Cana-de-açúcar na alimentação de vacas e novilhas leiteiras em crescimento

• Autor(a) principal: Rangel, Adriano Henrique do Nascimento
• Data de Publicação: 2005
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1806
• topic: Bovino de leite; Desempenho; Síntese de proteína; Cana-de-açúcar; Dairy cattle; Performance; Protein synthesis; Sugar-cane; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The objective of this work was to evaluate the effect of a sugar cane-based diet supplemented with soybean meal-based concentrate (SM) for dairy cows, on the consumption and apparent nutrient digestibility, milk production and composition, diet economicity, pH, and the ammoniacal nitrogen (N-NH3) concentration in the rumen fluid, urine urea excretion, serum urea nitrogen (SUN), nitrogen compound balance and microbial protein synthesis, compared to three other sugar cane-based diets with increasing levels of the mixture urea and ammonium sulphate (9:1) (urea), 0.4; 0.8 and 1.2 %, based on natural matter. A number of 12 pure and crossbred Holstein cows were arranged in three 4 x 4 Latin squares, distributed according to the lactation period. Following the analysis of variance, it was performed the decomposition of sums of squares for treatments into non-orthogonal contrasts related to the comparison between SM-based concentrate and the different urea levels, and the linear and quadratic effects related to the variation in urea levels. The diets were isonitrogenous with approximately 14% crude protein, based on dry matter (DM). The daily supply of concentrate was 1 kg per each 2 kg of produced milk. There were no differences (P> 0.05) in the consumption of DM, organic matter (OM), ether extract (EE), total carbohydrates (CHO), non-fiber carbohydrates (NFC), neutral detergent fiber (NDF) and DM g/kg0,75 among the experimental diets. A decreasing linear effect was found for consumption of NDF kg/day and NDF (%PV) among the different urea levels. There were no differences (P> 0.05) for the apparent digestibility coefficients (ADC) of DM, OM, CP, EE, NDF and NFC, when the diet with SM-based concentrate was compared with those having different urea levels. An increasing linear effect was found for CDCHO and TDNobs among the treatments with urea. No difference was found among the diets for milk production with and without correction to 3.5% fat, neither for milk composition when the diet with SM-based concentrate was compared with the diets with different urea levels. The diets containing urea compared with the SM-based concentrate showed a higher balance, justifying economically its use to reduce feeding costs of sugar cane-based diets. Rumen PH and N-NH3 did not differ (P>0.05) at sample collection times, comparing SM-based concentrate with the different urea levels. A quadratic effect was found for both collection times (P<0.05) among the urea diets. Urine urea excretion was lower (P <0.05) for the diet containing SM than the diets with 0.8 and 1.2% urea levels. There was no difference for SUN between the SM-based treatment and the different levels of urea. Nitrogen compound balance (NB) did not differ between the SMbased diet and the diets with different urea levels. The synthesis of microbial nitrogen compounds did not differ among the treatments. The correction of the sugar cane diet with 1.2% of the mixture urea and ammonium sulphate (9:1) proved to be the best economic option for dairy cows producing 20 L milk/day. The responses of heifers fed with corn silage-based diet plus 1.3 kg/day of concentrate ration were also compared with the three sugar cane-based diets corrected with 1% of the mixture urea and ammonia sulphate (9:1) (urea), with 1.3; 2 and 2.7 kg/day of concentrate ration. A total of 20 animals were used, 12 Holstein and 8 Brown Swiss heifers, with average initial liveweight of 176 kg. The experiment was arranged in a randomised block design, with 5 blocks, considering each animal as an experimental unit and the blocks formed on the basis of initial liveweight and breed. The consumption of dry matter (DMC) independently of the form of expression, organic matter (OM) and neutral detergent fiber (NDF) did not differ between corn-silage diet and sugar-cane diet. Higher consumption of ether extract (EE) (P <0.05) was found for cornsilage diet compared to the sugar cane-based diets. There was difference in the consumption of total carbohydrates (CHO) and non-fiber carbohydrates (NFC) between the corn-silage diet and the sugar-cane based diets (1.3 and 2 kg of concentrate). Lower NDT consumption was found between the corn-silage diet and sugar-cane diet (2 kg concentrate). There was significant effect (P <0.05) for coefficients of digestibility of CP, EE, CHO and NDF. No significant difference was found for total weight gain (TWG/kg) and average daily gain (ADG/kg/day) between the corn-silage based diet and the sugar-cane diet with 2.7 kg of concentrate, in relation to the sugar-cane diets. The treatment with corn silage showed the highest balance per animal (R$/head/day) and per weight gain (R$/kg). Rumen pH did not differ at the collection times among the experimental diets. N-NH3 was lower (P <0.05) three hours after feeding for corn silage-based diet compared to the sugar cane-based treatments.