An experiment was conducted to determine the available phosphorus (AP) requirement for post molted laying hens by using the broken line models, logistic model, saturation kinetics model and multivariate nonlinear mixed effects models. The experiment was conducted as a randomized complete block design with 5 dietary treatments (1, 1.5, 2, 2.5 and 3 g/kg of diet AP) and 6 replicates in each (72 hens per treatment). Hens were fed the experimental diets from 85 to 102 wk of age. Feed consumption and egg production were recorded daily, whereas body weight was obtained at the start of 85 and at the end of 102 wk of age and BW changes were calculated. Weekly, 1-d egg production weight was measured and egg mass was calculated. Egg qualities were measured at the end of 102 wk of age. According to the results, the optimal AP requirement from 85 to 102 wk of age for egg production, feed efficiency, egg mass, egg weight, average daily feed intake, shell breaking strength, shell thickness, egg shell percentage and BW changes were 2.1, 2.4, 2.1, 2.5, 1.8, 2.3, 2.1, 2.4 and 2.2 g/kg, respectively. The logistic model only was fitted to egg mass data and the AP requirement was 1.7 g/kg and was computed at 95% of the asymptotic response. AP requirement for maximizing the egg production and egg mass was 2.8 g/kg of diet, when multiple responses (egg production and egg mass) were analyzed simultaneously by using the multivariate nonlinear mixed effects models. The results of this study revealed that the broken line models fitted the data better than other models. According to the broken line models, the range of optimal AP requirement of post molted laying hens for various responses were 1.8 to 2.5 g/kg of diet.
In order to estimate the crude protein (CP) equivalence value of Natuzyme-p (NP) enzyme by using regression response equations, two experiments were carried out using Ross (308) broiler chicks. Graded levels of dietary CP (while amino acids levels were kept constant) and NP enzyme were used to derive the regression equation in the first experiment. Four levels of dietary CP and NP enzyme were fed to 160 feather-sexed male broiler chicks during the starter (0-28 d of age) and grower (28-42 d of age) period. Each diet was offered to four replicates of five chicks in a completely randomized design. Results obtained in experiment one failed to fit a regression equation between BW, dietary CP levels and NP enzyme. In experiment two, graded levels of CP changed along with the levels of lysine (Lys), Met+Cys and threonine (Thr). Regression equations between BW and dietary CP and NP enzyme were derived. Nonlinear and linear equations were generated for enzyme and CP. Based on an assessment of r² and P value, nonlinear equations were used to determine enzyme equivalence. The derived regression equations of body weight for CP were set to be equal with those obtained for NP and were solved; enzyme equivalence value for CP was calculated by subtracting the obtained value from CP content of basal diet. Crude protein equivalence value of NP at 28 and 42 d of age was estimated to be 0.96 and 0.38 %, respectively
A b s t r a c t The performance of bee colonies greatly depends on the quality of the queens. The current research was conducted at the apiary of the Faculty of Agriculture, Zanjan University, in Zanjan, Iran. Together, 24 rearing colonies were assigned to 4 grafting larvae age groups: 1-day-old, 2-day-old, 3-day-old, and emergency queens. Two feeding groups, fed and not fed, were created. The effects of reared queens on biological characteristics and performance of honeybee colonies (Apis mellifera meda) headed by those queens were measured. Age of grafted larvae significantly influenced the results. The performance ratios of the most efficient colonies headed by queens reared from 1-day-old larvae compared with the least-efficient queens reared from 3-day-old larvae were 118% in brood production, 140% in bee population, and 154% in honey production. However, the age of grafted larvae did not affect colony defense behavior. Supplemental feeding of rearing colonies increased brood production to 111%, bee population to 116%, and honey production to 115%. A combination of the effect of age of larvae and supplemental feeding resulted in twice as much honey (12 kg) produced by colonies with queens reared from 1-day-old larvae in fed rearing colonies compared to those with queens raised from 3-day-old larvae in unfed rearing colonies.
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