Effect of ensiling temperature on microbial inoculants and performance of dairy cows fed corn grain silage with sodium benzoate

• Ano de defesa: 2021
• Autor(a) principal: Gritti, Viviane Carnaval
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Aditivos químicos; Chemical additives; Fermentation end products; Inoculantes microbianos; Inoculants; Milk yield; Produção de leite; Produtos de fermentação
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11139/tde-20052021-155923/

Silage additives are recommended for corn-based silages in tropical conditions, such as whole-plant corn silage, high moisture corn, and rehydrated corn grain, to prevent losses at storage and enhanced aerobic stability. Sodium benzoate is a salt of an organic acid and has antifungal properties and it is used as a chemical additive for silages. The mechanism of sodium benzoate to prevent the presence of undesirable microorganisms in silages is related to the undissociated form of benzoic acid, which may pass across the cell membrane and release the hydrogen in the cytoplasm. But, the influence of sodium benzoate on animal performance still unknown. Another type of additives suitable for corn-based silages is the inoculants containing lactic acid bacteria (LAB), which can be divided into two major groups, homo-fermentative bacteria and hetero-fermentative bacteria. Higher ensiling temperatures typically lead to a shift from homolactic to heterolactic microbial populations, but the majority of silage microbiological knowledge focuses on optimal fermentation conditions, rather than optimal outcomes under environmental extremes. The objective of the first study was to evaluate the performance, feeding behavior, and ruminal parameters of Holstein lactating dairy cows fed diets with HMC or RCG, as the main source of starch, added or not 0.2% fresh matter of sodium benzoate (BEN). Also, to evaluate the chemical and physical composition, the fermentative profile, and the digestibility of HMC or RCG with or without sodium benzoate. As main results in both HMC and RCG silages, sodium benzoate reduced butyric acid concentration, reduced soluble protein. Moreover, sodium benzoate increased total-tract starch digestibility and milk production, and changed the cows eating behavior. However, RCG did not affect the performance of cows when compared to HMC. Even HMC and RCG differing in fermentation profile, grain moisture at harvesting did not affect dairy cow\'s performance, being RCG an efficient alternative of HMC. Even HMC and RCG differing in fermentation profile, grain moisture at harvesting did not affect dairy cow\'s performance, being RCG an efficient alternative of HMC. Sodium benzoate reduced protein solubility, fermentation end- products, development of spoilage microorganisms and improve starch digestibility, affecting dairy cow\'s chewing behavior and increasing milk yield by 0.8 kg/day. The objectives of the second trial were to study the patterns of fermentation between silages inoculated with LAB exposed to high- and low- levels of heat stress and corresponding ensiling temperatures. Commercial inoculants were heat-stressed at 30°C and 40°C for 24h incubated at 30°C and 45°C to test growth. Some inoculants decreased the growth when incubated at 45°C and heat- stress did not increase the adaptation of some inoculants, had no difference for inoculant 1 and increased the growth for inoculant 11 to high temperatures. The high temperature of ensiling decreased the formation of end products and increased the pH. HHS before ensiling was efficient in dropping the pH for some inoculants. Overall, prior exposure to heat stress of silage inoculant cultures produced varied effects on the performance of inoculants in culture and in the silo. In particular, prior exposure to high heat stress resulted in lower silage pH values and varied fermentation profiles when compared to LHS or uninoculated controls.