ABSTRACT: A reliable determination of endogenous phosphorus (P) excretion is required to measure P utilization in chickens accurately. The objective of this study was to investigate phosphorus (P) retention in broilers fed diets formulated with different feed ingredients. Sixty-four 15-d old broiler chicks were fed diets in which part of the dietary P was provided from dicalcium phosphate, maize, barley or soybean. Level of supplementation of each ingredient was calculated to provide two levels of total P (4.5 or 5.0 g kg−1 feed). Birds received a single injection of 3 MBq of 32P to determine endogenous P excretion using the isotope dilution technique. Four days after injection, blood and excreta were collected for analysis of inorganic and radioactive P. There were no differences among diets in total (p = 0.37) or endogenous (p = 0.65) P excretion or in P retention (p = 0.37) regardless of the supplemental feed material used in each diet. Daily P retention was increased (p = 0.004) as P intake increased, but the proportion of P ingested that was retained was not affected (p = 0.23) by the level of dietary P. The use of an isotopic tracer allows for accurate estimation of endogenous P in excreta, ranging from 0.24 to 0.42 mg P g−1 dry matter intake. The retention of P in growing chickens was not changed when 10-20 % of total P was provided by maize, barley or soybean.

ABSTRACT. Because of the relatively long growing cycle and the high cost of research into turkey production and nutrition, the potential benefits from modelling growth in this avian species are considerable. Though there are many studies aimed at evaluating animal growth models, the number of studies targeting growth models in turkeys is quite limited. In this paper we present a sinusoidal function to describe the evolution of growth in turkeys as a function of time based on data published by Aviagen. The new function was evaluated with regard to its ability to describe the relationship between body weight and age in turkeys and was compared to four standard growth functions: the Gompertz, logistic, Lopez, and Richards. The results of this study show that the new sinusoidal function precisely describes the growth dynamics of turkeys. Fitting the functions to different data profiles nearly always led to the same or less maximized log-likelihood values for the sinusoidal equation, indicating its suitability in describing growth data from turkeys.

A crescente demanda global por carne, em particular no Brasil, deverá aumentar a produção animal intensiva. Por conseguinte, os principais poluentes são o nitrogênio (N), fósforo (P) e gases de efeito de estufa (GEE). O nitrogênio pode ser um problema devido à lixiviação de nitrato para os corpos d'água, amônia e emissões de óxido nitroso para o ar. Carga de fósforo no solo decorrente da aplicação de esterco pode ser o problema principal, devido à tendência de o P acumular no solo e atingir os lençóis freáticos e rios. As fontes de emissões de GEE agrícolas incluem metano proveniente da fermentação entérica, armazenagem e e distribuição de estrume e óxido nitroso principalmente da aplicação de adubo na terra. A manipulação dietética tem demomstrado eficiência na redução da poluição de nutrientes/minerais e das emissões de GEE. Vários estudos têm demonstrado que a diminuição de proteína bruta na dieta podem reduzir substancialmente a excreção de N e a volatilização de amônia, sem comprometer a produtividade. Da mesma forma,a redução da ingestão de P em bovinos leiteiros pode reduzir a excreção de P em até 10%. Alterações do tipo de N e P consumidos e do nível energético da dieta sobre a quantidade e o tipo de N e P excretado também foram relatadas. A manipulação da dieta também tem impacto sobre a quantidade de emissões de gases de efeito estufa, em particular, a proveniente de fermentação entérica. A alimentação do gado com dietas contendo elevado teor de trigo baixo de fibra, por exemplo, reduz a produção de acetato no rúmen e acarreta menor produção de metano. Emissões decorrentes de estrume de animais alimentados com alto teor de fibra na dieta tendem a ser maiores. Evidenciou-se também que a dieta afeta as emissões de esterco no solo. Em decorrência do aumento do nível de produção para atender à demanda global de carne de ruminantes e produtos lácteos, a manipulação dietética será útil para atender às preocupações ambientais.

The growing global demand for meat and particularly in countries such as Brazil is expected to increase intensive animal production. Consequently the main pollutants of interest are nitrogen (N), phosphorus (P) and greenhouse gases (GHG). Nitrogen can be a problem through nitrate leaching to water bodies, ammonia, and nitrous oxide emissions to air. Phosphorus loading in soil from manure application can be the main issue due to the tendency of P to accumulate in soil and leach to groundwater and rivers. The sources of agricultural GHG emissions include methane from enteric fermentation, manure storage and spreading, and nitrous oxide mainly from application of manure on land. Dietary manipulation has proven to be an effective tool to reduce nutrient/mineral pollution and GHG emissions. Several studies have shown that decreasing crude protein in the diet could reduce N excretion and ammonia volatilization substantially without compromising productivity. Similarly, reducing P intake in dairy cattle has been shown to reduce P excretion by up to 10%. Changing the type of N and P consumed and energy level of diet has also been reported to affect the amount and type of N and P excreted. Dietary manipulation also has an impact on the amount of GHG emissions, particularly, from enteric fermentation. Feeding cattle with a high starch and low fiber diet, for example, reduces acetate production in the rumen, and leads to lower methane production. Emissions from stored manure from high fiber fed animals tend to be higher. Evidence is also available that diet affects emissions from manure applied soil. As level of production is increased to meet global demand for ruminant meat and milk products, dietary manipulation will be useful in addressing environmental concerns.