Urea Concentration in Bulk Milk as an Indicator of the Protein Supply at the Herd Level

Herd Reproductive Performance Related to Urea Concentration in Bulk Milk

“…Average urea levels in herds with cows treated for ovarian cysts and anoestrus compared with average urea levels in herds with non-treated cows. during the sampling period, is in agreement with Refsdal et al ( 1985). The high October level in herds from Bergen is probably due to the fact that a majority of the animals still was on pasture at the time of sampling.…”

“…A possible explanation could be that concentrates relatively rich in protein are commonly used to replace silage in the diet in this district, thereby tending to increase urea levels. Preliminary results indicate, however, that also in Hardanger a positive correlation existed between the crude protein content of the silage dry matter and the urea levels in bulk milk, supporting Refsdal et al ( 1985). T he data concerning the reproductive performance comprised both the indoor winter season and the summer season, whereas urea samples were collected during the winter season only.…”

“…In Hardanger forage diets with grass silage as the main roughage are commonly used. According to Refsdal et al (1985) this seems to involve a risk of feeding excessive amounts of protein and thereby elevating the milk urea levels. In Hedmark other roughages such as roots, hay, straw etc.…”

“…In a previous experiment (Refsdal 1983), a high correlation (r = 0.77, p < 0.01) between herd means of urea in blood and urea in bulk milk was found, indicating that analysis of bulk milk can be used to reflect the urea status of the herd. A later study (Refsdal et al 1985) showed that analysis of urea in bulk milk seemed to be a practical way of assessing the protein/energy ratio in the feeds at the herd level. The aim of the present investigation was to assess the relationship between bulk milk urea levels and the herd reproductive performance.…”

Effects of Dietary Heat Extruded Soybean Meal and Protected Fat Supplement on the Production, Blood and Ruminal Characteristics of Holstein Cows

“…Generally, after dietary protein was degraded into NH 3 by ruminal bacteria, if not synchronized with energy to synthesize microbial protein immediately, the ammonia level would increase in the rumen and become diffused through the ruminal epithelial tissue into the blood and transformed into ureanitrogen via the liver. The urea-N serves as an important indication of the leftovers from the microbial protein synthesis in the rumen, which also reflects the amount of degradable intake protein (Refsdal et al, 1985). The results showed that 2.5% protected fat inclusion in the diet did not produce any negative effect on the protein degradation and utilization in the rumen.…”