Efeito da adição de teores crescentes de ureia na cana-de-açúcar em dietas de vacas em lactação sobre a produção e composição do leite e viabilidade econômica

Abstract

RESUMOAvaliou-se o efeito da adição de teores crescentes de ureia (0,0; 0,5 e 1,0%) na matéria natural da canade-açúcar sobre a produção e composição do leite, eficiência alimentar e viabilidade econômica. Foram utilizadas 18 vacas em lactação, com produção média inicial de 21,3±0,8kg/dia de leite e com 83±7 dias em lactação, distribuídas em delineamento ensaio de reversão do tipo switch-back, 3x3. As dietas experimentais foram constituídas de cana-de-açúcar como volumoso único e concentrado, na relação de 50:50 (base MS). Não houve efeito da suplementação dos diferentes teores de ureia sobre a produção e composição do leite. Contudo, a eficiência alimentar (produção de leite/consumo de matéria seca) foi melhor nas dietas em que se utilizou ureia, sendo 1,14; 1,17 e 1,17, respectivamente, para as dietas com 0,0; 0,5 e 1,0% de ureia (P<0,05). Considerando-se apenas o custo alimentar, todas as dietas apresentaram saldo positivo, sendo que a dieta com 1,0% de ureia apresentou o melhor saldo.Palavras-chave: bovino, componentes do leite, custo ABSTRACTWe studied the effect of increasing 0.0, 0.5 and 1.0% urea in natural sugar cane on cow milk production and composition, food productivity and economic viability. Eighteen lactating cows were studied, they had avarage milk production of 21.3±0.8kg/day and were 83±7 days in lactation in a switch-back, 3 x 3 design. The experimental diets consisted of a unique concentrated sugar cane portion with the 50:50 relation (MS base). The results showed no effect of different urea concentrations on the milk production or composition. However, food productivity (milk production/dry matter consumption) was 1.14; 1.17, and 1.17 respectively on urea diets of 0.0; 0.5 and 1.0% (P<0.05

Performance of Holstein x Gyr dairy cows fed hydrolyzed sugarcane-based diets

“…These were the only studies on lactating cows in which there was any change in milk production or composition due to the inclusion of hydrolyzed sugarcane. The milk yields and compositions observed in the present study are within the ranges reported in previous studies in which sugarcane hydrolyzed with CaO was supplied to lactating cows: 7.29-19.98 kg milk cow −1 day −1 with 2.96%-3.41% protein, 3.23%-4.32% fat, 4.09%-5.63% lactose, and 11.22%-13.00% total solids (CARVALHO, 2008;SFORCINI, 2009;SILVA JÚNIOR et al, 2015;TEIXEIRA JUNIOR et al, 2015).…”

“…Illustrating this, Carvalho (2008) and Silva Júnior et al (2015) did not observe a positive effect (P>0.05) of sugarcane hydrolysis for 24 h with 0.75% to 2.25% CaO on the digestibility of DM, OM, CP, NDF and TDN. Similarly, there was no effect (P>0.05) on DM, CP, NDF, NDFap, ADF and TDN intake in diets based on sugarcane hydrolyzed for up to 48 h with 0.5% to 2% CaO (CARVALHO, 2008;SFORCINI, 2009;SILVA JÚNIOR et al, 2015;TEIXEIRA JUNIOR et al, 2015). As a direct reflection of the reduction in nutrient intake and digestibility of the diets in response to sugarcane hydrolysis with increasing amounts of CaO (Tables 3 and 4), there were linear reductions (P<0.05) in milk production corrected or not corrected to 4% fat and in protein, lactose and total solids content ( Table 5).…”

“…However, sugarcane presents nutritional limitations that restrict its use as an exclusive ingredient in the diet of high-producing ruminants, such as the low crude protein (CP) content in the DM of sugarcane forage (CAMPOS et al, 2017), which is on average 2.66% (VALADARES FILHO et al, 2010). The inclusion of nonprotein nitrogen sources, such as 1% urea (in fresh chopped sugarcane basis), in diets with 50% concentrates is a nutritional alternative for correcting the CP content of sugarcane, which, in addition to promoting a reduction in the costs of feeding cows, allows average milk yields of 22 kg day −1 to be reached (SOUZA et al, 2015).…”

“…Only five studies have compared the effects of chopped sugarcane supplied in natura versus hydrolyzed on the voluntary consumption of nutrients and on the production and composition of cow's milk (CARVALHO, 2008;SFORCINI, 2009;ALVES et al, 2010;SILVA JÚNIOR et al, 2015;TEIXEIRA JUNIOR et al, 2015). Irrespective of the dose and the alkalizing agent used (0.5% to 1% Ca(OH) 2 or 0.5% to 2.25% CaO), there was no effect of the chemical treatment of sugarcane on the DM intake of the diets.…”

Sugarcane with Elephant grass replacing sugarcane with urea in the diet of crossbred dairy cows1

“…No differences were found (p > 0.05) in milk composition between the studied treatments (Table 4). These results were also observed by Aguiar et al (2013), Souza et al (2015) and Teixeira et al (2015), in investigations with urea addition to sugarcane. Jesus et al (2012) found higher fat content.…”