Strategies to improve the nutritive value of whole-plant corn silage in diets for finishing beef cattle

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Título:
Strategies to improve the nutritive value of whole-plant corn silage in diets for finishing beef cattle
Autor: Machado, Juliana
Orientador: Nussio, Luiz Gustavo
Assuntos: Cobertura Do Silo; Colhedora De Forragem; Desempenho Animal; Filme De Vedação; Animal Performance; Forage Harvester; Sealing Film; Silo Cover
Notas: Tese (Doutorado)
Descrição: Whole-plant corn silage (WPCS) is a major source of forage for feedlot beef cattle in Brazil. During the ensilage process, the type of harvesting equipment and the silo sealing, cause changes in the silage and affect its nutritional value. Nonetheless, two trials were conducted to evaluate the effect of processing and inclusion level of WPCS and sealing strategies on the performance of finishing beef cattle. In the first trial, the objective was to evaluate the effect of WPCS processing with self-propelled or pull-type forage harvester on the performance of beef cattle in diets with high and low forage inclusion. The WPCS was harvested with approximately 30% dry matter (DM) with pull-type forage harvester (PTFH, without kernel processor, New Pecus PRF 2-4555) or self-propelled forage harvester (SPFH, with kernel processor, New Holland FR 500), adjusted for theoretical length of cut of 10 mm. Storage time was 219 days. Sixty Nellore bulls (405 kg ± 29,1 kg, 24 months old) were distrusted in blocks and allocated in 20 pens (3 animals per pen) for 102 days (12 days of adaptation + 90 days of diets comparison). The experimental diets were: 1) 15% WPCS harvested with PTFH; 2) 33% WPCS harvested with PTFH; 3) 15% WPCS harvested with SPFH; 4) 33% WPCS harvested with SPFH. Silage samples were collected from the silo panel to evaluate composition, fermentation products, temperature, density, pH and losses. Dry matter intake (DMI) was measured daily, whereas shrunk body weight (SBW) and other animal variables were measured at the beginning, middle and end of the diet comparison period. Silage data were presented as mean and standard deviation, and animal performance was analyzed as a randomized complete block design. The inclusion of 33% WPCS increased DMI by 10% (9.88 vs. 10.91 kg DM/d) and average daily gain by 14% (1.386 vs. 1.585 kg/d). Gain and carcass weight also improved with 33% WPCS in the diet. In addition, the increase in rumination, chewing, number of meals, and intake rate were results of a greater inclusion of WPCS in the diet. The performance and carcass characteristics of the cattle were similar for WPCS processed with different harvesters. The interaction between harvester and inclusion showed that cattle that the intake of 15% WPCS processed with SPFH had a preference for particles larger than 19 mm and medium particles between 8-19 mm. There was selection against fine particles. The net energy of maintenance and the total digestible nutrients of the silage were higher when the diet changed from 15 to 33% WPCS. Pressure and oxygen saturation increased, while fecal pH decreased, for cattle of treatment with 15% WPCS. In conclusion, the greater inclusion of WPCS in the diet improved the performance of finishing beef cattle. The performance of the cattle was not influenced by type of harvester used during WPCS harvesting. The objective of the second study was to compare the performance of beef cattle fed diets based on WPCS sealed with plastic films, with or without oxygen barrier (OB), protected with an anti- ultraviolet (anti-UV) cover or double-sided polyethylene (PE) film. The WPCS was harvested at 32% DM and packed in four duplicate silos (total of eight silos), simultaneously. The silos were divided in the transversal dimension and four treatments were applied to each one, as follows: 45 µm OB film protected with anti-UV cover (anti-UV+OB); 45 µm OB film protected with 120 µm double-sided PE film (PE120+OB); 50 µm PE film protected with anti-UV cover (anti-UV+PE50); 50 µm PE film protected with 120 µm double-sided PE film (PE120+PE50). Two silos were prepared for each treatment and the storage time of the first four silos was 300 days and the other four, 347 days. Silage samples were taken from the exposed panel of each silo to determine silage composition, fermentation products, microbial count, temperature, pH and dry matter loss. Sixty-four Nellore bulls (456 ± 42.8 kg) were divided in blocs by initial SBW and allocated to individual pens for 103 days (13 days of adaptation + 90 days of diet comparison). The experimental diets contained (on a DM basis) 70% concentrate and 30% of WPCS from the different sealing strategies. Dry matter intake (DMI) was measured daily, while SBW and other animal variables were measured at the beginning, middle and end of the feeding trial period. Silage and animal performance data were analyzed as a complete randomized block design. The silages stored under OB film protected with PE120 showed higher mold counts. Losses during silage feed-out were higher for films protected with PE120. During storage, the sealing strategy with anti-UV cover showed 9.60°C higher at 11:00 am and 4.22°C higher at 4:00 pm, compared to cover by PE120 film. The highest silage temperatures were verified in the upper layer, and the highest densities, in the bottom layer of the silo. Animals that received a diet containing silage from the PE120+OB treatment showed greater daily variation in DMI. The DMI, average daily gain and other carcass characteristics were similar between treatments. The results suggest that the protection of both films with an anti-UV or PE120 cover, equally affected silage quality and animal performance.
DOI: 10.11606/T.11.2022.tde-12082022-091814
Editor: Biblioteca Digital de Teses e Dissertações da USP; Universidade de São Paulo; Escola Superior de Agricultura Luiz de Queiroz
Data de criação/publicação: 2022-06-10
Formato: Adobe PDF
Idioma: Inglês

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Strategies to improve the nutritive value of whole-plant corn silage in diets for finishing beef cattle

Machado, Juliana

Biblioteca Digital de Teses e Dissertações da USP; Universidade de São Paulo; Escola Superior de Agricultura Luiz de Queiroz 2022-06-10

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