Replacement of dicalcium phosphate by rock phosphate in cattle diets: nutrients digestibility, plasma parameters, ruminal fermentation and microbial synthesis efficiency
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Data
2010-04-01
Autores
Coneglian, Sabrina Marcantonio
Branco, Antonio Ferriani
Guimarães, Kátia Cylene
Mano, Daniel Suzigan
Barreto, Julio Cezar
Fávaro, Vanessa Ruiz [UNESP]
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Editor
Sociedade Brasileira de Zootecnia
Resumo
Este estudo foi conduzido para avaliar os efeitos da substituição do fosfato bicálcico pelo fosfato de rocha na dieta de bovinos em crescimento. Foram determinados a digestibilidade aparente das dietas, a absorção aparente do fósforo, cálcio e flúor, o pH ruminal, a concentração de amônia ruminal, a eficiência microbiana e o fósforo no plasma utilizando-se cinco bovinos da raça Holandesa Preto-e-Branco, fistulados, pesando entre 275 e 283 kg. O delineamento estatístico foi um quadrado latino 5 × 5 e as dietas consistiram de 0, 25, 50, 75 e 100% de substituição do fosfato bicálcico pelo fosfato de rocha no suplemento mineral. A adição de fosfato de rocha nas dietas ocasionou aumento linear na ingestão, no fluxo omasal, no fluxo fecal e no desaparecimento total do flúor. As dietas não diferiram quanto à absorção aparente do cálcio, assim como em relação à ingestão, excreção, digestão e digestibilidades aparentes parcial e total da matéria seca, matéria orgânica, proteína bruta, fibra em detergente neutro e carboidratos não-fibrosos. O fósforo no plasma não foi influenciado pelos tratamentos e a média foi de 5,93 mg/dL. Não houve diferença para o pH ruminal e concentração de amônia ruminal. A substituição do fosfato bicálcico não afetou a síntese microbiana aparente e verdadeira de proteína. A total substituição do fosfato bicálcico pelo fosfato de rocha em suplementos minerais em bovinos em crescimento não afetou o ambiente ruminal e a síntese de proteína no rúmen. Assim, a substituição do fosfato bicálcico em dietas para bovinos em crescimento diminui a absorção de fósforo e deveria ser vista com cuidado dependendo dos requerimentos.
This study was conducted in order to evaluate the effects of replacing dicalcium phosphate by rock phosphate in diets of growing steers. It was determined the following aspects: apparent digestibility of diets; phosphorus (P), calcium and fluorine apparent absorption; ruminal pH; ruminal ammonia concentration; microbial efficiency and plasma P. Five rumen fistulated Holstein steers weighting 275 - 283 kg were used. Experimental design was a 5 × 5 Latin square and diets consisted of 0, 25, 50, 75 and 100% of dicalcium phosphate replacement by rock phosphate in the mineral supplement. Addition of rock phosphate in the diets produced a linear increase on intake, rumen outflow and fecal output and total disappearance of fluorine. Diets did not differ to apparent absorption of calcium as well as dry matter, organic matter, crude protein, neutral detergent fiber and non-fiber carbohydrates intake, excretion, digestion and partial and total apparent digestibility. Plasma phosphorus was not influenced by diets and the average was 5.93 mg/dL. There was no difference for ruminal pH and ruminal ammonia concentration. Dicalcium phosphate replacement did not affect apparent and true protein microbial synthesis. Total replacement of dicalcium phosphate by rock phosphate in growing steer mineral supplement did not affect ruminal environment and protein synthesis in rumen. Considering this, dicalcium phosphate replacement in growing steer diets decreases P absorption and depending on its requirements it should be carefully seen.
This study was conducted in order to evaluate the effects of replacing dicalcium phosphate by rock phosphate in diets of growing steers. It was determined the following aspects: apparent digestibility of diets; phosphorus (P), calcium and fluorine apparent absorption; ruminal pH; ruminal ammonia concentration; microbial efficiency and plasma P. Five rumen fistulated Holstein steers weighting 275 - 283 kg were used. Experimental design was a 5 × 5 Latin square and diets consisted of 0, 25, 50, 75 and 100% of dicalcium phosphate replacement by rock phosphate in the mineral supplement. Addition of rock phosphate in the diets produced a linear increase on intake, rumen outflow and fecal output and total disappearance of fluorine. Diets did not differ to apparent absorption of calcium as well as dry matter, organic matter, crude protein, neutral detergent fiber and non-fiber carbohydrates intake, excretion, digestion and partial and total apparent digestibility. Plasma phosphorus was not influenced by diets and the average was 5.93 mg/dL. There was no difference for ruminal pH and ruminal ammonia concentration. Dicalcium phosphate replacement did not affect apparent and true protein microbial synthesis. Total replacement of dicalcium phosphate by rock phosphate in growing steer mineral supplement did not affect ruminal environment and protein synthesis in rumen. Considering this, dicalcium phosphate replacement in growing steer diets decreases P absorption and depending on its requirements it should be carefully seen.
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Palavras-chave
fermentação ruminal, fontes de fósforo, fósforo plasmático, proteína microbiana, phosphorus sources, plasma phosphorus, rumen microbial protein, ruminal fermentation
Como citar
Revista Brasileira de Zootecnia. Sociedade Brasileira de Zootecnia, v. 39, n. 4, p. 815-823, 2010.