Avaliação de subprodutos agrícolas e agroindustriais na alimentação de bovinos

• Autor(a) principal: Azevêdo, José Augusto Gomes
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1711
• topic: Avaliação de alimentos; Resíduos agrícolas e agroindustriais; Valor energético; Feeds evaluation; Agricultural and agroindustrial residues; Energy value; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

This study evaluated the use of agricultural and agroindustrial by-products for feeding to cattle and was conducted in five experiments. In experiment I, 57 agricultural and agro-industrial by-products collected from different regions of Brazil were used to determine the chemical composition, in vitro digestibility of neutral detergent fiber (IVNDFD) and total digestible nutrients (TDN) in order to group the products with similar nutritional characteristics. In the first cluster, by-products belonging to Group 1 (G1) showed lower IVNDFD, lower than the TDN content, with values of 42.5% and 38.8% respectively. A new grouping was performed using the following variables discriminatory: available crude protein (ACP), ether extract (EE), neutral detergent fiber free to ash and nitrogen compounds (NDFap), lignin (LIG), non-fibrous carbohydrates (NFC), IVNDFD and TDN. In order to better characterize the by-products of G2, six subgroups (SG) were established (SG1 to SG6). The by- products of SG1 had the highest and lowest values of LIG (13.1% in DM) and TDN (54.5%), respectively. The by- products of SG2 had the highest value of NDFap (49.7% in DM), with values of NDT and IVNDFD greater than 60 and 70% respectively, and CP less than 20% of DM. Among all subgroups, those of SG3 had the highest values of TDN (77.2%) and IVNDFD (93.4%) and the lowest value of LIG (2.3% in DM). Amongst the discriminatory variables analyzed, the EE most influence in hierarchical establishing clustering in SG4 (19.0% of DM in EE). The SG5 by-products had the highest concentration of NFC (70.7% in DM). Different from the other subgroups, the SG6 by products had the highest value of ACP (16.5% in DM). The by-products belonging to the G1 have specific limitations for use in animal feeding, SG1 by-products should be, preferably, used as a partial roughage substitutes, that SG2, SG3, SG4 and SG5 byproducts should be used as a partial concentrated energy substitutes and SG6 byproducts should be used as partial protein concentrates substitutes. In experiment II aimed to evaluate the effects of inclusion of the source (pineapple, guava, papaya, mango and passion fruit) and the level (10 and 30%) of by-products of fruit in natura, in the diet of cattle, replacing part of corn silage on intake and total digestibility of nutrients, microbial protein production and the nitrogen balance, in addition to the prediction of digestible fractions and total digestible nutrients of these products. All animals received corn silage and the mixture was used urea / ammonium sulfate (9:1) for the remaining isonitrogenous diets. The intakes of dry matter (DM) (kg / day), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and total digestible nutrients (TDN), and the digestibility of CP, non-fibrous carbohydrates (NFC) and ether extract (EE) were affected (P <0.05) by the source of the by-product. There was an effect (P <0.05) for the level of inclusion of products in the digestibility of CP and EE. The byproducts of papaya, mango and pineapple showed energy 23.1, 18.0 and 7.1% respectively, higher than the corn silage. The source of the by-product influenced (P <0.05) in urinary excretion of derived from total purine, purine absorbed and microbial nitrogen, in addition to the intake (g/day), the excretion in feces and urine (g/day) of nitrogen compounds and nitrogen balance (g/day). The level of inclusion of the by-product in the diet affect (P <0.05) the urinary excretion of derived from total purine, purine absorbed and microbial nitrogen. The by-products of pineapple without crown, papaya and mango are higher than the energy value of corn silage and can partially replace energy concentrates in the diets of ruminants, with no damage on the intake, digestibility, microbial efficiency and nitrogen retention. The by- product of passion has the potential to partial roughage substitutes in the diets of ruminants, provided that observed levels of EE. The by-product of guava has limitations for use in diets of ruminants. In experiment III aimed to evaluate the effects of inclusion of the source (cocoa, shell cassava, stalk cassava and corn gluten feed) and level (10 and 30%) of agricultural and agro-industrial by-products, diet, replacing part of corn silage on the intake and total digestibility of nutrients, microbial protein production and the nitrogen balance, in addition to the prediction of digestible fractions and total digestible nutrients of these by-products. All animals received corn silage and the mixture was used urea / ammonium sulfate (9:1) for the remaining isonitrogenous diets. The intakes of dry matter (DM) (in g/kg PV g/kg PV0, 75) and neutral detergent fiber (NDF) (in g/kg PV) were affected (P <0.05) by source of by- product. The source of by-product affect (P <0.05) the digestibility of ether extract (EE) and non-fibrous carbohydrates (CNF). The by-product corn gluten feed showed energy 17% higher than the corn silage, while shell cassava, cocoa and stalk cassava showed energy 10, 19 and 38% lower than the observed value for corn silage. The source and the level of by-product did not affect the urinary excretion of derived from total purine, purine absorbed, microbial nitrogen and microbial efficiency. The source of the affected product (P <0.05) at intake (g/kg PV0, 75), the excretion in feces (g/kg PV0, 75) and urine (g/kg PV0,75, g/day) of nitrogen compounds and nitrogen balance (g/kg DMI). The corn gluten meal and cassava peel are products with the potential to replace, in part, the concentrated energy, without damage on the intake, digestibility, microbial efficiency and nitrogen retention. The byproduct of cassava stem has the potential to partial roughage substitutes in the diets of ruminants. The by-product of cocoa has limitations for use in diets of ruminants. In experiment VI aimed to assess the accuracy of the equations adopted by the NRC and Detmann, to estimate the energy content of agricultural and agroindustrial by-products. We evaluated the by-products of pineapple, cocoa, palm oil, beans, sunflower, guava, cassava bark, cassava stem, raw cassava, papaya, mango, passion fruit, turnip and corn gluten meal. All animals received corn silage and the mixture was used urea / ammonium sulfate (9:1) for the diets with two levels of each product, remained isonitrogenous. Among the models for prediction of digestible crude protein (CPad), the model presented Detmann 2 difference (P <0.05) by the test of null hypothesis for joint, while estimates by the models and NRC Detmann 1 were similar to those obtained by the observations in vivo (P>0.05). For digestible ether extract (EEad), non-fibrous carbohydrates digestible (NFCad) and neutral detergent fiber digestible (NDFd) observed that the model proposed by the NRC, differed (P <0.05), the significance test of the hypothesis of invalidity joint, with better adjustment to the model suggested by Detmann, with the result, the value P>0.05. However, among all the digestible fractions, the NDFd, presented the greater dispersion of points on the line of equal. The models of the NRC and Detmann may be effective in predicting total digestible nutrients (TDN) and digestible energy (DE), poi estimates did not differ (P> 0.05) of observed values, but also showed great dispersion of points in the line of equal respect. It is recommended to use the models proposed by Detmann to predict the digestible fractions of CP, EE and NFC in agricultural and agroindustrial by-products. There is a need for more research to develop more appropriate models to estimate the digestible fraction of NDF, as this was the main limitation for precise and accurate estimates of the energy value of agricultural and agroindustrial by- products. In experiment V aimed to evaluate the kinetics of degradation in situ, the kinetics of gas production in vitro and predicting the digestible neutral detergent fiber (NDFd) from the time of incubation, the parameters of kinetics of degradation in situ and in vitro, and adjusted equations for agricultural and agribusiness by- products. We evaluated the products of pineapple, cocoa, palm oil, corn gluten feed, beans, sunflower seeds, guava, cassava peel, cassava stem, raw cassava, papaya, mango, passion fruit and turnip. There were differences (P <0.05) between products in potentially degradable fraction (B) of the NDF and the rate of degradation of NDF in situ and in the final volume of gases generated by fibrous carbohydrates (VFCF). There were differences (P <0.05) between by-products for the period of latency and the fractional rate of degradation of CF in vitro. There equivalence (P> 0.05) between the values predicted in situ and observed in vivo in NDFd, however, there is little precision of estimates. The degradation in the time of incubation in vitro, 30 and 48 hours were equivalent to the observed values, but showed no accuracy in the estimation. The adjusted equations without lignin were not precise and accurate to estimate NDFd of agricultural and agroindustrial by-products. The equation with lignin and rate of digestion obtained by in vitro method showed more accurate estimates. The by-products beans, cassava and papaya peel have a higher availability of the NDF, while the guava is to lower availability of the NDF. The digestible fraction of NDF can be predicted by in vitro digestibility of NDF at 30 or 48 hours of incubation and the degradation of NDF obtained in situ for 24, 48 or 72 hours of incubation. However, the prediction seems to be best achieved by the time of incubation in situ for 72 hours. The equation set using the rates of digestion in vitro or in situ, can predict the availability of the NDF of agricultural and agroindustrial by-products.