Growth Hormones June 25, 2008 9:08 pm
Posted by Bret in Uncategorized.Tags: beef, cow, growth hormone, milk
5 comments
In response to Janelle’s question: “Have there been any significant changes to farm animals’ biology and behavior in the last few decades due to the increased use of growth hormones? Could our interference actually change or speed up their evolution as a species?”
Hormonal therapy has become an integral part of large animal veterinary medicine and livestock production. We use reproductive hormones to manipulate the estrus cycle of females to increase breeding efficiency, give hormones to animals to alter growth and development (largely for economic benefit) and remove naturally occurring hormones from animal to alter behavior and reproductive potential (spaying and neutering animals). So first some background information on growth hormones used in the animal industry:
Growth hormones have one basic principle, to increase production of an economically desirable commodity. Usually this is in the form of meat or milk. We’ll talk about these separately. First, to increase carcass yield from meat animals you must begin with an animal that has the potential to grow to your desired specifications, basically the genetic capability to grow, gain weight and convert feed to muscle mass. Hormonal additives are typically in the form of ear implants composed of estrogens, progesterones, synthetic anabolic steroids or a combination thereof. Estrogen and progesterone stimulate a natural release of growth hormone (GH) in higher levels than would naturally occur. This engages a cascade of metabolic processes that lower overall catabolism and increase the retention of amino acids by the animal’s body, thus leading to a significant gain in muscle mass over the animals life. Anabolic steroids are typically only used just prior to slaughter (if at all) for a short period of time as they create rapid growth but can sacrifice the quality of the meat if overused. So, growth hormone itself is not given, but rather other naturally occurring hormones are used to stimulate to animals body to produce its own GH.
When it comes to using hormonal therapy in increasing milk production the concept is similar. Recombinant bovine somatotropic hormone (rbST) has been widely publicized recently, especially in California where the dairy industry is huge. It is given to cows when they achieve peak lactation, typically about 10-12 weeks post-calving. It is a naturally occurring growth hormone that re-directs the use of absorbed nutrients to increase the milk yield over the course of an entire lactation. The cow does not produce more milk that she would naturally produce in a day at her peak lactation, but rather maintains that peak lactation for a longer period of time, thus increasing yield over the course of a lactation period (about 10 months). The cow isn’t over-milked or worn out as is often perceived, and no studies to this point have shown an increase in mastitis (udder infection) or other health issues.
These hormone supplements are perfectly safe for use and have all been approved by the FDA. When it comes to meat animal “enhancement” the animals receiving the treatment are not going to be used for breeding (and are usually steers or spayed heifers) and thus the effects are terminal and not propagated in the species. If these hormones are given to breeding animals they will usually have deleterious effects on reproductive capability and thus prevent any changes from entering the future gene pool. This is similar to men using anabolic steroids and having reduced testicular capacity due to negative feedback on hormonal regulation. rbST in dairy cows also does not alter the genetics of the cow or her offspring but may make it more difficult for that particular cow to be re-bred with the efficiency desired on large dairies (studies vary on conception rates in cows using rbST). They still breed back, it can just take longer under normal management practices.
Our interference with these additives is not altering the evolution of these species, but our breeding selections and genetic manipulations are certainly placing pressure on all species to change. This is nothing new and has been ongoing since humans first domesticated animals and sought out desired characteristics. I am not aware of any effects these additives have on behavior but I will look into it. I’m sure Dave will have something to say about the biotechnology and genetic modification of animals lately…
Why do we rarely see tornadoes strike major cities? June 20, 2008 12:11 am
Posted by imemerson in Uncategorized.1 comment so far
It is a common myth that cities are safe from tornadoes, spawned from the fact that we mostly see tornado damage in small towns and suburbs here in the U.S. The answer to this question can be found by looking at any map of the U.S. or looking out the window while flying. The area of the U.S. covered by cities is very small compared to the area covered by farmland, suburbs, and small towns. Hence, the odds of a tornado striking a major city are very small compared to one hitting a small town.
The Center for Severe Weather Research at the National Center for Atmospheric Research reached the same conclusion. In the U.S., the area known as Tornado alley stretches from Colorado and Wyoming in the west to Ohio in the east, North Dakota in the north to Texas and Louisiana in the South (see map here). There are roughly two dozen major metropolises in this area, but they make up only a small fraction (less than 1%) of the total area. Thus, it is more likely a tornado will strike an area that does not contain a major city.
Dr. Fujita at the University of Chicago (for whom the tornado intensity scale is named) suggested that urban heat island effects may have an impact on small tornadoes. His thinking was that the increased heat levels in the center of major metropolises may disrupt the formation of small tornadoes (which make up the majority of tornado strikes). This assertion has not been proven or disproven and weather researchers continue to investigate the impact of cities on tornado formation.
Questions? June 17, 2008 5:57 am
Posted by tungtide in Uncategorized.8 comments
If nobody’s going to ask any questions I’m going to start talking to myself.
Anyone interested in drug interactions and herbal supplements? I can talk about that for hours.
Congratulations, it’s a….blog? June 14, 2008 10:45 pm
Posted by tungtide in Uncategorized.add a comment
I had no idea that the Scientition blog was going to be born today, only that its arrival was on the horizon. I haven’t much else to say that isn’t already covered better in the Hello World introduction.
Please, email us, use the comments section and ask your questions. Otherwise, I’ll have to start asking myself questions and that will be followed by name calling, face punching, and a drunken stupor…actually that might be fun too.
Hello world! June 14, 2008 10:01 pm
Posted by imemerson in Uncategorized.add a comment
That title’s pretty funny if you ever took a computer programming class.
This blog is about science. Primarily, the crew here wants to answer your questions. It’s rare to have scientists interacting with the community and we want to provide that communication. We want you to ask questions because the only way to learn is to ask. Please send questions to the email addresses posted in the left sidebar. We will do our best to provide answers to the how and why of how our world works.
This crew has experience in many fields ranging from biology and biotechnology to atmospheric chemistry and veterinary medicine (no, we will not provide consultations for pet problems). More general questions from physics, chemistry, or computer and social sciences are also welcome. We will provide the best answers we can, with links to as much information as possible. That way, you can follow up if you want. We are also interested in other aspects of science such as ethics, funding, and public perception. Most of us are practicing scientists and can provide some behind-the-scenes insight that you might not be able to find elsewhere. But we are not omnipotent. We don’t know everything and some answers may still be open to additional research and interpretation. We’ll do our best, but always remember that science is always changing and growing.
Your comments and input are always welcome. But please be warned…we will not tolerate long harangues or presentation of misleading ideas or evidence on evolution, climate change, or other controversial topics. We are interested in providing good science to public. This is in contrast to many media outlets that just want to tell a story or create sound bites. Our job is to answer questions based on the best scientific evidence available and to hopefully dispel common myths surrounding some of these more controversial topics. We also want to start a dialog around the science rather than just the emotional or economic impact of the science. Different interpretations of evidence and serious debate are welcome, but name calling, non-scientific theories, and general flame wars will get the kibosh. We’re here to provide the best answers we can. So start asking so we can start answering.
imemerson
tungtide
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