The objective of this study was to evaluate the yield, nutritional value and potential ruminal degradation of Tifton 85 hay (Cynodon spp.) harvested at four regrowth ages (28, 35, 42 and 49 days) and fertilized with two nitrogen doses (N; 100 and 300 kg N ha-1). The experimental design was a randomized block design, arranged in a 4 x 2 factorial scheme, with six replications each. Nitrogen fertilization increased (p < 0.05) dry matter yield and digestible dry matter production of hay and also lignin and crude protein contents. Nitrogen fertilization increased (p < 0.01) the dry matter yield and the digestible dry matter production of hay, as well as lignin (p = 0.01) and crude protein (p = 0.01). The neutral detergent fiber corrected for ash and protein (p = 0.01), acid detergent fiber (p = 0.01) and cellulose (p = 0.02) adjusted to the quadratic function regression model of the regrowth ages. For potential rumen degradability hay, it was observed quadratic effect (p = 0.01) with maximum value of 73.1% at 37 days of regrowth. Tifton 85 hay fertilized with 300 kg ha -1 of N and harvested up to 37 days of regrowth results in higher hay dry matter yield, higher crude protein content, and better dry matter rumen degradability.

This study evaluated the effect of increasing levels of leucaena forage in sorghum: forage. In addition to pure sorghum, it was evaluated different levels of inclusion of leucaena (15, 30 and 50%) at the time of ensiling. Forage was ensiled in PVC tubes (100 mm diameter, 500 mm length) under the density of 500 – 600 kg m-3, a total of 20 silos were prepared, which were opened 35 days after ensiling. There was no effect (p > 0.05) of leucaena inclusion levels for pH, water activity (Aw) and total ammonia nitrogen (total NH3-N). There was an increasing linear effect (p < 0.05) for the content of dry matter (DM), crude protein (CP) and lignin that increased from 33.47 to 34.75%, 7.82 to 16.05% and from 7.29 to 9.93%, at the levels from 0 to 50% inclusion of leucaena, respectively. There was a decreasing linear effect (p < 0.05) for neutral detergent fiber corrected for ash and protein (NDFcp) and hemicellulose, which reduced from 56.65 to 48.37% and from 24.07 to 17.67% at the levels of 0 and 50% inclusion, respectively. For the ash content, there was a quadratic effect (p < 0.05), with a maximum at 8.3% with 8.9% inclusion of leucaena. The inclusion of up to 50% leucaena into sorghum silage is recommended, because, in addition to maintaining the fermentation quality, it also improved nutritional quality of sorghum silage.

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¹Graduandos em Zootecnia -UNIMONTES -Campus Janaúba, MG.²Graduanda em Pedagogia -UNIMONTES -Campus Janaúba, MG.

The aim was to evaluate intake and apparent digestibility, productive performance and nitrogen balance of the F1 Holstein/Zebu dairy cows fed sugarcane silage with different particle sizes containing or not calcium oxide (CaO). Eight F1 Holstein/Zebu cows, with average body weight of 521.5 ± 55.17 kg, and 60 ± 10 days in milk were used, distributed in two simultaneous 4x4 Latin squares. The treatments were composed of sugarcane in two particle sizes (15 and 30 mm) with and without addition of CaO (10 g/kg natural matter basis), being the treatments compared according to a 2 x 2 factorial arrangement. Data were analyzed by analysis of variance using the MIXED procedure of SAS (version 9.4). The intakes of the dry matter (13.05 kg/d), crude protein, non-fibrous carbohydrates and neutral detergent fiber were not modified (P > 0.05) by the inclusion of the calcium oxide, nor ot by particles size and interaction among both. However, there was interaction between CaO and particle size on dry matter digestibility (P = 0.002). The yield (13.85 kg/d) and composition of the milk were also not affected by diets (P > 0.05), similarly for nitrogen balance (P > 0,05). The addition of CaO to sugarcane silage with different particle sizes (15 and 30 mm) does not affect the yield and composition of the milk of Holstein/Zebu cows, nor the nitrogen balance. However, when CaO is added to sugarcane silage with reduced particle size, there is a loss in dry matter digestibility.