PMID- 36340427
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20221108
IS  - 2666-9102 (Electronic)
IS  - 2666-9102 (Linking)
VI  - 1
IP  - 1
DP  - 2020 Aug
TI  - When do dry cows get heat stressed? Correlations of rectal temperature, 
      respiration rate, and performance.
PG  - 21-24
LID - 10.3168/jdsc.2019-18019 [doi]
AB  - Previous studies have documented the negative effects of heat stress during the 
      dry period on dairy cow performance during the next lactation, but an easy method 
      to assess heat stress for dry cow management is lacking. In an effort to 
      determine a threshold for heat stress based on the physiological response of 
      respiration rate, an easily measured variable, an analysis including data 
      collected from 6 different studies (n = 144 cows) was performed to summarize the 
      correlations among rectal temperature (RT) and respiration rate (RR) during the 
      dry period, milk production during the first 8 wk of lactation (MK), calf birth 
      weight (CW), body weight at calving (BW), gestation length (GL), and dry matter 
      intake (DMI) pre- and postpartum. Studies were conducted in Florida during the 
      summer, and dry cows were assigned to 2 treatments: heat stress (only shade; HT, 
      n = 75 cows) and cooling (shade, fans, and soakers; CL, n = 69 cows). Average RT 
      (0.3 degrees C) and RR [26 breaths per min (bpm)] of HT cows increased compared with CL. 
      In addition, the CL group produced more milk (2.8 kg/d) during the first 8 wk of 
      the subsequent lactation relative to HT. Correlation analysis indicated that RR 
      of HT was negatively correlated with MK and GL. Within HT, RT was also negatively 
      correlated with MK and GL and tended to be negatively correlated with CW. In 
      addition to being negatively correlated with RT and RR, HT MK was positively 
      correlated with CW, GL, and DMI postpartum. In CL, no correlations were observed 
      for RR, but RT was positively correlated with BW, and MK was positively 
      correlated with DMI postpartum and tended to be positively correlated with GL. 
      Moreover, the overall RT was 39.1 +/- 0.48 degrees C and RR was 61 +/- 19.5 bpm, which 
      indicates that RR over 61 bpm is an indicator of heat stress in cows during the 
      dry period and can be easily assessed at the cow level. In summary, the more heat 
      load a cow carries in the dry period, the greater the negative effects are on 
      subsequent milk production, which may suggest a threshold for the effects of heat 
      stress. Also, variation among cows within the HT group indicates that cows with 
      longer gestation length have heavier calves, eat more postpartum, and produce 
      more milk, but not as much as CL cows.
CI  - (c) 2020.
FAU - Toledo, I M
AU  - Toledo IM
AD  - Institute of Food and Agricultural Sciences (IFAS) Extension, University of 
      Florida, Gainesville 32603.
FAU - Fabris, T F
AU  - Fabris TF
AD  - Department of Animal Sciences, University of Florida, Gainesville 32608.
FAU - Tao, S
AU  - Tao S
AD  - Department of Animal and Dairy Science, University of Georgia, Tifton 31793.
FAU - Dahl, G E
AU  - Dahl GE
AD  - Department of Animal Sciences, University of Florida, Gainesville 32608.
LA  - eng
PT  - Journal Article
DEP - 20200902
PL  - United States
TA  - JDS Commun
JT  - JDS communications
JID - 9918300983806676
PMC - PMC9623762
EDAT- 2020/09/02 00:00
MHDA- 2020/09/02 00:01
PMCR- 2020/09/02
CRDT- 2022/11/07 05:01
PHST- 2019/12/06 00:00 [received]
PHST- 2020/03/30 00:00 [accepted]
PHST- 2022/11/07 05:01 [entrez]
PHST- 2020/09/02 00:00 [pubmed]
PHST- 2020/09/02 00:01 [medline]
PHST- 2020/09/02 00:00 [pmc-release]
AID - S2666-9102(20)30030-2 [pii]
AID - 10.3168/jdsc.2019-18019 [doi]
PST - epublish
SO  - JDS Commun. 2020 Sep 2;1(1):21-24. doi: 10.3168/jdsc.2019-18019. eCollection 2020 
      Aug.