Beef cows with atypical estrous cyclicity at puberty produced calves with deficits in preweaning muscling, metabolic indicators, and myoblast function but not in feedlot performance.

Rebecca M Swanson,Rachel L Gibbs,Ty B Schmidt,Andrea S Cupp,Galen E Erickson,Dustin T Yates,Caitlin N Cadaret

doi:10.1093/tas/txaa119

Abstract

Beef cows with atypical estrous cyclicity at puberty produced calves with deficits in preweaning muscling, metabolic indicators, and myoblast function but not in feedlot performance.

Highlights

In cattle, age at puberty and number of estrous cycles prior to first breeding contribute to lifetime reproductive success (Perry et al, 1991)
In our university beef herd, we have identified a subset of cows that exhibited irregular pubertal cyclicity patterns between weaning and their first breeding season, which we postulate is associated with high androstenedione in follicular fluid (Cupp et al, 2019)
Cows with noncyclic or start–stop pubertal cyclicity calved 11.0 and 6.8 d later (P < 0.05) in the calving season, respectively, than cows with typical pubertal cyclicity, but birthweights did not differ among groups (Fig. 1)

Summary

Introduction

Age at puberty and number of estrous cycles prior to first breeding contribute to lifetime reproductive success (Perry et al, 1991). Cows with high androstenedione are subfertile but wean calves that average 17 kg heavier than the herd average (Summers et al, 2014). We hypothesized that this additional weight at weaning in their offspring is due to superior muscling and growth efficiency, characterized by better myoblast function, lean mass, and metabolic efficiency. The objective of this study was to test this hypothesis by evaluating growth and metabolic parameters in calves prior to weaning and in the feedlot, as well as carcass characteristics at harvest. We compared calves from cows that were classified as having typical pubertal cyclicity, start–stop pubertal cyclicity, or noncyclic puberty

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Conclusion