hemoglobin concentrations. The diets were isonitrogenous and isocaloric and contained 0, 15, and 30% cottonseed cake for 62 d. Blood samples were taken at the beginning, middle, and end of the experiment. Plasma total protein and globulins were higher at d 30 of the experimental period, but plasma albumin concentration, hematocrit, and hemoglobin were higher at the beginning of the experiment; plasma urea concentration was higher at d 60, and plasma glucose concentration was lower at d 30 of the experiment. The highest fraction in all treatments was albumin, followed by alpha 2-globulin and beta-globulin fractions, and there was no gamma 1-globulin fraction at d 30 and 60 of the experimental period. Liver examination showed significant differences in free gossypol content and accumulation, total N, and total protein percentage among the three treatments. Gossypol toxicity was not observed. The absence of gossypol toxicity in these animals has been attributed to detoxification of free gossypol by the formation of gossypol-protein complex in the rumen.