Reproductive activity in Quarter Horse mares with artificial light

Wednesday, July 23, 2014
Exhibit Hall AB (Kansas City Convention Center)
Jose A Ramírez-Godínez , Universidad Autónoma de Chihuahua, Chihuahua, Mexico
Jesica Delgado-Laphond , Universidad Autónoma de Chihuahua, Chihuahua, Mexico
Alberto Flores-Marińelarena , Universidad Autónoma de Chihuahua, Chihuahua, Mexico
Eduardo Santellano-Estrada , Universidad Autónoma de Chihuahua, Chihuahua, Mexico
Abstract Text:

The objective was to determine the effect of artificial light during the winter on the reproductive activity in Quarter Horse (QH) mares in Mexico. Sixty seven QH mares, 5 to 12 years old with an average weight of 480±20 kg, and body condition between 5 and 7 were randomly divided into a control group (G0, n=15), exposed to natural light and an artificial light group 1 (G1, n=52), exposed to artificial light to complete 16 h light from November 15 to February 15. Both groups were alternately monitored (every other day) with a teaser stallion to assess the presence of estrus, and the reproductive tract ultrasounded to monitor follicular growth and ovulation. Means for days to estrus, ovulation, pregnancy, services per conception and size of the ovulatory follicle were compared between treatments using the GLM procedure of SAS. The effect of treatments on ovulation rate per month was analyzed by Chi Square (χ2 test) using the FREQ procedure of SAS. The use of artificial light accelerated (P<0.001) the onset of estrus, ovulation and gestation considerably. The average time from exposure of artificial light to onset of estrus was 47±3.21 d (P<0.001) in G1 and 105±6.13 d in G0, and to ovulation 81.6±3.7 d with artificial light (G1) and 134.5±7.0 d control group (G0). The highest rate of ovulations (P<0.1) occurred in February (.46) in G1 and in April (.66) in G0, respectively. Diameter of the ovulatory follicle was similar (P>0.05) in mares in the control group (40.7±1.11 mm) than under artificial photoperiod (41.7±0.58 mm). The interval from the onset of artificial light to pregnancy was 96.54±4.46 d (G1) and 141.28±8.53 d with natural light (G0; P< 0.001). The services per conception (SPC) were similar (P<0.05) between treatments (1.6±0.123 SPC for artificial photoperiod and 1.7±.0236 SPC for controls, respectively). The use of artificial light from November to February in QH mares accelerated the presence of estrus and the ovarian activity (ovulation) which resulted in a higher proportion of earlier gestations in the year.

Keywords: Estrus, ovulation, mares