Our topic now is the Animal Production Unit and Concepts of Marginal Production. The topics we'll cover will be the basic animal production unit, how is that common across all the different species, the feeding for maintenance and production, how critical is that to the environmental impact as well as the economic efficiency of the farm, and we'll also discuss the efficiency of nutrient utilization as well as the environmental impact of high-yield animal production. The general animal system consists of young stock, which is commonly referred to as replacements, and production animals. Your young stock include your calves, your heifers, your piglets, your guilts, your peeps, your pullets, the whole terminology exists to describe the various young stock and their ages. And then on the other side, we have the production animal. These would be your dairy cows that actually produce the milk, the layers that lay the eggs, and, of course, these systems produce replacements that become young stock. On the beef and meat side of things, we have beef cows produce steers, so brood cows will produce steers or heifers that ultimately become part of the meat supply to society. Sows will produce piglets that are raised as meat. And lastly, we have the broiler industry that produces broilers that are raised for meat. And, of course, our dairy cows and layers, when they're culled from herds, become part of the provisioning the meat to society as well. Now, of course, over time producers desire to get the best genetic animals to become the replacements for future herd production units. And so, we like to make genetic progress, where we select the best animals to become the population of the future and there are a lot of emerging technologies that are allowing us to do that better. If we look at the basic animal groups in terms of their general inefficiencies, it can exist on the young stock side or on the production side. On the young stock side, for example, we could have a dairy that can raise a heifer to milking cow status in two years. We can also have dairies that it takes four years to raise an animal to become part of the milking unit. This introduces a lot of inefficiencies, because now we have to support an animal over a four-year period of time versus a two-year period of time. And yet, there are many parts of the world where that's a typical age at which we see animals first calving. On the production side, we tend to see globally low-yield. What this does is it requires, then, more nutrients to go into the maintenance of the animal rather than into the productive purposes of milk or meat. And so, these are the, the general inefficiencies that we see globally in the world. Now if we look at the feeds in production animals, we feed for maintenance. In other words, we have to feed an animal a certain level of nutrients to meet their daily activities. And, of course, this will be influenced by what type of housing they're reared in, what's the ambient temperature, do they get wet during the day? A number of factors will, can influence the maintenance of the animal. It's also a function of the size of the animal. Low-density feeds can often meet the maintenance requirements so poor quality forages that are available throughout the world can sometimes meet the maintenance of an animal. However, if not, the animal will, of course, lose weight. Now, maintenance, by concept, is the feed we feed with zero production. In other words, it's going into just allowing the animal to have normal activity around the barn. Zero production occurs. We feed additional amounts for production. And, of course, as we increase that level of feed we get higher and higher yield. So that's what we call high-density nutrients. Often this will be feeds of grains and byproducts that will go into these animal systems that allow us to get higher yields of production. And, of course, we have feeds for the replacement animal and the growth of the replacement animal as well. So when we look at what feeds are available in the dairy industry we have a spectrum of feeds that really aren't available to the human. In other words, you and I can't consume them. These are the vast pastures of the world that their only nutrient use is really through the livestock industries. And, of course, we can also feed byproducts. A lot of the byproduct feeds from the human food industry go in, directly into your animal industries. And then, of course, there are some foods that do compete with their use in the human food chain. And, but those are by far a small amount. If we look at pigs and chickens, we tend to see that yes, we use a lot of byproduct feeds, but they tend to compete more with feeds that are available to, to humans. Now, when we look at the spectrum of production across the world, we have animals that are fed slightly above maintenance. These are slightly above, so they get very, very little yield and then we have animals that are fed for high production or high-yield. This would be more typical of what you see in Europe or in the U.S. Let's look at this spectrum more intensely. Let's take an example of an extensive versus an intensive system. Both of these systems yield 100 pounds of milk. Let's say our extensive system, extensive system consists of two cows, each producing 50 pounds of milk and therefore yielding a total of 100 pounds of milk. Contrast that to an intensive system, where we have a high-yielding cow of 100 pounds of milk per day. Now, of course, when we look at these two systems, we have to look at the other populations of animals. Both of these systems yield 100 pounds of milk, but the extensive system is going to require that I have a larger replacement herd; in fact, almost double the number of replacement herd animals that I'm going to have to feed to yield to society a hundred pounds of milk, compared and contrasted to the intensive system. When we look at this on an energy basis, your typical cow, for maintenance, requires about 10 mcals of energy per day. This is, again, to move around the barn and to, to deal with changes in ambient temperature and what have you. We also have to feed the replacement animals behind them and in this case, we're saying they average about seven mcals of energy per day. And then on top of this, we feed per production. But notice that in this situation, these maintenance costs are fixed relative to production. As we add more nutrients to the ration, we increase the milk yield and so on the extensive system, we're going to have to add 16.2 mcals of additional energy to make that 50 pounds of milk versus the intensive system, we can add an additional 32. So, on our extensive system, it takes 67 mcals of energy to make 100 pounds of milk versus the intensive system, it required only 50 mcals of energy. That's what happens when we partition maintenance and replacement energy in terms of feeding cattle. So, in the extensive systems, 52 percent of the energy was used for replacement and maintenance, in contrast to the extensive, intensive system, where only 35 percent of the energy was used for maintenance or replacement. So the trend in the industry, of course, is to move to these higher milk-yielding levels because of this efficiency. This has impacts on the financial efficiency of a farm as well as the environmental efficiency. And these factors are directly influenced by management. Better herds that manage their cattle and, and livestock effectively can see higher yields performance in these animals. It's the basis of environmental efficiency as well as economic efficiency. Typically, if we look at animal numbers versus yield at the producer level, we see rates of return by adding a cow to the dairy in the range of six to 20 percent but rates are returned by increasing milk yield range from 78 to 100 percent, a gain reflecting this dilution of animal maintenance as a function of higher, higher yield. Now, on the environmental side, we see that there is a reduction in the amount of CO2 equivalentsper kilogram of edible protein as we increase production levels. Here we're looking at the various production groups. We have beef, dairy cattle, dairy goats, fattening pigs, and in, in each group, we have a higher increasing yields. So, here we're looking at gains per day of 500 to 1,500 grams per day. And similarly, we're seeing changes in yield from left to right for the different industries. If we look at the CO2 equivalents per kilogram of edible protein, we see that the low-production systems, we have much higher levels of CO2 equivalents and thus having a greater negative impact on the environment, in contrast to higher yields, where we reduce that. And basically, the fundamental principle that's happening here is that these higher- production systems are pushing more of those nutrients into product rather than animal maintenance and replacement and that's the nature of their efficiency. So the importance of yield is critical. High-yield per animal reduces the maintenance costs. High-yield increases the economic efficiency of the operation and high-yield reduces the environmental impact per unit of production. So, in summary, the basic animal unit consists of young stock, replacements, and production animals. Feeds are fed for maintenance and production. Low quality feeds may be sufficient for maintenance, but very rarely will support high production. Many feeds that are, are unavailable for human consumption can effectively be used in our animal production systems. Higher quality feeds leads to higher production. As production increases, a greater proportion of nutrients are captured in products and this, therefore, will reduce the CO2 equivalents per product produced by higher yield.