ABSTRACT. The objective was to evaluate the ruminal disappearance rate of dry matter and NDF of black oat haylage subjected to mechanical and chemical dehydration and six wilting periods in the field, as follows: 0, 3, 6, 9, 12 and 15 days. Forage haylages were ensiled and stored in PVC mini-silos for 60 days until opening for in situ evaluations. The pre-set ruminal incubation times were: 0, 6, 12, 24, 36 and 48 hours. Regardless of the dehydration time, forage subjected to mechanical dehydration showed ruminal disappearance rates of dry matter and NDF, thus DISDM-48h and DISNDF-48h were superior for this method compared to the chemical method. There was a reduction in DISDM-48h and DISNDF-48h with advancing time of wilting in the field for haylage dehydrated by the chemical method. In general, the chemical dehydration method seems to be more related to better haylage making practices than nutritional factors, where the haylage obtained by mechanical dehydration is superior.

Resumo Objetivou-se neste trabalho avaliar alimentos energéticos quanto a composição química, degradabilidade ruminal in situ da matéria seca (DMS), cinética ruminal e taxa de desaparecimento ruminal da matéria seca. Foram avaliados sete alimentos (tratamentos): grão de milho moído, grão de aveia moído, grão de cevada moído, farelo de trigo, casca de soja, radícula de malte e gérmen de milho, num delineamento inteiramente casualizado com quatro repetições cada. Para a incubação dos materiais foram utilizados dois bovinos com cânula ruminal, e cada tratamento foi submetido a sete períodos de exposição ao rúmen (0, 3, 6, 9, 12, 18 e 24 horas). Dentre os alimentos avaliados, a casca de soja teve o maior teor de fibra em detergente neutro (68,91%) e apresentou a menor DMS em 24 h (64,91%). O grão de cevada moído e o grão de milho moído tiveram os menores níveis de fração solúvel (FS) (26,34% e 28,7%, respectivamente), porém o grão de cevada moído apresentou a maior DMS em 24 h (90,48%), que por conciliar estes parâmetros teve a maior taxa de desaparecimento ruminal (2,50%.h-1), enquanto o grão de aveia moído teve a maior FS (47,75%) e a menor taxa de desaparecimento ruminal (1,09%.h-1).

Abstract This study aimed to evaluate energetic feedstuffs regarding chemical composition, in situ ruminal degradability of dry matter (DMD), ruminal kinetics and ruminal disappearance rate of dry matter. Seven feedstuffs (treatments) were evaluated: ground corn, ground oat, ground barley, wheat bran, soybean hull, malt root and corn germ, in a completely randomized design of four repetitions each. Two bovines ruminally cannulated were used for incubation, wherein each treatment was subjected to seven periods of exposure to the rumen (0, 3, 6, 9, 12, 18 and 24 hours). Among the evaluated feedstuffs, soybean hull had the highest neutral detergent fiber (NDF) content (68.91%) and the lowest DMD at 24 h (64.91%). Ground barley and ground corn contained the lowest content of soluble fraction (SF) (26.34 and 28.7%, respectively), among which ground barley had the highest DMD at 24 h (90.48%) and therefore showed the highest rumen disappearance rate (2.50%.h-1) by combining both parameters, while the ground oat presented the highest SF (47.75%) and the lowest rumen disappearance rate (1.09%.h-1).

Objetivou-se avaliar a ingestão de matéria seca, ganho de peso diário, conversão alimentar, digestibilidade e as características da carcaça de novilhos alimentados com dietas à base de silagens de dois híbridos de milho. Os tratamentos foram as silagens de milho provenientes dos híbridos LG6030 PRO e P30B39H. O delineamento experimental foi o inteiramente casualizado, com seis repetições, em esquema de parcelas subdivididas no tempo, em três períodos de avaliação. Animais alimentados com a silagem de milho LG6030 PRO tiveram maior (P<0,05) ganho médio de peso e melhor conversão alimentar. O tipo de silagem não alterou (P>0,05) a ingestão de matéria seca, ganho médio de carcaça e ganho de carcaça no período de terminação. Contudo, com o hibrido LG 6030 PRO houve melhor eficiência de transformação da matéria seca consumida em carcaça, apesar de menor eficiência de transformação do ganho de peso em carcaça (73,7 contra 76,9%) comparativamente com a dieta com silagem de P30B39H. Além disso, a digestibilidade aparente foi maior (P<0,05) para silagem de milho do híbrido LG6030 PRO, obtendo eficiência de digestão 3,4% superior. Os componentes de rendimento não integrantes da carcaça não foram alterados em função das variações dietéticas das silagens avaliadas. Sendo assim, recomenda-se o híbrido LG6030 PRO para produção de silagem.

This work aimed to evaluate the dry matter consumption, daily weight gain, feed conversion, digestibility and carcass characteristics of confined steers fed with silages from different corn hybrids. The treatments were the silages from the hybrids LG6030 PRO and P30B39H. The experimental design was totally randomized, with 6 repetitions, in a split-plot scheme, in three evaluation periods. Animals fed with silage from hybrid LG6030 PRO showed a higher daily weight gain and better food conversion. The silage type did not alter (P>0.05) dry matter consumption, average carcass gain and carcass gain during the finishing period. However, the hybrid LG6030 PRO improved the efficiency transformation of consumed dry matter into carcass, despite the decrease of efficiency of transformation of weight gain into carcass (73,7 vs 76.9%) comparatively to animals fed with P30B39H silage. Diets containing the hybrid LG6030 PRO reflected in an increase of 3.4% of apparent digestibility. There were no differences of non-carcass components yield between the treatments in this experiment. It is recommended LG6030 PRO for silage production.

RESUMO. As enzimas podem ser aditivos interessantes em dietas de alta energia para gado em confinamento. No entanto, a literatura é inconsistente para este assunto. Assim, este trabalho foi realizado para avaliar o desempenho de touros em confinamento com dietas de alta densidade energética, composto apenas de uma mistura de 85% de grãos de milho inteiros e 15% de núcleo proteico-vitamínico-mineral, com ou sem inclusão de enzimas à base de xilanase. Os tratamentos foram CON - dieta sem enzimas (controle) e ENZ - dieta com enzimas (5 g animal dia-1). Foram utilizados 32 touros, com idade média de 11 ( 2, peso inicial médio de 365 kg ( 5 e terminados por 119 dias. O delineamento experimental foi inteiramente casualizado, consistindo em dois tratamentos e oito repetições, em que cada repetição foi representada por uma baia com dois animais. ENZ aumentou o ganho de peso (1,69 vs. 1,33 kg dia-1) e melhorou a conversão alimentar (4,60 vs. 6,03 kg-1) na fase de adaptação dos animais em confinamento. Os animais que receberam ENZ aumentaram 1,65% do rendimento de carcaça e foram 7,57% mais eficientes na transformação da matéria seca consumida no ganho de carcaça em relação ao CON. As características de carcaça de touros terminados em confinamento não foram alteradas em função da inclusão de enzimas. O complexo de xilanase pode aumentar eficiência de touros de confinamento.

ABSTRACT. Enzymes can be an interesting additive in high energy diets for feedlot cattle. However, literature is inconsistent on this subject. Thus, this study was conducted to evaluate animal performance of feedlot bulls receiving high energy diet, composed of a mixture of 85% whole corn grain and 15% protein-mineral-vitamin nucleus, without or with xylanase included in the diets. Diets consisted of: CON - diet without enzymes (Control) and ENZ - diet with enzymes (5 g animal day-1). Thirty-two bulls were used, with an average age of 11 ( 2 months, average initial weight of 365 ( 5 kg, and finished for 119 days in feedlot. The experimental design was completely randomized, consisting of two treatments and eight replications, where each replication was represented by a stall with two animals. ENZ increased the weight gain (1.69 vs. 1.33 kg day-1) and improved the feed conversion (4.60 vs. 6.03 kg-1) in the adaptation period of the animals. Animals receiving ENZ increased 1.65% of carcass yield and were 7.57% more efficient in the conversion of dry matter consumed into carcass gain in relation to CON. Carcass traits of feedlot-finished bulls were not altered by inclusion of enzymes. Xylanase-complex could increase efficiency in feedlot bulls.

ABSTRACT The objective of this study was to evaluate the production performance and carcass traits of feedlot steers fed a high-energy diet supplemented with doses of an enzyme complex (0, 2.5, 5.0, and, 7.5 g animal−1 day−1). Thirty-two ½ Angus ½ Nellore crossbred steers at an average age of 12 months and an average initial weight of 422 kg, were kept in a feedlot for 77 days. The roughage-free diet was composed of a mixture of whole corn grain and a protein-mineral-vitamin mix at a constant ratio of 85:15, on a dry matter basis. A completely randomized block design was adopted, consisting of four treatments and four replicates, in which each replicate was represented by a stall with two animals. Each gram of product added to the diet led to a decrease of 0.0818 kg in daily dry matter intake (DMI), whereas fat thickness at the ribs and at the hindquarter increased by 0.3850 and 0.080 mm, respectively. Feed efficiency increased by 0.0054 kg BW kg DMI−1 per gram of enzyme added. Apparent dry matter digestibility had a quadratic response, with maximum digestion manifested at the dose of 4.78 g animal−1 day−1. The gradual inclusion of enzyme complex reduces the DMI but increases feed efficiency and carcass fat cover of feedlot steers.

RESUMO. O objetivo do experimento foi avaliar a composição nutricional, a recuperação de matéria seca (MS) e a estabilidade aeróbia de silagens de cereais de inverno submetidas a diferentes tempos de estocagem. Os materiais utilizados foram o trigo (Triticum aestivum cv. BRS Gralha Azul), cevada (Hordeum vulgare cv. BRS Brau), aveia branca (Avena sativa cv. URS Guará), aveia preta (Avena strigosa cv. Embrapa 139) e triticale (X Triticosecale cv. IPR 11), em três tempos de estocagem: 60, 120 e 180 dias. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 5x3. Na avaliação nutricional, a silagem de cevada apresentou baixos teores de fibra em detergente ácido (FDA; 331; 355 e 378 g kg MS-1, para 60, 120 e 180 dias, respectivamente) e altos de nutrientes digestíveis totais (NDT; 558; 544 e 531 g kg MS-1 para 60, 120 e 180 dias, respectivamente), além de alta recuperação de MS e estabilidade aeróbia. O trigo e o triticale apresentaram decréscimo na recuperação de MS com o aumento dos dias de estocagem, embora tenham apresentado alta estabilidade aeróbia. O tempo de estocagem influenciou de maneira distinta as forrageiras, no entanto, tempos de estocagem acima de 60 dias não proporcionaram benefícios para as variáveis avaliadas.

ABSTRACT. The objective of the experiment was to evaluate the nutritional composition, dry matter (DM) recovery and aerobic stability of winter cereal silages under different storage periods. The materials used were wheat (Triticum aestivum cv. BRS Gralha Azul), barley (Hordeum vulgare cv. BRS Brau), white oat (Avena sativa cv. URS Guará), black oat (Avena strigosa cv. Embrapa 139) and triticale (X Triticosecale IPR 11), in three storage periods: 60, 120 and 180 days. The experiment was conducted in a 5x3 factorial, completely randomized design, consisting of five forage species and three storage periods, with five replicates. In nutritional assessment, barley silage presented low values of acid detergent fiber (ADF; 331.2, 355.2 and 378.5 g kg DM-1 for 60, 120, 180 days, respectively), high total digestible nutrients (TDN; 558.2, 544.7 and 531.6 g kg DM-1 for 60, 120, 180 days, respectively), high DM recovery and aerobic stability. Wheat and triticale showed a decrease in DM recovery with the increase in storage length, although showed high aerobic stability. The storage period had a different effect on forages; however, storage period above 60 days provided no benefits for the variables evaluated.