Strategies for cow/calf production systems
By Phillip Lancaster, Robert Larson and Dustin Aherin
Cow-calf operations are complex systems involving many factors that affect productivity and profitability. Also, achieving maximum animal performance may not result in maximum profit.
Forage species and productivity, cattle genetics, calving season and distribution, stocking rate, weaning age, winter and supplemental feed resources, and cattle prices relative to input costs are just a few of the factors that can impact the profitability of a cow-calf operation.
In addition to these 10 main factors, many of these factors interact with each other resulting in a complex web of ways the profitability of a cow-calf operation could be impacted. A better understanding of this web of factors would improve management strategies for cow-calf operations.
Sustainability of beef cattle production has come under scrutiny in recent years, and the industry needs to make progress in improving sustainability. Environmental sustainability and methane emissions are the primary concern at the current time.
The cow-calf sector of the industry produces 60 to 70% of the greenhouse gas emissions (1, 2); thus, improvements in this sector would make a large impact on the environmental sustainability of beef production as a whole.
In order to make improvements in profitability and environmental sustainability of cow-calf operations, a better understanding of the interaction of factors is needed. However, field research to evaluate all the possible combinations of factors impacting cow-calf operations is nearly impossible and not practical.
Systems models provide an effective method to evaluate multiple factors and their interactions simultaneously. Recently the Beef Cattle Institute developed a stochastic, dynamic beef cattle simulation model (BCSM) that will allow us to determine the most likely factors impacting profitability and environmental sustainability of cow-calf operations. The objective of the study was to determine the importance of four factors on the profitability and sustainability of cow-calf production using a sensitivity analysis in the BCSM.
The BCSM represents a cow-calf production system in the Kansas Flint Hills simulating individual animals on a daily time-step. The model computes animal age, weight, body condition score, lactation, nutrient requirements, nutrient availability, reproductive status, morbidity and mortality. The current version of the model computes the feed required for a cow to achieve a BCS of 5 at calving; thus, little variation in reproduction is expected and the variation among cows and herds is evident in the feed consumed and the feed costs.
The BCSM simulates a herd of 100 breeding females exposed to a bull for 63 days. Calves are weaned on the date which the oldest calf is 220 days old. All open cows are sold at weaning and cows 13 years old at weaning are culled. Heifers are kept to replace culled females. The genetic base of the cow herd is Angus using genetic information from the American Angus Association, calf and cull cow prices are from Livestock Marketing Information Center, and pasture rent is from the Kansas Bluestem Pasture Survey.
Cows grazed pasture starting May 1 and were removed from pasture when residual forage reached 50% of forage yield, which represents forage utilization for a moderate stocking rate. A protein supplement is provided when forage digestibility is less than 50% TDN, and an energy supplement is provided during the grazing season if a cow decreases to BCS 4. The winter feed ration is fed from the end of grazing in the fall to the start of grazing the next production year.
Comparison with standard performance data In the first analysis, we evaluated combinations of mature cow weight and peak milk yield on BCSM outputs, and compared these results to field data from the Cow Herd Appraisal Performance Software (CHAPS) program in North Dakota. Cow herds ranging in mature body weight from 1,000 to 1,700 pounds (lb) and ranging in peak milk yield from 15 to 30 lb were simulated. The BCSM compared very well with CHAPS data where the mean age of cows in the herd was very similar (Figure 1).
The BCSM estimated slightly greater percentage of open cows, percentage of pregnancy losses, and calf mortality than was reported in the CHAPS dataset. The average cow age is a function of pregnancy losses.
However, the BCSM estimated slightly lesser calf birth weight and significantly lesser calf weaning weight than CHAPS data even though weaning age was similar. The lesser birth weight and weaning weight could be due to differences in growth potential and/or nutrition.
In the BCSM simulation, creep feed was not provided to nursing calves, but the use of creep feed is not recorded in the CHAPS dataset. Additionally, the growth equations used in the BCSM were developed using data from postweaning calves and may not accurately estimate the average daily gain of preweaning calves based on some preliminary data analysis from the Beef Cattle Institute.
Overall, the BCSM adequately simulated a cow-calf production system when compared with field data. There are improvements that could be made to the model, but the BCSM appears to be an effective tool to evaluate factors impacting productivity and profitability of cow-calf production.
Evaluation of four improvement strategies For the second analysis, we evaluated the impact of four strategies to improve profitability and sustainability of cow-calf production systems:
Model outputs important to reproductive efficiency (percentage cycling in first 21 days (d) of the breeding season, postpartum interval, pregnancy percentage, percentage calving in the first 21 d of the calving season), productivity (weaning weight of calves, pounds of calf weaned per cow exposed), profitability (revenue, purchased feed cost, total variable cost, returns), and sustainability (feed consumed per pound of calf weaned) were captured.
The primary driver of methane emissions is feed intake and thus feed consumed per pound of calf weaned is a good proxy for the methane emissions intensity of the production system. The BCSM was ran for 1,000 simulations of a 100-cow herd over a 15-year time span of 2004 to 2018. The output values represent the average of a herd.
The mean, standard deviation, minimum and maximum values for the model outputs are presented in Table 1. The mean percentage of cows cycling in first 21 days of the breeding season, pregnancy percentage and percentage of cows calving in first 21 days of the calving season were 88.11, 92.96 and 59.40%, respectively, which agree with the experimental results (3-6).
Average calf weaning weight was 457 lb, which is lesser than current weaning weights. Additionally, pounds of calf weaned per cow exposed is less than data from the Texas Standard Performance Analysis program.
As discussed above, we believe the growth equations developed using data from postweaning calves does not accurately estimate the average daily gain of preweaning calves resulting in less than expected calf weaning weights. Regardless of the mean weaning weight, the variation in weaning weight is correct, which is the critical piece for this analysis.
Cows required 928 lb of supplement and 4075 lb of winter feed on average, which agree with data from the Kansas Farm Management Association. The mean feed intake per pound weaned was 26.49 lb/lb.
Feed intake per pound of calf weaned is a good measure of efficiency and sustainability. The primary driver of methane emissions is feed intake, and thus, feed intake per pound of calf weaned is a good proxy for the methane emissions intensity (i.e., methane per pound of beef produced).
The Kansas Farm Management Association from 2015 to 2019 reports similar economic values as those from the BCSM with revenue of $773.04 ($708.12 for BCSM), feed cost of $290.07 ($385.44 for BCSM) and total variable cost of $749.26 ($667.82 for BCSM) per cow. The slight discrepancies could be due to values from the BCSM covering the time period from 2004 to 2018.
Table 1. Descriptive statistics for model outputs of a 100-cow herd.
In the analysis of the importance of each strategy to productivity, economic, and sustainability outputs, postpartum interval (PPI) had a strong influence on reproductive measures of percentage cycling in first 21 days of breeding season, pregnancy percentage and percentage calved in first 21 days of calving season (Table 2).
In contrast, maintenance energy requirement, forage digestibility and forage production per acre had no effect on reproductive outputs. Calf weaning weight was most influenced by maintenance energy requirement and forage digestibility because both decreasing maintenance energy requirement and increasing forage digestibility increased the amount of energy available for gain.
The influence on grazing days per acre was interesting and not completely expected. Increasing the forage production had a strong influence on increasing the grazing days per acre, which makes sense, but increasing forage digestibility had a moderate influence on decreasing the grazing days per acre.
The reason for this is that forage of greater digestibility will pass through the rumen quicker allowing the cow to eat more forage per day, and this is reflected in the feed intake equation used in the model. Therefore, the cows consume the available forage quicker shortening the grazing season.
There is a tradeoff when grazing a more digestible forage in that on one hand calves are consuming more energy for gain and grow faster, but cows consume more forage depleting the forage supply quicker.
A very important metric for overall cow herd productivity is pounds of calf weaned per cow exposed, which was influenced by maintenance energy requirement, forage digestibility and PPI.
Decreasing maintenance energy requirement and increasing forage digestibility had moderate influences on the numerator because they increased calf weaning weight. Decreasing PPI had a moderate influence on the denominator by increasing the number of cows that conceived. A combination of strategies may have the strongest influence on pounds of calf weaned per cow exposed.
0.22
Table 2. Standardized correlation coefficients between strategies and model outputs.
MAINT = net energy for maintenance requirement; ForageTDN = digestibility (TDN) of pasture forage; PPI = postpartum interval; ForageYield = yield of forage per acre.. Values near zero indicate low importance, ± 0.10 to 0.29 indicates weak importance, ± 0.30 to 0.49 indicates moderate importance; and ± 0.50 to 1.00 indicates strong importance of the strategy to the output.
Decreasing maintenance energy requirement and increasing forage digestibility had strong influences in decreasing the amount of supplement used during the grazing season, and moderate influences on increasing the amount of winter feed used because both strategies resulted in cows consuming more forage per day decreasing the grazing season.
However, increasing forage production had strong influence on decreasing winter feed used and total purchased feed because of the strong influence on increasing grazing days per acre.
Feed intake per pound of calf weaned was most influenced by decreasing maintenance energy requirement and increasing forage digestibility because these strategies increased calf weaning weight indicating that increasing the output of the cow-calf production system is likely to have a large impact on sustainability and methane emissions intensity.
Decreasing the maintenance energy requirement also had a moderate effect on decreasing total purchased due to less supplement required to maintain body condition score of cows.
Greater revenue was moderately influenced by decreasing maintenance energy requirement and increasing forage digestibility because of the effect on calf weaning weight, whereas PPI and forage production had little influence.
Purchased feed cost was only weakly influenced by increasing forage production even though total purchased feed was strongly influenced by forage production indicating that feed price has a large influence on feed cost even relative to the amount of feed used.
Increasing forage production had a moderate influence, decreasing maintenance energy requirement had a weak influence, and forage digestibility and PPI had little influence on decreasing total variable costs.
Decreasing maintenance energy requirement had a moderate influence, and forage digestibility and forage production had a weak influence on increasing returns.
In conclusion, cow-calf production systems can be accurately simulated through mathematical models, which can be an effective tool to evaluate potential management strategies to improve profitability and sustainability of cow-calf production.
Of the four strategies evaluated in this analysis, decreasing maintenance energy requirements of the cow herd had the largest overall impact on our key metrics of returns (i.e., profitability) and feed intake per pound of calf weaned (i.e., sustainability).
However, increasing the digestibility of forage was also an important strategy to both of our key metrics, and increasing the forage yield per acre was important to decreasing winter feed cost and increasing returns. A combination of strategies may have the largest overall effect.
References 1. Beauchemin, K.A.; Henry Janzen, H.; Little, S.M.; McAllister, T.A.; McGinn, S.M. Life Cycle Assessment of Greenhouse Gas Emissions from Beef Production in Western Canada: A Case Study. Agric. Syst. 2010, 103, 371–379, doi:10.1016/j.agsy.2010.03.008. 2. Rotz, C.A.; Asem-Hiablie, S.; Place, S.; Thoma, G. Environmental Footprints of Beef Cattle Production in the United States. Agricultural Systems 2019, 169, 1–13, doi:10.1016/j.agsy.2018.11.005. 3. Doornbos, D.E.; Bellows, R.A.; Burfening, P.J.; Knapp, B.W. Effects of Dam Age, Prepartum Nutrition and Duration of Labor on Productivity and Postpartum Reproduction in Beef Females. J. Anim. Sci. 1984, 59, 1–10. 4. Richards, M.W.; Spitzer, J.C.; Warner, M.B. Effect of Varying Levels of Postpartum Nutrition and Body Condition at Calving on Subsequent Reproductive Performance in Beef Cattle. J. Anim. Sci. 1986, 62, 300–306. 5. Rutter, L.M.; Randel, R.D. Postpartum Nutrient Intake and Body Condition: Effect on Pituitary Function and Onset of Estrus in Beef Cattle. J. Anim. Sci. 1984, 58, 265–274. 6. Vizcarra, J.A.; Wettemann, R.P.; Spitzer, J.C.; Morrison, D.G. Body Condition at Parturition and Postpartum Weight Gain Influence Luteal Activity and Concentrations of Glucose, Insulin, and Nonesterified Fatty Acids in Plasma of Primiparous Beef Cows. J. Anim. Sci. 1998, 76, 927–936.
Lancaster is a beef cattle nutritionist and Larson is a veterinarian and beef cattle reproductive physiologist, both with Beef Cattle Institute, Kansas State University; and Aherin is director of strategy for Fresh Meats, Tyson Foods.
