Calcium levels and calcium:available phosphorus ratios in diets for white egg layers from 42 to 58 weeks of age

The experiment was conducted to determine the nutritional requirement of calcium and the best calcium:available phosphorus ratio for commercial layers at the post-laying peak. A total of 324 Hy-Line W-36 laying hens were utilized in the period from 42 to 58 weeks of age, distributed in a completely randomized design in a 3 × 3 factorial arrangement, composed of three levels of calcium (39, 42 and 45 g/kg) and three calcium:phosphorus ratios (12.12:1; 10.53:1; and 9.30:1), totaling nine treatments with six replications and six birds per experimental unit. There was no significant effect from the calcium levels × calcium:phosphorus ratio interaction for any of the variables studied. The calcium levels and the calcium:phosphorus ratios did not affect the variables performance or egg and bone quality. At the evaluation of the calcium:phosphorus balance, as the levels of calcium of the diet were raised, the intake of calcium and phosphorus and the contents of mineral matter and calcium in the excreta increased linearly, and the retention of calcium by birds decreased linearly. With the reduction of the calcium:phosphorus ratios of the diet, intake, retention and excretion of phosphorus by layers increased. Diets containing calcium at 39 g/kg and a calcium:phosphorus ratio of 12.12:1, corresponding to an increase in calcium of 3.51 g/bird/day and available phosphorus of 289 mg/bird/day, meet the requirements of calcium and available phosphorus of white egg layers in the period from 42 to 58 weeks of age

Levels of calcium and calcium/phosphorus relation in diets for white laying hens from 24 to 40 weeks of age

Este experimento foi conduzido no setor de Avicultura do Departamento de Zootecnia, da Universidade Federal de Viçosa, objetivando-se determinar a exigência nutricional de cálcio e a melhor relação cálcio/fósforo em rações para poedeiras leves de 24 a 40 semanas de idade. Foram utilizadas 324 aves Hy-Line W-36, distribuídas em um delineamento inteiramente casualisado em esquema fatorial 3x3, composto de três níveis de cálcio (3,9; 4,2 e 4,5 %) e três relações cálcio/fósforo (9,3; 10,53 e 12,12/1) totalizando 9 tratamentos, 6 repetições e 6 aves por unidade experimental. Com exceção dos níveis de cálcio e de fósforo na ração, que foram obtidos por suplementação de calcário (50% fino e 50% grosso) e fosfato bicálcico, os demais nutrientes atenderam as recomendações preconizadas por Rostagno et al. (2005). Foram avaliados o desempenho produtivo (produção, peso e massa de ovo; ganho de peso; consumo de ração; conversão alimentar por dúzia e por massa de ovo), a qualidade do ovo (gema; albúmen; casca; espessura de casca; gravidade específica; matéria mineral, cálcio e fósforo na casca e ovos perdidos), características ósseas (peso, matéria mineral, cálcio e fósforo na tíbia), balanço de cálcio e fósforo (matéria mineral, cálcio e fósforo na excreta; consumo de cálcio; consumo de fósforo; cálcio e fósforo retido pelas aves) e mortalidade. Não houve interação (P>0,05) entre os níveis de cálcio e as relações cálcio/fósforo para nenhuma das variáveis estudadas, porém os níveis de cálcio promoveram efeito (P 0.05) between calcium levels and ratios of calcium / phosphorus ratio for the variables studied, but levels of calcium promoted effect (P <0.05) on weight and shell percentage, calcium bark, lost eggs, consumption of calcium and phosphorus, calcium and phosphorus excretion, calcium and phosphorus retained. The calcium / phosphorus significantly (P <0.05) feed intake, weight gain, feed conversion per dozen eggs and egg mass, intake of calcium and phosphorus, phosphorus excretion and phosphorus retained. For the other variables was not significant effect neither for nor calcium levels to calcium / phosphorus ratio. Diets containing 4.5% calcium and the calcium: phosphorus 12,12:1, corresponding to a calcium intake of 3.71 g / hen / day and phosphorus of 306 mg / bird / day, guarantee satisfactory performance in diets for laying hens from 24 to 40 weeks.Fundação de Amparo a Pesquisa do Estado de Minas Gerai

Digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age

The objective of this study was to determine the ideal digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age. Two hundred and forty Hy-Line W-36 laying hens at 24 weeks of age were distributed in a completely randomized design, with five treatments, eight replicates and six birds per experimental unit. The digestible tryptophan levels in the experimental diets were 1.57; 1.68; 1.79; 1.90 and 2.01 g/kg, providing ratios of digestible tryptophan:digestible lysine of 0.215; 0.230; 0.245; 0.260 and 0.275. The increase in the levels of digestible tryptophan in the diet linearly improved the feed intake, digestible tryptophan intake, digestible lysine intake, egg production, egg mass, feed conversion per egg mass and utilization efficiency of digestible lysine for eggs mass. There were quadratic effects from the digestible tryptophan levels on egg weight. For the efficiency of utilization of digestible lysine for egg mass, there was better adjustment of the data to the LRP model. The level of digestible tryptophan in the diet from which the plateau occurred was 0.184%. This level corresponded to the intake of 142 mg/bird/day of digestible tryptophan and digestible tryptophan:digestible lysine ratio of 0.252. The ideal digestible tryptophan:digestible lysine ratio recommended in diets for laying hens from 24 to 40 weeks of age is 0.252 (25.2%)

Calcium levels and calcium:available phosphorus ratios in diets for white egg layers from 42 to 58 weeks of age

The experiment was conducted to determine the nutritional requirement of calcium and the best calcium:available phosphorus ratio for commercial layers at the post-laying peak. A total of 324 Hy-Line W-36 laying hens were utilized in the period from 42 to 58 weeks of age, distributed in a completely randomized design in a 3 × 3 factorial arrangement, composed of three levels of calcium (39, 42 and 45 g/kg) and three calcium:phosphorus ratios (12.12:1; 10.53:1; and 9.30:1), totaling nine treatments with six replications and six birds per experimental unit. There was no significant effect from the calcium levels × calcium:phosphorus ratio interaction for any of the variables studied. The calcium levels and the calcium:phosphorus ratios did not affect the variables performance or egg and bone quality. At the evaluation of the calcium:phosphorus balance, as the levels of calcium of the diet were raised, the intake of calcium and phosphorus and the contents of mineral matter and calcium in the excreta increased linearly, and the retention of calcium by birds decreased linearly. With the reduction of the calcium:phosphorus ratios of the diet, intake, retention and excretion of phosphorus by layers increased. Diets containing calcium at 39 g/kg and a calcium:phosphorus ratio of 12.12:1, corresponding to an increase in calcium of 3.51 g/bird/day and available phosphorus of 289 mg/bird/day, meet the requirements of calcium and available phosphorus of white egg layers in the period from 42 to 58 weeks of age

Digestible tryptophan: digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age

Submitted by Franciele Moreira ([email protected]) on 2020-03-23T19:39:00Z No. of bitstreams: 2 Artigo - Arele Arlindo Calderano - 2012.pdf: 305812 bytes, checksum: b8d16573bb6b513c01d653ae269e04b3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2020-03-24T14:39:16Z (GMT) No. of bitstreams: 2 Artigo - Arele Arlindo Calderano - 2012.pdf: 305812 bytes, checksum: b8d16573bb6b513c01d653ae269e04b3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2020-03-24T14:39:17Z (GMT). No. of bitstreams: 2 Artigo - Arele Arlindo Calderano - 2012.pdf: 305812 bytes, checksum: b8d16573bb6b513c01d653ae269e04b3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2012The objective of this study was to determine the ideal digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age. Two hundred and forty Hy-Line W-36 laying hens at 24 weeks of age were distributed in a completely randomized design, with five treatments, eight replicates and six birds per experimental unit. The digestible tryptophan levels in the experimental diets were 1.57; 1.68; 1.79; 1.90 and 2.01 g/kg, providing ratios of digestible tryptophan:digestible lysine of 0.215; 0.230; 0.245; 0.260 and 0.275. The increase in the levels of digestible tryptophan in the diet linearly improved the feed intake, digestible tryptophan intake, digestible lysine intake, egg production, egg mass, feed conversion per egg mass and utilization efficiency of digestible lysine for eggs mass. There were quadratic effects from the digestible tryptophan levels on egg weight. For the efficiency of utilization of digestible lysine for egg mass, there was better adjustment of the data to the LRP model. The level of digestible tryptophan in the diet from which the plateau occurred was 0.184%. This level corresponded to the intake of 142 mg/bird/day of digestible tryptophan and digestible tryptophan:digestible lysine ratio of 0.252. The ideal digestible tryptophan:digestible lysine ratio recommended in diets for laying hens from 24 to 40 weeks of age is 0.252 (25.2%)