title: Effect of extended photoperiod during winter on growth and onset of puberty in Murrah buffalo heifers.
abstract: OBJECTIVE
  To investigate the effect of extended photoperiod on growth rate, hormonal levels, and puberty in Murrah heifers.
  
  
  METHODS
  About 14 Murrah buffalo heifers were divided into normal day photoperiod (NDP; n=7) and extended NDP (ENDP; n=7) groups. The ENDP group was exposed to 4 h of extended photoperiod with artificial light (160 lux) after sunset for 3 months during winter.
  
  
  RESULTS
  Group, age and group-by-age interaction effects on plasma glucose concentrations were non-significant (p>0.05). A significant effect of age on non-esterified fatty acids (p<0.05), cholesterol (p<0.01), and triglycerides (p<0.05) concentrations was observed. Group and group-by-age interaction effects on plasma T3, T4, leptin, 17 β estradiol, prolactin and melatonin concentrations were non-significant (p>0.05) while significant (p<0.05) age effect on T4, leptin and melatonin concentrations was observed. With respect to the circadian pattern of melatonin and prolactin, the group, time and group-by-time interaction effects were non-significant (p>0.05). Average daily gain and dry matter intake of heifers were non-significant between the NDP and ENDP groups but were comparatively higher in ENDP group. By the end of the experiment, 6 out of 7 heifers attained puberty in ENDP group in comparison to 4 out of 7 in NDP group.
  
  
  CONCLUSIONS
  Extending the photoperiod by artificial light for 4 h during winter season resulted in better growth rate and early onset of puberty in Murrah buffalo heifers.
authors.affiliation: Division of Dairy Cattle Physiology, National Dairy Research Institute, Karnal, Haryana, India.
authors.forename: Ashwani Kumar
authors.initials: AK
authors.lastname: Roy
authors.affiliation: Division of Dairy Cattle Physiology, National Dairy Research Institute, Karnal, Haryana, India.
authors.forename: Mahendra
authors.initials: M
authors.lastname: Singh
authors.affiliation: Division of Dairy Cattle Physiology, National Dairy Research Institute, Karnal, Haryana, India.
authors.forename: Parveen
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Division of Dairy Cattle Physiology, National Dairy Research Institute, Karnal, Haryana, India.
authors.forename: B S Bharath
authors.initials: BS
authors.lastname: Kumar
keywords: buffalo; leptin; melatonin; metabolites; photoperiod; prolactin, puberty