Providing heat-stress abatement to late-lactation Holstein cows affects hormones, metabolite blood profiles, and hepatic gene expression but not productive responses

Abstract

Our objective was to evaluate the effects of providing shade and shade combined with evaporative cooling on production, cow activity, metabolism, and hepatic gene expression of late-lactation Holstein dairy cows under moderate heat-stress conditions. Forty-eight multiparous Holstein cows were used in a completely randomized block-design trial and randomly assigned to 1 of 3 treatments: control (CTL), without access to shade; access to artificial shade (SH); and shade combined with evaporative cooling (SHplus). Results were analyzed using a mixed procedure with repeated measures. No differences were observed in DMI. Milk yield was not different among treatments, but lactose concentration was greater in SHplus. Treatments CTL and SH had greater BW losses than SHplus. Control cows spent less time grazing. The CTL and SH had higher p.m. rectal temperatures than SHplus, whereas CTL had the highest p.m. respiration rate. Control cows had greater serum insulin levels. Control and SH had greater BHB and urea concentrations and lower glucose concentration compared with SHplus. The hepatic expression of PCK1 , PDK4 , and HP genes was downregulated in SH and SHplus relative to control. Hepatic expression of NFKB1 was downregulated, whereas SOCS2 was upregulated, for SHplus compared with CTL. Despite the absence of treatment effects on productive variables, changes in blood profiles and hepatic expression of target genes were observed among treatments. These results suggest that the provision of shade combined with evaporative cooling was effective in alleviating the negative effects of heat stress.