title: Uraemia in the mare: effects of seasonal variations, of energy level of the diet and individual differences.
abstract: Uraemia variations in the heavy breed mare were studied in different situations. A study with 35 mares during an entire grazing season was conducted. The mean uraemia varied between 48.5 and 67.5 mg/100 ml plasma, with season and type of grass. The highest values were found with first-cycle pasture grass. Uraemia was lower with winter diets: 28.6 to 36.0 mg/100 ml. A study using 15 mares fed isonitrogenous diets based on hay or straw, and concentrates offered two different levels, between two months before and 8 days after foaling, showed that the physiological stage had a very moderate effect on uraemia, but that it was higher with a low concentrate level (35.6 to 44.0 mg/100 ml plasma from one period to another) than with a high concentrate level (25.8 to 33.3 mg/100 ml). An analysis on two herds of 7 and 5 mares sampled 9 times during a whole year showed that the individual effect is highly significant. It could not be explained by age differences. These measurements have further defined some sources of variation other than the nitrogen concentration of the diet.
mesh_terms: D000375:Aging; D000821:Animal Feed; D000818:Animals; D005260:Female; D006736:Horses / Q000097:blood*; D006109:Poaceae; D012621:Seasons; D014508:Urea / Q000097:blood*
chemical_list: D014508:Urea