Estimativas da produção de leite por vacas holandesas mestiças, segundo o sistema CNCPS, em dietas contendo cana-de-açúcar com diferentes valores nutritivos

Abstract

RESUMO -O objetivo do presente estudo foi usar os dados observados sobre as variações nos teores da fibra em detergente neutro (FDN), lignina e das frações de carboidratos e das correspondentes taxas de degradação de 15 variedades de cana-de-açúcar, para avaliar a disponibilidade destes nutrientes em promover produção de leite de vacas holandesas mestiças, usando o sistema CNCPS. Um suplemento nutricional composto de silagem de milho, caroço de algodão, farelo de soja e uréia foi usado para complementar as exigências nutricionais destes animais na produção de 10 kg de leite diário. Os valores utilizados para predizer as respostas na produção de leite foram: FDN (%MS) -40, 50 e 60, lignina (%FDN) 10,14 e 18, taxas de digestão (%/h) dos carboidratos não fibrosos (CNF) -10,20 e 30 e taxa de digestão (%/h) dos carboidratos fibrosos (CF) -1, 2,5 e 4. A cana-de-açúcar, quando usada como principal volumoso da dieta, acarretou redução na ingestão de matéria seca e energia, limitando a produção de leite destes animais. A predição da quantidade de leite que poderia ser produzida em função da quantidade de energia metabolizável (EM), fornecida pela dieta, decresceu 24%, quando o teor de FDN aumentou de 40 para 60%, para um percentual de 14% de lignina. Também houve acréscimo de 14% na produção de leite, quando a taxa de digestão dos CF aumentou de 1 para 2,5%/h. Embora as variações nos teores de FDN e lignina e nas taxas de digestão dos carboidratos, das variedades de cana-de-açúcar, tenham promovido grande efeito sobre a produção de leite das vacas mestiças, torna-se necessária a validação destes resultados.Palavras-chave: cana-de-açúcar, produção de leite, simulação, vacas mestiças Estimates of the Milk Production by Crossbred Holstein Cows, in Accordance to CNCPS System, in Diets Containing Sugar Cane with Different Nutritive ValuesABSTRACT -The objective of the present study was to use the observed data on the changes of the neutral detergent fiber (NDF), lignin and carbohydrate fractions and of the related degradation rates of 15 sugar cane varieties, to evaluate this nutrient availability in promoting the milk production of the crossbred Holstein cows using the CNCPS system. A concentrate supplement compose by corn silage, whole cottonseed and soybean meal and urea was used to attend the nutritional requirement of this animals to produce 10 kg of daily milk. The values used to predict the response in the milk production were: NDF (%DM) -40,50 and 60, lignin (%NDF) 10,14 and 18, digestion rates (% /h) of the non fiber carbohydrates (NFC) -10,20 and 30 and digestion rate (% /h) of the fiber carbohydrates (FC) -1, 2,5 and 4. The sugar cane, when used as main forage in the diet, caused a reduction in the dry matter intake and energy, limiting the milk production of these animals. The prediction of the amount of milk that could be produced in function of the amount of energy metabolizable (ME), supplied by the diet, decreased 24% when the FDN content increased from 40 to 60%, for a 14% of lignin. There was also an increme...

Performance and metabolite profile of dairy cows fed tropical grasses and concentrates containing crude protein with low or high degradability

“…The low intake of the SC-based compared with the EGSbased diets may be related to the lower degradation and passage rates of SC, as reported by Fernandes et al (2001). Waldo et al (1972) proposed a model of interdependence among the intake, passage, and degradation rates that reinforces the causal relationship between the ruminal dynamics of digesta and nutrient intake of SC diets.…”

“…The dietary synchronization is important for microbial growth and, depending on the availability of non-fibrous carbohydrates, the microbial biomass uses degradable nitrogen more efficiently Malafaia et al, 1998;1999;Vieira et al, 2000c;Favoreto et al, 2008;Fernandes et al, 2014). Because of the nutritional imbalances of sugarcane, e.g., high soluble sugars and low protein content, it should be used with caution to prevent excess nutrient losses (Fernandes et al, 2001). Broderick (2003) stated that in addition to synchronizing the availability between carbon and nitrogen in the rumen, it is important to provide high-quality protein to be directly digested by the intestinal enzymes of the host.…”

“…However, the milk production of animals that consumed EGS was higher than that of animals that consumed SC, despite the higher plasma urea-N concentration of EGS. Sugarcane exhibits a low nutritional value and high availability of sugars in the rumen, which may limit the general use of N compounds by the animal (Fernandes et al, 2001).…”

“…Considering the amino acid requirement of lactating animals and dietary amino acid supply, it is possible that RUP sources can promote better productive responses when combined with forages such as sugarcane or elephant grass silage. Sugarcane exhibits a pronounced imbalance of nutrients and is usually only supplemented with NPN (Fernandes et al, 2001), whereas both elephant grass and corn silages provide more protein and RDP levels (Cabral et al, 2000;Lacerda et al, 2004). Thus, it is possible that supplementation with RUP reduces ammonia production in the rumen (Seymour et al, 1992).…”

Evaluation of the Cornell Net Carbohydrate and Protein System model on the prediction of dry matter intake and milk production of grazing crossbred cows

“…Lagunes et al (1999) and Fernandes et al (2001) observed strong influence of the fiber fraction in the CNCPS prediction on the performance of lactating crossbred cows. The high fiber content is a marked characteristic of tropical forages, which contributes directly to the low quality of this forage (Van Soest, 1994).…”