The Journal of Extension - www.joe.org

August 2017 // Volume 55 // Number 4 // Tools of the Trade // 4TOT6

Maximizing Use of an Extension Beef Cattle Data Set: Part 2—Reproductive Rates

Abstract
Previously, we described CHAPS20Y, a historical data set, and trends in CHAPS20Y calving distributions. In this article, we describe reproductive rates, including total females exposed to bull(s), pregnancy, pregnancy loss, calving, calf death loss, weaning, culling, and replacement percentages. Yearly mean exposed females increased from 1994 through 2013, consistent with a greater replacement percentage versus culling percentage. Yearly mean reproductive percentages varied over time. Factors such as weather, body condition, temperament, nutrition, and health likely contributed to this variation. CHAPS20Y is a tool Extension professionals can use to understand beef reproductive rates and help producers set and achieve their herd management goals.


Jennifer M. Ramsay
Beef Data Specialist
Dickinson Research Extension Center
North Dakota State University
Dickinson, North Dakota
jennifer.m.ramsay@ndsu.edu

Lauren L. Hulsman Hanna
Assistant Professor
Department of Animal Sciences
North Dakota State University
Fargo, North Dakota
lauren.hanna@ndsu.edu

Kris A. Ringwall
Extension Livestock Specialist and Director
Dickinson Research Extension Center
North Dakota State University
Dickinson, North Dakota
kris.ringwall@ndsu.edu

Introduction

We used data from Cow Herd Appraisal Performance Software (CHAPS) to create CHAPS20Y, a 20-year beef herd data set spanning from 1994 through 2013, as an Extension tool for understanding trends in beef production (Ramsay, Hulsman Hanna, & Ringwall, 2016). In Part 1 of this series, we described calving distribution data from CHAPS20Y (Ramsay, Hulsman Hanna, & Ringwall, 2017). In this article, we describe CHAPS20Y reproductive rate data, including

  • total numbers of females exposed to bull(s), hereafter referred to as total exposed females;
  • pregnancy, calving, and weaning percentages;
  • pregnancy loss and calf death loss percentages; and
  • culling and replacement percentages.

Herein we describe CHAPS20Y reproductive rate data to provide background for other Extension professionals who are working to help beef producers set and achieve herd management goals. We present yearly means, 20-year averages, and linear trends over time.

Describing Reproductive Rate Data

Total Exposed Females

CHAPS defines total exposed females as the number of females exposed to at least one bull plus any pregnant culled females for a selected date range—from one breeding season to the next—which spans approximately 1 year (Ramsay et al., 2016). For CHAPS20Y, the yearly mean total exposed females ranged from 192 to 286, with a 20-year average of 228 (Figure 1).

Figure 1.
Yearly Mean Number of Females Exposed to Bull(s) with 20-Year Average Trend Line

Reproductive Percentages

The CHAPS program calculates percentages related to various aspects of reproduction (reproductive percentages) according to Beef Improvement Federation (2010) guidelines and recommendations put forth by Ringwall & Berg (1990). For most of the calculations, CHAPS uses an "adjusted total exposed females" value, which is the number of total exposed females minus the number of pregnant culled females. In calculating reproductive percentages for each herd, CHAPS uses the following equations (multiplying the results of each equation by 100):

Yearly cumulative mean pregnancy, calving, and weaning percentages for CHAPS20Y are displayed in Figure 2. Pregnancy percentages ranged from 90.5% to 94.6%, with a 20-year average of 93.0%. Calving percentages ranged from 89.7% to 94.0%, with a 20-year average of 92.3%. Weaning percentages ranged from 85.4% to 91.6%, with a 20-year average 89.8%.

Figure 2.
Yearly Mean Pregnancy, Calving, and Weaning Percentages with 20-Year Average Trend Lines

As shown in Figure 3, yearly mean pregnancy loss percentages ranged from 0.5% to 1.3%, with a 20-year average of 0.74%. Figure 4 shows that yearly mean percentages of calf death losses relative to the number of exposed females ranged from 2.7% to 5.1%, with a 20-year average of 3.4%, and that yearly mean percentages of calf death losses relative to the number of calves born ranged from 3.0% to 5.8%, with a 20-year average of 3.7%.

Figure 3.
Yearly Mean Pregnancy Loss Percentages with 20-Year Average Trend Line

Figure 4.
Yearly Mean Calf Death Loss Percentages (Relative to the Number of Exposed
Females and the Number of Calves Born) with 20-Year Average Trend Lines

Yearly mean culling percentages and replacement percentages are shown in Figure 5. Culling percentages ranged from 10.9% to 16.3%, with a 20-year average of 13.8%, and replacement percentages ranged from 13.2% to 20.3%, with a 20-year average of 16.7%.

Figure 5.
Yearly Mean Culling and Replacement Percentages with 20-Year Average Trend Lines

Yearly Minimums and Maximums

To demonstrate herd-to-herd variation in the CHAPS20Y data set, we present yearly herd minimums and maximums for total exposed females (Table 1); pregnancy, calving, and weaning percentages (Table 2); pregnancy loss and calf death loss percentages (Table 3); and culling and replacement percentages (Table 4).

Table 1.
Minimum and Maximum Total Females Exposed to Bull(s)

Year Total exposed females
Min. Max.
1994 70 428
1995 76 403
1996 71 490
1997 60 498
1998 52 577
1999 61 560
2000 58 555
2001 73 597
2002 63 605
2003 62 596
2004 61 580
2005 54 978
2006 55 1,071
2007 61 907
2008 60 902
2009 62 1,023
2010 58 984
2011 61 1,008
2012 51 964
2013 66 1,088

Table 2.
Minimum and Maximum Pregnancy, Calving, and Weaning Percentages

Year Pregnancy Calving Weaning
Min. Max. Min. Max. Min. Max.
1994 85 99 82 98 82 97
1995 86 98 78 97 68 96
1996 79 99 79 99 75 99
1997 78 100 78 99 68 99
1998 80 99 77 99 77 97
1999 75 99 75 98 70 99
2000 77 100 77 100 76 100
2001 87 100 86 99 78 97
2002 82 100 81 100 80 100
2003 78 100 76 100 73 100
2004 66 100 66 100 66 100
2005 85 100 84 100 80 100
2006 78 100 76 100 76 99
2007 79 100 76 100 76 100
2008 80 100 80 100 75 100
2009 72 100 72 100 65 100
2010 79 100 78 100 77 100
2011 80 100 77 100 68 100
2012 86 100 86 100 83 100
2013 76 100 76 100 69 100

Table 3.
Minimum and Maximum Pregnancy Loss and Calf Death Loss Percentages

Year Pregnancy loss Calf death lossa Calf death lossb
Min. Max. Min. Max. Min. Max.
1994 0 3 0 7 0 8
1995 0 12 0 12 0 15
1996 0 3 0 9 0 10
1997 0 6 1 25 1 30
1998 0 4 0 6 0 7
1999 0 3 0 11 0 12
2000 0 3 0 8 0 8
2001 0 4 0 11 0 12
2002 0 4 0 10 0 10
2003 0 13 0 10 0 11
2004 0 5 0 12 0 13
2005 0 8 0 10 0 13
2006 0 3 0 13 0 14
2007 0 11 0 9 0 9
2008 0 6 0 8 0 9
2009 0 8 0 21 0 21
2010 0 4 0 12 0 13
2011 0 11 0 12 0 14
2012 0 4 0 10 0 11
2013 0 5 0 11 0 12
aTotal exposed females. bTotal number of calves born.

Table 4.
Minimum and Maximum Culling and Replacement Percentages

Year Culling Replacement
Min. Max. Min. Max.
1994 4 27 3 42
1995 5 35 7 45
1996 4 31 6 50
1997 5 40 8 66
1998 0 25 6 30
1999 0 31 1 39
2000 5 30 5 38
2001 5 29 1 33
2002 3 30 5 37
2003 1 45 1 30
2004 3 57 5 45
2005 1 57 2 64
2006 2 74 1 68
2007 0 52 1 57
2008 5 53 0 30
2009 3 38 0 24
2010 0 30 0 50
2011 4 32 0 40
2012 0 41 0 23
2013 6 78 0 33

Using CHAPS20Y Reproductive Rate Data to Increase
Extension Knowledge

We have demonstrated that an increase in total exposed females in CHAPS20Y herds occurred over time. Replacement percentages were greater than culling percentages for all years. Both pregnancy loss and replacement percentages showed slight decreases over time. All reproductive percentages varied from year to year, and herd minimums and maximums varied to a greater extent. In this section, we outline possible causes of these trends and variations.

Total Exposed Females and Culling and Replacement Percentages

In CHAPS20Y herds, yearly mean total exposed females increased 33% over the 20-year period. Similarly, from 1990 to 2010, the size of all CHAPS herds increased 38%, from 141 to 228 (Ringwall, 2011). Each year CHAPS20Y replacement percentages exceeded culling percentages, contributing to increases in herd size. This follows a trend of producers' expanding herd sizes during favorable market conditions (Estes, 2015).

Weather affects culling and replacement percentages. During droughts, producers may cull more and replace less to minimize feed costs (Ringwall, 2012). In 2012, drought conditions occurred in the northern plains (National Oceanic and Atmospheric Administration, 2013), where most CHAPS20Y herds are located (Ramsay et al., 2016). CHAPS20Y culling percentages increased during this period. Cows are also culled because of poor reproductive performance, health, and disposition, as well as due to age and physical problems (Powell, 2013).

Pregnancy, Calving, and Weaning Percentages, Including Death Losses

Pregnancy, calving, and weaning percentages are interrelated measures of reproductive success affected by pregnancy loss and calf death loss. Poor weather may explain some of the variation in CHAPS20Y pregnancy loss and calf death loss. In 1997, a spring storm caused a spike in calf death losses among CHAPS herds (Ringwall, 2015). During the winter of 1996–1997, the northern plains received up to 200% of normal precipitation, including 100 in. of snow (Macek-Rowland, Burr, & Mitton, 2001). Calf deaths increase as precipitation increases and temperature decreases (Azzam et al., 1993).

Dam condition, temperament, nutrition, and health also affect reproduction. Cows with higher than average body fat have higher pregnancy rates and reduced pregnancy losses compared to thinner cows (Herd & Sprott, 1998), whereas aggressive cows have reduced reproductive rates (Cooke, Bohnert, Cappellozza, Mueller, & DelCurto, 2012). Proper nutrition and herd health are important for optimizing reproduction (Perry, Daly, & Melroe, 2009). Health and vaccination history affect pregnancy loss and calf death loss (Waldner & Kennedy, 2008; Wenzel & Hanosh, 2011). All these factors likely contributed to herd-to-herd and year-to-year variation in CHAPS20Y reproductive rates.

Conclusion

Using CHAPS20Y as a tool of the trade, we have added to the Extension knowledge base and broadened Extension thinking on beef cattle reproductive rates. Additionally, we have identified some of the factors affecting reproductive rates. Extension professionals can use this information to help producers manage their herds to achieve their goals.

Acknowledgments

We thank Lee Tisor, Wanda Ottmar, and Michelle Stolz for their management of the CHAPS database.

References

Azzam, S. M., Kinder, J. E., Nielsen, M. K., Werth, L. A., Gregory, K. E., Cundiff, L. V., & Koch, R. M. (1993). Environmental effects on neonatal mortality of beef calves. Journal of Animal Science, 71, 282–290. Retrieved from http://digitalcommons.unl.edu/animalscifacpub/481

Beef Improvement Federation. (2010). Guidelines for uniform beef improvement programs (9th ed.) (revised September 2016). Retrieved from http://beefimprovement.org/content/uploads/2013/07/BIFGuidelinesFinal_updated0916.pdf

Cooke, R. F., Bohnert, D. W., Cappellozza, B. I., Mueller, C. J., & DelCurto, T. (2012). Effects of temperament and acclimation to handling on reproductive performance of Bos taurus beef females. Journal of Animal Science, 90, 3547–3555. Retrieved from https://www.animalsciencepublications.org/publications/jas/pdfs/90/10/3547

Estes, S. (2015). National cattle herd numbers on the rise. Retrieved from http://www.hpj.com/livestock/national-cattle-herd-numbers-on-the-rise/article_839e6e8d-ef7a-5c2c-86fe-c8f2b5c895d3.html

Herd, D. B., & Sprott, L. R. (1998). Body condition, nutrition and reproduction of beef cows. Retrieved from http://agrilifecdn.tamu.edu/victoriacountyagnr/files/2010/07/Body-Condition-Nutrition-Reproduction-of-Beef-Cows.pdf

Macek-Rowland, K. M., Burr, M. J., & Mitton G. B. (2001). Precipitation in the northern plains, September 1996 through April 1997. Retrieved from https://pubs.er.usgs.gov/publication/cir1185A

National Oceanic and Atmospheric Administration. (2013). National Centers for Environmental Information, state of the climate: Drought for annual 2012. Retrieved from http://www.ncdc.noaa.gov/sotc/drought/201213

Perry, G., Daly, R., & Melroe, T. (2009). Increasing your calf crop by management, pregnancy testing, and breeding soundness examination of bulls. Retrieved from http://pubstorage.sdstate.edu/AgBio_Publications/articles/ExEx2068.pdf

Powell, J. (2013). Culling the beef cow herd. Retrieved from https://www.uaex.edu/publications/PDF/FSA-3092.pdf

Ramsay, J. M., Hulsman Hanna, L. L., & Ringwall, K. A. (2016). Maximizing use of Extension beef cattle benchmarks data derived from Cow Herd Appraisal Performance Software. Journal of Extension, 54(3), Article 3TOT5. Available at: http://www.joe.org/joe/2016june/tt5.php

Ramsay, J. M., Hulsman Hanna, L. L., & Ringwall K. A. (2017). Maximizing use of an Extension beef cattle data set: Part 1—Calving distribution. Journal of Extension, 55(3), Article 3TOT5. Available at: https://joe.org/joe/2017june/tt5.php

Ringwall, K. A. (2011). BeefTalk: Twenty years of great beef production. Retrieved from https://www.ag.ndsu.edu/news/columns/beeftalk/beeftalk-twenty-years-of-great-beef-production/

Ringwall, K. A. (2012). BeefTalk: Understanding culling and replacement rates critical. Retrieved from https://www.ag.ndsu.edu/news/columns/beeftalk/beeftalk-understanding-culling-and-replacement-rates-critical/

Ringwall, K. A. (2015). BeefTalk: Nice weather for calving is priority one. Retrieved from https://www.ag.ndsu.edu/news/columns/beeftalk/beeftalk-nice-weather-for-calving-is-priority-one/

Ringwall, K. A., & Berg, P. M. (1990). CHAPS II: Cow Herd Appraisal Performance Software user guide. Retrieved from https://library.ndsu.edu/repository/handle/10365/22560

Waldner, C. L., & Kennedy, R. I. (2008). Associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus, antibodies against bovine viral diarrhea virus, or antibodies against infectious bovine rhinotracheitis virus in calves. American Journal of Veterinary Research, 69(7), 916–927. Retrieved from http://avmajournals.avma.org/doi/abs/10.2460/ajvr.69.7.916

Wenzel, J. C., & Hanosh, T. J. (2011). Pregnancy loss in beef cattle. Retrieved from http://aces.nmsu.edu/pubs/_b/B228.pdf