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Effect of vitreousness, granulometry and bacterial inoculant on the composition and quality of rehydrated corn and sorghum silages

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Author(s):
Marcos André Arcari
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia
Defense date:
Examining board members:
Marcos Veiga dos Santos; Ives Cláudio da Silva Bueno; Francisco Palma Rennó; Arlindo Saran Netto; Dannylo Oliveira de Sousa
Advisor: Marcos Veiga dos Santos; Francisco Palma Rennó
Abstract

Previous studies have indicated that the inclusion of ground rehydrated corn silage (RCS) in dairy cows diet can increase the starch digestibility and the grain protein, increasing the dairy cows performance. However, no studies were carried out to evaluate the influence of grain particle size, bacterial inoculant use and grain vitreousness of corn and sorghum on the composition, quality and digestibility of RCS throughout the ensiling time. In addition, there are few studies about inclusion of RCS in dairy cows diet with some variation of CP content and rumen degradable protein (RDP). To investigate the influence of inoculant use, granulometry, vitreousness content and ensilage time on the chemical composition of ground rehydrated corn and sorghum silage, and the protein content variation and degradability in dairy cow diets, there were developed a set of 5 experiments. The variables evaluated were the productive performance and nitrogen balance of dairy cows fed RCS (Exp 1 and 2) and the chemical composition, fermentative profile and digestibility of the silage and starch during the ensiling time (Exp 3, 4 and 5). Thus, this study was organized in 5 sequential experiments, in which two of them (Exp. 1 and 2) used lactating cows and the others (Exp 3, 4 and 5) used experimental mini silos. The specific objectives of Exp. 1 and 2 were to evaluate the effect in dairy cows diet of: 1) CP content (130, 160 and 180 g CP/kg DM) with total substitution by RCS, 2) RDP content by urea content variation (80, 100 and 120 g RDP / kg PB) with total substitution of ground dry corn by RCS. For Exp. 1 and 2, there were used 15 Holstein cows in third lactation (> 100 <200 days), approximately 550 kg BW, distributed in a 3 × 3 latin square design with 5 contemporary squares, with 3 periods of 21 days and 3 treatments. The cows were alocated in a free-stall, fed twice a day with a feed intake individual control and twice milking per day. In Exp. 1 and 2, the variables evaluated were: nutrient intake, total apparent digestibility, milk yield and composition, rumen fermentative parameters and nitrogen balance. The experiments 3, 4 and 5 were carried out in experimental mini silos (500g) with rehydrated corn and sorghum silages, that aimed to evaluate the effect of: 3) the vitreousness content (low, medium and high) of corn cultivars, the inclusion of inoculant (Lactobacilus buchneri) or not and the ensilage time (0, 15, 30, 60, 120, 240 and 400 days); 4) granulometry (whole, 8, 2 and 1mm) of high vitreousness corn, the inclusion or not of inoculant (Lactobacilus buchneri) and the ensilage time (0, 15, 30, 60, 120, 240 and 400 days); 5) granulometry (8, 2 and 1 mm), bacterial inoculant (Lactobacillus buchneri, Lactobacillus plantarum and Pediococus acidilactici and Lactobacillus buchneri (50%) + Lactobacilus plantarum and Pediococus acidilactici (50%)) and the ensiling time (0, 15, 30, 120 and 360 days) of rehydrated sorghum grain. The variables analyzed in experiments 3, 4 and 5 were the chemical composition of silage (DM, CP, soluble protein, starch, N-NH3 and pH) and 7-hour in situ digestibility of the starch and silage protein. For the experiment 5, the production and composition of the rumen fermentation gases were also evaluated. The rehydrated corn and sorghum silages has particular characteristics of fermentation and increase the digestibility according to the particle size, vitreousness and use of inoculant throughout the ensiling time. The results observed in the present set of experiments suggest that the particularities associated with the previous ensiling process, inoculation or the hybrids used to make the silage may influence the conservation and the digestibility. In addition, the use of rehydrated corn silage, even with high starch apparent total digestibility, did not allow the use of lower CP content or higher RDP content than those predicted by NRC 2001. (AU)

FAPESP's process: 14/20877-7 - Processing and ensiling of hydrated corn grain in diets of dairy cows
Grantee:Marcos André Arcari
Support type: Scholarships in Brazil - Doctorate