The effect of feed supplementation on the onset of puberty in Brazilian dairy heifers

Meirelles, Cyro Ferreira; Abdalla, Adibe Luiz; Vitti, Dorinha Miriam Silber Schmidt

doi:10.1590/s0103-90161994000200026

Cited by 2 publications

(1 citation statement)

References 6 publications

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“…In other ungulates, the onset of puberty can be influenced by age, weight, health and environmental factors [17][18][19], although often it is body weight that is most strongly correlated with initiation of ovarian cyclicity. In cattle, Wiltbank [20] refers to a critical age-to-weight ratio that must be reached before heifers attain puberty, whereas Meirelles et al [19] suggested most begin cycling at about 65% of the mature body weight. In this study, pubertal female body weights were highly variable: 38 -65% of the adults.…”

Section: Discussionmentioning

confidence: 99%

Endocrine correlates of puberty in female Asian elephants (Elephas maximus) at the Pinnawala elephant orphanage, Sri Lanka

Mendis

Jayasekera

Rajapakse³

et al. 2017

BMC Zool

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Background: Previous studies have established ovarian cycle characteristics of adult Asian elephants using progestagen analyses, but little work has been done on young elephants to determine age at puberty. Demographic studies of wild Asian elephants suggest females give birth at about 12-18 years of age (conceiving at 10-16 years of age based on a 2-year gestation). However, there are a few examples of zoo elephants giving birth at only 5-6 years of age, so they would have started cycling much earlier. This study was carried out at the Pinnawela Elephant Orphanage (PEO) in Sri Lanka, where a herd of >80 captive elephants breeds successfully, resulting in a unique opportunity to monitor hormones and document initiation of ovarian cyclicity in young females, thus contributing to the normative reproductive database for this species. Results: We measured serum progestagens in samples collected every 10 days for 18 -24 months from 11 females (3.5-15 years of age), and found six (5.5 -12 years of age) already were cycling at study onset. Four females started cycling during the study at 4.5, 5.5, 7.5 and 15 years of age. There were no quantitative or qualitative differences between the first pubertal luteal phase and those of subsequent cycles. Of the 46 ovarian cycles observed, 78% were associated with clear behavioral signs of estrus (heightened bull attentiveness, and willingness of females to be mounted) during the late non-luteal period when progestagens were low. The average body weight at puberty was ~48% of that of adult female elephants at PEO. Conclusions: Asian elephants under human care, including under semi-captive conditions, may reach puberty earlier than those in the wild, perhaps due to better nutrition and reaching a body weight capable of supporting reproductive activity at a younger age. Thus, facilities with bulls need to carefully manage elephants to avoid accidental pregnancies in young females that may be too small to safely carry a pregnancy to term.

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Section: Discussionmentioning

confidence: 99%

Endocrine correlates of puberty in female Asian elephants (Elephas maximus) at the Pinnawala elephant orphanage, Sri Lanka

Mendis

Jayasekera

Rajapakse³

et al. 2017

BMC Zool

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Sequence Analysis Suggests Positive Selection on the Bovine Prodynorphin Gene

Garcia

Castellote

Corva

2020

BAG

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Dynorphin A is an endogenous opioid peptide that is part of the KNDy system in the hypothalamus of mammals. This peptide acts as an inhibitor of the GnRH pulse generation, thus regulating the onset of puberty and reproductive cycles. The PDYN gene encodes the propeptide Prodynorphin, the precursor of Dynorphin A. Despite its physiological relevance, PDYN has not emerged as a candidate gene associated with puberty in genomic association studies conducted in cattle. The present work aimed to search for signatures of selection on the PDYN gene among cattle breeds. To this, the whole genome sequences from 57 samples of ten cattle breeds were used. The samples were grouped based on breed selection history and their productive differences, particularly in terms of sexual precocity. The population structure was analyzed using Principal Component Analyses. To evidence recent selection processes, neutrality tests, such as Tajima’s D and Fu & Li’s F* and D* were performed in defined functional regions of PDYN. The putative promoter of PDYN showed a population structure that is in agreement with the criteria considered to make the groups. In that region, neutrality tests were consistently negative and resulted in statistically significant for the dairy breeds. Also, these breeds exhibited less variability in the haplotype analyses than the others. The results presented here suggest that regulatory regions of PDYN could be under positive selection, particularly in dairy breeds. Key words: reproduction; KNDy neurons; Dynorphin; signatures of selection.

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The effect of feed supplementation on the onset of puberty in Brazilian dairy heifers

Cited by 2 publications

References 6 publications

Endocrine correlates of puberty in female Asian elephants (Elephas maximus) at the Pinnawala elephant orphanage, Sri Lanka

Endocrine correlates of puberty in female Asian elephants (Elephas maximus) at the Pinnawala elephant orphanage, Sri Lanka

Sequence Analysis Suggests Positive Selection on the Bovine Prodynorphin Gene

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