Male Reproductive Traits and Their Heritabilities in Beef Cattle

– K. M. Cammack M. G. Thomas and R. M. Enns, published in The Professional Animal Scientist 25 ( 2009 ):517–528, and condensed from the original manuscript by Steve Boyles, OSU Beef Extension Specialist

Male Reproductive Measures
Measures of fertility need to be considered not only in the female, but also in the male. Natural service has historically been, and continues to be, used in most beef cattle operations; therefore, acceptable bull fertility is critical to the success of these operations. Bull management is highly intertwined with female fertility, bull fertility, and cow management. Bull fertility may be affected by the number of cows a particular bull is expected to service and, in natural mating, the length of the mating period, as well as the serving capacity of the bulls. Fertility measures may be superficially increased in bulls exposed to a small number of cows during a lengthy breeding season. However, determining the proper bull-to-cow ratio is challenging because these influences are in addition to issues of pasture size and topography, multiple water sources within a pasture, and behavior

Scrotal Circumference
Scrotal circumference is used to predict the quality and quantity of spermatozoa-producing tissue and age at puberty. A scrotal circumference measurement of 28 to 30 cm is generally associated with onset of puberty; specifically, 52 and 97% of males are pubertal when scrotal circumference is 28 and 30 cm, respectively. Increased scrotal circumference has been associated with increased sperm production but decreased semen quality. Reported heritability estimates for scrotal circumference were generally Continue reading

Female Reproductive Traits and Their Heritabilities in Beef Cattle

– K. M. Cammack M. G. Thomas and R. M. Enns, published in The Professional Animal Scientist 25 ( 2009 ):517–528, and condensed from the original manuscript by Steve Boyles, OSU Beef Extension Specialist

Female Reproductive Measures
Biological and economical efficiencies of cow-calf production are largely dependent on successful reproduction. Improvements in reproductive performance can be up to 4-fold more important than improvements in end-product traits in a conventional cow-calf operation selling market calves at weaning. Whereas estimates of heritability for many reproductive traits are low, some exist that have moderate heritabilities, and there are important genetic correlations between reproductive traits and other production traits that are moderately to highly heritable.

Beef female fertility has been recorded and measured in a multitude of ways, including age at first calving, calving date, first insemination conception (nonreturn rate), days to first breeding (days open), pregnancy rate, calving interval, longevity, and stayability.

Age at Puberty
Age at puberty is used as a measure of heifer fertility and may influence subsequent reproductive trait performance. Reproductively efficient heifers reach puberty earlier, and therefore can potentially conceive earlier in the breeding season. Cumulatively, it should be noted that age of puberty had a Continue reading

Small Herd Sire Decisions: The Heifer Bull Dilemma

Garth Ruff OSU Extension Henry County

Bull buying season is almost upon us, and for the smaller cow-calf operators in the region, I think it time to ask the question: Do you need to buy a heifer bull? Year over year as I sit and watch bull buying decisions being made, I have observed producers faced with the dilemma of buying a calving ease “heifer bull” or a higher performance sire with a slightly higher birth weight. Part of the dilemma is the total the cost of the bull, where locally, a “heifer bull” will cost more, due to the willingness of cattlemen to pay for calving ease sires.

Before tackling this question it is important to recognize that the past quarter century, the beef industry has made tremendous strides in the area of genetic improvement, a large part of which can be attributed to the adoption and understanding of Expected Progeny Differences (EPD’s).  With a desire for calving ease, one of the most studied and most utilized EPD’s by cattlemen when purchasing bulls is Birth Weight (BW) and more recently, Calving Ease Direct (CED). Another data point to consider is the Accuracy of a Continue reading

Match EPDs to Your Ideal Grazing Management Style

Dean Kreager, Licking County Agriculture and Natural Resources Educator (originally published in Farm & Dairy)

As we move into January the grazing season is over for most and ended long ago for many, such as me, thanks to a dry fall.  Now is the time to start putting some thought into breeding decisions.  Is this the year to purchase a new bull?  What semen do I need to order so it will be in my tank when the cows come in heat?

In cattle, EPDs are the expected progeny differences in performance between offspring of different sires.  Sheep have a similar system of EBVs (estimated breeding values) but they are not as commonly used.  EPDs are available for a large number of production, maternal, and carcass traits.  The use of EPDs gained value with the first national cattle summary which was published in 1971.  The value of this data has improved with time.  Breeds have improved data collection and DNA evaluations have become common so that now the value of EPD’s is greater than ever.  These DNA enhanced EPDs can provide results equivalent to 10 to 36 calves for many traits but sometimes all these numbers get confusing.

Since this is a grazing column, let’s look at a few of the EPDs that are related to grazing Continue reading

OCA Replacement Female Sale Fast Approaching

John F. Grimes, OCA Replacement Female Sale Manager

This is a reminder to attend the seventh annual Ohio Cattlemen’s Association Replacement Female Sale.  The sale will be held Friday, November 29 at the Muskingum Livestock facility located at 944 Malinda Street in Zanesville and will begin at 6:00 p.m. This sale represents an excellent opportunity for anyone looking to add quality young replacement females to their herd.

At the time of this writing, there are approximately 100 lots selling in the sale consisting of bred heifers, bred cows, and cow-calf pairs.  All females selling are less than five years of age at sale time.  A detailed listing of the cattle selling with complete breeding information and videos of the cattle will soon be posted at the Ohio Cattlemen’s Association web site: http://www.ohiocattle.org/ .  Look under the “Events and Programs” tab and click on “Replacement Female Sale”.

Below is a list of the sale consignors and the cattle selling Continue reading

Beef AG NEWS: Developing a Mating System for Beef Cattle

With more than 70 recognized beef cattle breeds in the U.S. it can be difficult to decide exactly which breed or combination of breeds work best in any given situation. In this broadcast, John Grimes and Duane Rigsby discuss considerations for choosing the beef breed or breeds that can best accomplish the breeding and marketing goals of the individual cattleman.

Beef AG NEWS: Tools for Genetic Improvement in Beef Cattle

In this broadcast of the Beef AG NEWS, John Grimes and Duane Rigsby discuss how EPDs, genomics, genomic enhanced EPDs and selection indexes can be utilized for the selection of individual animals that best fit the criteria for your beef herd mating system.

Genetic Markers and Their Use in Feedlot Cattle

Steve Boyles, OSU Extension Beef Specialist

Carcass characteristics are economically important but can be difficult to measure pre-harvest. Therefore, genetic markers associated with these traits may provide valuable information to decision makers. The success of genetic markers depends on the accuracy of molecular breeding values (MBV). Researchers at Oklahoma State University evaluated molecular breeding values for yield and quality grades for commercial beef cattle and reported it in their publication:

Yield and quality grade outcomes as affected by molecular breeding values for commercial beef cattle.
N. M. Thompson, E. A. DeVuyst, B. W. Brorsen, and J. L. Lusk.
J. Anim. Sci. 2015.93:2045–2055

Independent validations report significant correlations between molecular breeding values and the traits they predict. However, many of these molecular breeding values explain Continue reading

Beef AG NEWS: Considerations for Selecting your Next Herd Sire

With calving season in full swing throughout much of Ohio, breeding season is right around the corner. That means bull buying season is here.

In this edition of Beef AG NEWS, show host Duane Rigsby visits with OSU Extension Beef Coordinator John Grimes about herd sire selection considerations including everything from selecting a breeder to work with, to the specifics of actually selecting the bull you ultimately choose to purchase.