PALAVRAS CHAVE ADICIONAISDegradabilidade efetiva. Degradabilidade potencial.ADDITIONAL KEYWORDS Effective degradability. Potential degradabilbity. RESUMOObjetivou-se com este trabalho avaliar a degradabilidade in situ da matéria seca, proteína bruta e fibra em detergente neutro das silagens de variedades de cana-de-açúcar com aditivos. A avaliação da degradabilidade foi realizada segundo um delineamento em blocos casualizados, em esquema fatorial 2 x 6 sendo duas variedades de cana (IAC 86-2480 e RB 86-7515), e cinco aditivos (ureia, NaOH, CaO, milho grão moído e Lactobacillus buchneri), mais a silagem-controle, com 3 blocos (animais). A fração solúvel e a degradabilidade efetiva da matéria seca das silagens com NaOH e CaO aumentaram. A fração solúvel e a degradabilidade efetiva da proteína bruta foram maiores nas silagens com ureia. A degradabilidade efetiva da fibra em detergente neutro das duas variedades foi maior nas silagens com NaOH e CaO. As silagens com NaOH e CaO são de melhor valor nutricional, pois apresentam maior degradabilidade efetiva da matéria seca e fibra em detergente neutro. A variedade IAC 86-2480 apresenta melhor valor nutricional em relação à RB 86-7515, devido à maior degradabilidade efetiva da matéria seca. SUMMARYThe aim of this work was to evaluate the in situ degradability of the dry matter, crude protein and neutral detergent fiber of two sugarcane varieties ensiled with additives. The evaluation of the degradability was carried out according to a random blocks design, in factorial scheme 2 x 6, being two cane varieties (IAC 86-2480 and RB 86-7515), and five additives (urea, NaOH, CaO, corn and Lactobacillus buchneri), plus the control silage, with 3 blocks (animals). The NaOH and the CaO increased the values of soluble fraction and the effective degradability of dry matter. The soluble fraction and the effective degradability of the crude protein were higher with urea. The effective degradability of the neutral detergent fiber of the two varieties was higher in the silages with NaOH and CaO. The silages treated with NaOH and CaO are the best in nutritional value, because of the highest effective degradability of dry matter and neutral detergent fiber. The IAC 86-2480 variety presents better nutritional value than RB 86-7515, due to the highest effective degradability of dry matter.

The aim of this study was to evaluate the effect of increasing concentrate supplementation levels on the intake, nutrient digestibility, and performance of crossbred steers during the dry period of the year. The experiment was developed on Princesa do Mateiro farm, in the municipality of Ribeirão do Largo, located in the southwest region of Bahia State, Brazil. Forty uncastrated male crossbred (½ Holstein-Zebu) steers with an average body weight (BW) of 232.55 ± 24.97 kg were distributed into four treatments in a completely randomized design with ten replicates. The animals were managed in an experimental area formed by Brachiaria brizantha cv. Marandu, in an intermittent grazing system. Treatments consisted of the following supplementation levels: 0.2% BW, with 60% crude protein (CP); 0.3% BW, with 40% CP; 0.4% BW, with 30% CP; and 0.5% BW, with 24% CP. The intakes of forage dry matter in kg/day and %BW and neutral detergent fiber corrected for ash and protein (NDFap) in %BW decreased linearly, whereas the intake of non-fibrous carbohydrates corrected for ash and protein in kg/day and average daily gain increased linearly. Therefore, the use of supplementation at 0.5% BW (24% crude protein) to provide gains of up to 0.500 kg/day is recommended for grazing steers during the post-weaning period in the dry season of the year.

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Objetivou-se avaliar o comportamento ingestivo de bovinos Nelore submetidos a diferentes níveis de substituição de silagem de sorgo por cana-de-açúcar ou bagaço de cana amonizado com ureia. Foram confinados 35 animais machos não castrados, distribuídos em sete tratamentos: 100% silagem de sorgo; 70% de silagem de sorgo + 30% de cana-de-açúcar; 30% de silagem de sorgo + 70% de cana-de-açúcar; 100% de cana-de-açúcar; 70% de silagem de sorgo + 30% de bagaço de cana amonizado com ureia; 30% de silagem de sorgo + 70% de bagaço de cana amonizado com ureia e 100% de bagaço de cana amonizado com ureia. Todos os animais foram submetidos a observação visual para avaliação do comportamento ingestivo aos 15, 30 e 50 dias do período experimental. O aumento do teor de cana na dieta em substituição à silagem de sorgo, não provocou alterações nos tempos de alimentação, ruminação e ócio dos animais. Já a substituição da silagem de sorgo por bagaço de cana amonizado com ureia provocou alterações no comportamento ingestivo, reduzindo o tempo de alimentação e aumentando o tempo de ruminação dos animais. O número de ciclos de ruminação e a duração destes ciclos foram afetados por ambos volumosos substitutos. Palavras-chave: ócio, ruminação, tempo de alimentação.

The objective was to evaluate the rumen degradability of dry matter, crude protein and fiber fraction of some oilseed byproducts. Oilseed byproducts evaluated were: Sunflower Meal, Cotton Cake and Castor Bean Cake. The rumen degradability test was performed following a split plot randomized complete block design with three treatments (plots) and seven incubation times (subplots) and six blocks (animals). The readily soluble fraction of the dry matter of sunflower meal was 35.0% higher than the same fraction of cotton cake and castor bean cake (mean 24.46%, P < 0.01). The highest potential degradability of crude protein (P < 0.01) was verified in castor bean cake (96.90%, 5% rate of passage). Sunflower meal had the lowest insoluble fraction of the fiber fraction, 34.4%, compared to cotton cake and castor bean cake, with 64.4% and 39.4%, respectively (P < 0.01). Sunflower meal had the highest fiber effective degradability (25.2%). Sunflower meal presented better values of ruminal parameters of dry matter, crude protein and neutral detergent fiber in relation to the other byproducts.