JWSS - Journal of Water and Soil Science

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Effect of different sources of fat on performance of broiler chicks was studied. Three hundred and thirty six chicks were divided into 42 groups of 8 chicks per group. Seven isoenergetic and isonitrogenous diets, mainly based on corn and soybean meal were prepared and fed. These treatments were as follows: corn + soybean meal + (5% tallow, 5% cotton seed crude oil, 5% cotton seed soapstock, 2.5% tallow + 2.5% crude oil, 2.5% tallow + 2.5% soapstock, or 2.5% crude oil + 2.5% soapstock). One control diet without any source of fat was also included. Results showed that average feed intake of diets with different sources of fat up to 56 days old, was not differed from control group. Different sources of fat and their combinations increased weight gain and improved feed conversion. But soapstock had no effect on performance. Added fats increased abdominal fat of chickens. Therefore, if is concluded that on the contrary to soapstock, tallow and crude oil enhanced performance of broiler chickens.

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An experiment with 720 pullets was conducted to investigate the effect of dietary energy levels of pullet and dietary energy and fat of laying ration on subsequent performance parameters during 14-20 and 22-44 weeks of age. In the first period, white leghorn pullets were fed with two diets of low and high density energy (2600 and 3200 Kcal ME/kg). In the lating period (second period), birds, in each treatment of pullet period, were fed with six diets containing three levels of low, medium and high energy (2600, 2750 and 2900 kcal/kg) at two levels of supplemental fat (zero and 2%). All diets were formulated to meet minimum NRC (1994) requirements of amino acids and protein. This experiment was done in randomized complete block designs with 5 replicates. The levels of energy in the growing period did not affect egg production, egg weight, daily feed intake, feed conversion rate and age of pubertal maturity in laying period, but pullets fed with high energy diet had significantly higher weights as compared to low energy diet in the beginning of laying period. In the laying period, the use of supplemental fat (2%) improved egg production and egg weight, but feed intake and feed conversion rate were not affected. Means of feed conversion rate, feed intake and egg production during laying period in low energy diet were greater than those as compared to high energy diet, but egg weight was not affected by energy level of diets. Low energy intake to protein intake ratio in low energy diet versus high energy diet may be a reason for greater egg production in lower energy than in higher energy diets.

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Wheat as a main food source is partly lost in different ways such as planting, harvesting, storage and even in consumption processes. This calls for attention to reducing these losses through application of the results from agricultural research, use of new farming practices, improvements in management system and repair and renewal of farm machinery. The present study considers the design, development and evaluation of a new pneumatic air reel system as a replacement for the conventional mechanical reel. To evaluate the new system, laboratory and field tests were conducted.

 In the laboratory tests, the air velocity was measured along the fan outlet width at a 10 centimeter interval from the outlet to 40 centimeters away from it, and corresponding curves of air velocity distribution along the fan outlet width were drawn. On the basis of the results, 13 fans were calculated to be required on the cutting platform of a 14-foot (4.3 meter) combine. The results from the field tests of mechanical and air reels show that grain losses of air reel during harvesting are less than those of the mechanical reel because the air reel has no mechanical contact with the crop and applies less shock on plant stem than the mechanical reel. According to the results, grain losses increased linearly with increasing fan speed. In addition to the change of fan speed (2247, 2503, 2860, 3218 and 3932 RPM), three air discharge directions of 10, 20 and 30 degrees from horizontal line were examined. According to the data analysis in Randomized Complete Block Design (RCBD) through Tukey’s procedure (15 treatments and 6 samples in each treatment), there were significant differences between grain loss at these directions and mechanical reel at a level of 5%. A wind direction of 20 degrees and fan speeds of 2503 to 2860 RPM are recommended.

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An experiment was carried out on 384 7d old commercial broiler chicks (Lohman) to study the effect of changes in source and level of dietary calcium and limestone particle size on the performance and tibial growth and calcification of broiler chicks. From day 1 to day 7, the chicks were fed with the commercial basal diet. On day 7, the chicks were weighted and randomly assigned to 64 groups, six chicks of similar body weight (82.2±5.4) per group. Each of the eight experimental diets was fed to eight groups of chicks for an experimental period of 49 days. Two calcium sources (oyster shell and limestone), two calcium levels (100% NRC and 85% NRC) and three particle sizes of limestone [ground (less than 0.15 mm), medium (0.6 to 1.18 mm) and coarse (1.18 to 4.75 mm)] were added to diets with the same energy based on a Randomized Complete Design, in which levels of calcium were nested into calcium sources. Particle sizes were nested into calcium sources and levels.

Limestone significantly increased phosphorus retention (in percentage of phosphorus ingestion) at the age of 21 and 56 days and increased tibial length, dry weight and ash weight at 56 days. Calcium level of 85% NRC significantly decreased feed intake and feed conversion, especially during the starter, and increased calcium retention (in percentage of calcium ingestion) at 21 and 42 days. Phosphorus retention and cortical thickness of tibia at 21 and 42 days, tibial dry weight, ash weight and ash percentage at 42 day, were significantly increased with calcium level of 100% NRC. Coarse and medium particle sizes of limestone as compared to ground particle size, significantly improved feed intake and feed conversion, especially during the starter. Medium particle size of limestone with calcium level of 85% NRC and coarse particle size of limestone with calcium level of 100% NRC, significantly improved tibia ossification characteristics and increased calcium and phosphorus retention. By using calcium level of 85% NRC, coarse and medium particle sizes of limestone compared to ground particle size, significantly diminished percentage of leg abnormalities.

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An experiment was conducted to determine growth and carcass characteristics of male broilers subjected to early feed restriction. Restricted birds were fed equivalent to 1/5*BW^0.67 Kcal/day/bird between days 7 and 14. On days 0 to 7 and 14 to 56, all chickens received feed ad-libitum. Diets of feed-restricted birds were supplemented with 15% higher methionin and cystine recommended by NRC (1994) during refeeding in starter and grower periods. No significant differences were observed for liver, breast, heart, carcass and liver fat between early restricted birds and ad-libitum control at 56 days of age. Body weight for restricted broilers were significantly (P<0.05) lower than that of controls in 56 days. However, restricted broilers had significantly lower total-feed to gain ratio than the unrestricted control. Restricted broilers that received diets high in total sulfur amino acids in starter and grower periods had singnificantly lower abdominal fat pad than control birds.

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Evaluation of uric acid contents of poultry excreta was examined for use in the estimation of apparent protein digestibility. Uric acid was determined either by high-performance liquid chromatography or by spectrophotometric method. A high-pressure liquid chromatographic assay was used with absorbance measured at 285 nm. The method used a reverse-phase system with a C18-bonded column (250*4.6 mm, i.d.). The mobile phase was distilled deionized water. Injection volume was 20 l with a flow rate of 1 ml/min. Correlation (r) between the two methods for uric acid content of excreta from birds fed diets with different methionine levels was 0.976. The uric acid values were then used to determine apparent protein digestibility. The apparent protein digestibility values, when corrected for uric acid nitrogen, were comparable with those calculated from amino acid analysis.

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An experiment with a 33 factorial arrangement in a completely randomized design with 450 day-old broilers was conducted to study the effect of energy level and time of change from starter to finisher diets on performance and economic aspects of broilers. Broiler chickens were fed at three levels of dietary energy (2800, 3000, and 3200 KcalME/Kg) from 1-42 days of age. Starter and finisher diets were changed at 16, 21, and 26 days of age and then finisher diets were fed up to 42 days of age. The effect of diet energy and changing time from starter to finisher diets on body weight and feed conversion at 26 days of age were significant (P<0.01). By increasing energy level and changing time from starter to finisher diets, at this age, body weight increased and feed conversion ratio decreased. Energy conversion decreased by decreasing the levels of energy content of diet and increasing time of change from starter to finisher diets (P<0.01). At 42 days of age, the effects of diet energy and changing time from starter to finisher diets did not show any significant effects on feed and energy conversion in contrast, body weight at this age increased significantly as a result of increasing time of change from starter to finisher diets (P<0.05). From 1-42 days of age, the interaction between diet energy and changing time from starter to finisher diets on feed and energy conversion was significant (P<0.05). The results from this study suggest that increasing diet energy and changing time from starter to finisher diets for producing broilers with less than 2 kg will improve their general performance.

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In addition to farm operations, power tillers in Iran are also engaged in load and passenger transportation. Inspite of their noise and adverse effects on power tiller drivers and bystanders, they have not been adequatly investigated. The initial survey in the present investigation on a 13-hp power tiller at 2200 rpm engine speed revealed that its noise was 92 dB(A), compared to the standard limit of 85 dB(A) which is disappointing. The test site was prepared according to international standards and the noise signals emitted from the system were measured and analyzed in time and frequency domains for audio frequency range (20 – 20000 Hz). The results showed that the noise intensity was higher by 7.74 to 10.75 dB(A) for the microphone position at driver’s ear compared to the bystanders position and that the engine speed played a great role in noise generation for power tiller. This is because the noise increases up to 8.5 dB(A) with engine speed variations. Finally, the power tiller prediction models of sound pressure levels at driver’s ear and bystanders were determined using the experimental data.

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An experiment was conducted with the male Ross broiler chicks from 1 to 42 days of age to test the effects of different dietary protein and lysine levels on performance, carcass characteristics, and N excretion. Treatment diets consisted of three levels of supplemental lysine in starter and grower period (0, 0.15, and 0.30 %) and the two levels of protein (20.84, 17.84 in starter, and 18.12, 16.12% in grower period) with 2900 Kcal ME/kg diet. The results indicated that the Reducing dietary protein decreased significantly the weight gain in starter, grower, and total period up to 6, 4.6, and 5.6%respectively (P<0.05). It also decreased the feed consumption in starter period (P<0.05). Decreasing dietary protein had no significant effect on gain to feed ratio and breast meat yield, but increased abdominal fat percentage significantly (P<0.05). Increasing dietary lysine increased the feed consumption in starter and weight gain, gain to feed ratio in grower and total period of the experiment (P<0.05). Increasing lysine in diet caused a significant increase in breast meat and tight yield, and percentage. Adding supplemental lysine reduced the N excretion in starter period significantly (P<0.059). N excretion reduced significantly by decreasing dietary protein (P <0.05). Dietary treatments had not significant effect on mortality percentage. The results of the present experiment indicated that with providing limiting amino acids and adding supplemental lysine to diet, the crude protein could be reduced up to 3 and 2 percent in starter and grower periods respectively. Reducing the crude protein had not adverse effect on the feed efficiency.

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In the current experiment seven catheterized broiler breeder hens were used at 60 weeks of age. Retention of ¹⁴CO₂ in the body of the hens following continuous infusion of NaH¹⁴CO₃ during each of tow-30-hr continuous infusion studies was determined. Oxidation rate plateau was established within two hours in each experiment. Recovery of ¹⁴CO₂ at the steady state in the first and second study were 91.09 and 87.55 percent respectively and were not significantly different. Mean breath ¹⁴CO₂ recovery was 89.32 percent and hence retention was 10.68 percent. Recovery of ¹⁴CO₂ in breath was not significantly affected by laying of egg or photoperiod. Recovery of ¹⁴CO₂ during the fed state was significantly lower than the fasted state. The results of this experiment indicated that, using of uncorrected data for the retained isotope into body, lead to 10.68 percent AA requirements underestimation in broiler breeder hens by indicator amino acid oxidation technique.

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Among the biodiversity of soil microorganisms, bacteria have the basic role in soil functions. In order to determine the diversity and abundance of soil bacteria in arid regions, and also to study the effect of agricultural practices on them, a study was conducted in winter wheat fields on Shirvan, Mashhad and Gonabad. In each region, high and low input fields of winter wheat and a natural system for comparison were selected. Use of agricultural inputs was criteria for selection of low and high input fields in each region. Soil sampling was done on fields and natural systems and organic matter content, abundance and diversity of soil bacteria were measured in soil samples. Species richness and abundance of soil bacteria was affected by region and so that natural system of Gonabad has the minimum of species richness among the studied systems and the differences of other systems was not significant. Abundance of soil bacteria in 1 g dry soil was maximum in Gonabad and minimum in Shirvan. Abundance of soil bacteria was affected by organic matter and in low and high input systems of Gonabad and low input system of Mashhad was greater than other systems. Overall, 19 species of bacteria that belonged to 4 genus were detected. Results showed that species richness and abundance of soil bacteria in studied systems were relatively low and agricultural practices have not significant impact on these organisms, so that species richness and abundance of soil bacteria were improved in agricultural systems of Mashhad and Gonabad. Pattern of bacterial diversity showed that regional and agricultural stresses were affected on bacterial function so that in high level of stresses, species richness decreased and function of soil bacteria was restricted to decomposition of organic matter. Therefore, organic matter of soil must be increased and agricultural stresses must be decreased to improve of soil bacterial functions.