ABSTRACT. The aim of this study was to relate the occurrence of visible losses in silage (effluent, spoiled top-layer and during feedout) with silage-making practices, physical and chemical characteristics of silage, and milk composition in Brazilian dairy herds. One-hundred and eight silos from 95 farms, in the State of Parana, were visited for data collection. Data were analyzed by Fisher's Exact and Pearson Correlation Test. Effluent loss was higher in silages with the lowest dry matter content. Using unwalled clamp (drive-over piles) silos, neglecting a protection over the plastic film, and unloading silage with a bucket increased the occurrence of top spoilage. Feedout losses were higher in farms where: the crop was harvested with self-propelled machines; the particle size was larger, and the silage density was lower. There was no relationship between visible losses and silage composition or milk composition, except for milk fat content that, unexpectedly, there was a positive correlation with spoiled silage in the top-layer. Silage losses are reduced by adopting good practices during silage production and feedout.

ABSTRACT: Ensiling corn for longer periods is a strategy used to increase rumen bacteria access to starch. In fact, when corn is ensiled for insufficient periods, starch digestibility decreases, as evidenced by excreted starch. This study investigates the effects of corn silage ensiling time on starch digestibility of dairy cows through fecal starch analysis. The trial was conducted during the spring of 2013 and the fall of 2014 on twenty dairy herds located in the state of Paraná, southern Brazil. Total mixed ration (TMR), whole-plant corn silage (WPCS) and fecal samples were collected for determination of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin and starch. Apparent total tract starch digestibility (ATTSD) was calculated using equations developed by Fredin et al. (2014) and Bal et al. (1997). Data were analyzed using the CORR, REG and GLM procedures of SAS. Spring and fall WPCS were ensiled for 260 and 132 days, respectively (p < 0.01). There was no difference (p > 0.05) in ATTSD-Fredin from season to season though there was a trend (p = 0.11) towards greater ATTSD-Bal for spring samples. ATTSD-Bal was positively correlated with ensiling days (r = 0.31). Starch digestibility was not negatively affected by WPCS harvesting maturity. Differences in post-ruminal starch digestion, variation between farms in DM intake and diets, limitations of the equations, influence of uncontrolled factors, and the small number of experimental units might have contributed to the absence of significant results. Overall, Bal et al. (1997) equation was more efficient in distinguishing ATTSD from different ensiling periods.

Os objetivos deste trabalho foram determinar as concentrações de P disponível extraído pelos métodos de Mehlich-1 (M1), Resina trocadora de íons (RTI) e Morgan Modificado (MM), após 36 meses de experimentação com aplicação de fosfatos em um sistema de integração lavoura-pecuária (SILP). Ainda, verificar qual método de extração proporciona melhor correlação com atributos da cultura do milho. O delineamento empregado foi em esquema fatorial incompleto, com quatro repetições. Foram aplicadas doses de P2O5, na superfície do solo, por ocasião da semeadura da forrageira de inverno, nas formas de superfosfato triplo (SFT), fosfato natural reativo (FNR) e termofosfato magnesiano (TFM). Após 36 meses, procederam-se coletas de solos das camadas de 0-5; 5-10; 10-15; 15-20 cm, visando determinar as concentrações de P disponível. Na cultura do milho foram quantificados o rendimento de massa seca (RMS), o rendimento de grãos (RG), o acúmulo de fósforo na massa seca (P-MS) e a exportação de fósforo (P-Ex). A RTI extraiu maiores quantidades de P disponível, seguida do extrator de M1 e do MM. Nos tratamentos que receberam aplicação de SFT, os extratores de M1 e RTI obtiveram eficiência semelhante quando correlacionados com os atributos de RMS, RG, P-MS e P-Ex do milho. Para as fontes insolúveis em água (FNR e TFM), o P extraído pela RTI melhor se correlacionou com o P-MS e o P-Ex. A solução de MM foi ineficiente para prever a biodisponibilidade de P para o milho, cultivado em solo que recebeu a aplicação de doses e fontes de P, em SILP.

The objectives of this study were to assess the concentrations of available phosphorus (P) extracted using the Mehlich-1 (M1), ion exchange resin (IER) and modified Morgan (MM) methods after 36 months of experimentation with the application of phosphates in a crop-livestock integration system (CLIS). Moreover, this study aimed to assess which extraction method provides the best correlation of P concentrations with the maize crop attributes. The treatments consisted of applying annual doses of P2O5 on the soil surface of the total area during the sowing of winter forage crops in the form of triple superphosphate (TSP), rock phosphate (RP) or magnesium thermophosphate (MTP). After 36 months of experimentation, soil samples were collected from the 0-5, 5-10, 10-15 and 15-20 cm layers to assess the concentrations of available P. The dry matter yield (DMY), the grain yield (GY), the accumulation of phosphorus in the dry matter (P-DM) and the export of phosphorus (P-Ex) were quantified in maize. The IER method extracted greater amounts of available P, followed by the M1 and MM extractions. The treatments that included the application of TSP and either the M1 or IER extractions had similar efficacies when correlated with the DMY, GY, P-DM and P-Ex attributes of maize. The P extracted by the IER was most correlated with P-DM and P-Ex for the water-insoluble P sources (RP and MTP). The MM solution was ineffective at predicting the availability of P for maize grown in a soil with that had received varying doses and sources of P applications in a CLIS.

O objetivo deste trabalho foi verificar os efeitos de fontes e doses de fósforo (P), aplicados na superfície do solo, por ocasião da semeadura de forrageiras anuais de inverno, sobre o acúmulo de P e rendimento das culturas de milho, soja, aveia preta e azevém anual, em um sistema de integração lavoura-pecuária, ao longo de três anos. O experimento foi instalado em abril/2009, no município de Castro-PR, empregando-se delineamento em blocos ao acaso e esquema fatorial incompleto, com quatro repetições. Foram aplicadas doses (0; 60; 120 e 180 kg ha-1) de P2O5 total por ocasião da semeadura da forrageira de inverno, nas formas de superfosfato triplo (SFT), fosfato natural reativo (FNR-Arad) e termofosfato magnesiano (TFM). Foram avaliados os rendimentos de massa seca de aveia preta (2009 e 2011) e azevém anual (2010), de grãos de milho (2009/10 e 2011/12) e soja (2010/11), e o acúmulo de P nestas culturas. O uso de SFT aumentou o rendimento de massa seca total (MST) e acúmulo de P apenas para a aveia preta no primeiro ano. No segundo ano, a aplicação de TFM proporcionou maior acúmulo de P para o azevém anual. Para a soja, tanto a aplicação de TFM quanto de SFT proporcionaram maior acúmulo e exportação de P nos grãos. No terceiro ano, o uso de TFM proporcionou maior rendimento de MST e acúmulo de P tanto para a aveia preta quanto para a cultura do milho, caracterizando maior efeito residual.

The aim of this study was to assess the effects of the sources and levels of surface-applied (broadcast) phosphorus (P) when sowing the winter annual forages on phosphorus accumulation and yields of maize, soybean, black oat and annual ryegrass crops in a crop-livestock integration system over three years. The experiment was established in April 2009, in the municipality of Castro, Parana, Brazil. The treatments consisted of the broadcast application when sowing the winter forages of four doses (0, 60, 120 and 180 kg ha-1 year-1) of total P2O5 as triple superphosphate (TSP), rock phosphate (RP-Arad) and magnesium termophosphate (MTP). The dry matter yields of black oat (2009 and 2011), annual ryegrass (2010), maize (2009/10 and 2011/12) and soybean (2010/11) and the accumulation of P in these crops were assessed. TSP provided the highest yield of total dry matter (TDM) and P accumulation only for black oat in the first year of cultivation. In the second year, MTP resulted in higher P accumulation than occurred with the other P sources in annual ryegrass and soybean, and both MTP and TSP provided higher P accumulation and grain export. In the third year, MTP provided a higher TDM yield and P accumulation for both the black oat and maize crops, resulting in the greatest residual effect over time.