Calculating Reproductive Performance in Beef Operations: The University of Florida Beef Herds’ 2019 Breeding Season

Mario Binelli, Angela M. Gonella-Diaza, Thiago Martins, Cecilia C. Rocha, Felipe A. C. C. Silva, Federico Tarnonsky, Sergio Roskopf, Owen Rae, Danny Driver, Nicolas DiLorenzo, Jose Dubeux, and David Thomas

Introduction

Cow-calf operations are predominant in Florida. For most producers, the bottom line is how many pounds of weaned calves they will be able to market in a given year. While many factors impact that endpoint, reproductive performance comes first: no calf, no revenue. Fewer calves, less revenue. Lighter calves, less revenue. It is that simple. However, when it comes to reproductive performance, there is much confusion and even misinformation among producers. Much of the confusion stems from two specific points: how to calculate reproductive performance and how to evaluate performance data. The first objective of this publication is to review the basic calculations of reproductive performance. After producers calculate the reproductive performance of the herd, they need a reference point to compare their results. The second objective of this article is to report the reproductive performance of two beef herds of the University of Florida, located in north (UF/IFAS NFREC in Marianna) and central Florida (Beef Units in Gainesville). This report will be updated annually to provide a moving benchmarking target for the industry in Florida. A companion EDIS publication, Calculating Calf Performance in Beef Operations: The University of Florida Beef Herds 2019–2020 Calving Season, addresses a second component of reproductive performance affecting producers’ bottom line, which is calf performance. This report is intended to be used by county faculty educating producers on the subject of reproductive performance and by producers who may need a reference point to benchmark the performance of the operation.

Reproductive Performance Calculations

Regarding the calculations of reproductive performance, the simplest measure is Pregnancy Rate. In systems with a defined breeding season, Pregnancy Rate is:

Pregnancy Rate (%) = Number of females pregnant / Number of females that entered the breeding season (x100)

For operations without a defined breeding season, use a limited time frame for calculation (e.g., a 12-month period). Pregnancy Rates are usually calculated after a pregnancy diagnostic that is conducted at least 30 days after the end of the breeding season. For herds that utilize artificial insemination (AI), it is usual to calculate the Pregnancy Rate to that insemination. In that situation, a pregnancy test is usually conducted 30 days after the AI. Other common measures of reproductive performance are:

Calving Rate (%) = (Number of calves born / Number of females that entered the breeding season) x 100

Weaning Rate (%) = (Number of calves weaned / Number of females that entered the breeding season) x 100

Pregnancy Maintenance (%) = (Number of calves born / Number of females diagnosed as pregnant) x 100

Pregnancy Loss (%) = 100 – Pregnancy maintenance (%)

Calf Survival (%) = (Number of calves weaned / Number of calves born) x 100

Calf Loss (%) = 100 – Calf Survival (%)

Reproductive Performance of UF Beef Herds

Producers always ask what numbers they should aim for. There is no definitive answer, because different performances are expected from different production systems. Producers may find it useful to utilize the numbers from this report as a reference point to gauge the reproductive performance of their operations. To that end, it is always useful to look at real numbers obtained from reliable sources. Here, we present a yearly report of the reproductive performance of the University of Florida beef herds. Each University herd operates according to its respective regional characteristics and specific management (Table 1 and Figure 1). Figure 2 presents the synchronization protocol, reproductive performance, pregnancy maintenance, and calf survival data for both the Gainesville (UF/IFAS Beef Unit) and the Marianna (UF/IFAS North Florida Research and Education Center) herds for the 2019 breeding season/2019–2020 calving season.

Table 1. Overview of the reproductive management of the UF Beef Units.

Variable

Gainesville

Marianna

Main breed composition

Angus x Brahman crossbreds

Angus, Brangus, Braford

Date breeding season started: heifers

2/8/2019

3/22/2019

Date breeding season started: cows

2/15/2019

3/29/2019

Duration of breeding season

85–100 days

80–85 days

Days after AI bulls were introduced

15

4–8

Bull:Cow ratio

1:40

1:22

Calendar distribution of the breeding season (orange), calving season (blue), and weaning (green bar) on the UF/IFAS beef herds. In both herds, the breeding season starts when females are artificially inseminated, following a synchronization protocol (Figure 2). Bulls are introduced a few days after AI (Table 1) and removed at the end of the breeding season. The calving season is consistent with the average gestation length in cattle (283 days). Because all females are inseminated on day 1 of the breeding season, AI calves are born first and calves from natural service follow.
Figure 2. Synchronization protocol, Pregnancy Rate, Pregnancy Maintenance (number of calves born alive divided by number of females pregnant), and Calf Survival (number of calves weaned divided by number of calves born alive) for the Gainesville (panels A, C, and E) and the Marianna herds (panels B, D, and F).
Credit: Binelli’s Lab, UF/IFAS

Synchronization protocols (Figure 2, panels A and B) are a precise sequence of hormonal treatments that are administered to a group of females in order to synchronize heats. Drugs used were GnRH analogs, prostaglandin F2-alpha analogs (PGF), and progesterone from intravaginal releasing devices, such as a CIDR. All females submitted to the protocol were artificially inseminated; pregnancy rates from that insemination varied from 28%–56%, depending on the female category (Figure 2, panels C and D, blue bars). After AI, females were exposed to clean-up bulls. The final pregnancy rates of the breeding season, including pregnancies both from the AI and from natural service, are shown in Figure 2, panels C and D (orange bars). There were fetal losses that occurred between the last pregnancy check and the expected calving date. These losses were usually low and varied from 0%–7%, depending on the female category (Figure 2, panels E and F, blue bars). Finally, calf losses occurred between calving and weaning and averaged 3%–6% (Figure 2, panels E and F, orange bars).

Summary

In this article, we reported local reproductive performance information, using breeds that are relevant to the production systems in the state. We confirmed that it is possible to obtain adequate pregnancy rates to A.I. + natural service within a limited breeding season. We show that reproductive success and fetal and calf survival varied according to the female category.

Acknowledgments

We thank the Gainesville and the Marianna Beef Units’ staff for their hard work, as well as the students who collaborated on data collection and compilation. We are grateful to Zoetis for the donation of synchronization drugs (Gainesville and Marianna) and Select Sires for the donation of semen (Marianna).

Peer Reviewed

Publication #AN365

Date: 2021-06-17
DiLorenzo, Nicholas
Dubeux, Jose C. B.
Binelli, Mario
Gonella-Diaza, Angela Maria
Rae, Owen D
Animal Sciences

Related Topics

Management Commercial

About this Publication

This document is AN365, one of a series of the Department of Animal Sciences, UF/IFAS Extension. Original publication date May 2021. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.

About the Authors

Mario Binelli, PhD, assistant professor, Department of Animal Sciences; Angela M. Gonella-Diaza, DVM, PhD, assistant professor, UF/IFAS North Florida Research and Education Center; Thiago Martins, DVM, PhD, postdoctoral fellow, Department of Animal Sciences; Cecilia C. Rocha, DVM, Department of Animal Sciences; Felipe A. C. C. Silva, DVM, Department of Animal Sciences; Federico Tarnonsky, DVM, UF/IFAS NFREC; Sergio Roskopf, DVM, UF/IFAS NFREC; Owen Rae, DVM, professor, Department of Large Animal Clinical Sciences, UF College of Veterinary Medicine; Danny Driver, MSc, general manager, Department of Animal Sciences; Nicolas DiLorenzo, PhD, associate professor, UF/IFAS NFREC; Jose Dubeux, PhD, associate professor, UF/IFAS NFREC; and David Thomas, general manager, UF/IFAS NFREC; UF/IFAS Extension, Gainesville, FL 32611.

Contacts

  • Mario Binelli