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

Metabolizable energy equivalence of guanidinoacetic acid in corn soybean meal-based broiler diets

ABSTRACT In this study, we evaluated how guanidinoacetic acid (GAA) addition in diets with various metabolizable energy (ME) contents affects the performance of broiler chickens. We also estimated the equivalence of GAA in ME. We distributed 1,280 one-day-old broilers in a completely randomized design with eight treatments, eight replicates, and twenty birds per experimental unit. Treatments were based on ME levels (2,775-2,875-2,975 kcal/kg; 2,850-2,950-3,050 kcal/kg; 2,925-3,025-3,125 kcal/kg; or 3,000-3,100-3,200 kcal/kg, from 1 to 7, 8 to 21, and 22 to 42 days of age) and the inclusion of GAA (0 or 600 mg/kg). Supplementation of GAA increased weight gain in broilers at an energy level of 2,908 kcal/kg and improved feed conversion ratio (FCR) at energy levels of 2,908 and 2,983 kcal/kg. There was a linear reduction in feed intake and an improvement in FCR of broilers with increasing levels of energy in diets, with and without GAA addition. Solving the equivalence equation, by applying each of the weighted average energy levels studied. indicates the GAA equivalence of 133, 103, 74, and 44 kcal/kg of diet. In conclusion, GAA supplementation improves broilers’ efficiency of energy use; the average ME equivalence of 600 mg/kg of GAA is 88.5 kcal/kg

Tryptophan:lysine ratio in diets for white leghorn hens

Foram realizados dois experimentos com o objetivo de determinar as relações ideais dos aminoácidos triptofano digestível:lisina digestível em rações para poedeiras leves de 24 a 40 (Experimento I) e de 42 a 58 (Experimento II) semanas de idade. Em cada experimento foram utilizadas 240 poedeiras Hy-Line W-36, distribuídas em delineamento inteiramente ao acaso, com cinco tratamentos, oito repetições e seis aves por unidade experimental. Ao completarem 24 e 42 semanas de idade as aves foram submetidas aos tratamentos experimentais que consistiram de rações isonutritivas, exceto para os níveis de triptofano digestível. No experimento I os níveis de triptofano digestível nas rações foram 0,157; 0,168; 0,179; 0,190 e 0,201%, proporcionando relações triptofano digestível:lisina digestível de 21,5; 23,0; 24,5; 26,0 e 27,5 respectivamente. Foi utilizado um nível subótimo de lisina digestível nas rações de 0,730%. No experimento II os níveis de triptofano digestível nas rações foram 0,149; 0,160; 0,171; 0,182 e 0,193%, proporcionando relações triptofano digestível:lisina digestível de 21,5; 23,1; 24,6; 26,2 e 27,8 respectivamente. Foi utilizado um nível sub ótimo de lisina digestível nas rações de 0,694%. Em ambos os experimentos os seguintes parâmetros foram avaliados: consumo alimentar (ração, triptofano digestível e lisina digestível), porcentagem de postura, peso dos ovos, massa de ovos, conversão alimentar (dúzia e massa de ovos), eficiência de utilização de lisina digestível (massa e número de ovos), porcentagem dos componentes dos ovos, ganho de peso e balanço de nitrogênio. No experimento I houve efeito linear dos níveis de triptofano digestível sobre o consumo de ração, de triptofano digestível e de lisina digestível, a porcentagem de postura, a massa de ovos, a conversão alimentar por massa de ovos, a eficiência de utilização de lisina por massa de ovos e o ganho de peso. Também foi observado efeito quadrático sobre o peso dos ovos. Para a eficiência de utilização de lisina por massa de ovos houve melhor ajuste dos dados ao modelo LRP, sendo obtida menor soma de quadrado dos desvios. O nível de triptofano digestível na dieta a partir do qual ocorreu o platô foi de 0,184%. Esse nível correspondeu ao consumo de 142 mg/ave/dia de triptofano digestível e a relação ideal triptofano digestível:lisina digestível de 25,2%. xi No experimento II foi observado efeito linear sobre o consumo de triptofano digestível. Houve efeito quadrático sobre a porcentagem de postura, a massa de ovos, a conversão alimentar por massa de ovos e a eficiência de utilização de lisina por massa de ovos. Para a conversão alimentar por massa de ovos foi obtido 0,178% como nível ótimo, que correspondeu ao consumo de 158 mg/ave/dia de triptofano digestível e a relação ideal triptofano digestível:lisina digestível de 25,6%. Aplicando-se o limite de confiança de 95% para a resposta da equação quadrática foi obtida a relação de 24,3%. As relações ideais triptofano digestível:lisina digestível recomendadas nas dietas para poedeiras leves de 24 a 40 e de 42 a 58 semanas de idade são de 25,2% e 24,3%, respectivamente.Two experiments were carried to determine the ideal ratio of digestible tryptophan:digestible lysine in diets for light laying hens from 24 to 40 and 42 to 58 weeks of age. A total of 240 laying hens Hy-Line W-36 were used in each experiment. The hens were distributed in a completely randomized experimental design with 5 treatments, 8 replicates and 6 hens per experimental unit. When they completed 24 (experiment I) and 42 (experiment II) weeks of age the birds received the experimental treatments that consisted of diets isonutrient, except for levels of digestible tryptophan. In the experiment I the levels of digestible tryptophan used in diets were 0.157; 0.168; 0.179; 0.190 and 0.201%, providing ratios of digestible tryptophan: digestible lysine of 21.5; 23.0; 24.5; 26.0 and 27.5. Was used a suboptimal level of digestible lysine in the diets of 0.730%. In the experiment II the levels of digestible tryptophan used in diets were 0.149; 0.160; 0.171; 0.182 and 0.193%, providing ratios of digestible tryptophan:digestible lysine of 21.5; 23.1; 24.6; 26.2 e 27.8. Was used a suboptimal level of digestible lysine in the diets of 0.694%. In both experiments the following parameters were evaluated: food intake (feed, digestible tryptophan and digestible lysine), egg production, egg weight, egg mass, feed conversion (dozen eggs and egg mass), efficiency of digestible lysine utilization (mass and number of eggs), percentage of egg components, weight gain and nitrogen balance. In the experiment I there was a linear effect on feed intake, digestible tryptophan intake, digestible lysine intake, egg production, egg mass, feed conversion per egg mass, efficiency of lysine utilization per egg mass and weight gain. We also observed a quadratic effect on egg weight. For the efficiency of digestible lysine utilization per egg mass there was best fitted of the data to the LRP model. For the LRP model was obtained smallest sum of squared deviations. The level of digestible tryptophan in diet from which the plateau occurred was 0.184%. This level corresponded to intake of 142 mg/bird/day of digestible tryptophan and the ideal ratio of digestible tryptophan:digestible lysine of 25.2%. In the experiment II was observed linear effect on digestible tryptophan intake. There was quadratic effect on egg production, egg mass, feed conversion per egg mass and efficiency of lysine utilization per egg mass. For feed conversion per egg mass 0.178% was obtained as optimal level. xiii This level corresponded to intake of 158 mg/bird/day of digestible tryptophan and the ideal ratio of digestible tryptophan:digestible lysine of 25.6%. Applying the limit of 95% for the quadratic response was obtained the ratio of 24.3%. The ideal ratio of digestible tryptophan:digestible lysine recommended in diets for light laying hens from 24 to 40 and 42 to 58 week of age are 25.2% and 24,3%, respectively.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Values of chemical composition and of energy of feedstuffs of vegetable origin determined with poultry of different ages

Foram realizados quatro ensaios de metabolismo no Departamento de Zootecnia da Universidade Federal de Viçosa com a finalidade de determinar a energia metabolizável aparente (EMA) e a energia metabolizável aparente corrigida (EMAn) de 10 alimentos de origem vegetal para aves de diferentes idades. Os alimentos estudados, que também tiveram sua composição química determinada, foram: farelo de soja 45%, farelo de soja 48%, soja integral extrusada, soja integral desativada, soja integral micronizada, farinha de soja desativada, concentrado protéico de soja, farelo de glúten de milho 21%, gérmen de milho e quirera de arroz. Utilizou-se o método de coleta total de excretas para determinar os valores de EMA e de EMAn. Os tratamentos consistiram dos 10 alimentos e uma ração referência. O delineamento experimental utilizado foi o inteiramente casualizado, com 11 tratamentos e 6 repetições. No primeiro ensaio foram utilizados 528 pintos de corte machos de 10 a 17 dias de idade, com 8 aves por repetição. No segundo ensaio foram utilizados 396 frangos de corte machos de 26 a 33 dias de idade, com 6 aves por repetição. No terceiro ensaio foram utilizados 198 frangos de corte machos de 40 a 47 dias de idade, com 3 aves por repetição. No quarto ensaio foram utilizados 132 galos, com 2 aves por repetição. Os valores de EMAn, em kcal/kg com base na matéria natural, determinados com frangos de 10 a 17, 26 a 33, 40 a 47 dias de idade e com galos foram, respectivamente: 2069, 2148, 2272 e 2231 para o farelo de soja 45%; 2214, 2225, 2319 e 2247 para o farelo de soja 48%; 3322, 3331, 3405 e 3493 para a soja integral extrusada; 3016, 3067, 3139 e 3388 para a soja integral desativada; 3557, 3638, 3828 e 3869 para a soja integral micronizada; 2292, 2348, 2518 e 2502 para a farinha de soja desativada; 2356, 2399, 2509 e 2486 para o concentrado protéico de soja; 1826, 1882, 2110 e 1942 para o farelo de glúten de milho 21%; 2605, 2764, 2925 e 2832 para o gérmen de milho; e 2967, 3029, 3096 e 3026 para a quirera de arroz. Para os alimentos farelo de soja 45%, soja integral desativada, soja integral micronizada, farinha de soja desativada, farelo de glúten de milho 21% e gérmen de milho observou-se melhora significativa nos valores de EMAn com o aumento da idade das aves.Four assays were carried in the Animal Science Department of the Federal University of Viçosa with the objective of determine the apparent metabolizable energy (AME) and the nitrogen corrected apparent metabolizable energy (AMEn) of ten feedstuffs of vegetable origin for poultry of different ages. The feedstuffs studied, that also had its chemical composition determined, were: soybean meal 45%, soybean meal 48%, extruded full-fat soybean, deactivated full-fat soybean, micronized full-fat soybean, deactivated soybean meal, soybean protein concentrate, corn gluten meal 21%, corn germ and rice broken. The method of total excreta collection was used to determine the value of AME and AMEn. The treatments consisted of the 10 feedstuffs and one ration reference. The birds were distributed on completely randomized experimental design, with 11 treatments and 6 repetitions. In the first assay, it was used 528 broiler chicks males from 10 to 17 days of age, with 8 animals by repetition. In the second assay, it was used 396 broiler chicks males from 26 to 33 days of age, with 6 animals by repetition. In the third assay it was used 198 broiler chicks males from 40 to 47 days of age, with 3 animals by repetition. In the fourth assay it was used 132 roosters, with 2 animals by repetition. The AMEn values (kcal/kg) with base in the natural matter, determined with broiler chicks from 10 to 17, 26 to 33, 40 to 47 days of age and with roosters were, respectively: 2069, 2148, 2272 and 2231 for soybean meal 45%; 2214, 2225, 2319 and 2247 for soybean meal 48%; 3322, 3331, 3405 and 3493 for extruded full-fat soybean; 3016, 3067, 3139 and 3388 for deactivated full-fat soybean; 3557, 3638, 3828 and 3869 for micronized full-fat soybean; 2292, 2348, 2518 and 2502 for deactivated soybean meal; 2356, 2399, 2509 and 2486 for soybean protein concentrate; 1826, 1882, 2110 and 1942 for corn gluten meal 21%; 2605, 2764, 2925 and 2832 for corn germ; and 2967, 3029, 3096 and 3026 for rice broken. For the feedstuffs soybean meal 45%, deactivated full-fat soybean, micronized full-fat soybean, deactivated soybean meal, corn gluten meal 21% and corn germ significant improvement was observed in the AMEn values with the increase of the age of the poultry.Conselho Nacional de Desenvolvimento Científico e Tecnológic