Cooling Holstein cows and heifers before parturition during summer: physiological responses prepartum and productive responses postpartum

Abstract

The aim was to compare physiological parameters prepartum and productive responses postpartum of multiparous cows, and first-calf heifers cooled 30 d before parturition.  Twelve cows and twelve heifers were subjected to a cooling system for 30 d before the predicted calving date. Before calving, respiration frequency (RF) was measured twice a day (AM and PM) once a week; also, a blood sample was obtained from the coccygeal vein once a week for a biochemical profile. After calving, productive parameters measured were calf birth weight and growth until weaning, colostrum, milk quality, and milk production. Mature cows had 6.5% less RF (P<0.05) than heifers during the morning, but this difference increased to 23% during the afternoon (P<0.01). Mature cows exhibited higher (P<0.05) mean corpuscular volume, mean corpuscular hemoglobin, and platelet distribution width than heifers; however, heifers showed higher (P<0.05) red blood cell count than mature cows. In comparison, colostrum fat was higher (P<0.05) in heifers, protein, SNF, and density were similar between groups. Milk quality did not differ between cows and heifers, but milk yield at 30, 60, 90, 120, and 150 d was higher (P<0.05) in mature cows than in heifers. Calf mortality, calf birth weight, body weight at 30 and 60 d, as well as daily weight gain at 60 d, were similar in both groups of mothers. In conclusion, mature cows showed better physiological and productive responses than heifers when cooled with spray and fans for 30 d prepartum under hot and dry stressful conditions.