Serum Urea Nitrogen and Conception Rate: The Usefulness of Test Information

Abstract

Total of 627 AI in 332 Holstein cows in nine herds were used to examine the relationship between serum urea N and conception rate. Cows were assigned randomly to one of three isocaloric diets varying in protein degradability and content. The AI occurred from 50 to 150 DIM. Mean serum urea N for each cow from 50 to 150 DIM was used to examine conception rate and serum urea N. The clinical interpretation of serum urea N on conception rate is evaluated using Bayes theorem from two approaches (dichotomization vs. continuous). Test information resulting from dichotomization of serum urea N into high and low categories (maximizing the average of test sensitivity and specificity) is compared with likelihood ratio approaches allowing a continuous measure. Likelihood ratio test indicates that conception rate decreases with serum urea N of > 14.9 mg/dl, but dichotomized test suggests that the decrease does not occur until serum urea N is > 20 mg/dl.

Substituição do milho e do feno de capim-tifton por palma forrageira. Produção de proteína microbiana e excreção de uréia e de derivados de purina em vacas lactantes

“…De acordo com Fergunson et al (1993) e Garcia-Bajalil et al (1998), dietas com excesso de PB ou PDR, ausência de carboidratos fermentáveis ou assincronia entre degradação de carboidratos e disponibilidade de energia promovem grande concentração de uréia no sangue e/ou excreção de uréia no leite e na urina, o que não foi observado neste experimento, possivelmente em virtude do correto balanceamento protéico das dietas experimentais e da presença de CNF da palma, que promoveram melhor sincronismo na degradação desses nutrientes.…”

Effects of eCG in Milking Dairy Cows with High Levels of BUN and Synchronized with Ovsynch Protocol

“…Cattle consuming diets that generate high levels of plasma ammonia cause high levels of ammonia in follicular fluids 47 . Cultured oocytes with high concentrations of urea resulted in fewer oocytes successfully progressing to metaphase II 17 . When oocytes were exposed to high levels of urea in vitro 40 or to metabolism of high protein diets in vivo 2,47 , the resulting embryos were less likely to develop to the blastocyst stage.…”

“…Reduced conception rates occur following sustained BUN greater than 19 mg/dL or milk urea nitrogen (MUN) greater than 15.4 mg/dL 9,17,45 .…”

“…A consequence of high dietary crude protein is elevated plasma urea nitrogen (BUN) concentrations which have been associated with decreased fertility in dairy cows 9,12,17 . Reduced conception rates occur following sustained BUN greater than 19 mg/dL or milk urea nitrogen (MUN) greater than 15.4 mg/dL 9,17,45 .…”

Effect of the dry matter intake level on the sanguine profile of glucose, insulin, urea, estrogen and progesterone and concentration of IGF-I in the follicular liquid of crossbred heifers

“…The negative effect of the urea has been related to the decrease of the uterine pH (Elrod and Butler, 1993), which could harm the initial embryonic development (Santos and Amstalden, 1998). Fergunson et al (1993) stated that the conception rate in the herd decreased when the circulating levels of urea were above 20 mg/100 ml. In this experiment, all of the treatments presented, on average, levels below this as responsible for the negative effects in the reproduction.…”