Avaliação bioeconômica de estratégias de alimentação em sistemas de produção de leite

• Ano de defesa: 2005
• Autor(a) principal: Rennó, Francisco Palma
• Orientador(a): Pereira, José Carlos
• Banca de defesa: Leite, Carlos Antonio Moreira , Rodrigues, Marcelo Teixeira , Campos, Oriel Fajardo de , Fonseca, Dilermando Miranda da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Bovino de leite; Nutrição animal; Simulação; Economia; Administração rural; Produção animal; Alimentação e rações
• Palavras-chave em Inglês: Dairy cattle; Animal nutrition; Computer simulation; Economy; Rural administration; Animal production; Feeds and feeding
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1690

This work was carried out to: 1) apply a simulation model for the bioeconomic evaluation of feeding strategies for dairy herds; 2) evaluate the physical productivity and the bioeconomic efficiency of feeding systems for dairy cows when varied feeding strategies are used, based in different forages, for cows of five levels of milk yield; 3) establish a method of evaluation of the physical productivity and bioeconomic efficiency of forages considering multiple restrictions to create bases for the evaluation of feeding strategies in milk production systems; and 4) evaluate the bioeconomic efficiency of cows of different levels of milk yield per lactation. The simulation model was developed with the programs CNCPS v5.0 and electronic spreadsheets of Microsoft Excell®, in way to simulate the production and demands of nutrients of a complete lactation for cows of different milk yield levels. The bioeconomic evaluations was carried out in seven feeding strategies: Strategy (EST) 1-corn silage (Zea mays) as exclusive forage, along all lactation (SIM); EST 2-corn silage during the dry season and graze on a pasture of palisadegrass (Brachiaria brizantha sp.) during the rain season (SIM+BRI); EST 3-corn silage during the dry season and graze on a pasture of napiergrass (Pennisetum purpureum, cv. Napier) during the rain season (SIM+NAP); EST 4-corn silage during the dry season and graze on a pasture of bermudagrass (Cynodon dactylon, cv. Tifton-85) during the rain season (SIM+TIF); EST 5-sugarcane (Saccharum sp.) during the dry season and graze on a pasture of palisadegrass during the rain season (CAN+BRI); EST 6-sugarcane during the dry season and graze on a pasture of napiergrass during the rain season (CAN+NAP); EST 7-sugarcane during the dry season and graze on a pasture of bermudagrass during the rain season (CAN+TIF). Considering all the feeding strategies evaluated and the methodology used, with evaluations of diets in function of the lactation phases, and involving cows of five milk yield levels, be carried out approximately 375 simulations in CNCPS v.5.0 for obtaining the data for bioeconomic evaluations of the use of different foods. Considering the definition of the used methodology and adopted ration formulation system, were simulated approximately 855 diets in CNCPS v.5.0. For evaluation of the feeding strategies was used the "Traditional methodology, evaluating the production and profitability per animal and per area unit. Also an alternative methodology was developed, denominated of Adjusts for the Level of Capital , based on the production per unit of area, considering different levels of use of inputs (concentrate) and of capital for hectare. In this evaluation two limits variables are considered in each analysis: area and level of input, or area and capital level. The production costs were evaluate through the following variables: total consumption of concentrated (CTC); relationship milk yield produced (kg) by supplied concentrate (kg) (L:C); total cost with the concentrate (CUTC); medium cost per kg of concentrate (CMC); total cost with the forages (CTV); total cost of the diet (CTD) and medium daily cost of the diet (CMD). The economical evaluations of the different feeding strategies were analyzed through the following variables: income over feeds costs, appraised for the total income by lactation (RMCA/Lac) and medium daily income (RMCA/Dia); productivity per hectare (PROD/ha); animals per hectare (Vaca/ha) and profitability per hectare (LUCR/ha). Using the Traditional methodology in the bioeconomic evaluations, the RMCA demonstrated interaction among the feeding strategy with the milk yield levels. The strategies based on corn silage during the dry season and pastures during rain season resulted in larger RMCA for all of the milk yield levels, in spite of the other feeding strategies present closed results, depending on the milk yield level. In the evaluated strategies, as greater as was the milk yield per cow, greater was the PROD/ha and the RMCA/ha. As larger the support capacity of forages, or, as larger the capacity rate per area, inside certain feeding strategy and milk yield level, higher will be the PROD/ha and the RMCA/ha. For RMCA per cow, forages of greater energy density result in decreased feeding costs and increase in the income per animal. The RMCA/ha was strongly influenced by the support capacity of the forages, in all milk yield levels. Using the methodology Adjusts for the Level of Capital , were evaluated different levels of use of concentrate and capital expense with feeding per unit of area, be estimate regression equations of PROD/ha and RMCA/ha in function of these levels. In this methodology not occur the disproportionate use of inputs and capital expense with feeding per unit of area when are evaluated different feeding strategies. The obtained results showed differences in the bioeconomics evaluations carry out by the Adjusts for the Level of Capital methodology in relation to Traditional methodology. In general, mainly in the largest levels of capital use, the feeding strategies based on forages of better quality showed the best results in PROD/ha and RMCA/ha. However, in the levels of smaller capital use, the feeding strategies based on forages of high productivity per hectare showed the better results in analyzed variables. In relation to evaluation of the bioeconomic efficiency of cows of different milk yield levels, the largest biological efficiency of cows of greater milk yield per lactation not result, necessarily, in larger bioeconomic efficiency. The efficiency of the concentrate use, when evaluated in cows of growing milk yield per lactation, follows the law of the decreasing returns, influencing the bioeconomic efficiency when is larger the milk yield level for cow.