JWSS - Journal of Water and Soil Science

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This experiment was conducted to investigate the effects of intensity of restricted early feed and increased nutrient density after restriction period on performance and compensatory growth in broilers. Two hundred and eighty-eight broiler (Lohman) chicks in a completely randomized design in a 2*3 factorial arrangement of treatments were employed. Birds were fully fed from 7 to 13d or 100% of adlibitum intake on a daily basis. The diets were diluted at 25% and 50% levels with rice hulls. After the restriction period, birds were fed with a diet, formulated to meet all their nutrient needs, according to the NRC (1994) or 10% of protein, methionine and lysine above NRC in the realimentation diet from 13 to 21d. Body weight, feed intake, daily gain and feed conversion were determined weekly and selected carcass characteristics (liver, intestine and abdominal fat pad) were measured at 49 days of age. Feed restriction significantly (P<0.01) decreased body weight gain and feed conversion during the restriction period. Birds were able to fully recover body weight depression up to 49d. The intensity of restriction had no effect on body weight, feed intake, daily gain and feed efficiency at 49d (p>0.05). Increased nutrient density had no effect on growth rate, feed intake and feed efficiency for fully-fed birds and restricted birds at 49d. The results from this experiment showed that broiler chicks may be expected to gain weight similar to chicks with fully feeding even after restricted early feed if fed with NRC diets. The effect may be due to compensatory growth.

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This experiment was conducted to study the effects of using cotton-seed meal on the performance and carcass yield of broiler chickens at different ages. The experiment was performed in a completely randomized design with four treatments and five replicates for each treatment. The experimental treatments included the levels of 0, 3.5, 7, and 10.5% of cotton-seed meal in diets fed to chickens at 7-21 days of age. Except for the control group, these levels for grower (21-42 d of age) was increased to 7, 14, and 21% and for finisher (42-56 d of age) to 14, 21, and 21%, respectively. For the purposes of this study, 260 day-old chicks were reared in litter until 7 days of age. On day 7, chicks were divided into 20 pens with 13 chicks in each pen. NRC (1994) recommendation was used in balancing experimental diets. The chickens were weighed weekly throughout the experimental period (7-56 d). The main observations were body gain, feed intake and feed conversion ratio. Physical analysis of carcass was done at the end of the experimental period and percentages of carcass, abdominal fat, liver, pancreas and digestive tract to live body weight were calculated. The use of cotton-seed meal and the increase of the levels through different ages had no significant effects on body weight, daily gain, feed intake, feed conversion ratio, and carcass components. Increasing the level of cotton-seed meal in the diet at 7-21 days of age had significant effects on feed intake (P<0.05) and increased it. The results of this experiment indicate that we can use cotton-seed meal at levels of 7,14, and 21% of diets, respectively, in starter, grower and finisher stages without having any adverse effects on the performance and carcass yield of broiler chickens.

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This study was conducted to evaluate the effects of different levels of energy and protein on the performance of male broiler breeder chicks. Three hundred and sixty day-old Arian male broiler breeder chicks were used in a 2×3 factorial experiment with two levels of metabolizable energy (3050 and 3200 Kcal/Kg) and three levels of protein and sulfur amino acids (110% NRC, NRC and 90% NRC) in a completely randomized design with four replicates per treatment. Results obtained from the whole of the experiment’s period (0-49 days of age) indicated that level of dietary energy had a significant effect on body weight and daily gain (P<0.05). Increasing of the energy levels from 3050 to 3200 kcal/kg increased body weight (2216g vs 2314g) and daily gain (45.2 vs. 47.2 g per day). Dietary energy level had no effect on feed intake, feed conversion and carcass components. Increasing of dietary protein significantly increased body weight and daily gain and decreased feed conversion and percentage of abdominal fat pad (P<0.05). The results of this study indicated that we can fed Arian male broiler breeder chicks by using diets containing 3200 Kcal ME/kg and protein and sulfur amino acid levels according to NRC recommendation or 10% higher during 0-21, 21-42 and 42-49 days of age and achieve suitable growth rate and body weight.

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This experiment was conducted to evaluate the effects of 7 experimental diets (2 diets containing 100 and 200 mg vitamin E (VE)/kg and 5 diets containing 0, 0.5, 1, 1.5 and 2% green tea powder (GTP) ) on performance and breast and thigh meat oxidative stability of broiler chicks during different storage times. A total of 364 male broiler chicks were divided to 28 groups of 13 chicks each. Then every 4 groups were randomly allocated to one of experimental diets. During the experimental period (7-42 days of age) feed intake, weight gain and feed conversion of the experimental groups were measured. On day 42, 2 birds from each replicate (8 chicks per treatment) were weighed, slaughtered and their muscles of breast and thigh were minced and stored at 4ºC. Meat oxidative stability of the samples was determined on days 0, 6 and 9 of storage time using thiobarbituric acid test (TBA test). The results showed that addition of the VE and GTP to diets tended to significantly (P<0.05) reduce live body weight, weight gain, feed intake and abdominal fat accumulation and increase feed conversion ratio and pancreas size compared to control group. Increasing storage time from 0 to 6 and 9 d significantly (P< 0.05) increased TBA number. Lipid peroxidation and TBA values in thigh muscle were significantly (P<0.05) higher than breast muscle (1.46 vs. 0.359 mg Malonaldehyde/kg meat). Different dietary levels of GTP in diets did not have any significant effect on prevention of meat lipid peroxidation. In addition, the values of TBA in meat of the groups fed diets containing high levels of GTP significantly (P<0.05) increased in comparison to control group and those fed VE supplemented diets.

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