Effect of extended photoperiod during winter on growth and onset of puberty in Murrah buffalo heifers

Abstract

Aim: To investigate the effect of extended photoperiod on growth rate, hormonal levels, and puberty in Murrah heifers. Materials and 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 ß 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 groupby- time interaction effects were non-significant (p>0.05). Average daily gain and dry matter intake of heifers were nonsignificant 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. Conclusion: 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.