Urea for dairy cows in the postpartum: urea levels in the plasma and uterine pH

[摘要] The objective of this work was to evaluate the effects of increasing levels of urea in the diets in postpartum crossbred dairy cows on plasma level of N-urea (NUP) and uterine pH in the estrus and luteal phase. Sixteen crossbred cows (Holstein-zebu) with body condition score at parturition between 3.5 and 4.0 (1 to 5 scale) were assigned in four treatments with diets made up with corn silage and concentrate in the proportion of 60:40 as: T1=0.0; T2=0.7; T3=1.4; and T4=2.1% of urea in the dry matter. The uterine pH was measured four hours after the diet intake, during the estrus and luteal phase from the second or third estrous cycle postpartum period in dairy cows. Simultaneously, blood samples were collected for determination of the level of plasma urea. The dry matter intake from 70 to 110 days of lactation reduced from 0.7% of urea. The levels of plasma N-urea were not affected in the samples collected during the estrus (19.59 mg/dL). The uterine pH during estrus (6.66) and luteal phase (6.97) were not affected by the different levels of urea.

[学科分类] 兽医学

[关键词] cattle;non-protein nitrogen;reproduction     IntroduçãoO ambiente uterino é dinâmico e apresenta diferenças nas fases do ciclo estral;devido à regulação esteroidogênica dos ovários e a secreção endometrial (Butler;2000);sendo que o pH e a concentração iônica da secreção uterina durante a fase luteal podem ser influenciados pela ingestão de dietas contendo elevados teores de proteína;provocando redução da fertilidade de vacas leiteiras no pós-parto (Butler;1998)