Numbered Publications by Darrh Bullock
ASC-266: Reproduction in the Bull
Les Anderson, Darrh Bullock, Kevin Laurent, Jeff Lehmkuhler, Katherine VanValin | Oct. 11, 2024 (New)
The fertility of the herd bull is essential to a successful cow-calf operation. In many respects, it is more of a concern than the fertility of a single cow. Sub-fertile bulls create lower calving rates and can be responsible for poor herd-weaning weights: For every heat cycle a female fails to conceive, there is a corresponding decrease in calf weaning weight from 25 to 45 pounds because of a younger calf being weaned. It does not take long to realize that poor fertility or infertility of a bull can be extremely expensive to the cow-calf producer.
ASC-265: Estrus Synchronization Protocols for Beef Females
Les Anderson, Darrh Bullock, Kevin Laurent, Jeff Lehmkuhler, Katherine VanValin | Oct. 11, 2024 (New)
Artificial insemination (AI) can be an effective tool for beef producers to use to make faster genetic progress in the herd. Unlike the dairy industry where cattle are handled multiple times a day, incorporation of AI can be difficult because beef cattle are not handled often or easily. Decades ago, scientists began developing methods to control the expression of estrus to decrease the amount of labor and time required for AI. An understanding of estrus synchronization protocols can be beneficial to producers considering using AI in their genetic program.
ASC-263: Converting from Year-round to Controlled Calving
Les Anderson, Darrh Bullock, Ben Crites, Kevin Laurent, Jeff Lehmkuhler, Katherine VanValin | Jul. 19, 2024 (New)
In the United States more than half (55%) of all beef cow-calf operations do not have a defined calving season. Typically, in these operations, bulls are not removed from the herd and remain with the cows the entire year. This "uncontrolled breeding" results in cows calving over several months or, in some cases, cows calving every month. Calving year-round presents many challenges in herd management and decreases productivity. In some cases, producers have an off-the-farm job and limited time can be left to dedicate to the cowherd. In these scenarios, it is crucial to maximize time and labor efficiency.
ASC-264: Artificial Insemination in Beef Cattle
Les Anderson, Darrh Bullock, Kevin Laurent, Jeff Lehmkuhler, Katherine VanValin | Jul. 19, 2024 (New)
Successful artificial insemination (AI) breeding programs depend on adequate facilities, good herd health programs, sound nutritional management, using experienced and well-trained technicians, high fertility semen, and the ability to observe or synchronize a fertile estrus. Most problems and(or) failures in AI programs are associated with poor nutritional development in replacement heifers, inadequate body condition of cows at and after calving, failure to identify or control estrus in females, and/or failure to breed them at the proper time. Rarely is infertility the result of poor-quality semen or technician error.
ID-273: Match-a-Yak: a Tool to Minimize Inbreeding in North American Yaks
Les Anderson, Darrh Bullock, Ted Kalbfleisch, Jeff Lehmkuhler, Mary McCarty | Sep. 25, 2023 (New)
The domesticated yak (Bos grunniens) arrived in North America in the late 1890s. A few animals were imported into Canada and North American zoos and became the foundation of the North American genetic pool. Research was conducted in Alaska hybridizing them with Highland cattle in the early 1900s. A handful of yaks were imported into the United States in the early 1900s and again later in the 1980s. However, the genetic diversity of the North American yak is limited, necessitating a need to manage breeding programs to reduce inbreeding.
ASC-256: Comparison of Production Levels Among U.S. Beef Breeds
Darrh Bullock | Aug. 8, 2023 (New)
Genetic trends for beef breeds, for many traits, are on the move. The genetic trend for growth in most breeds is strongly positive. Maternal weaning weight (milk) on the other hand is breed dependent, with some breeds showing strong selection for increased milk and others slightly reducing their genetic potential for milking ability. For that reason, it is important to monitor relative differences between breeds for various production traits to assist beef producers in their breed selection decisions.
ASC-248: Vitamin Supplementation for Beef Cattle
Les Anderson, Darrh Bullock, Kevin Laurent, Jeff Lehmkuhler, Katherine VanValin | Jul. 18, 2022 (New)
Beef cattle have defined requirements for vitamins. In some instances, vitamin supplementation may be necessary to avoid deficiencies. Vitamins are classified into two categories: water-soluble and fat-soluble. Water-soluble vitamins include the B vitamins, such as riboflavin, thiamin, and niacin, as well as vitamin C. Fat-soluble vitamins include vitamins A, D, E, and K. Supplementation for beef cattle generally focuses on vitamins A and E. This is because the rumen microbes synthesize the water-soluble vitamins and vitamin K in sufficient quantities to avoid deficiencies. Vitamin D requirements can often be met by exposure to the sun and would therefore only be of concern for cattle in confinement housing.
ASC-169: Beef Sire Selection Manual, 2021
Darrh Bullock | Apr. 1, 2021 (Major Revision)
In principle, genetic improvement is a straight-forward exercise that results from using above-average selection candidates as the parents of the next generation. In practice, the devil is in the details. Both bull breeders and bull buyers need to consider their breeding objectives, defining the list of traits that need to be modified to advance the towards their goal.
ID-108: The Kentucky Beef Book, 2021
Les Anderson, Michelle Arnold, Darrh Bullock, Kenny Burdine, Roy Burris, Ben Crites, Jimmy Henning, Steve Higgins, Steve Isaacs, Kevin Laurent, Jeff Lehmkuhler, Lee Moser, Gregg Rentfrow, Kylie Schmidt, Ray Smith, Chris Teutsch, Lee Townsend, Katherine VanValin, Paul Vijayakumar | Mar. 23, 2021 (Major Revision)
Kentucky is ideally suited for cattle production. The main feed for cattle is a renewable resource Kentucky has in abundance--forages. The majority of the state's terrain favors cattle production over row crops. Kentucky farms cover 14 million acres, with approximately half of that occupied by forage grasses and legumes. Our natural resources and climate permit the growth of most cool-season and warm-season species. Water is readily available in all areas of the state, and we have a relatively long growing season.
ID-263: Alternative Protein Sources for Cattle
Les Anderson, Darrh Bullock, Darrell Johnson, Kevin Laurent, Jeff Lehmkuhler, Katherine VanValin | Jul. 2, 2020 (New)
Kentucky has several bourbon distilleries and one fuel ethanol plant. The spent grains from the production of ethanol is utilized as a protein source in livestock feed. Shutdowns for fuel ethanol plants may also occur as a result of unfavorable profit margins when crude oil prices are low. Most distilleries and fuel ethanol plants will have a scheduled maintenance shutdown each year. During a shutdown, availability of distillers grains and other coproducts from these plants may be limited or unavailable. So, the question is what else can I feed in place of distillers grains?
