Environmental implications of inositol phosphates in animal manures

Animal production in the USA is valued at more than $100 billion and has consolidated significantly during the last 20 years, with a larger number of animals being produced on an increasingly smaller land base (Kellogg et al., 2000). Manure generated from animal production is currently estimated to exceed 335 million t of dry matter per year in the USA, while global manure production is estimated at —13 billion t of dry matter per year (Mullins et al., 2005). Manures contain significant amounts of phosphorus, with values between 6.7 and 29.1 g P/kg on a dry weight basis reported for several species of animals (Barnett, 1994). This phosphorus includes inorganic and organic forms, with the latter constituting between 10°/a and 80% of the total (Peperzak et al., 1959; Gerritse and Zugec, 1977). Inositol phosphates are one of the primary organic phosphorus species found in manures, with myo-Inositol hexakisphosphate typically being the most abundant (Peperzak el al., 1959; Barnett, 1994; Turner and Leytem, 2004)

What aspect of dietary modification in broilers controls litter water-soluble phosphorus: Dietary phosphorus, phytase, or calcium?

Environmental concerns about phosphorus (P) losses from animal agriculture have led to interest in dietary strategies to reduce the concentration and solubility of P in manures and litters. To address the effects of dietary available phosphorus (AvP), calcium (Ca), and phytase on P excretion in broilers, 18 dietary treatments were applied in a randomized complete block design to each of four replicate pens of 28 broilers from 18 to 42 d of age. Treatments consisted of three levels of AvP (3.5, 3.0, and 2.5 g kg -1) combined with three levels of Ca (8.0, 6.9, and 5.7 g kg-1) and two levels of phytase (0 and 600 phytase units [FTU]). Phytase was added at the expense of 1.0 g kg -1 P from dicalcium phosphate. Fresh litter was collected from pens when the broilers were 41 d of age and analyzed for total P, soluble P, and phytate P as well as P composition by 31P nuclear magnetic resonance (NMR) spectroscopy. Results indicated that the inclusion of phytase at the expense of inorganic P or reductions in AvP decreased litter total P by 28 to 43%. Litter water-soluble P (WSP) decreased by up to 73% with an increasing dietary Ca/AvP ratio, irrespective of phytase addition. The ratio of WSP/total P in litter decreased as the dietary Ca/AvP ratio increased and was greater in the phytase-amended diets. This study indicated that while feeding reduced AvP diets with phytase decreased litter total P, the ratio of Ca/AvP in the diet was primarily responsible for effects on WSP. This is important from an environmental perspective as the amount of WSP in litter could be related to potential for off-site P losses following land application of litter

Interaction of calcium and phytate in broiler diets: 1. Effects on apparent prececal digestibility and retention of phosphorus

Phytate P utilization from soybean meal (SBM) included in broiler diets has been shown to be poor and highly dependent on dietary Ca intake. However, the effect of Ca on P utilization and on the optimal ratio of Ca to nonphytate P (Ca:NPP) when diets contained varying levels of phytate has not been clearly shown and was the objective of this research. A factorial treatment structure was used with 4 dietary Ca levels from 0.47 to 1.16% and 3 levels of phytate P (0.28, 0.24, and 0.10%). Varying dietary phytate P levels were obtained by utilizing SBM produced from 3 varieties of soybeans with different phytate P concentrations. Ross 508 broiler chicks were fed 1 of 12 diets from 16 to 21 d of age. Excreta were collected from 16 to 17 d and from 19 to 20 d of age and ileal digesta was collected at 21 d of age. Apparent prececal P digestibility decreased when dietary Ca concentration increased and was higher when diets contained low-phytate SBM. The apparent digestibility of Ca and percentage of phytate P hydrolysis at the distal ileum were not reduced when dietary phytate P concentration increased. Including low-phytate SBM in diets reduced total P output in the excreta by 49% compared with conventional SBM. The optimum ratio of Ca:NPP that resulted in the highest P retention and lowest P excretion was 2.53:1, 2.40:1, and 2.34:1 for diets with 0.28, 0.24, and 0.10% phytate P. These data suggested that increased dietary Ca reduced the extent of phytate P hydrolysis and P digestibility and that the optimum Ca:NPP ratio at which P retention was maximized was reduced when diets contained less phytate P

Interaction of calcium and phytate in broiler diets: 2. Effects on total and soluble phosphorus excretion

Dietary Ca has been reported to influence the amount of phytate excreted from broilers and affect the solubility of P in excreta. To address the effects of dietary Ca and phytate on P excretion, 12 dietary treatments were fed to broilers from 16 to 21 d of age. Treatments consisted of 3 levels of phytate P (0.10, 0.24, and 0.28%) and 4 levels of Ca (0.47, 0.70, 0.93, and 1.16%) in a randomized complete block design. Feed phytate concentrations were varied by formulating diets with 3 different soybean meals (SBM): a low-phytate SBM, a commercial SBM, and a high phytate Prolina SBM having phytate P concentrations of 0.15 to 0.51%. Fresh excreta was collected from cages during 2 separate 24-h periods; collection I commenced after the start of dietary treatments (16 to 17 d) and collection II followed a 3-d adaptation period (19 to 20 d). Ileal samples were also collected at 21 d. Excreta samples were analyzed for total P, water soluble P (WSP), and phytate P, whereas ileal samples were analyzed for total P and phytate P. Results indicated that excreta total P could be reduced by up to 63% and WSP by up to 66% with dietary inclusion of low-phytate SBM. There was a significant effect of dietary Ca on both the excreta WSP and the ratio of WSP:total P. As dietary Ca increased, the excreta WSP and WSP:total P decreased, with the effects being more pronounced following a dietary adaptation period. There was a linear relationship between the slope of the response in WSP to dietary Ca and feed phytate content for excreta from collection II (r(2) = 0.99). There was also a negative correlation between excreta phytate concentration and excreta WSP during both excreta collections. The response in WSP to dietary manipulation was important from an environmental perspective because WSP in excreta has been related to potential for off-site P losses following land application

Escarificação ácida, temperatura e luz no processo germinativo de sementes de Senna alata (L.) Roxb

O objetivo deste trabalho foi determinar o tempo ótimo de escarificação das sementes de Senna alata em ácido sulfúrico e verificar o efeito da temperatura, em condição de luz e escuro, na germinação de sementes dessa espécie. As sementes foram imersas em ácido sulfúrico concentrado por períodos de 0, 15, 30 e 60 minutos, e o teste de germinação realizado em BOD a 25ºC, utilizando quatro repetições de 50 sementes em cada período de tempo, sendo o delineamento estatístico inteiramente casualizado com 4 tratamentos. No segundo experimento, para verificar o efeito da temperatura e da condição de luz mais adequada a germinação, utilizou-se temperaturas de 10 a 45ºC, com intervalos de 5ºC, em condição de luz fluorescente branca ou escuro contínuo (gerbox preto). Utilizou-se o delineamento experimental inteiramente casualizado, disposto em esquema fatorial 8x2, com 4 repetições, de 50 sementes cada. Em todos os testes as avaliações da porcentagem e índice de velocidade de germinação foram feitas diariamente, durante 10 dias, onde as sementes foram consideradas germinadas quando apresentaram 2 mm de raiz. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de probabilidade. A escarificação do tegumento com ácido sulfúrico durante 60 minutos, foi ideal para as sementes de Senna alata, por proporcionar maiores valores na porcentagem e velocidade de germinação. A germinação ocorre entre 15 e 40ºC, sendo consideradas fotoblásticas neutras entre 20 e 40ºC e fotoblásticas negativas preferenciais a 15ºC. O melhor desempenho germinativo foi obtido nas temperaturas de 25, 30 e 35ºC, onde ocorreram maior porcentagem e velocidade de germinação.The aim of this study was to establish the optimum scarification time for Senna alata seeds in sulfuric acid, as well as to verify the effect of temperature on seed germination for this species under conditions of light and darkness. Seeds were immersed in concentrated sulfuric acid for periods of 0, 15, 30 and 60 minutes, and the germination test was carried out in a BOD chamber at 25ºC, using four replicates of 50 seeds for each time period. Experimental design was completely randomized with 4 treatments. In the second experiment, temperatures from 10 to 45ºC, with 5ºC intervals, were used under conditions of fluorescent white light or continuous darkness (black "gerbox") in order to verify the temperature effect and the most suitable light condition for germination. Experimental design was completely randomized, in an 8x2 factorial arrangement, with 4 replicates of 50 seeds each. In all tests, germination percentage and speed index were daily evaluated for 10 days. Seeds were considered germinated when the radicle length was 2 mm. Data were subjected to analysis of variance and means were compared by Tukey's test at 5% significance. The tegument scarification with sulfuric acid for 60 minutes was optimal for Senna alata seeds since it led to higher values of germination percentage and speed. Germination occurs between 15 and 40ºC, and seeds are considered neutral photoblastic between 20 and 40ºC and negative photoblastic especially at 15ºC. The best germination performance was observed at 25, 30 and 35ºC, at which germination percentage and speed were higher