JWSS - Journal of Water and Soil Science

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This experiment was carried out to determine the relationship of plasma triglycerides and carcass dry matter with abdominal fat. One of the problems of broiler is carcass fatness, especially abdominal fat due to rapid growth of broilers which is not the consumer preference. Six hundred one-day-old commercial broiler chicks (Lohman) were divided into 40 groups, 15 chicks per group. Each one of the 10 experimental diets, in which barley was substituted for corn at levels of 0, 5, 10, 20 and 40%, was fed to 4 groups of chicks for 56 days. All diets were isoenergetic and isonitrogenous. Rice hulls was used to make diets isoenergetic. At days 42, 49 and 56, one male and one female were selected from each pen and after blood sampling, the birds were killed, eviscerated and percentages of carcass and amount of abdominal fats were measured. Blood samples were used to determine plasma triglycerides, cholesterol and total lipids. The results showed that increasing abdominal fat reduced carcass moisture content. Correlation between abdominal fat and plasma triglycerides was positive and significant (p<0.05). Correlation between abdominal fat and carcass moisture was negative and significant (P<0.01). The regression equations indicated that abdominal fat can be estimated from plasma triglycerides and carcass moisture content. The equations also indicated that using several parameters for estimating abdominal fat is better than single parameter estimation.

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Two experiments were designed and conducted to evaluate the effect of tallow and the nutritional value of millet and the effect of substituting millet for corn on the performance of laying hens. In the first experiment, the nitrogen corrected true metabolizable energy (TMEn) of tallow and millet was determined. Also the digestibility of dry matter (DM), protein, fat and crude fiber of millet was determined using the Sibbald's method. In the second experiment, with a completely randomized design and in a factorial arrangement, the effect of different levels of substitution of corn (0.0, 25, 50 and 75%), introduction of tallow at various amounts of 0, 3 and 6 percent, and also the effect of processing millet (ground and unground) on the diet of HY-Line layers from 26 to 38 weeks of age were studied. The criteria used were egg production rate, egg weight, egg output, feed intake, and feed conversion ratio. The results from the first experiment showed that screening millet increased its true metabolizable energy. Furthermore, crude fiber digestibility increased as a result of introducing fat into the diet (p<0.05). The results from the second experiment revealed that grinding millet had no significant effect on the performance of laying hens, but feed conversion ratio tended to improve in diets containing ground millet. Substitution of any amount of millet for corn significantly improved egg weight, egg output, and feed intake (P<0.05). Introduction of tallow by 6% significantly increased feed intake (P<0.05) too.

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Two experiments were conducted to evaluate the nutritional value of millet and tallow for broiler chickens. In the first experiment, the nitrogen corrected apparent metabolizable energy (AMEn) of millet and tallow were determined by the method of Sibbald. In the second experiment, a 3×5 factorial experiment was designed to evaluate the effects of 3 levels of tallow and 5 levels of substitution of corn with millet in broiler diets. Animal fat was included in the diets at levels of 0%, 3% and 6% and millet was replaced for corn at levels of 0%, 25%, 50%, 75% and 100%. Each diet was tested in 4 replicates including 12 chicks per replicate. Live body weights, feed consumptions and feed conversion ratios were determined weekly for all replicates. The AMEn of unground, ground, screened and ground and tallow were 3260, 3204, 3237 and 8166 Kcall/kg, respectively. Replacement of corn by millet at all levels did not have any adverse effect on body weight, feed consumption and feed conversion ratio at 56th day of age. Body weights, feed consumptions and feed conversion ratios were significantly increased (p<0.05) with increasing animal fat. The results indicated that millet has high energy value and appears to be at least equal to corn in promoting weight gains in broiler chickens.

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A 46-day feeding trial was conducted with rainbow trout (Oncorhynchus mykiss) to examine the effects of partial substitution of plant protein sources with fish meal in diets. Three different sources of plant protein including soybean, sunflower and cottonseed meals were substituted by fish meal at four levels of 10, 20, 30 and 40 percentages. Each diet was assigned to triplicate groups of fish in a completely randomized design as a 3×4 factorial arrangement, with a control diet. Seven hundred and eighty fish were used in this trial. Twenty fish were randomly assigned to each of 39 pens and were acclimated in these pens to the experimental conditions two weeks before treatments began. This substitution caused no significant differences in all the criteria measured with control diet. Fish fed diets of 30 and 40 percent soybean meal substitution showed greater weight gain and better growth performance, lower FCR and higher PER values in comparison with the fish receiving other diets, although the differences were not significant. Irrespective of substitution levels, comparison of fish fed by three different sources of plant protein in their diets showed that the fish fed diet containing sunflower meal had significantly (p<0.0l) lower final mean weight and growth performance, higher FCR and lower PER than the fish receiving soybean and cottonseed meal diets. Relative liver weight of fish receiving soybean meal diets was significantly (p<0.0l) higher than those fed with cottonseed meal diets, but the difference was not significant when compared with the fish fed with the sunflower meal diets. Partial replacement of cottonseed meal resulted in a higher energy availability to fish and also better performance of fish. However, diets containing soybean meal showed not much effects on performance of rainbow trout. These results indicate that cottonseed and soybean meals can be recommended as a suitable and fish meal-sparing ingredient in diets for rainbow trout.

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In a completely randomized design, 600 commercial day old broiler chickens were used to study the possibility of replacing corn with barley. Each of 10 experimental diets in which corn was replaced with barley at levels of 0, 5, 10, 20 and 40 percent, with and without tallow, were given to 4 replicates of 15 chickens each. At 42, 49 and 56th days of age, one male and one female from each pen were killed. Body weight gain, feed intake and feed conversion ratio were not affected by different levels of barley at 42th day of age. Increasing the level of barley had not effect on body weight gain at 56th day of age. Feed conversion ratio improved slightly due to addition of 4% tallow to the diets containing different levels of barley. Abdominal fat was increased due to added tallow in males and females. Increasing slaughter age increased abdominal fat in both sexes. Difference in abdominal fat in females was more than males.

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A total of adult leghorn roosters and 360 day-old broiler chicks were used in two completely randomized experiment to evaluate metabolizable energy (ME) and feeding value of faba beans in broiler rations. In a factorial arrangement with 10 treatments and 3 replicates chicks were fed isonitrogenous rations containing either 0, 10, 20 or 30 percent of raw, cooked or dehulled faba beans for 8 weeks. Data from sibbald procedure showed cooking had no significant effect on energy value of beans, while dehulled beans had a significantly (p < 0.05) higher energy value. Final body weights at 8th week of age were unaffected due to processing of beans. No significant differences were observed in liver weight, abdominal fat or feed efficiency ratio due to processing and/or percentage of beans in the ration. Raw, whole beans significantly (p < 0.05) increased percentage and weight of pancreas compared to those that had consumed dehulled beans. This indicates that trypsin inhibitor is located in hulls. Cooked beans reduced pancreas size to normal, indicating destruction of inhibitor due to cooking. One interesting point is that the control group which consumed more soybean meal had a pancreas weight of 4.67 grams comparable to 4.83 grams of pancreas weights of chicks consuming raw, whole beans. This last fact indicates that soybean meals might not have received enough heat treatments during processing, which requires further investigation.