Estimativa da excreção urinária de derivados de purinas a partir do consumo de NDT e determinação da contribuição endógena em vacas de leite

• Autor(a) principal: Pellizzoni, Samantha Gusmão
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5054
• topic: Holandesa; Leite; Nitrogênio microbiano; Holstein cows; Milk; Microbial nitrogen; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The objective was to estimate the urinary excretion of purine from the TDN consumption and determine the endogenous contribution in dairy cows. The experiment was conducted at the Unidade de Ensino, Pesquisa e Extensão em Gado de Leite (UEPE-GL) during the month of March 2010. Twelve Holstein cows purebred and crossbred, allocated in a completely randomized design with three treatments based on production of milk, which were assessed as high, medium and low bands by taking the following production: 33,50; 18,42 and 11.07 kg of milk / day, respectively.The diet consisted of corn silage ad libitum and concentrate fed at a rate of one kilogram for every three pounds of milk produced. The experimental period lasted 15 days, se ven to eight days for adaptation and implementation of collection of urine, faeces, blood and milk, as well as to evaluate the consumption and digestibility. Milkings were carried out in two hours, from 6:00 h and 16:00 h. The results were evaluated by analysis of variance, using the 5% level of probability of type I error, through the SAS, by using the t test to compare means. Relations between the daily excretion of purine derivatives and the consumption of total digestible nutrients (TDNI), digestible organic matter intake (DOMI) and dry matter intake (DMI) were assessed using linear regression. No significant differences (P>0.05) for lactose and milk fat, however, the percentage of protein was higher for cows with low production (P<0.05). Intakes of all nutrients, except for neutral detergent fiber corrected for ash and protein (NDF) and neutral detergent fiber indigestible (NDFi) were higher for animals for higher production. The digestibility of dry matter (DM), organic matter (OM), crude protein, and non-fiber carbohydrates and contents of total digestible nutrients (TDN) did not differ between treatments (P> 0.05), whereas the digestibility of ether extract and NDF were influenced by the level of milk production, and lower for cows of high production. The levels of urea nitrogen in plasma and milk and excretion of nitrogenous (N) in urine were highly correlated and higher (P<0.05) for more productive animals, indicating that the concentration varied with the level of milk production. Urinary excretions of purine derivatives (PD) and urea, as well as the relations of allantoin: creatinine, uric acid, creatinine, purine derivatives, creatine and urea, creatinine, when compared between different times of collection and spot urine collection total urine for 24 hours, no significant difference (P>0.05). The synthesis of ruminal microbial crude protein and excretion of PD were associated with intake of TDN and digestible organic matter (DOM), being raised from 23.48 mmol of SD for each kg of TDN consumed, 25.50 mmol SD for each kg of digestible organic matter, revealing that both relations can be used to make these estimates. The gathering spot can be used to estimate the daily excretion of purine derivatives and urea in the urine of cows, regardless of the level of production. Both the use of TDN intake and consumption of MOD can be used in order to estimate the urinary purine derivatives. Whereas the excretion of PD in mmol/kgPC0,75 and dry matter intake expressed as g/kg PC0,75, obtained the value of the fraction of endogenous DP mmol/kgPC0.2370,75.