ABSTRACT The objective was to assess the effects short-term use of monensin and Acacia mearnsii tannins as feed additives on nutrient intake, digestibility, and CH4 production in cattle. Six rumen-cannulated Holstein cows were distributed in two 3×3 Latin square experimental design, and each experimental period lasted 21 days. The basal diet was composed of corn silage and concentrate in a 50:50 dry matter (DM) basis proportion. Treatments were control, monensin (18 mg kg−1 of DM), and tannin-rich extract from Acacia mearnsii (total tannins equivalent to 6 g kg−1 of DM). Nutrient intake and apparent digestibility coefficients were not affected by the addition of monensin or tannins to diets. However, tannins showed a tendency to reduce crude protein digestibility. Monensin decreased CH4 emission by 25.6% (g kg−1 of body weight) compared with the control treatment. Monensin is more effective than Acacia mearnsii tannins in reducing CH4 emissions in the short term, considering a diet of the same roughage:concentrate proportion for cattle.

ABSTRACT. Dry matter intake (DMI), nutrient intake and enteric CH4 emission were evaluated in 48 Nellore cattle (392 ± 27 days of age). Equations were generated from intake data and evaluated using root mean square prediction error (RMSPE), and validated by cross-validation. Equations that included DMI and hemicellulose intake (HEMI) [ C H 4 M J d - 1 = 4.08 ± 1.65 + 11.6 ± 2.34 D M I k g d - 1 - 33.4 ± 7.21 H E M I ( k g d - 1 ) ]; DMI and total carbohydrate intake (TCHI) [ C H 4 M J d - 1 = 5.26 ± 1.69 - 6.3 ± 1.47 D M I k g d - 1 + 8.8 ± 1.81 T C I k g d - 1 ]; metabolizable energy intake (MEI) and cellulose intake (CELI) [ C H 4 M J d - 1 = 5.16 ± 1.72 - 0.13 ± 0.048 M E I M J d - 1 + 7.37 ± 1.53 C E L I k g d - 1 ], and non-fiber carbohydrate intake (NFCI) [ C H 4 M J d - 1 = 3.14 ± 1.48 + 3.65 ± 1.05 N F C I k g d - 1 ] resulted in the lowest RMSPE (14.3, 14.1, 14.3 and 14.7%, respectively). When literature equations were evaluated using our database, the most accurate predictions were obtained with equations that included DMI and lignin intake (RMSPE = 15.27%) and MEI, acid detergent fiber intake and lignin intake (RMSPE = 15.7%). The mean error of predicting enteric CH4 emission with the equations developed in this study based on DMI and nutrient intake is 17% and the most accurate predictions are obtained with equations including DMI, carbohydrate intake and MEI.

Resumo: O objetivo deste trabalho foi avaliar a qualidade da pastagem e a emissão de metano (CH4) entérico de bovinos Curraleiro Pé-duro x Nelore, em pastagem de Megathyrsus maximus 'Mombaça', tanto a pleno sol como em consórcio com palmeiras de babaçu (Attalea spp.), no bioma Amazônia. O delineamento experimental foi inteiramente casualizado, com seis novilhos por sistema, e as avaliações foram realizadas nos períodos seco (2015) e no chuvoso (2016). Em comparação à forragem no sistema a pleno sol, a forragem no sistema silvopastoril apresentou maiores teores de proteína bruta, extrato etéreo, nutrientes digestíveis totais e digestibilidade in vitro da matéria orgânica, e menores teores de matéria seca, fibra em detergente neutro e carboidratos totais (CHOT). No período das águas, o sistema silvopastoril apresentou maiores teores de proteína bruta e reduções de carboidratos não fibrosos e CHOT. As emissões de CH4 foram semelhantes entre os sistemas, tendo variado de 44,0 a 74,2 kg por animal por ano. No período seco, a emissão por quilograma de matéria seca ingerida e a perda de energia bruta por metano foram menores no sistema silvopastoril. No período chuvoso, as emissões foram similares entre os tratamentos. O sistema silvopastoril oferece pastagem de boa qualidade na seca e, considerando-se o ciclo com ambos os períodos, é mais eficiente (emissão de CH4 pelo ganho de peso diário) do que o sistema a pleno sol.

Abstract: The objective of this work was to evaluate the quality of pasture and enteric methane (CH4) emission of Curraleiro Pé-duro x Nellore cattle in a pasture of Megathyrsus maximus 'Mombaça', both in full sun and in a consortium with babassu palms (Attalea spp.) in the Amazonian biome. The experimental design was completely randomized, with six steers per system, and the evaluations were done during the dry period (2015) and rainy period (2016). In comparison to forage in the full sun system, forage in the silvopastoral system showed, in the dry period, higher levels of crude protein, ether extract, total digestible nutrient, and in vitro digestible organic matter, and lower levels of dry matter, neutral detergent fiber, and total carbohydrate (TCHO). In the rainy period, forage in the silvopastoral system showed higher levels of crude protein and a reduction of nonfibrous carbohydrate and TCHO. The CH4 emissions were similar in both systems within the same period, and ranged from 44.0 to 74.2 kg per year per animal. During the dry period, the emission per kilogram of dry ingested matter and the loss of gross energy as methane were lower in the silvopastoral system. During the rainy period, the emissions were similar in both systems. The silvopastoral system yields forage with good quality in the dry period, and considering both periods, it is more efficient (emission of CH4 per daily weight gain) than the system in full sun.

ABSTRACT The objective of this study was to evaluate the effect of lipid sources on voluntary intake, digestibility, performance, and CH4 emission of Nellore steers grazing Brachiaria brizantha cv. Xaraés forage in the dry season. Forty-five Nellore steers with average weight of 442±34 kg were alloted into one of the five treatments: without additional fat; with palm oil; with linseed oil; with protected fat; and with whole soybeans. The supplements were provided daily and quantities were adjusted to 1% of body weight and diets were formulated in accordance with the Cornell Net Carbohydrate and Protein System. The experimental design was completely randomized with five treatments and two replications. There were no effects on dry matter, organic matter, and neutral detergent fiber intake with the inclusion of lipids in the diet. The neutral detergent fiber showed decreased digestibility in animals receiving linseed oil and palm oil treatments compared with animals receiving the diet without additional fat. The linseed oil treatment reduced CH4 emissions by 38% when expressed in mg/d/kg BW and tended to reduce the emission in g/d/kg BW0.75. Lipid sources did not affect the weight gain of the animals. The intake and performance of grazing Nellore steers supplemented at 1% body weight with lipid sources were not modified. However, fiber digestibility was reduced with palm or linseed oil addition. Linseed oil reduced enteric CH4 emissions. Linseed oil has the potential to reduce enteric CH4 emissions in continuous tropical grazing systems based on B. brizantha grass.

Feed intake and average daily gain (ADG) in Nellore cattle were determined to calculate residual feed intake in two performance tests: first during the growth phase (RFIgrowth) and then during a measurement of the methane emission phase (RFImet). During the RFIgrowth test, 62 males and 56 females were classified as low-, medium-, and high-RFI. Enteric methane emission was measured in 46 animals; 23 males used for RFImet measurement plus 23 females (22 low-RFIgrowth and 24 high-RFIgrowth). Diet consisted of Brachiaria brizantha cv. Marandu hay (445 g/kg DM) and concentrate (555 g/kg DM). During the RFIgrowth and RFImet phases, DMI was lower in the animals with low RFI, with no difference in ADG. Residual feed intake was -0.359 and 0.367 kg DM/d for low- and high-RFI animals. Enteric methane emission (g/d, g/kg BW0.75 and g/kg ADG) did not differ between RFIgrowth classes. Enteric methane emission (g/d) was higher in high RFImet and lower in low RFImet males. Spearman correlations among traits obtained during both tests, which were high between metabolic BW (r = 0.959) and between DMI (r = 0.718), and zero between ADG (r = -0.062), resulted in moderate correlation between RFIgrowth and RFImet (r = 0.412). However, it is not possible to confirm that high-efficiency animals release less enteric methane, since different results were obtained when enteric methane was compared between the RFIgrowth and RFImet classes.

Zebu cattle fed high concentrate diets may present inconsistent performance due to the occurrence of metabolic disorders, like acidosis. The isolated use of ionophores and virginiamycin in high grain diets can improve animal performance and reduce the incidence of such disorders, but recent studies suggested that their combination may have an additive effect. Thus, 72 Nellore steers, 389 ± 15 kg initial body weight (BW), were confined and fed for 79 days to evaluate the combination of virginiamycin and salinomycin on performance and carcass traits. Animals were allocated to a randomized complete block design by BW, in a 2 × 2 factorial arrangement of treatments, with two concentrate levels (73 and 91 %) and two virginiamycin levels (0 and 15 mg kg-1), and salinomycin (13 mg kg-1) included in all diets. The interaction was not significant (p > 0.05). Dry matter intake (DMI), average daily gain (ADG), gain-to-feed ratio (G:F), starch consumed, and fecal starch content were higher (p < 0.05) for the 91 % concentrate treatment. These animals also had higher (p < 0.05) hot carcass weight and dressing percentage. Virginiamycin-treated animals showed lower DMI, but ADG and G:F did not differ (p > 0.05) between treatments. Starch consumed and estimated dietary net energy for maintenance (NEm) and gain (NEg) were higher (p < 0.05) for virginiamycin-treated animals, with no substantial effects on carcass traits. The inclusion of virginiamycin in finishing diets containing salinomycin reduced DMI while maintaining ADG and improving NEm and NEg, suggesting an additive effect of virginiamycin and ionophores, but without affecting carcass quality.

Avaliou-se o desempenho de ovinos alimentados com dietas compostas por silagens de ponta de cana (Saccharum officinarum) e de soja (Glycine max). Utilizaram-se 24 cordeiros da raça Morada Nova, com idade média de 75 dias e peso vivo médio inicial de 16,98kg. Avaliaram-se as dietas: T1=20% silagem de ponta de cana + 80% de concentrado; T2=20% silagem de ponta de cana + 30% silagem de soja + 50% de concentrado; T3=20% silagem de ponta de cana + 60% silagem de soja + 20% de concentrado. O delineamento foi em blocos casualizados, com oito repetições, sendo cada animal uma repetição. Avaliaram-se os consumos de matéria seca, matéria orgânica e matéria mineral; proteína bruta; extrato etéreo; fibra em detergente neutro e em detergente ácido; ganho de peso e conversão e eficiência alimentar. Os ganhos de peso total e diário, a conversão e a eficiência alimentar foram semelhantes, com valores médios de 7,9kg animal-1; 133,3g animal-1 dia-1; 6,2 e 0,17; respectivamente. Dietas compostas por silagem de ponta de cana enriquecidas com silagem de soja + concentrado proporcionam maior consumo de nutrientes em relação às dietas compostas somente pela silagem de ponta de cana + concentrado. Silagem de ponta de cana suplementada com concentrado proteico ou com silagem de soja e menor participação de concentrado resulta em ganhos de peso, conversão e eficiência alimentar semelhantes.

The objective of this study was to evaluate the performance of sheep fed with diets consisting of different proportions of soybean silage and sugarcane tip silage. Twenty four lambs from Morada Nova breed were used, with an average age of 75 days and average weight of 16.98±2.62kg. The following diets were evaluated: T1 = 20% sugarcane tops silage + 80% concentrate, T2 = 20% sugarcane tops silage + 30% soybean silage + 50% concentrate, T3 = 20% sugarcane tops silage + 60% soybean silage + 20% concentrate. The experimental design was a randomized complete block with eight repetitions and each animal was a repetition. It was evaluated the intake of dry matter, organic matter, ash, crude protein, ether extract, neutral detergent fiber, acid detergent fiber, weight gain, and feed conversion ratio and efficiency. The total weight gain, average daily gain, feed conversion ratio and efficiency were similar, with average values of 7.9kg animal-1, 133.3g animal-1 day-1, 6.2 and 0.17, respectively. Diets based on sugarcane tops silage enriched with soybean silage + concentrate provide greater nutrient intake in relation to diet composed only of sugarcane tops silage + concentrate. Sugarcane tops silage supplemented with protein concentrate or enriched with soybean silage with lower inclusion of concentrate resulted in similar weight gains and feed conversion efficiency.

O objetivo deste experimento foi avaliar a densidade populacional e a dinâmica do perfilhamento em capim-marandu submetido a estratégias de pastejo rotativo e adubação nitrogenada. Os tratamentos corresponderam à combinação de duas metas de altura pré-pastejo (25 e 35 cm) e duas doses de aplicação de nitrogênio (50 e 200 kg ha-1 ano-1) em arranjo fatorial 2 x 2 alocadas às unidades experimentais segundo delineamento de blocos completos casualizados, com quatro repetições. Foram avaliadas a densidade populacional de perfilhos inicial (DPPi), intermediária (DPPm) e final (DPPf), as taxas de aparecimento (TAP), morte (TMP) e o índice de estabilidade (IE) da população de perfilhos. A DPPi foi semelhante para todos os tratamentos, com diferenças se acentuando ao longo da estação de crescimento, resultando em maior DPPf nos pastos manejados a 25 cm de altura pré-pastejo. A mortalidade de perfilhos foi maior nos pastos manejados a 35 cm, com diferenças em aparecimento sendo registradas somente a partir de fevereiro de 2010. Pastos manejados a 25 cm apresentaram maior estabilidade da população de perfilhos. Não houve efeito do nitrogênio nas variáveis analisadas, sendo que a melhor estratégia de manejo correspondeu à altura pré-pastejo de 25 cm, independente da dose de nitrogênio utilizada.

The objective of this experiment was to evaluate tiller population density and the dynamics of the tillering process in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization. Treatments corresponded to combinations between two targets of pre-grazing conditions (sward surface height of 25 and 35 cm) and two rates of nitrogen application (50 and 200 kg ha-1 year-1), and were allocated to experimental units according to a 2 x 2 factorial arrangement in a randomised complete block design, with four replications. The following response variables were studied: initial (TPDi), intermediate (TPDm) and final (TPDf) tiller population density as well as the rates of tiller appearance (TAR) and death (TDR) and the tiller population stability index (SI). TPDi was similar to all treatments, with differences in tiller population density becoming more pronounced as the experiment progressed, resulting in larger TPDf on swards managed at 25 cm pre-grazing height. Tiller death was larger on swards managed at 35 cm, with differences in tiller appearance being recorded only from February 2010 onwards. Stability of tiller population was higher on swards managed at 25 cm pre-grazing height. Overall, there was no effect of nitrogen on the studied variables, and the most adequate grazing strategy corresponded to the pre-grazing height of 25 cm, regardless of the nitrogen application rate used.

O objetivo deste trabalho foi avaliar metas de manejo para capim-marandu (Urochloa brizantha cv. Marandu) submetido a pastejo rotativo e a doses de nitrogênio, de janeiro de 2009 a abril de 2010. Os tratamentos consistiram da combinação de duas frequências de pastejo (altura pré-pastejo de 25 e 35 cm) e de duas doses de fertilizante nitrogenado (50 e 200 kg ha-1 por ano) em delineamento de blocos ao acaso com arranjo fatorial 2x2 e quatro repetições. A altura de pós-pastejo estipulada foi de 15 cm. Maiores valores de ganho de peso médio por animal por dia (0,629 e 0,511 kg dia-1) e por hectare (886 e 674 kg ha-1), bem como de taxa de lotação (3,13 e 2,85 UA ha-1), foram observados nos pastos manejados com altura pré-pastejo de 25 cm. A aplicação de 200 kg ha-1 de N resultou em aumentos na percentagem de folhas na massa de forragem pós-pastejo, nas taxas de acúmulo de forragem, na taxa de lotação e no ganho de peso por área. A mais adequada estratégia de manejo corresponde à altura pré-pastejo de 25 cm, independentemente da dose de nitrogênio utilizada.

The objective of this work was to assess management targets for marandu palisade grass (Urochloa brizantha cv. Marandu) subjected to rotational stocking and to nitrogen fertilization rates, from January 2009 to April 2010. Treatments consisted of a combination of two grazing frequencies (pre-grazing heights of 25 and 35 cm) and two levels of nitrogen application (50 and 200 kg ha-1 per year). in a completely randomized block design, in a 2x2 factorial arrangement, with four replicates. The established post-grazing height was 15 cm. Greater values of daily weight gain per animal per day (0.629 and 0.511 kg day-1), weight gain per hectare (886 and 674 kg ha-1), and stocking rate (3.13 and 2.85 AU ha-1) were found for pre-grazing height of 25 cm. The application of 200 kg ha-1 of N increased the percentage of leaves in post-grazing forage mass, forage accumulation rate, stocking rate, as well as weight gain per hectare. The best grazing strategy corresponds to the pre-grazing height of 25 cm, regardless of the nitrogen application.

Comparou-se o efeito do grão de milho colhido seco (87% MS) ou ensilado úmido (70% MS ), associado à silagem de planta de milho (20% MS da dieta) ou bagaço de cana de açúcar (12% MS da dieta), sobre a composição corporal e taxas de deposição dos componentes químicos corporais em 32 tourinhos Santa Gertrudis com idade média de dez meses e peso inicial médio de 245 kg. Os animais foram mantidos em baias individuais parcialmente cobertas por 124 dias , após adaptação de 33 dias. Quatro animais foram abatidos ao final da adaptação para determinação da composição inicial. Os outros 28 animais foram distribuídos nos quatro tratamentos. O delineamento utilizado foi de blocos ao acaso em arranjo fatorial 2x2 (dois volumosos x dois processamentos do milho grão), e testados os seguintes tratamentos: silagem de milho + milho úmido (Si-MU); silagem de milho + milho seco (Si-MS); bagaço cru + milho úmido (Ba-MU) e bagaço cru + milho seco (Ba-MS). Não houve interação entre volumoso e processamento do milho para nenhuma variável avaliada. Na comparação de volumosos, a silagem de planta de milho foi superior ao bagaço para ganho de peso vazio, taxa de deposição dos tecidos e de energia. O milho úmido aumentou o teor de gordura, a taxa de deposição de lipídeos e o teor de energia no ganho de peso. Estes resultados são consistentes com os dados de desempenho, demonstrando que a silagem de grão de milho aumentou o teor de energia líquida. Os resultados também sugerem que o bagaço de cana propicia um ambiente ruminal pior para o desempenho do animal que aquele obtido com uso da silagem de planta inteira de milho.

The effect of corn grain harvested at 87%DM or harvested at 70%DM ground and ensiled were evaluated. Diets contained different roughage sources, either corn silage (20% of the diet DM) or sugarcane bagasse (12% of the DM). Thirty two Santa Gertrudis bulls with initial average age of ten months and initial average weight of 245 kg were fed an adaptation diet for 33 days. After that period four animals were slaughtered to obtain initial body composition. The other 28 animals were allotted to the four treatments for a 124 days experimental feeding period. The experimental design was randomized blocks in 2 X 2 factorial arrangement (two roughage sources X two corn grain sources) with seven replicates, testing the following treatments: corn silage+high moisture corn (Si-MU); corn silage+dry corn grain (Si-MS); sugarcane bagasse+high moisture corn (Ba-MU) and sugarcane bagasse+dry corn grain (Ba-MS). There were no interactions between roughage and grain source for any variable evaluated. Corn silage was superior than sugarcane bagasse for daily empty body gain, and for deposition rates of all chemical components and energy. High moisture corn increased fat and energy content in the gain as well as the rate of lipid deposition. Data demonstrated that sugarcane bagasse is a poor roughage source in high concentrate diets when compared to whole plant corn silage. Results are also consistent with an increase in net energy content of ensiled corn grain.

Foram utilizados 32 tourinhos Santa Gertrudis inicialmente com dez meses de idade e 245 kg de peso, alimentados em confinamento com dietas contendo 88% de concentrado. Quatro animais foram abatidos no início do experimento (linha base) para estimativa da composição corporal inicial. Os 28 animais restantes foram distribuídos em baias individuais com delineamento de blocos ao acaso em arranjo fatorial 2x2 (dois volumosos x dois processamentos do milho grão) com sete repetições. Os volumosos incluíam silagem da planta de milho ou bagaço de cana-de-açúcar e os dois processamentos do grão de milho, o grão colhido seco e triturado e o colhido e ensilado úmido. Estimou-se, por intermédio da regressão do logaritmo do conteúdo corporal de energia, em função do logaritmo do peso do corpo vazio, o conteúdo de energia e proteína para ganho de peso em qualquer faixa de peso vazio incluída neste trabalho: para ganho de 1 kg, em um animal de 300 kg, foram necessárias 3,64 Mcal/dia de energia e 129,5 g de proteína.

Thirty two Santa Gertrudis bulls with ten months of age and 245 kg average live weight were fed 88% concentrate diets with corn silage or sugarcane bagasse and dry corn or high moisture corn. Four animals were slaughtered in the beginning of the experiment for initial body composition determination. Other 28 animals were distributed on four treatments. The experimental design was randomized blocks in 2 X 2 factorial (two roughage X two corn sources) with seven replicates. Regression equation of log body energy content as a function of log empty body weight (EBW) provided estimation of body energy content at any EBW range included in this research: for weight gain of 1 kg, an animal of 300 kg requires 3.64 Mcal/day of energy and 129.5 g of protein.