PMID- 21524528
OWN - NLM
STAT- MEDLINE
DCOM- 20110823
LR  - 20110428
IS  - 1525-3198 (Electronic)
IS  - 0022-0302 (Linking)
VI  - 94
IP  - 5
DP  - 2011 May
TI  - The low fertility of repeat-breeder cows during summer heat stress is related to 
      a low oocyte competence to develop into blastocysts.
PG  - 2383-92
LID - 10.3168/jds.2010-3904 [doi]
AB  - It was hypothesized the lower fertility of repeat-breeder (RB) Holstein cows is 
      associated with oocyte quality and this negative effect is enhanced during summer 
      heat stress (HS). During the summer and the winter, heifers (H; n=36 and 34, 
      respectively), peak-lactation (PL; n=37 and 32, respectively), and RB (n=36 and 
      31, respectively) Holstein cows were subjected to ovum retrieval to assess oocyte 
      recovery, in vitro embryonic developmental rates, and blastocyst quality 
      [terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling 
      (TUNEL)-positive cells and total cell number]. The environmental temperature and 
      humidity, respiration rate, and cutaneous and rectal temperatures were recorded 
      in both seasons. The summer HS increased the respiration rate and the rectal 
      temperature of PL and RB cows, and increased the cutaneous temperature and 
      lowered the in vitro embryo production of Holstein cows and heifers. Although 
      cleavage rate was similar among groups [H=51.7% +/- 4.5 (n=375), PL=37.9% +/- 5.1 
      (n=390), RB=41.9% +/- 4.5 (n=666)], blastocyst rate was compromised by HS, 
      especially in RB cows [H=30.3% +/- 4.8 (n=244) vs. 23.3% +/- 6.4 (n=150), PL=22.0% +/- 
      4.7 (n=191) vs. 14.6% +/- 7.6 (n=103), RB=22.5% +/- 5.4 (n=413) vs. 7.9% +/- 4.3 
      (n=177)]. Moreover, the fragmentation rate of RB blastocysts was enhanced during 
      the summer, compared with winter [4.9% +/- 0.7 (n=14) vs. 2.2% +/- 0.2 (n=78)] and 
      other groups [H=2.5% +/- 0.7 (n=13), and PL=2.7% +/- 0.6 (n=14)] suggesting that the 
      association of RB fertility problems and summer HS may potentially impair oocyte 
      quality. Our findings provide evidence of a greater sensitivity of RB oocytes to 
      summer HS.
CI  - Copyright (c) 2011 American Dairy Science Association. Published by Elsevier Inc. 
      All rights reserved.
FAU - Ferreira, R M
AU  - Ferreira RM
AD  - Departamento de Reproducao Animal da Faculdade de Medicina Veterinaria e 
      Zootecnia da Universidade de Sao Paulo, Sao Paulo, SP, Brazil 05508-000. 
      robertinhavet@yahoo.com.br
FAU - Ayres, H
AU  - Ayres H
FAU - Chiaratti, M R
AU  - Chiaratti MR
FAU - Ferraz, M L
AU  - Ferraz ML
FAU - Araujo, A B
AU  - Araujo AB
FAU - Rodrigues, C A
AU  - Rodrigues CA
FAU - Watanabe, Y F
AU  - Watanabe YF
FAU - Vireque, A A
AU  - Vireque AA
FAU - Joaquim, D C
AU  - Joaquim DC
FAU - Smith, L C
AU  - Smith LC
FAU - Meirelles, F V
AU  - Meirelles FV
FAU - Baruselli, P S
AU  - Baruselli PS
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Dairy Sci
JT  - Journal of dairy science
JID - 2985126R
SB  - IM
MH  - Animals
MH  - Blastocyst/physiology
MH  - Cattle
MH  - Cattle Diseases/*physiopathology
MH  - Female
MH  - Fertility/*physiology
MH  - Heat Stress Disorders/physiopathology/*veterinary
MH  - Hot Temperature/*adverse effects
MH  - Oocytes/growth & development/*physiology
MH  - Pregnancy
MH  - Pregnancy Rate
MH  - *Seasons
EDAT- 2011/04/29 06:00
MHDA- 2011/08/24 06:00
CRDT- 2011/04/29 06:00
PHST- 2010/10/06 00:00 [received]
PHST- 2011/01/25 00:00 [accepted]
PHST- 2011/04/29 06:00 [entrez]
PHST- 2011/04/29 06:00 [pubmed]
PHST- 2011/08/24 06:00 [medline]
AID - S0022-0302(11)00214-1 [pii]
AID - 10.3168/jds.2010-3904 [doi]
PST - ppublish
SO  - J Dairy Sci. 2011 May;94(5):2383-92. doi: 10.3168/jds.2010-3904.