RESUMO O objetivo deste estudo foi desenvolver uma equação específica para a conversão de valores de pressão (psi) em volume (ml) para o Laboratório de Bromatologia da Universidade Federal do Oeste do Pará. Para tanto, avaliou-se a cinética fermentativa ruminal de rações regionais por meio da técnica semiautomática de produção de gases in vitro. Para configurar a equação alvo, amostras de milho moído, farelo de soja, farelo de arroz, capim Mombaça, torta de cupuaçu, resíduos de mandioca e folhas de bananeira foram incubadas e a pressão e os volumes dos gases produzidos durante o processo de fermentação foram medidos em tempos predeterminados e relacionado. Esses dados de volume de gases produzidos foram utilizados para determinar, por meio da aplicação do modelo logístico bicompartimental, os parâmetros cinéticos da fermentação ruminal. A equação encontrada para o laboratório foi V = 0,3757P2 + 1,5972P + 0,2189. Milho moído e resíduo de mandioca apresentaram maior taxa de degradação de carboidratos não fibrosos (0,120 e 0,163% / h respectivamente) e maior volume final de gás (228,91 e 273,17 ml / g de MS, respectivamente). Quanto à taxa de degradação dos carboidratos fibrosos, milho moído (0,023% / h), farelo de arroz (0,023% / h) e resíduo de mandioca (0,021% / h) apresentaram as maiores taxas de degradação. Assim, foi identificada uma equação específica para ser utilizada no Laboratório de Bromatologia da Universidade Federal do Oeste do Pará, de acordo com o método aplicado e a altitude das instalações.

ABSTRACT The objective of this study was to develop a specific equation for the conversion of pressure values (psi) to volume (ml) for the Laboratory of Bromatology of the Federal University of Western Pará. To this end, the ruminal fermentation kinetics of regional feedstuffs were evaluated using the semi-automatic technique of in-vitro gas production. To set up the targeted equation, samples of ground corn, soybean meal, rice bran, Mombasa grass, cupuassu pie, cassava residues, and banana leaves were incubated and the pressure and volumes of the gases produced during the fermentation process were measured at predetermined times and related. These data on the volume of produced gases were used to determine, by applying the bi-compartmental logistic model, the ruminal fermentation kinetics parameters. The equation found for the laboratory was V = 0.3757P2 + 1.5972P + 0.2189. Ground corn and cassava residue showed a higher degradation rate of non-fibrous carbohydrates (0.120 and 0.163 %/h respectively) and higher final gas volume (228.91 and 273.17 ml/g of DM, respectively). As for the degradation rate of fibrous carbohydrates, ground corn (0.023 %/h), rice bran (0.023 %/h), and cassava residue (0.021 %/h) presented the highest degradation rate. Thus, a specific equation to be used at the Laboratory of Bromatology of the Federal University of Western Pará was identified, according to the method applied and the altitude of the premises. Ruminal fermentation kinetics of cassava residue and rice bran showed the same parameters as corn, which may suggest the possibility of replacing corn in the diet of ruminant animals.

Resumo: O objetivo deste trabalho foi avaliar os efeitos do plano alimentar e do grupo racial sobre o consumo e a digestibilidade de nutrientes, o balanço de nitrogênio e o desempenho de novilhas leiteiras em condições tropicais. Trinta e seis novilhas - 12 Holandês, 12 Gir e 12 Girolando F1 (½ Holandês × ½ Gir) - foram alojadas em sistema “tie-stall” e distribuídas aleatoriamente, tendo-se adotado delineamento inteiramente casualizado, em arranjo fatorial 3x3 (planos alimentares e grupos raciais). As dietas foram formuladas para possibilitar ganhos de peso de 200, 400 e 800 g por dia, correspondentes aos planos alimentares de 11, 14 e 19 g kg-1 de peso corporal (PC), respectivamente. As novilhas Gir dentro do plano de 11 g kg-1 consumiram mais matéria seca, fração fibrosa (g kg-1 de PC-0,75) e energia metabolizável (kcal de PC-0,75) do que as novilhas Girolando e Holandês. A digestibilidade do extrato etéreo foi 13,85% superior para as novilhas Gir, em comparação às Girolando F1 no plano de 19 g kg-1. O aumento do plano nutricional tem efeito quadrático no consumo de nutrientes e linear no ganho de peso médio diário, mas não influencia o coeficiente de digestibilidade. Novilhas Gir leiteiras e Girolando F1 apresentam eficiência nutricional semelhante à das novilhas Holandês.

Abstract: The objective of this work was to evaluate the effects of nutritional plans and breed composition on nutrient intake and digestibility, nitrogen balance, and performance of dairy heifers in tropical conditions. Thirty-six heifers - 12 Holstein, 12 Gyr, and 12 Gyrolando F1 (½ Holstein × ½ Gyr) - were housed in a tie-stall system and randomly distributed, adopting a completely randomized design in a 3×3 factorial arrangement (nutritional plans and breed composition). The diets were formulated to enable weight gains of 200, 400, and 800 g per day, corresponding to the nutritional plans 11, 14, and 19 g kg-1 body weight (BW), respectively. The intake of dry matter, fibrous fractions (g kg-1 BW-0.75), and metabolizable energy (kcal-1 BW-0.75) in the 11-g kg-1 plan were greater for Gyr heifers than for Gyrolando and Holstein heifers. Ether extract digestibility was 13.85% higher for Gyr heifers compared with Gyrolando F1 in the 19-g kg-1 plan. The increase in the nutritional plans shows a quadratic response to nutrient intake and a linear response to average daily gain, but does not affect the digestibility coefficients. Gyr and Gyrolando F1 heifers present similar nutritional efficiency to that of Holstein heifers.

Resumo: O objetivo deste trabalho foi avaliar a qualidade da silagem, o perfil de fermentação, o consumo e a digestibilidade de seis cultivares de sorgo para alimentação de ovinos. 'SF 15', 'IPA 2502', 'BRS 655', 'BR 601', 'BRS 506' e 'Sudão' foram cultivadas em delineamento de blocos ao acaso com cinco repetições, colhidos e ensilados quando as plantas atingiram o estádio pastoso da maturidade dos grãos. A qualidade da silagem foi determinada em silos de laboratório. O consumo e a digestibilidade aparente foram determinados durante 22 dias, tendo-se utilizado 24 cordeiros da raça Santa Inês (35,5±2,21 kg) distribuídos aleatoriamente entre os tratamentos. A silagem de 'IPA 2502' apresentou os menores teores de matéria seca, fibra em detergente neutro e fibra em detergente ácido; os maiores teores de carboidratos não fibrosos e nutrientes digestíveis totais; e a maior degradabilidade da matéria seca. As silagens oriundas de 'BR 601' e 'BRS 506' apresentaram os maiores valores de proteína bruta, enquanto aquelas de 'SF 15' e 'Sudão', os maiores teores das frações fibrosas. Os cordeiros alimentados com a silagem de 'IPA 2502' consumiram mais matéria seca e carboidratos não fibrosos, e a sua digestibilidade de proteína bruta também foi maior do que a oriunda do consumo da silagem de outras cultivares. 'IPA 2502' destaca-se por suas características nutricionais, as quais resultaram em melhor desempenho animal.

Abstract: The objective of this work was to evaluate the silage quality, fermentation profile, intake, and digestibility of six sorghum cultivars for sheep feeding. 'SF 15', 'IPA 2502', 'BRS 655', 'BR 601', 'BRS 506', and 'Sudão' were cultivated in randomized complete block designs with five replicates, harvested, and ensiled when plants reached the soft-dough grain stage. Silage quality was determined in laboratory silos. Intake and apparent digestibility were determined during 22 days, using 24 Santa Inês lambs (35.5±2.21 kg) randomly distributed in the treatments. Silage from 'IPA 2502' had the lowest contents of dry matter, neutral detergent fiber, and acid detergent fiber; the highest nonfibrous carbohydrate and total digestible nutrient contents; and the greatest dry matter degradability. Silages from 'BR 601' and 'BRS 506' showed the highest values of crude protein, whereas those of 'SF 15' and 'Sudão' had the highest levels of fibrous fractions. Lambs fed silage from 'IPA 2502' consumed more dry matter and nonfibrous carbohydrates, and their crude protein digestibility was also greater than that from the consumption of other cultivar silages. 'IPA 2502' stands out for its nutritional characteristics, which resulted in better animal performance.

RESUMO: O objetivo deste estudo foi avaliar a divergência nutricional de clones de Brachiaria ruziziensis através da composição química e cinética de fermentação ruminal in vitro. Os tratamentos consistiram de 23 clones de Brachiaria ruziziensis (15, 16, 46, 174, 411, 590, 651, 670, 768, 776, 844, 859, 950, 965, 970, 975, 1067, 1093, 1296, 1765, 1806, 1894 e 1972), e as testemunhas Brachiaria ruziziensis cv ‘Kennedy’, Brachiaria brizantha cv ‘Marandu’ e a Brachiaria decumbens cv ‘Basilisk’, colhidas com 27 dias de rebrota. O delineamento experimental utilizado foi o de blocos casualizados, com 26 tratamentos (genótipos) e três repetições. A avaliação da divergência nutricional foi realizada utilizando-se a análise de componentes principais e agrupamento aglomerativo hierárquico. Com base nas seguintes variáveis discriminatórias: digestibilidade in vitro da matéria seca; fibra em detergente neutro; lignina; proteína bruta; taxa de degradação de carboidratos não fibrosos e; taxa de degradação de carboidratos fibrosos. A avaliação da divergência nutricional dos clones de B. ruziziensis baseou-se nos dois primeiros componentes principais (DIVMS e FDN), explicando 96.2% da variância total. As variáveis de menor contribuição para a discriminação dos clones foram as taxas de degradação dos carboidratos fibrosos e não fibrosos. Na análise de agrupamento aglomerativo hierárquico foram identificados cinco grupos distintos, em que o grupo V, formado pelos clones 46, 768 e 1067 destacou-se em relação aos demais por apresentar valores superiores de digestibilidade in vitro da matéria seca.

ABSTRACT: The aim of this study was to evaluate the nutritional diversity of Brachiaria ruziziensis clones through chemical composition and in vitro kinetics of ruminal fermentation. Twenty three clones of Brachiaria ruziziensis were used (15, 16, 46, 174, 411, 590, 651, 670, 768, 776, 844, 859, 950, 965, 970, 975, 1067, 1093, 1296, 1765, 1806, 1894 and 1972) and Brachiaria ruziziensis cv. ‘Kennedy’, Brachiaria brizantha cv. ‘Marandu’ and Brachiaria decumbens cv. ‘Basilisk’ as controls within 27 days of harvesting. The experimental design used randomized blocks with 26 treatments (genotypes) and three replications. Evaluation of the nutritional divergence was performed using principal components analysis, based on the following discriminatory variables: in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), lignin, crude protein (CP), degradation rate of non-fibrous carbohydrates (KdNFC) and degradation rate of fibrous carbohydrates (KdFC). The evaluation of the nutritional diversity of Brachiaria genotypes was based on the two main components (IVDMD and NDF), which explains 96.2% of the total variance Variables of lower contribution to the discrimination of the clones were as degradation rates of the fibrous and non-fibrous carbohydrates. In the agglomerative hierarchical grouping analysis, five distinct groups were identified, where V group, formed by clones 46, 768 and 1067 have higher values of IVDMD compared to the other clones.

RESUMO: Avaliou-se o efeito da inclusão da silagem da raiz de mandioca sobre os parâmetros ruminais e o balanço de compostos nitrogenados em bovinos de origem leiteira. Utilizou-se cinco animais, canulados no rúmen, não lactantes e com peso corporal médio de 389 kg. Os animais foram distribuídos em um quadrado latino cinco x cinco, sendo cinco dietas com níveis de inclusão (0,00; 3,62; 7,23; 10,84; e 14,54% da matéria seca da dieta) da silagem da raiz de mandioca e cinco períodos. Cada período constituiu-se em 10 dias de adaptação e cinco dias para a coleta dos dados. As excreções de nitrogênio na urina e nas fezes não foram influenciadas (P>0,05) pela inclusão da silagem da raiz de mandioca nas dietas. O consumo de nitrogênio total (CNT) e o balanço de nitrogênio (BN) apresentaram comportamento quadrático e linear crescente, respectivamente. Obteve-se o menor CNT (142,14 g/dia) no nível de inclusão de 5,82% de silagem da raiz de mandioca. As concentrações de ureia (U) e de nitrogênio ureico (NU) na urina e no plasma não modificaram (P>0,05). Observou-se comportamento quadrático (P<0,05) nas excreções de U e NU na urina, com ponto de mínimo de 131,13 e 61,20 g/dia, respectivamente, no nível de 7,27% de inclusão da silagem da raiz de mandioca. Não houve interação (P>0,05) entre os níveis da silagem da raiz de mandioca e o tempo de coleta do conteúdo ruminal para os ácidos graxos de cadeia curta, o pH e o nitrogênio amoniacal (N-NH3). Apenas o teor de N-NH3 apresentou comportamento quadrático, em função dos níveis de inclusão, obtendo-se o ponto mínimo (12,62 mg/100 mL de conteúdo ruminal) no nível de 5,98%. O nível de 7,23% de silagem da raiz de mandioca na dieta foi mais eficiente na utilização dos compostos nitrogenados. As dietas contribuem de forma semelhante para a produção dos ácidos graxos de cadeia curta, sem interferir no pH ruminal.

ABSTRACT: The effect of inclusion of cassava root silage on ruminal parameters and nitrogenous compounds in dairy cattle was evaluated. Five cattle cannulated in the rumen and with average body weight of 389 kg were distributed into a Latin square 5x5, with five levels of inclusion (0.00, 3.62, 7.23, 10.84 and 14.54% of the diet dry matter) of cassava root silage and five periods (10 days for adaptation and five days for data collection). The nitrogen excretion in urine and feces were not affected (P>0.05) by inclusion of cassava root silage in the diet. The total nitrogen intake (CNT) and nitrogen balance (NB) showed an increasing quadratic and linear behavior, respectively. The lowest CNT (142.14g/day) was obtained with the inclusion of 5.82% silage cassava root. The concentration of urea (U) and urea nitrogen (UN) in plasma and urine did not change (P>0.05). There was a quadratic behavior (P<0.05) in excreta of U and NU in the urine, with minimum point of 131.13 and 61.20g/day respectively, at the level of 7.27% inclusion of the cassava root silage. No interaction (P>0.05) was between the levels of cassava root silage and the collection time of rumen contents for the short-chain fatty acids, pH and ammonia nitrogen (NH3-N). Only the N-NH3 protein showed quadratic behavior, according to the inclusion levels, with the minimum point (12.62mg/100ml of rumen contents) at the level of 5.98%. The level of 7.23% of cassava root silage in the diet was more efficient with the use of nitrogen compounds. The diets contribute similarly to the production of short chain fatty acids, without disturbing the rumen pH.

The objective of this study was to evaluate agronomic characteristics of 32 sorghum cultivars (Sorghum bicolor(L). Moench) in the Brazilian semi-arid region. The experimental design was set up in randomized blocks with three replications. Treatments were the 32 sorghum cultivars. The evaluated variables were: plant height, stem diameter, tiller density, number of green leaves per tiller, average leaf length, dry matter content, fresh matter production and dry matter production (DMP) in kg/ha, and the percentage of the components panicle, leaf blade and stem. To avoid associative effects due to the presence of positive correlation with DMP, the variables plant height, number of plants per hectare and fresh matter production were excluded for being part of the discriminatory variables of the cluster. Based on the cluster analysis and subjective cutting in 20% dissimilarity, five groups were hierarchically set up. It was not possible to find groups with higher values of panicle and DMP simultaneously; however, group number 5 met significant values for both variables, with mean values of 15,037.63 kg/ha of DMP and 11.36% of panicle, besides 13.65% of leaf. Groups 3, 4 and 5 show high potential for dry matter production, especially group 5. The presence of evident variation among cultivars allows for a selection of more productive and, thus, more suitable cultivars for silage production in semi-arid regions.

The objective of this study was to evaluate the in situ and in vitro degradation kinetics and to predict the digestible neutral detergent fiber (dNDF) from the incubation times; in situ and in vitro degradation kinetic parameters; and equations fitted for agricultural and agro-industrial byproducts. Byproducts from pineapple, cocoa, palm kernel, corn gluten meal, common bean, sunflower, guava, cassava bark, cassava stems, cassava foliage, papaya, mango, passion fruit and turnips were evaluated. There were differences between the byproducts as for the potentially neutral detergent fiber (NDF) fraction and the in situ NDF degradation rate in the final volume of the gases generated by fibrous carbohydrates (FC), for the lag time and for the in vitro fractional degradation rate of the FC. There was equivalence between the dNDF values predicted in situ and those observed in vivo; however, there was low precision of estimates. The degradability in the in vitro incubation times of 30 and 48 hours presented equivalence with the values observed, but also did not present precision in the estimates. The equations fitted without lignin were not precise and accurate to estimate the dNDF of agricultural and agro-industrial byproducts. The equation with lignin and with the digestion rate obtained by the in vitro method presented more precise estimates. Byproducts from common bean, cassava bark and papaya presented greater NDF availability, whereas those of guava had the lowest NDF availability. The digestible NDF fraction was best predicted with the in situ incubation time of 72 hours. The equation fitted utilizing in vitro or in situ digestion rates enables the prediction of the NDF availability of agricultural and agroindustrial byproducts.

The objective of this study was to evaluate the divergence of bromatological and fermentative characteristics of silages of 25 sorghum (Sorghum bicolor L. Moench) hybrids. The experimental design was completely randomized with 25 treatments and four replications. The mean values of pH differed with variation from 3.45 to 3.87 for hybrids 866005 and 870051, respectively, and the mean pH value was 3.66. The average percentage of lactic acid ranged from 2.90 to 7.43 dag/kg of dry matter (DM) in hybrids 870035 and 866005, respectively, with an average of 4.65 dag/kg DM. Through cluster analysis by the Tocher method and average Euclidean distance based on the fermentative characteristics, five groups were formed: one with 18 hybrids, another with four and three groups with one hybrid in each. In group three, there were the hybrids that showed the highest values of lactic acid. Hybrids 870025, 870035, 870081, 870095, 866034, and 870031 showed higher DM content and the hybrid BRS 610 had the lowest average compared with the others. Hybrids 1F305, BRS 610, Volumax, and XBS60329 had the lowest levels of non-fiber carbohydrates and higher neutral detergent fiber corrected for ash and protein. Despite the fermentative and bromatological divergences between hybrids, they are not a limiting factor to silage production.

The objective of this study was to evaluate the nutritional divergence between ten genotypes of forage peanut, based on chemical composition as well as fermentation and in vitro degradation kinetic characteristics. Treatments consisted of ten genotypes of Arachis pintoi, namely eight accessions (31135, 30333, 15121, 31828, 15598, 31534, 13251 and 31496) and two cultivars (cv. Belmonte and cv. Amarillo). The genotypes were harvested in each plot at a height of 3 cm from the ground, in 42-day intervals, during the time of heaviest rainfall. For the multivariate analysis the following variables, the following were used: crude protein, neutral detergent fiber, potential degradation in 48 hours, degradation rate of insoluble potentially degradable fraction and degradation rate of non-fibrous carbohydrate. The application of the hierarchical clustering analysis, using the Euclidian distances matrix of standardized averages allowed for the identification of five homogeneous groups. Among them, the accessions 31828, 31534, 15121 and cv. Belmonte stood out nutritionally among the remaining genotypes evaluated, depicting as promising for the utilization in ruminant feeding.

The objective of this study was to evaluate the use of different mathematical models to describe growth of grazing beef cattle. Data of 20 Nellore bulls with initial weight of 129±28.1 kg and final weight of 405±62.0 kg were used. The animals were randomly divided into four plots and placed on B. decumbens Stapf pastures. Three plots received concentrate supplement with different protein profiles and the fourth plot received only mineral supplement. Animals were weighed every 28 days to design growth curve of full body weight. Five mathematical models were evaluated to describe animal growth: Multiphase, Linear, Logarithmic, Gompertz and Logistic models. Assessment of adequacy of the models was performed by using coefficient of determination, simultaneous F-test for identity of parameters, concordance correlation coefficient, root of the mean square error of prediction and partition of the mean square error of prediction. The analysis of the pairwise mean square error of prediction and the delta Akaike's information criterion were used to compare the models for accuracy and precision. Evaluation of all the tested models showed that all of them were able to predict variability among animals. However, Gompertz, Logarithmic and Logistic models created individual predictions that were not satisfactory. Models differed from each other concerning accuracy and precision; the best were in the following order: Multiphase, Linear, Gompertz, Logarithmic and Logistic. The Multiphase model was more efficient than the others for description of grazing beef cattle growth.

Objetivou-se avaliar os efeitos da inclusão de subprodutos de frutas in natura (abacaxi, goiaba, mamão, manga e maracujá) e do nível (10 e 30%) utilizado na dieta de bovinos em substituição parcial à silagem de milho sobre o consumo e a digestibilidade total dos nutrientes, a produção de proteína microbiana (Pmic) e o balanço de nitrogênio e sobre a predição das frações digestíveis e nutrientes digestíveis totais (NDT) desses subprodutos. Todos os animais receberam silagem de milho e mistura ureia/sulfato de amônio (9:1) para que as rações se mantivessem isonitrogenadas. Os consumos de matéria seca (MS) (kg/dia), matéria orgânica (MO), proteína bruta (PB), fibra em detergente neutro (FDN) e NDT, além da digestibilidade de PB, extrato etéreo (EE) e carboidratos não-fibrosos (CNF) foram afetados pela origem do subproduto. Houve efeito para o nível de inclusão dos subprodutos na digestibilidade da PB e EE. Os subprodutos de mamão, manga e abacaxi apresentaram valor energético 23,1; 18,0 e 7,1%, respectivamente, superior ao da silagem de milho. A fonte do subproduto influenciou as excreções urinárias de derivados de purinas totais e purinas absorvidas e a produção de proteína microbiana, além da ingestão (g/dia), a excreção dos compostos nitrogenados nas fezes e na urina (g/dia) e o balanço de nitrogênio (g/dia). O nível de inclusão dos subprodutos na dieta afetou as excreções urinárias de derivados de purinas totais e purinas absorvidas e a produção de proteína microbiana. Os subprodutos de abacaxi, mamão e manga têm valor energético superior ao da silagem de milho e podem substituir parcialmente concentrados energéticos em dietas para ruminantes. O subproduto de maracujá tem potencial para substituir parcialmente volumosos em dietas para ruminantes. O subproduto de goiaba apresenta limitações para uso em dietas para ruminantes.

The objective of this study was to evaluate the effects of inclusion of by-product of fresh fruit (pineapple, guava, papaya, mango and passion fruit) used in the diet for bovines partly replacing corn silage on intake and total nutrient digestibility, on the production of microbial protein and the nitrogen balance and on prediction of digestible fractions and total digestible nutrients (TDN) of these by-products. All animals received corn silage and the urea/ammonium sulfate (9:1) mixture so diets would remain isonitrogenous. The intakes of dry matter (DM) (kg/day), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and TDN, and the digestibility of CP, non-fibrous carbohydrates (NFC) and ether extract (EE) were affected by the source of the by-product. There was an effect for the level of inclusion of products in the digestibility of CP and EE. The by-products of papaya, mango and pineapple showed energy values of 23.1, 18.0 and 7.1% respectively, higher than corn silage. The source of the by-product influenced urinary excretion of derived from total purine, purine absorbed and production of microbial protein, 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 the urinary excretion of derived from total purine, purine absorbed and microbial protein production. The by-products of pineapple, papaya and mango have energy value higher than corn silage and they can partly replace energy concentrates in diets for ruminants. The by-product of passion fruit has the potential to partly replace roughage in the diets of ruminants. The by-product of guava has use limitations in diets of ruminants.

Avaliou-se nesta pesquisa o efeito da inclusão de óxido de cálcio (cal) e dos tempos de exposição da cana-de-açúcar à cal sobre o desempenho de novilhas Nelore, a digestibilidade dos componentes da dieta e a síntese de proteína microbiana ruminal (PBMic) e comparou-se o dióxido de titânio ao óxido crômico para estimar o consumo individual de concentrado. Utilizaram-se 30 fêmeas Nelore com aproximadamente 24 meses de idade e pesos médios de 285 ± 31 kg, alojadas em seis baias coletivas. As dietas foram arranjadas em esquema fatorial 3 × 2, com três níveis de cal (0; 0,5 ou 1% na matéria natural) e dois tempos de exposição (zero e três dias). Os tempos de exposição da cana-de-açúcar à cal não tiveram efeitos sobre as quantidades de nitrogênio microbiano, os consumos de matéria seca (MS) e orgânica (MO), proteína bruta (PB), total de nutrientes digestíveis e o ganho médio diário, porém influenciaram os consumos de extrato etéreo (EE), fibra em detergente neutro corrigida para cinzas e PB (FDNcp) e carboidratos não-fibrosos (CNF). Os níveis de cal influenciaram de forma linear decrescente os consumos de MO, FDNcp, CNF e NDT, e o GMD. Todavia, não foram observados efeitos dos indicadores (dióxido de titânio e óxido crômico) nem interações do tempo de exposição e do nível de cal sobre os consumos de MS, MO, PB, EE, FDNcp, CNF e NDT. Interações significativas do tempo de exposição e do nível de inclusão de cal foram observadas para as digestibilidades aparentes totais da MS, MO, PB e FDN e para o teor de NDT. Os indicadores dióxido de titânio e óxido crômico são igualmente efetivos para estimar os consumos individuais de concentrado de bovinos alimentados em grupo. O fornecimento de cana-de-açúcar armazenada durante três dias sem cal não altera o desempenho de novilhas em crescimento.

It was evaluated in this work the effects of levels of inclusion and exposure times of sugarcane to calcium oxide on the performance of Nellore heifers, digestibility of dietary components and synthesis of ruminal microbial protein and it was compared titanium dioxide to chromium oxide to estimate the individual intake of concentrate. It was used 30 Nellore females at approximately 24 months of age and average body weight of 285 ± 31 kg and age of 24 months housed in six pens (50 m² approximately), each one of them with five animals (feeding group). The diets were allocated in a 3 × 2 factorial arrangement, containing three levels of calcium oxide (0; 0.5 and 1.0% of sugarcane fresh matter) and two levels of exposure time (0 and 3 days). There were no effects of calcium oxide exposure time on the intake of microbial nitrogen, dry matter (DM), organic matter (OM), crude protein (CP) and total digestible nutrients (TDN) and daily weight gain, but, it affected the intake of ether extract (EE), neutral detergent fiber corrected for ash and CP contamination (NDFcp), and nonfiber carbohydrate (NFC). The levels of whitewash decreased linearly the intake of OM, NDFap, NFC, and ADG. However, it was not observed effects of the markers (titanium dioxide and chromic oxide) nor interactions among exposure time and level of whitewash on intakes of DM, CP, EE, NDFap, NFC and TDN. Significant interactions between exposure time and level of inclusion of whitewash were observed for total aparent digestibility of DM, OM, and NDF and for content of TDN. Titanium oxide and chromic oxide are equally effective for estimating individual intakes of concentrate by bovine fed in group. Supply of sugar cane stored for three days without whitewash does not change performance of growing heifers.

Objetivou-se avaliar equações adotadas pelo NRC e Detmann para estimar o conteúdo energético de subprodutos agrícolas e agroindustriais. Foram avaliados subprodutos de abacaxi, cacau, dendê, feijão, girassol, goiaba, mandioca casca, mandioca haste, mandioca rama, mamão, manga, maracujá, nabo e farelo de glúten de milho. Todos os animais receberam silagem de milho e mistura ureia/sulfato de amônio (9:1) para que as rações com os dois níveis de cada subproduto se mantivessem isonitrogenadas. Entre os modelos de predição da proteína bruta digestível (PBad), o modelo Detmann 2 apresentou diferença pelo teste de hipótese para nulidade conjunta (THNC), enquanto as estimativas pelos modelos NRC e Detmann 1 foram similares às obtidas pelas observações in vivo. Para extrato etéreo digestível (EEad), carboidratos não-fibrosos digestíveis (CNFad) e fibra em detergente neutro digestível (FDNd), as estimativas obtidas pelo modelo proposto pelo NRC diferiram, pelo teste de significância da hipótese de nulidade conjuntas, das observações in vivo e o melhor ajustamento foi obtido pelo modelo sugerido por Detmann, tendo como consequência, o valor. No entanto, entre todas as frações digestíveis, a FDNd foi a que apresentou maior dispersão dos pontos em relação à linha de equalidade. Os modelos NRC e Detmann podem ser considerados eficientes em predizer nutrientes digestíveis totais (NDT) e energia digestivel (ED), pois as estimativas não diferem dos valores observados, contudo apresentam também grande dispersão dos pontos em relação à linha de equalidade. Recomenda-se usar os modelos propostos por Detmann para predizer as frações digestíveis da PB, EE e dos CNF em subprodutos agrícolas e agroindustriais.

The objective of this work was to evaluate the equations adopted by the NRC and Detmann to estimate the energy content of agricultural and agroindustrial byproducts. It was evaluated byproducts 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 urea/ammonium sulfate (9:1) so rations with the two levels of each byproduct remained isonitrogenous. Among the models for digestible crude protein prediction (CPad), Detmann 2 model presented difference by the hypotheses test for joint null while estimates by the NRC and Detmann 1 models were similar to those obtained by in vivo observations. For digestible ether extract (EEad), digestible non-fibrous carbohydrates (NFCad) and digestible neutral detergent fiber (NDFd), the estimates obtained by the model proposed by the NRC differed, by the test of significance of hypotheses of joint null, to in vitro observations and the best adjustment was obtained by the model suggested by Detmann, having as a consequence, the value. However, among all the digestible fractions, NDFd presented the greatest dispersion of points regarded to equality line. NRC and Detmann models can be considered as efficient in predicting total digestible nutrients (TDN) and digestible energy (DE) because the estimates do not differ from the observed values, however they also present great dispersion of the points regarded to equality line. It is recommended to use the models proposed by Detmann for predicting digestible fractions of crude protein, ether extract and non fibrous carbohydrates on agriculture and agroindustrial byproducts.

Objetivou-se desenvolver e avaliar novas equações para predição do consumo de matéria seca (CMS) em bovinos Nelore e mestiço, utilizando-se meta-análise. Os dados utilizados para estimar os parâmetros foram coletados em experimentos de desempenho independentes com bovinos Nelore e mestiço nas fases de recria e engorda, compilados a partir de 561 unidades experimentais. Antes de propor uma equação para predizer o CMS, observou-se que o grupo genético foi uma fonte de variação estatisticamente significativa. Neste sentido, equações para predizer o CMS em bovinos Nelores e mestiços foram desenvolvidas de forma independente. As equações de regressão para bovinos mestiços foram: CMS = -2,6098 + 0,08844PV0,75 + 4,4672GMD - 1,3579GMD2 e CMS = -1,0094 + 0,01608PV + 4,4363GMD -1.2548GMD2. As equações de regressão para bovinos Nelore foram: CMS = -2,7878 + 0,08789PV0,75 + 5,0487GMD - 1,6835GMD2 e CMS = -1,3559 +,0159PV + 5,6397GMD - 1,8494GMD2. Para avaliar as equações ajustadas, utilizaram-se dados de experimentos independentes publicados entre 2005 e 2008 na Revista Brasileira de Zootecnia. As equações (CMS) para Nelore superestimaram o CMS para estimativas menores que 7 e maiores que 10 kg d-1. Para bovinos mestiços, as dispersões de 3 kg·d-1 foram observadas quando pontos extremos foram avaliados, no entanto, quando a equação incluiu PV0,75, o intercepto não diferiu de zero e a inclinação não diferiu de 1. Não é possível ajustar uma única equação para predizer o CMS para bovinos de corte em condições tropicais, porque há diferenças entre Nelores e mestiços. Equações ajustadas que incluem GMD e PV0,75 devem ser usadas como um método alternativo para predizer o CMS em bovinos Nelores e mestiços em condições tropicais.

The study was carried out to develop and to evaluate new equations to predict dry matter intake (DMI) of Nellore and Zebu-crosses cattle using meta-analysis procedure. The data used to estimate the parameters were collected from independent performance experiments using growing and fattening Nellore and Zebu-crosses cattle, and they were compiled from 561 experimental units. Before proposing an equation to predict DMI, it was observed that the genetic group was a source of statisticaly significant variation. Therefore, equations to predict dry matter intake in the Zebu-Crosses and Nellore cattle were independently developed. The regression equations for Zebu-crosses cattle were: DMI = -2.6098 + 0.08844BW0.75 + 4.4672ADG - 1.3579ADG2 and DMI = -1.0094 + 0.01608BW + 4.4363ADG -1.2548ADG2. The regression equations for Nellore cattle were: DMI = -2.7878 + 0.08789BW0.75 + 5.0487ADG - 1.6835ADG2 and DMI = -1.3559 + 0.0159BW + 5.6397ADG - 1.8494ADG2. In order to evaluate fitted equations, it was utilized data from independent experiments published from 2005 to 2008 in the Revista Brasileira de Zootecnia. The equations (DMI) for Nellore overpredicted dry matter intake for estimates lower than 7 and higher than 10 kg·d-1. For Zebu-crosses cattle, dispersions of 3 kg d-1 were observed when extreme intakes were evaluated, however, when the equation included BW 0.75, the intercept did not differ from zero and the slope did not differ from 1. It is not possible to fit only one equation for preditcting DMI for beef cattle in tropical conditions, because there are differences between Zebu and Zebu-crosses. Fitted equations that include ADG and BW 0.75 should be used as an alternative method to predict dry matter intake of Zebu-crosses and Nellore beef cattle in tropical conditions.

Objetivou-se avaliar o efeito da inclusão de cal e dos tempos de exposição da cana-de-açúcar à cal sobre o consumo e as digestibilidades total e parcial dos nutrientes e parâmetros ruminais e comparar o dióxido de titânio e o óxido crômico como indicadores para estimar a excreção de matéria seca (MS) fecal e o fluxo abomasal de MS. Utilizaram-se seis fêmeas nelores, com pesos médios de 250 ± 19 kg, fistuladas no rúmen e no abomaso, distribuídas em um quadrado latino incompleto 6 x 6. O experimento foi arranjado em esquema fatorial 3 x 2, com três níveis de cal (0; 0,5 ou 1% da matéria natural) e dois tempos de armazenamento da cana (0 e 3 dias). Não houve efeito dos tempos de armazenamento, nem interação entre os níveis de cal e os tempos de armazenamento, sobre o consumo de nutrientes. Contudo, os níveis de cal aumentaram linearmente os consumos de MS, matéria orgânica (MO) e carboidratos não-fibrosos. Os tempos de armazenamento reduziram a digestibilidade aparente total da MS, MO e fibra em detergente neutro corrigida para cinzas e proteína (FDNcp), mas não influenciaram a digestibilidade aparente ruminal dos nutrientes. A inclusão de cal aumentou o consumo de nutrientes digestíveis totais (NDT), mas não afetou a digestibilidade total e ruminal dos nutrientes. Os indicadores produziram resultados similares para as estimativas de digestibilidade aparente total e ruminal de todos os nutrientes avaliados. Foram observadas interações para o pH ruminal. Contudo, os valores de nitrogênio amoniacal foram influenciados somente pelos tempos de amostragem. A adição de cal não tem efeito sobre a preservação da cana-de-açúcar, mas influencia positivamente o consumo de MS, MO e NDT pelos animais. Os marcadores dióxido de titânio e óxido crômico produzem estimativas de digestibilidades similares.

It was aimed to evaluate the effect of inclusion and times of sugar cane exposition to whitewash on intake and total and partial digestibility of nutrients and ruminal parameters and to compare titanium dioxide and chromium oxide as markers to estimate fecal dry matter excretion and dry matter abomasal flow. It was used six rumen and abomasum cannulated Nellore females, with average body weight of 250 ± 19 kg, distributed in an incomplete 6 x 6 latin square design. The experiment was set in a 3 x 2 factorial scheme with three levels of whitewash (0; 0.5 or 1.0% natural matter) and two times of sugar cane storage (0 and 3 days). There was no effect of storage times neither interaction among levels of whitewash and storage times on the intake of nutrients. However, levels of whitewash linearly increased consumption of dry matter (DM), organic matter (OM) and non-fibrous carbohidrates (NFC).Storage times reduced total apparent digestibility of dry matter, organic matter and neutral detergent fiber corrected for ash and protein (NDFap), but they did influence ruminal apparent digestibility of the nutrients. The inclusion of whitewash increased the consumption of total digestible nutrients (TDN), but it did not affect total digestibility and ruminal digestibility of the nutrients. The markers produced similar results for the estimates of total and ruminal apparent digestibility of all the evaluated nutrients. Interactions for ruminal pH were observed. However, values of amonical nitrogen were only influenced by sampling times. Addition of whitewash does not affect preservation of sugarcane, but it positively influences consumption of DM, OM, and TDN of the animals. The markers produced similar estimative to total tract and ruminal apparent digestibility of all nutrients. Titanium dioxide and chromium oxide markers produce similar estimates of digestibility.