Ken Olson: Matching cattle to your environment | TSLN.com

Ken Olson: Matching cattle to your environment

Ken Olson

In my last contribution to this column, we discussed the increasing size of beef cows over the last few decades and the influence on nutrient requirements. I would like to continue that theme in today’s column.

The two major conclusions from the previous column were that cattle have changed dramatically over the last two or more decades; mature cows are probably 200 pounds bigger than two decades ago, and not surprisingly, bigger cows take more feed to meet their nutrient requirements.

The next questions are: Has productivity of these larger cows increased by an adequate amount to cover that additional feed cost, and does their larger size affect their ability to meet their requirements from grazing?

Put another way, how much more does a bigger cow have to produce to cover her higher feed bill? To answer that question, let’s calculate feed efficiency in a somewhat unique way: pounds of feed consumed by the cow annually to produce a pound of weaned calf weight. Using the total amount of feed eaten annually by a 1,200- or 1,400-pound cow, which was 9,353 and 10,406 pounds for each cow size, respectively, we get the values in Table 1.

Note in Table 1 that “feed efficiency” is about equivalent on the diagonal where weaning weight is 50 pounds greater for the 1,400-pound cow, versus the 1,200-pound cow. Thus, for every 200-pound increase in cow mature weight, one needs about a 50 pounds increase in weaning weight. Producers will need to evaluate performance trends of their cowherd and genetic potential of future sires to determine if this can be attained.

Let’s move on to the next question: does a cow’s larger size and genetic potential affect her ability to meet her nutrient requirements from grazing? In other words, does she match her environment?

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Given that larger size and higher milk production increase nutrient requirements, the most important characteristic of the environment to match cows to is the nutrient supply that the forage provides. Range and pasture grazing resources vary tremendously in amount of forage and level of nutrition in the forage. Thus, cow biological type (size, growth potential, milk production, etc.) needs to be matched to local grazeable forage resources.

Extremes in biological type seldom match, and intermediate types are usually most efficient. For example, a study conducted by Don Kress and others in northern Montana in the 1980s and ’90s compared five breed combinations that progressively increased genetic potential for growth, size and milk production:

1. Straightbred Herefords

2. Angus X Hereford

3. ¼ Simmental X ¾ Hereford

4. 1/2 Simmental X 1/2 Hereford

5. ¾ Simmental X ¼ Hereford

As one would expect, the progression to greater potential lead to larger weaning weights. However, weaning weight per cow exposed (WW/CE), which incorporates reproductive performance by the cows with growth of the calves, changes the story. Cows in Group 5 could not harvest enough forage to meet their nutrient requirements so their pregnancy rates were lowered to the point that their WW/CE was lower than the intermediate groups. Thus, Groups 1 and 5, the extremes, had the lowest WW/CE. Economic analyses indicated that profitability was closely reflected in WW/CE.

Additionally, scarce or abundant forage resources move the best biological type toward the extremes, but not to the limit. A similar study was conducted by Ag Canada in the same era. They used two locations, one each with abundant and scarce forage resources. In this study, the breed combination supporting the highest WW/CE was a larger and greater milk producing biological type than the optimum type for the scarce resource location. However, in neither case was it the most or least productive breed combination.

Additionally, risk (magnitude of lost WW/CE because of choosing the wrong level of cow size and productivity for the environment) was greater in poorer forage conditions. In other words, making a mistake in choosing the best biological type had greater consequences in poorer forage conditions.

What does this mean? Allowing mature cow size to increase without managing it can lead to cows that will be challenged to be productive under a given set of forage resources. If cows are too big, they will struggle to remain reproductively sound unless additional, harvested feed resources are provided. The cost of these feeds will further exacerbate the need for those larger cows to produce enough additional pounds of weaned calf to pay their feed bill.

In my last contribution to this column, we discussed the increasing size of beef cows over the last few decades and the influence on nutrient requirements. I would like to continue that theme in today’s column.

The two major conclusions from the previous column were that cattle have changed dramatically over the last two or more decades; mature cows are probably 200 pounds bigger than two decades ago, and not surprisingly, bigger cows take more feed to meet their nutrient requirements.

The next questions are: Has productivity of these larger cows increased by an adequate amount to cover that additional feed cost, and does their larger size affect their ability to meet their requirements from grazing?

Put another way, how much more does a bigger cow have to produce to cover her higher feed bill? To answer that question, let’s calculate feed efficiency in a somewhat unique way: pounds of feed consumed by the cow annually to produce a pound of weaned calf weight. Using the total amount of feed eaten annually by a 1,200- or 1,400-pound cow, which was 9,353 and 10,406 pounds for each cow size, respectively, we get the values in Table 1.

Note in Table 1 that “feed efficiency” is about equivalent on the diagonal where weaning weight is 50 pounds greater for the 1,400-pound cow, versus the 1,200-pound cow. Thus, for every 200-pound increase in cow mature weight, one needs about a 50 pounds increase in weaning weight. Producers will need to evaluate performance trends of their cowherd and genetic potential of future sires to determine if this can be attained.

Let’s move on to the next question: does a cow’s larger size and genetic potential affect her ability to meet her nutrient requirements from grazing? In other words, does she match her environment?

Given that larger size and higher milk production increase nutrient requirements, the most important characteristic of the environment to match cows to is the nutrient supply that the forage provides. Range and pasture grazing resources vary tremendously in amount of forage and level of nutrition in the forage. Thus, cow biological type (size, growth potential, milk production, etc.) needs to be matched to local grazeable forage resources.

Extremes in biological type seldom match, and intermediate types are usually most efficient. For example, a study conducted by Don Kress and others in northern Montana in the 1980s and ’90s compared five breed combinations that progressively increased genetic potential for growth, size and milk production:

1. Straightbred Herefords

2. Angus X Hereford

3. ¼ Simmental X ¾ Hereford

4. 1/2 Simmental X 1/2 Hereford

5. ¾ Simmental X ¼ Hereford

As one would expect, the progression to greater potential lead to larger weaning weights. However, weaning weight per cow exposed (WW/CE), which incorporates reproductive performance by the cows with growth of the calves, changes the story. Cows in Group 5 could not harvest enough forage to meet their nutrient requirements so their pregnancy rates were lowered to the point that their WW/CE was lower than the intermediate groups. Thus, Groups 1 and 5, the extremes, had the lowest WW/CE. Economic analyses indicated that profitability was closely reflected in WW/CE.

Additionally, scarce or abundant forage resources move the best biological type toward the extremes, but not to the limit. A similar study was conducted by Ag Canada in the same era. They used two locations, one each with abundant and scarce forage resources. In this study, the breed combination supporting the highest WW/CE was a larger and greater milk producing biological type than the optimum type for the scarce resource location. However, in neither case was it the most or least productive breed combination.

Additionally, risk (magnitude of lost WW/CE because of choosing the wrong level of cow size and productivity for the environment) was greater in poorer forage conditions. In other words, making a mistake in choosing the best biological type had greater consequences in poorer forage conditions.

What does this mean? Allowing mature cow size to increase without managing it can lead to cows that will be challenged to be productive under a given set of forage resources. If cows are too big, they will struggle to remain reproductively sound unless additional, harvested feed resources are provided. The cost of these feeds will further exacerbate the need for those larger cows to produce enough additional pounds of weaned calf to pay their feed bill.

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