Beef cow type, then and now, Part 2

Welcome to 2024! Where has the time gone? It seems like yesterday that I was thinking that graduating from high school in 1977 would be an eternity in the future. Now I appreciate what they meant when my elders used to say they wish they could go back to days gone by. Oh well, with a little optimism, the future can be pretty good too.

Last month I started the discussion of 70 years of change in beef cow type. Now, let’s continue but from the perspective of how the evolution of beef cow size and type has affected how we look at nutrition and management of beef cows in the 21st century.

In 2006 at the Beef Improvement Federation symposium in Choctaw, Mississippi, Amy L. Kelley from Montana State University presented a proceedings paper entitled, The relationship of genetics and nutrition and their influence on animal performance. To summarize her paper, producers rely heavily on both genetics and nutrition to achieve their production goals. Superior beef cattle genetics resulted in type change with the realization that cattle will not perform at their optimum level without meeting their increasing nutrient requirements. Larger cattle and the continental breeds finding their way into North America increased the genetic potential for increased growth rate (i.e. increased weaning weights, increased post-weaning gains, and increased mature size). In addition, leaner beef was realized with these cattle. The energy requirements of beef cattle were originally based on British breeds of cattle (Lofgreen and Garrett California Net Energy System, 1968). With bigger cattle came a change in how we view nutritional requirements. A concomitant change in nutritional requirements was indicated and therefore the National Research Council’s (NRC) Nutrient Requirements of Beef Cattle needed adjustments (Kelley, 2006).

The NRC requirements for beef cattle are based on body weight, and peak milk yield. Therefore, it’s no surprise that larger cattle producing more milk will require more energy and likewise more crude protein (CP), calcium (Ca), and phosphorus (P) and other nutrients to maintain milk production, and as related to the calf, for the calf to achieve its full genetic potential for gain (growth). Overall, the implications of the larger British breed cattle and the continental breeds are increased mature size with the related increase in maintenance requirements, increased milking ability, increased feed intake (and therefore increased feed cost to be recovered), and decreased fat (influence on carcass quality and yield). These cattle needed to be fed differently to take advantage of genetics and reproduction.

From my perspective this is a good time in the discussion to climb up on my apple box and share a couple of thoughts about matching cow type to your environment and resources, and tie that back to reproduction. A few questions we could ask: Do we have lots of grass during the grazing season or is grass limited? Length of winter-feeding period? When are the calves marketed? Spring calving vs. fall calving? Just a few questions that have a bearing on the cow type that is right for a particular situation.

Here’s an example: Let’s say producer 1 is limited by seasonality of grass production. Their summer grass is pretty much dried up by July 15 and unless some timely rains come in the late summer or fall, it’s pretty much a dry grass and supplementation situation (this is an example of a lot of our territory here in eastern Washington). Producer 2 has pretty much the same situation for summer grass but has some irrigated acreage that can support cows late in the summer when the range grass is of low quality. A different cow type is indicated for the two operations.

Now before I discuss the cow type needed for each of the previously describe scenarios, please understand that when I talk about a smaller cow, I’m not referring to going back to the previously described small cow of the 1960s (she had plenty of problems of her own). Also, I’m not going to put weights on small, medium, and large cows. Weights are relative, just like body condition score and not tied to any absolute standard. Rather I would be talking more about an approach to cow size as cows are viewed today by the beef industry (i.e. feeder cattle grades, and cattle relative to the size of carcasses produced). Producer 1 might be much better off with a moderate sized cow with moderate milk producing ability. Imagine if producer 1’s herd was to be dominated by large, high-milking cows, the forage resource is not there to support the milk-producing potential of those cows. Many of you have heard me talk about the biological priority for nutrients in beef cows. Remember that nutrients are partitioned by cows in this order: 1) maintenance, 2) growth, 3) lactation, 4) reproduction. This is why the cows in producer 1’s scenario may be at risk of reproductive failure (reproduction is fourth on the list of nutrient priorities). This is especially true of young cows (first- and second-calvers) with their need to grow to mature size and lactate at the same time, using what body reserves they have, and putting them at even higher risk for reproductive failure. On the other hand, producer 2’s situation is a bit more forgiving when it comes to cow milking ability. The additional forage resources in the late summer help the cow milk up to her potential and maintain body weight and body condition (related to reproduction). This is why I don’t recommend huge, high milk EPD cows for herds in the desert southwest or other highly arid environs. They just don’t match the resources. Every producer must match their cow type to their environment, and that means that each operation won’t necessarily have the same cow type. If your cows look different than your neighbors’, that’s great! Each producer must fit cow type into their operation.

The milk production example is only one piece of the puzzle. There is an inexorable link between nutrition and reproduction of beef cow herds. In reality, the goal of nutrition programs is to meet requirements and maintain an optimal reproductive rate. Notice I said optimal, sometimes it’s too expensive to feed for maximum of all performance traits, but optimum provides a good balance between cost and revenue (it is important to find that balance). Reproduction is compromised when dietary nutrients are unable to meet basal requirements. As noted above, cows in poor body condition partition nutrients to growth and they mobilize body reserves (let’s target a body condition score of 5 on a 1 to 9 beef cow scale). In addition, the post-calving interval can lengthen (resulting in a longer breeding season and reduced uniformity of the calf crop). At worst, due to poor body condition, cows can enter an anestrous state (i.e. estrous cycle stops). The mechanisms are complex but can be a result of catabolic hormones and mobilization of body reserves, which can lead to cessation of reproductive function by reduced synthesis and secretion of reproductive hormones (Cassady et al., 2009). When you consider the total cost of a beef cow operation, the bottom line is that if we do a good job of controlling feed costs and maintaining reproduction in the herd, we go a long way to realizing profitability in cow-calf enterprises.

In addition to size, there are a host of factors that affect the nutrient requirements of beef cows. This isn’t an exhaustive list, but taken together with cow size and type, here’s some factors affecting the nutrient requirements of cows:

• Biological priority for nutrients for nutrients (discussed above)

• Stage of production (dry, pregnant, lactating, last trimester, spring vs fall calving; cows, heifers, bulls, steers)

• Weather (above and below the thermoneutral zone)

• Cow Weight (it requires more feed to maintain body weight and body condition for larger cattle; for each 100 lb. of increase in body weight, the cows’ energy required for maintenance increases about 0.57 Mcal/day; likewise for each 100 lb. of increase in body weight, the cows’ crude protein requirement increases about 0.1 lb.)

• Cow body condition (target body condition score (BCS) 5 at calving; highest probability of pregnancy at breeding back is BCS 5-7)

• Milk production (peak lactation 60 to 90 after calving, then declines rapidly)

• Age (Consider management groups: 2- and 3-year-old cows at greatest risk for reproductive failure; may benefit from separating cows and feeding young, thin, or very old cows separately)

• Physical activity (related to geography and location relative to feed and water)

Lots of changes have taken place in cow size and type. It is my hope that I have provided some relevant examples as to how the evolution of cow type has affected how we look at feeding and management of cow. Resources are as diverse as the number of individual operations. Each operation needs to fit cow size and type to their operation.

Did you know that how we approach feeding the pregnant cow can affect her calf’s performance many months and even years after the calf is born? Next month we will look at what in my world as a ruminant nutritionist is called ‘fetal programming’. It’s cool, stay tuned!

— Don Llewellyn is the WSU Lincoln County Extension Director in Davenport. He can be emailed at don.llewellyn@wsu.edu