Cow Herd Description
The SJBRC herd was dispersed in Fall, 2010. The majority of the herd was transferred to Akron, CO while Fort Lewis College purchased 40 cows. The cow herd had been bred up from the System 1 cross using Red Angus bulls since 2001. Females are generally synchronized and bred using semen donated by Select Sires, followed by clean up bulls. Trials conducted in 2005-06 dictated the use of more clean-up bulls so we currently have 13 bulls.
Management practices have included feeding steers at CSU (01-03) to collect carcass data and selling all steers at weaning (04-05). Approximately 80 replacement heifers are introduced into the herd each year.
We have utilized a combination of CIDRs and timed breeding in both heifers and cows.
A five year study was undertaken in 2001 to evaluate growth and reproductive traits as well as the economic viability of two different calving seasons. The traditional time of calving in Colorado occurs during the months of March and April. Interest has existed in recent years, as to the viability of calving cows and heifers at a later time period in the spring or early summer, in an effort to more closely match cow nutrient requirements with forage nutrient content.
Early research centered on the development of inbred lines of Hereford cattle and subsequent line crossing among lines. Selection for improved breeding values for economic traits was practiced concurrently. The effects of inbreeding on reproduction and growth traits was practiced concurrently. The effects of inbreeding on reproduction and growth traits, along with the effects of hybrid vigor upon crossing have been well documented. Increased inbreeding has been shown to have detrimental effects on reproductive traits and measures of early growth. Heterosis estimates averaged 10% for weaning weight and ranged from 5 to 10% for postweaning growth traits. Response to selection studies indicated that the development of inbred lines, with subsequent line crossing, resulted in significant genetic progress over time. Line cross calves averaged 4.62 lbs./year improvement over a 25 year period.
The Center has pioneered work in the genetics of reproduction, which has had a large impact on beef cattle performance programs throughout the world. Scrotal circumference in yearling bulls, as a measure of testicle size, had been shown to be a highly heritable trait that is easily and accurately measured. It is an excellent predictor of age at puberty but is independent of bull libido or serving capacity. Complete breeding soundness examinations have been taken on all yearling bulls at the Center since the mid 1950s and scrotal circumference has been measured since 1969.
In yearling heifers, age at puberty, reproductive tract score and pelvic measures have been taken in recent years. Age at puberty is fairly highly heritable and is lowly but favorably related to subsequent measures of reproduction and productivity. Reproductive tract score, obtained by rectal palpation, is a measure that is useful in selecting replacement heifers for breeding. Pelvic measures in both yearling bulls and heifers are highly heritable and should respond to selection. It is expected that increased pelvic area should result in less calving difficulty in two-year-old, first calf heifers. Studies on calving ease indicate that the overall measure is lowly heritable; however, component traits such as birth weight and pelvic area are highly heritable and emphasis is being placed on indicator traits of calving ease.
The heritabilities and the phenotypic, genetic and environmental relationships among growth traits including birth weight, weaning weight, yearling weight and annual cow weights through 10 years of age have been obtained. These studies indicate that measures of growth are moderately to highly heritable. Growth curves for females from birth through maturity indicate large line differences in rate of maturity. Studies are continuing to ascertain if these line differences are primarily due to differences in levels of mild production among the lines.
Individual feed consumption for bull calves has been obtained for many years during the postweaning performance test. Several different measures of feed efficiency have been evaluated and have been shown to be moderately heritable. Improved efficiency of feed utilization during the feeding period should enhance the competitive nature of beef cattle with other meat producing species.
Estimates of Expected Progeny Difference values (EPD), indicating the genetic worth of individual animals, are being used to identify animals that are superior for various measures of reproduction, milk, growth and mature size for use in the selection program. The most advanced models using Best Linear Unbiased Prediction (BLUP) methodology are being used. Using these procedures, the genetic improvement in these traits over the past 50 years will be studied and compared to previous studies on the herd.
Several side studies have been conducted over the years. Cancer eye in Hereford cattle, which usually occurs later in life, had been shown to be moderately heritable and can be nearly eliminated through selection. Eye, eyelid and pigmentation around the eye studies show these traits to be highly heritable. Udder shape and teat size and shape is also highly heritable. Hoof length is highly heritable. All of these problem traits can be effectively selected against and eliminated from the herd. High altitude disease (Brisket Disease), which causes cattlemen at high altitudes serious problems through cattle losses, has been thoroughly studied. Pulmonary arterial pressure (PAP) measures have been shown to be a very good indicator of susceptibility to brisket disease, and differences in PAP values have been shown to be highly heritable. Cattlemen at high altitudes can use bulls with low PAP values to eliminate this problem from their herd. All bulls sold at the Center are measured for PAP values.
In 1985, a project was designed and initiated at the Center which sought to address several questions related to composite cattle crossbreeding. The focal point of the project has been to determine if crossing of phenotypically alike composite lines which differ in breed make-up will work to reduce variation yet produce high levels of heterosis.
Research at the Center has provided opportunities for graduate student research projects. Over 40 M.S. theses and Ph.D. dissertations have been written on data collected at the Center. Over 200 scientific papers and popular articles have been published in April of each year along with performance data on bulls offered for sale.