Impact of a nutritional immunomodulator in dry cows heat stressed with an electric blanket model

• Published in: Journal of dairy science 2024-12
• Main Authors: Casarotto, L.T., Cattaneo, L., Glosson, K.M., Humphrey, B.D., Chapman, J.D., Dahl, G.E.
• Format: Article
• Language: English
• Subjects: hyperthermia; immunity; prenatal; productivity
• ISSN: 0022-0302; 1525-3198; 1525-3198
• DOI: 10.3168/jds.2024-25878

Heat stress (HT) in the dry period reduces yield and health in the next lactation. Previous work indicates that feeding OmniGen-AF® (OMN) mitigates the detrimental effects of HT. Electric blankets (EB) can induce heat stress in lactating cows, but EB have not been used with dry cows. The objectives of this study were to explore efficacy of the EB on cows during the dry period as well as examine the impact of feeding OMN to HT cows. We hypothesized that EB would increase body temperature in dry cows and OMN would ameliorate the impacts of HT. Fifty Holstein cows were housed individually in a tie-stall barn upon dry-off ~48 d before expected calving (223.7 ± 5 d carried calf) and cows were fitted with EB or no blanket (NB). Within EB and NB, cows were fed OMN (OMN; 56 g/d) or did not receive OMN (CON), which resulted in a 2x2 factorial of 4 treatments: NBCON, EBCON, NBOMN, and EBOMN. Throughout the dry period, DMI, water intake, and respiration rate (bpm) were measured daily, and rectal temperature was measured twice daily. After calving, all the cows were cooled and managed identically, and milk yield and composition were measured at each milking. Use of EB increased rectal temperature and respiration rate relative to NB regardless of diet, whereas OMN treatment did not affect rectal temperature or respiration rate. DMI was reduced by over 1 kg/d with EB and OMN feeding reversed this effect. Water intake increased with EB relative to NB, but OMN was without effect. Treatment did not impact gestation length. In early lactation, EB cows produced 6 kg/d less energy corrected milk relative to NB, and OMN reversed the impact on milk yield in EB cows. These data support the hypotheses that EB induce heat stress in dry cows and that OMN effectively mitigates the detrimental effects of heat stress in the dry period.