Abstract
Objective: The present work aimed to study the effect of progesterone (CIDR)-based GnRH treatments plus eCG (1000 or 500 IU) on inducing and synchronizing the onset of puberty in buffalo-heifers. Methods: Buffalo-heifers (n=28) were randomly allocated into four treatment protocols (7 each): (G1, CIDR- eCG1000- GnRH), (G2, CIDR- eCG 500- GnRH), (G3, CIDR-GnRH) and (G4, CIDR- alone). The largest follicle diameter (LFD) and antral follicles counts (AFC) of small (≤ 4mm), medium (> 4mm- ≤8mm) and large follicles (>8mm) were estimated by transrectal ultrasonography on Days 0, 8, and 11. Also, the LFD was estimated on Day 13 as well. Results: On Day 11, the AFC of both small and medium-sized follicles was higher in G1 compared with G2 (P < 0.05) and with both G3 and G4 (P < 0.01). The AFC of large follicles was the greatest (P < 0.05) in G1compared with all groups but did not differ among G2, G3, and G4 on Day 11. On Day 13, the LFD showed non-significant variation between G1 and G2 as well as between G3 and G4. It showed a significant increase in G1 (P < 0.01) and G2 (P < 0.05) compared with either G3 or G4. The conception rate was the highest (P<0.05) in G1 compared with all groups. Conclusion: It could be concluded that the incorporation of eCG at a dose of 1000 IU in P4 (CIDR) based together with GnRH treatment protocol induces and synchronizes puberty in buffalo-heifers at the age of puberty.
Highlights
Puberty in heifers is a process of acquiring reproductive competence (Hossein-Zadeh, 2011)
It could be concluded that the incorporation of eCG at a dose of 1000 IU in P4 (CIDR) based together with GnRH treatment protocol induces and synchronizes puberty in buffalo-heifers at the age of puberty
It was noted that while the mean ± standard error of mean (SEM) of medium antral follicles counts (AFC) in G2 showed a significant (P < 0.05) increase compared with G4, it showed a non-significant (P> 0.05) increase compared with G3 (Fig. 2 B)
Summary
Puberty in heifers is a process of acquiring reproductive competence (Hossein-Zadeh, 2011). The delayed and asynchronous onset of puberty, silent heat, and long postpartum ovarian quiescence are the main causes of poor reproductive performance in buffaloes (Verma et al, 2019). Great variations in the age at attaining puberty in buffalo heifers (Perera, 2008) lead to wide variation and delay in the age at first breeding (Ettema and Santos, 2004) and in the age at first calving (Bhatti et al, 2007; Sarwar et al, 2009). Hormonal inadequacies and immaturity of the reproductive neuroendocrine axis is the main cause of delayed puberty in wellmanaged buffalo-heifers (Nanda et al, 2003). The initiation of highfrequency release of GnRH and LH pulses is a prerequisite for the onset of puberty (Day et al, 1984). The GnRH plays an important role in the regulating secretion of LH, follicular development, and secretion of steroid hormones (Gupta and Carviel, 2016)
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