JWSS - Journal of Water and Soil Science

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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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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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This experiment was conducted to evaluate the effects of adding acetic acid to drinking water on the performance and ileal microorganisms of broiler chickens. In a completely randomized design with 5 treatments and 5 replicates, 300 day-old commercial mail broiler chicks (ROSS) were divided into 25 groups, 12 chicks per group. Each of the five levels of acetic acid added to drinking water (0.0, 0.1, 0.2, 0.3, and 0.4%) were given to five replicates for a period of 21 days. All groups were fed a practical corn-soybean based diet. During the experiment, chickens were not fed any antibiotics or coccidiostats. The diet formulation for all groups was the same. At 14 and 28 days of age, one chicken of each replicate was weighed and killed by cervical dislocation. Ileal contents were collected and used for microbial evaluation. At 49 days of age, one bird from each pen was killed to weigh gastrointestinal tract, liver, pancreas and abdominal fat. The number of total aerobes and colliforms per gram of ileal contents were enumerated on the appropriate bacteriological media. There was no significant difference in feed intake, weight gain, feed to gain ratio, live body weight, gastrointestinal tract, abdominal fat, liver and pancreas weights (p>0.05). Also, the differences among treatments for total aerobe and coliform counts were not significant (p>0.05). Under the conditions of this study, addition of acetic acid as an organic acid into drinking water at the levels used could not affect the performance and ileal microbial counts of chickens.

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Digestible lysine and sulfur amino acid (SAA) requirements of Ross male broilers were determined during the starter period in two experiments. Broilers were fed a control corn-soy diet (3200 kcal MEn/kg and 23% CP) for 6 days and then randomly assigned to dietary treatments until 16 days of age. The basal diet containing 19% CP was prepared in order to be deficient in lysine for experiment 1 and SAA for experiment 2. Seven graded increment levels of L-lysine HCl or Dl-methionine were added in absences of starch in experiment 1 and 2, respectively. All diets contained 3200 kcal MEn/kg and all essential amino acids, except for the test amino acid, were 10% higher than the NRC (1991) recommendations. The digestible lysine requirements of broilers based on broken-line and exponential models were 1.04 and 1.01%, respectively. The digestible SAA requirements for the mentioned models were 0.846 and 0.841%, respectively.

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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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A feeding trail was conducted to evaluate the effects of diets contaminated with Aflatoxin B1 (AFB1) on the performance and blood enzymes of broiler chickens. In a randomized complete-block design with 4 blocks and 4 treatments, 112 day-old male broiler chicks were divided into 16 groups, 7 chicks per. Treatments consisted of three levels of AFB1 in starter diet (0.4, 0.8, and 1.2 ppm) along with a control group (no AFB1). Feed intake and body weight gain were recorded on a weekly basis. On days 7, 14, 21, and 28, one bird from each replicate was weighed, and killed to collect the blood samples, and to weigh its proventriculus, gizzard, duodenum and pancreas, heart, liver, spleen, bursa of fabricius, and brain. Feeding AFB1 significantly decreased feed intake and body weight gain and increased relative weight of liver (p<0.05). Relative weight of brain decreased on day 7 and then showed a significant increase by day 28 (p<0.05). AFB1 significantly (P<0.05) increased serum activity of aspartate amino transferase (AST) and alanine amino transferase (ALT) and decreased serum activity of lactate dehydrogenase (LDH) enzymes. Generally, this study demonstrated that, alongside other negative effects, AFB1 could also have adverse effect on the brain of broilers.

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In order to study the effect of corn, Ghods wheat, Falaat wheat, and triticale with or without enzyme addition on perormance and digestive tract characteristics, an experiment was carried out by using 288 male broiler chickens in a compeletly randomized design with 4*2 factorial arrangement for 57 days. Enzyme addition significantly decreased both feed conversion ratio of chickens fed Ghods wheat and triticale, and weight gain of chickens fed Ghods wheat. Growth performance of chickens fed Ghods wheat with enzyme was not significantly different compared with corn without enzyme. Enzyme addition decreased ileum relative weight of chickens. Gizzard and proventriculus of chickens fed Falaat wheat and triticale were heavier than those of other treatments. According to the results, enzyme supplementation showed positive effect on triticale and especially Ghods wheat based diets.