No abstract

The objective of this study was to evaluate the performance of beef heifers on Stapf. cv. Marandu grass pastures that were managed at three herbage allowances under continuous grazing with a variable stocking rate and were provided with mineral mix supplement or supplements with energy and protein. Seventy-two test heifers and 48 put-and-take heifers were used in a randomised design in a 3 × 2 factorial arrangement [three herbage allowances (1.5, 2.0, and 2.5 kg of green dry matter/kg of bodyweight, and two supplementation levels (mineral mix or 0.3% bodyweight of a mineral–protein–energy supplement)], with two replicates per treatment (paddocks), to maintain the pre-established forage allowance. No significant difference was observed in the gain per hectare as a function of the herbage allowance, but 2.5 kg green dry matter/kg bodyweight provided the greatest average daily gain of bodyweight (0.605 kg/animal/day). The energy/protein supplementation provided the greatest average daily gain compared with animals fed only the mineral mix. The supplements in the diet of beef heifers fed at 0.3% of bodyweight increased bodyweight gains without compromising the gain per hectare at different herbage allowances.

The objective of the present experiment was to evaluate the ability of n-alkanes to estimate dry matter (DM) intake (DMI) and digestibility (DMD) in Nellore beef cattle fed a tropical grass cut at two growth stages (30 or 60 days). The effect of two different faecal sampling procedures (daily pool-Total-or rectal spot-Spot-samples) was also tested. Differences in faecal concentration between sampling methods were lower than 2% and 0.7% for 30-d and 60-d old grass, respectively, with slightly higher values in Spot samples. Faecal recoveries were not affected by the grass growth stage, except in the cases of C 31 , C 33 , and C 35 (P b 0.05), which were lower for 30-d compared to 60-d. There was lower ratio (P b 0.05) between internal and external recovery alkane pairs C 31 /C 32 , C 33 /C 32 and C 35 /C 36 in treating 30-d treatment than in 60-d old grass. Faecal recovery of natural alkanes increased with chain length, recoveries up to 77.0% (C 35 ), whereas dosed alkanes C 28 , C 32 and C 36 showed average recoveries of 94.2%, 97.2% and 86.8%, respectively. Estimates of DMI were different from current values (P b 0.05) when used C 31 /C 32 , C 33 /C 32 and C 35 /C 36 natural/dosed alkane pairs, regardless of the sampling procedure. An exception was the DMI estimated using the C 35 /C 36 alkane pair of the samples of total sampling, which does not differ from the actual values (P N 0.05). However, using recovery-corrected faecal concentrations reduced the differences between observed and estimated values (P N 0.05). Similarly, the DMD was underestimated with the alkanes C 31 , C 33 and C 35 , regardless of the method of sampling. Observed effect of forage development stage in the estimates of DMD (P b 0.05), (lower values for 30-d treatment were observed than in the 60-d), due to lower faecal recovery of alkanes in the 30-d treatment. By correcting the concentrations of alkanes with the faecal recovery of the individual alkane, the differences between the estimated and actual values were canceled (P N 0.05), regardless of age of forage, the alkane used or the sampling method.

RESUMO -O efeito da amonização com uréia (5,0% matéria seca) do feno de Brachiaria brizantha, com dois teores de umidade (15 ou 30% de umidade), associado a três fontes de urease (feno de capim Brachiaria decumbens, capim-elefante [Pennisetum purpureum] e leucena [Leucaena leucocephala]), foi avaliado. Foram determinados os teores de proteína bruta (PB), fração solúvel (A), frações de proteína verdadeira solúvel e insolúvel em borato fosfato (B1 e B2), fração de proteína potencialmente degradável (B3) e fração da proteína insolúvel em detergente ácido (C). Avaliaram-se os teores de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), celulose (CEL), hemicelulose (HEM) e lignina (LIG) e digestibilidade in vitro da matéria seca (DIVMS). O delineamento experimental foi o de blocos inteiramente casualizados, com 10 tratamentos (dois controles, 15 e 30% umidade, sem uréia e sem urease; dois controles, 15 e 30% umidade, com uréia e sem urease; seis combinações de fontes de urease e conteúdo de umidade) e três repetições. A amonização dos fenos com diferentes conteúdos de umidade, associados a fontes de urease, aumentou os teores de PB e da fração A, mas não afetou B1 e B2. Contudo, as frações B3 e C diminuíram em reposta à amonização. A aplicação de uréia nos fenos de 30% de umidade, associados ou não a fontes de urease, diminuiu os teores de FDN. A adição de fontes de urease não alterou os teores dos constituintes da parede celular, quando comparada aos tratamentos amonizados com uréia. Os tratamentos aplicados não proporcionaram efeitos consistentes sobre os teores de FDA e de CEL dos fenos e não afetaram os teores de LIG. A aplicação de uréia associada a 15 ou 30% de umidade foi favorável para aumentar o nitrogênio solúvel do feno de Brachiaria brizantha e diminuir o nitrogênio indisponível para o ruminante.Palavras-chave: Brachiaria decumbens, capim-elefante, leucena, tratamento químico Evaluation of Urease Sources in the Ammoniation of Brachiaria brizantha Hays with TwoMoisture Levels ABSTRACT -The urea ammoniation (5.0% dry matter) effects in Brachiaria brizanta hay baled with two moisture contents (15 or 30% moisture), and three urease source (Brachiaria decumbens hay, elephantgrass (Pennisetum purpureum), leucena (Leucaena leucocephala)) was evaluated. The crude protein (CP), soluble nitrogen fraction (A), borate phosphate true protein fractions (B1 and B2), potentially degradable protein fraction (B3), acid detergent insoluble protein (C) were analyzed. The NDF, ADF, cellulose, hemicellulose and lignin contents and in vitro dry matter digestibility (IVDMD) were analyzed. The experiment was conducted according to a completely randomized block design with 10 treatments (two control, 15 and 30% moisture, without urea and urease; two controls, 15 and 30% moisture, with urea and urease; six combinations of urease source and moisture levels), with three replicates. Ammoniation increased CP, and A fractions of the hays baled with different moisture contents associated to urease source; however urea app...

ResumoObjetivou-se avaliar as características agronômicas e químico-bromatológicas de híbridos de milho para ensilagem. Os tratamentos avaliados foram nove híbridos de milho (MX 300, RB 9308, 2B655, XB 6012, GNZ 2500, PL6890, PRE 32D10, PRE 22T10 e AG 1051), com três repetições. As maiores produções de MV foram verificadas nos híbridos PL6890 e PRE 32D10, enquanto a maior produção de MS foi observada no híbrido PRE 32D10 (13,43 t ha -1 ). Os híbridos PRE 32D10 e PRE 22T10 destacaram-se por apresentarem maior porcentagem de lâminas foliares em relação à planta inteira, enquanto a menor porcentagem de colmos foi encontrada nos híbridos MX 300, 2B655 e XB 6012, entretanto a maior relação folha:colmo foi verificada no híbrido XB 6012 (0,49). Observou-se maior teor de PB no híbrido PRE 32D10 (9,10% da MS), enquanto o menor teor de FDN (57,78% da MS) e celulose (24,27% da MS) foram verificados no híbrido GNZ 2500. O híbrido PL6890 apresentou maior teor de FDA (39,20 % da MS) e lignina (8,63% da MS), os demais híbridos apresentaram valores inferiores. Verificou-se menor N retido na FDN (NIDN) no híbrido RB 9308, enquanto a menor retenção de N em FDA (NIDA) ocorreu no híbrido 2B655. A menor capacidade tampão (CT) foi verificada no híbrido 2B655 (0,29). Embora haja diferenças na composição químico-bromatológica dos híbridos de milho avaliados neste estudo, recomenda-se utilizar os híbridos MX 300, PL6890 e PRE 32D10 por apresentarem produção de matéria seca mais elevada, os quais podem refletir na amortização dos custos na produção das silagens. Palavras-chave: Parede celular, população de plantas, produtividade, Zea mays AbstractOur aim was to evaluate agronomic and chemical characteristics of corn hybrids to ensiling. It were evaluated nine corn hybrids (MX 300, RB 9308, 2B655, XB 6012, GNZ 2500, PL6890, PRE 32D10, PRE 22T10 e AG 1051), with three replicates. The higher fresh matter yield were observed in the hybrids PL6890 and PRE 32D10, while the dry matter yield was observed in the hybrid PRE 32D10 (13.43 t ha -1 ). The hybrids PRE 32D10 and PRE 22T10 stood out to present higher percent of leaf in relation to whole plant, while the lower percent of stems was found in the hybrids MX 300, 2B655 and XB 6012, however the higher leaves: stems relation was found in XB 6012 (0.49). There was higher CP

This work was carried out to study the effects of replacing corn by different levels of cassava starch (0; 12.5; 22.8 and 32.7%) on performance and carcass characteristics of bulls finished in feedlot. Thirtytwo crossbred bulls (½ Aberdeen Angus vs. ½ Nellore) with 18 months old and 380 + 24 kg live weight were used in a completely randomized experimental design with four treatments and eight replications. The experiment was realized during 56 days with 14 days for adaptation. The complete diets [roughage (cottonseed hulls) + concentrate (corn, soybean meal and cassava starch)] were given at 8 am and at 4 pm to bulls. It was analyzed the initial weight (IW), final weight (FW), average daily gain (ADG), dry matter intake (DMI), feed conversion (FC), hot carcass dressing (HCD), fat thickness (FAT), Longissimus muscle area (LMA), leg length (LL) and cushion thickness (CT). The IW, FW, ADG, FC, HCW, HCD, FT, LMA, LL and CT did not present difference (P > 0.05) among levels of replacing corn by cassava starch. The results obtained on performance and carcass traits using cassava starch by-products as a replacement for corn can be considered satisfactory. Key words: Beef cattle, cassava, cattle performance, cotton hulls, feedlot ResumoObjetivou-se com este trabalho avaliar o efeito do nível de substituição (0; 12,5; 22,8 e 32,7%) do milho pelo resíduo de fecularia de mandioca sobre o desempenho e características de carcaça de bovinos em confinamento. Trinta e dois machos inteiros mestiços (½ Aberdeen Angus vs. ½ Nelore) com 18 meses

RESUMO -Avaliaram-se os efeitos da temperatura do processo de extrusão sobre as características das frações nitrogenadas e dos carboidratos, do extrato etéreo, da digestibilidade in vitro da proteína e do fator antitríptico da soja e do milho. O experimento foi conduzido em delineamento experimental inteiramente casualizado, com três repetições, em esquema fatorial 5 × 4, composto de cinco combinações de soja e milho (100% soja; 75% soja e 25% milho; 50% soja e 50% milho; 25% soja e 75% milho; 100% milho, com base na matéria seca) e quatro temperaturas de extrusão (sem extrusão; e extrusão a 80, 100 ou 120 o C). O processo de extrusão promoveu aumento na fração lipídica e redução nos teores de fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA), que variaram de acordo com a proporção de milho e soja e com a temperatura de processamento, conseqüentemente, os teores de proteína insolúvel em detergente neutro (PIDN) e proteína insolúvel em detergente ácido (PIDA) sofreram redução. A mesma tendência foi observada nos teores de lignina, que foram menores nas misturas com até 50% de soja, processadas a 120 o C. A extrusão, independentemente da temperatura, promoveu aumento da fração A dos carboidratos, tanto no milho como na soja. Nas frações B2 e C diminuíram com a maior participação de soja na mistura. A extrusão reduziu as frações nitrogenadas A, B1 e C, fato observado nas misturas contendo soja. O processamento promoveu aumento da fração B2, exceto no milho a 100%. Alterações menos significativas foram observadas na fração B3. O processamento por extrusão não altera a digestibilidade in vitro da proteína de milho e soja, no entanto, reduz a quantidade de inibidor de tripsina quando as misturas desses grãos são processadas a 120ºC.Palavras-chave: digestibilidade, fração carboidrato, fração lipídio, fração nitrogenada, inibidor de tripsina, temperatura Chemical changes in soybean and corn processed by extrusion ABSTRACT -The effects of temperatures of extrusion process on characteristics of nitrogen and carbohydrates fractions, ether extract, in vitro protein digestibility and trypsin inhibitor factor of soybean and corn. The experiment was conducted in a completely randomized design, with three replicates in a 5 × 4 factorial arrangement, with five combinations of soybean and corn (100% soybean, 75 soybean and 25 corn, 50 soybean and 50 corn, and 25 soybean and 75 corn, 100% corn, %DM) and four temperatures of extrusion (without extrusion and extrusion at 80, 100 or 120 o C). The process of extrusion promoted increase in the lipid fraction and reduction in levels of neutral detergent fiber (NDF) and acid detergent fiber (ADF), which changed according to the proportion of soybean and corn and the temperature of processing, consequently, the levels of neutral detergent insoluble protein (NDIP) and acid detergent insoluble protein (ADIP) reduced. The same trend was observed in levels of lignin, which were lower in combinations with up to 50% of soybean, processed at 120 o C. The extrusion, regardless of...

-The objective of the present study was to evaluate the characteristics of the sward canopy of Marandu grass during the rainy season, the wet-to-dry transition and the dry seasons, between March and September 2004, under intermittent grazing, and to correlate those characteristics with the performance of crossbred heifers receiving mineral supplements ad libitum or protein supplements. The experiment consisted of a randomized block design with three blocks (set of 13 paddocks), each containing five crossbred heifers per experimental unit, totaling 15 replicates. The heifers were given protein supplements daily in individual stalls and received an average 4 g/kg/day of the supplement during the rainy season and 5 g/kg/day during the dry season. Their weight gain was assessed monthly. The pasture structure was assessed through destructive sampling, and the bromatological composition of esophageal extrusa samples was also assessed. Analysis of variance was used to assess performance, and regression analysis was used to evaluate the sward canopy characteristics in relation to the months of the year. A cluster procedure was used to determine the similarity between the months of the year under assessment. Two different groups were formed for pasture evaluation: one group including the months of March to July and another group including the months of August and September. The first group exhibited a better canopy structure than the second group. This fact was corroborated by the animal performance, which was lower during the months of the second group. Low-intake protein supplementation was effective in increasing the performance of the grazing heifers. Pasture structure is critical for animal performance in a grazing environment, regardless of the type of supplementation.