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Objective This study ascertained effects of cactus pear in association with different roughage in the diet of F1 Holstein/Zebu cows on intake, nutrient digestibility, nitrogen balance, ingestive behavior and performance. Methods Eight cows with 72±11 days of lactation were used. The experimental design was simultaneous in two 4×4 Latin squares. Four experimental diets were used: Diet 1, sorghum silage as exclusive roughage; Diet 2, sorghum silage associated with cactus pear in a proportion of 50% of the roughage (dry matter basis); Diet 3, elephant grass ( Pennisetum purpureum cv. Roxo) as exclusive roughage; Diet 4, elephant grass associated with cactus pear in a proportion of 50% of the roughage. The roughage:concentrate ratio was 75:25. Results Dry matter intake (p = 0.01) was higher with sorghum silage. There were differences in dry matter intake (p = 0.01), crude protein (p<0.01), ether extract (p = 0.01), non-fibrous carbohydrates (p<0.01) and total digestible nutrients (p = 0.01) among the diets. Cactus pear in the diet reduced water intake by 44.52% (p<0.01). The nitrogen balance was 59.71% and 27.49% lower in animals treated with exclusive sorghum silage and sorghum silage associated with cactus pear in relation to diets with elephant grass and elephant grass associated with cactus pear, respectively (p<0.01). The diets did not influence the milk production (p = 0.70), 3.5% fat corrected milk production (p = 0.72) or feed efficiency (p = 0.61). Conclusion The association of cactus pear with sorghum or elephant grass silage does not alter milk production, reduces the intake of dry matter and water and improves the digestibility of nutrients.

The objective was to evaluate the productivity, chemical composition, ruminal degradability of dry matter and digestibility of BRS capiaçu grass (Pennisetum purpureum Schum.) managed at five regrowth ages. A completely randomized design with ten replications was used in the BRS capiaçu elephant grass subjected to five cutting intervals (30, 60, 90, 120 and 150 days) in the summer, making a total of 50 plots with a useful area of 4 x 2 m. There were daily increases in the dry matter production in the order of 382 kg ha-1, with 49,859 kg ha-1 being produced at 150 regrowth days. The dry matter content and organic matter linearly increased (P < 0.01) at different regrowth ages. The crude protein content, in vitro dry matter digestibility and in vitro digestibility of neutral detergent fiber linearly reduced (P < 0.01) 0.037%, 0.196% and 0.256% per day, respectively. Potential degradability of dry matter decreased from 68.9% at 30 days to 44.7% at 150 regrowth days (0.194 percentage units per day). The rate of degradation of fraction B 'c' was not modified (P = 0.94), averaging 1.46% hour-1. In the cultivation of BRS capiaçu elephant grass in the summer season, in the northern region of Minas Gerais, the age for harvesting between 90 and 120 days of regrowth is recommended.

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The objective of this study was to evaluate the effects of wilting times and application of an enzymatic-bacterial inoculant on the fermentative profile and nutritional characteristics of BRS capiaçu grass silage in a semi-arid region. Four wilting times treatments (control, 6, 24, and 30 h), with or without the addition of an enzymatic-bacterial inoculant, were analyzed as a split-plot completely randomized design with eight replications. Parameters of the rumen degradability test were analyzed using a split-plot completely randomized block design with four replications. There was no interaction between wilting times and inoculant application on pH, ammoniacal nitrogen (NH 3 -N), and aerobic stability of BRS capiaçu silage. Aerobic stability was reduced by 1.2 h for every 1-h increase in wilting time. Inoculant application reduced the pH values by 2.59% and extended the aerobic stability of the silage by 19 h. There was a significant interaction of wilting times and inoculant application on the levels of malic, succinic, lactic, and acetic acids. Inoculant application increased the contents of dry matter, ash, crude protein, insoluble neutral detergent fiber, and total carbohydrates by 3. 63, 6.13, 7.73, 6.39, and 9.97% compared with non-inoculated silages, respectively. Wilting times for up to 30 h and application of enzymatic-bacterial inoculant improves the fermentative profile and chemical composition and reduces dry matter losses of silage of BRS capiaçu grass harvested at 100 days of regrowth.

ResumoObjetivou-se por meio deste trabalho avaliar o efeito de nitrogênio sobre a morfogênese e rendimento forrageiro do capim-elefante cv. Pioneiro. O delineamento experimental utilizado foi em blocos casualizados com cinco repetições, totalizando 20 unidades experimentais. Os tratamentos corresponderam a quatro doses de nitrogênio (100, 200, 300 e 400 kg ha -1 ano -1 ). O experimento foi mantido sob condições irrigadas. Foram realizados cortes avaliativos a 50 cm do solo com valores de interceptação luminosa (95%) sem intervalos pré-definidos. Observou-se que a adubação nitrogenada aumentou significativamente (P<0,05) a produção de matéria seca por hectare, taxa de aparecimento foliar (folhas dias -1 perfilho -1 ), taxa de alongamento foliar (cm folha -1 dia -1 ) e taxa de alongamento de colmo (cm perfilho -1 dia -1 ). O processo de senescência foliar nesta forrageira é acelerado com o aumento das doses de nitrogênio e taxa de aparecimento foliar, consequentemente reduzindo o filocrono. É necessário um estudo sobre a viabilidade econômica de doses mais elevadas de nitrogênio em pastos de capim elefante cv. Pioneiro. Palavras-chave: Alongamento de colmo, aparecimento foliar, filocrono, Pennisetum purpureum AbstractObjective of this work by evaluating the effect of nitrogen on forage yield and morphogenesis of elephant grass cv. Pioneer. The experimental design was randomized blocks with five replications, totaling 20 experimental units. Treatments consisted of four nitrogen levels (100, 200, 300 and 400 kg ha -1 yr -1 ). The experiment was conducted under irrigated conditions. Evaluative cuts were made at 50 cm soil with values of light interception (95%) without pre-defined intervals. It was observed that N fertilization increased significantly (P<0.05) the production of dry matter per hectare, leaf appearance rate (leaves days -1 tiller -1 ), leaf elongation rate (cm tiller -1 day -1 ) and stem elongation rate (cm day -1 ). The process of

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ABSTRACT. The aim of this work was to determine ruminal degradation of neutral detergent fiber of grasses of the genus Cynodon, harvested at four cutting ages. It was used a randomized block design, with five treatments arranged in a split plot, the five evaluated genotypes: Tifton 85, Jiggs, Russel, Tifton 68 and Vaquero; were the plots and ages of cutting were the subplots: 28, 48, 63 and 79 days. By adding one day in the cutting age, there was a linear reduction in the effective degradability of neutral detergent fiber of blade and stem of 0.16 and 0.18%, respectively. The increase in the cutting age had a linear and positive influence on the undegradable neutral detergent fiber with daily increments for leaf and stem of 0.12 and 0.18%, respectively. At the 28 regrowth day, all genotypes showed higher content of potentially degradable insoluble fraction, effective degradability and lower undegradable fraction of the neutral detergent fiber of blade and stem in relation to other ages, in this way this interval is recommended for cutting management.Keywords: degradation, forage, ruminants, management.Degradabilidade ruminal da fibra em detergente neutro de gramíneas Cynodon spp. em quatro idades de rebrota RESUMO. Objetivou-se por meio deste trabalho determinar a degradação ruminal da fibra em detergente neutro de gramíneas do gênero Cynodon, colhidas em quatro idades de corte. Foi utilizado o delineamento em blocos ao acaso, com cinco tratamentos arranjados em um esquema de parcelas subdivididas, sendo os cinco genótipos: Tifton 85, Jiggs, Russel, Tifton 68 e Vaqueiro; estudadas as parcelas e as quatro idades de corte as subparcelas: 28, 48, 63 e 79 dias. À medida que aumentou um dia na idade de corte, houve redução linear da degradabilidade efetiva da fibra em detergente neutro da lâmina e do colmo em 0,16 e 0,18%, respectivamente. O avanço na idade de corte influenciou linearmente e positivamente a fração indegradável da fibra em detergente neutro com incrementos diários para a lâmina foliar e para o colmo de 0,12 e 0,18%, respectivamente. Na idade de 28 dias de rebrota, todos os genótipos apresentaram maiores teores de fração insolúvel potencialmente degradável, degradabilidade efetiva e menor fração indegradável da fibra em detergente neutro da lâmina e do colmo em relação às demais idades, sendo desta forma recomendado esse intervalo para manejo de corte.Palavras-chave: degradação, forragem, ruminantes, manejo.