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Are cows athletes? Adaptability says soAre cows athletes? Adaptability says so

June 2, 2016

8 Min Read
Are cows athletes? Adaptability says so

*Dr. Travis Mulliniks is an assistant professor in the department of animal science at the University of Tennessee based at the Plateau Research & Education Center in Crossville, Tenn.

BEEF cattle in the U.S. graze in a variety of unique environments that differ in climate, topography and forage quality and quantity. These differences are accentuated by dynamic and unpredictable weather patterns, which affect forage production and, subsequently, increase variability in cow performance.

Animals commonly react to these variable conditions by initiating adaptive responses to cope with extreme conditions such as stress (Stott, 1981). To date, a tremendous amount of research has shown the benefit of animal breeds adapted to certain environmental stressors. However, production practices that modify the production environment with purchased or harvested feedstuffs can buffer the coping mechanisms livestock express.

Dr. Mark Petersen with the Agricultural Research Service's Ft. Keogh Livestock & Range Research Laboratory in Miles City, Mont., has always stated that cows are athletes and should be managed accordingly. That may seem like a crazy concept to most people, but considering the amount of environmental pressure a cow is expected to perform under, coupled with the nutrient demands of lactation and reproduction, the reasons become clearer.

If athletes train to have an increased adaptive capacity and tolerance to stress, why don't we manage cows under a similar methodology to increase their adaptive resilience to environmental stresses? Instead, common livestock practices tend to manipulate the animal's nutritional environment to a degree that may completely buffer its capacity to become more adaptive, ultimately making it less energy efficient.

In human fitness, an interesting aspect of skeletal muscle is its adaptability. If a muscle is stressed (within tolerable limits), it adapts and improves function. Conversely, if a muscle receives less stress than it's used to, it atrophies. Therefore, adaptation requires a systematic application of environmental stress that is sufficient enough to elicit adaptation but not so severe that a loss in production occurs.

If the stress is insufficient to overload the body, then no adaptation occurs, which is the case with a lot of cow herd management practices. So, can we use a model for capacity adaptability and environmental stress to increase the energy efficiency and longevity of the cow herd? Is the "feed them to breed them" mentality decreasing efficiency and/or the cow's inherent capacity to cope with environmental stress?

 

Research

Are cows athletes? Adaptability says so

Adaptive capacity confers resilience to nutritional insults, given that livestock have the ability to modify their nutrient requirements with minimal losses in production.

Petersen et al. (2014) illustrated that cows experiencing a dynamic environment are coping with the change by altering nutrient requirements compared with cows that are in relatively static surroundings. Conversely, cows managed in more controlled situations or static environments have a decreased aptitude for energy utilization efficiency.

To illustrate this, Mulliniks et al. (2015) utilized data sets from research stations in New Mexico and Tennessee. Although the nutritional supply during the breeding season is much greater in Tennessee, pregnancy rates were significantly less in Tennessee (88%) than in the nutrient-restricted environment of New Mexico (96%).

Input costs to achieve these production measures must be taken into account to calculate efficiency differences. The current annual cost of production in Tennessee is $800 per cow, whereas it is roughly half that amount in New Mexico at $440 per cow.

In addition, Mayfield (2012) reported that longevity in the Tennessee herd was only 3.5 years, which is quite a bit less than the 61% retention rate of the heifers remaining in the herd after five years of age (Mulliniks et al., 2013a), illustrating short- and long-term effects of adaptive capacity on cow herd productivity.

So, what happens if environmentally adapted heifers are taken out of their dynamic environment and developed in a static nutritional environment?

In New Mexico, Mulliniks et al. (2013a) showed the effect of programing animals to fit their given production environment. Yearling beef heifers were developed on native range and received one of two protein supplements — low rumen undegradable protein (RUP) or high RUP — while a control set of heifers was developed in a feedlot.

During the developmental treatment period, feedlot-raised heifers had increased average daily gain (1.5 lb. per day) from the initiation of treatments to the start of breeding compared with range-raised heifers consuming low-quality range with protein supplementation (0.58 lb. per day).

Even with the low average daily gain until breeding, the retention rate through five years of age for range-developed heifers fed a high-RUP supplement was 68%, compared with 41% for heifers fed a lower-RUP supplement and 42% for feedlot heifers (Figure). This study may indicate how allowing for adaptive responses can have effects on long-term biological and economic efficiency.

 

Strategies

Flexible and opportunistic strategies are necessary for successful management in variable environments. Successful strategies have to be engrained in a clear understanding of the challenges facing the grazing animal and its natural abilities to meet and adapt to these challenges.

For example, Mulliniks et al. (2012) illustrated, over a six-year period, that not all animals need to be fed to achieve a target body condition score of five or greater at calving, which allows them to utilize body stores as a nutrient source during periods of energy deficiency to maintain reproductive competence.

The cows from this study were the offspring of cows that were managed in a low-input production system ($35-50 per cow per year in feed inputs) for multiple generations. Thus, preplanned management strategies to allow for bodyweight loss during periods of moderate feed restriction, followed by nutrient re-alimentation during periods of increased nutrient supply, can be used to improve energy utilization efficiency (Freetly et al., 2008).

The capacity for animals to cope with environmental changes may depend on the degree of their metabolic flexibility (i.e., the phenotypic response to an environmental change). Having high metabolic flexibility may be tied significantly to the animal's adaptability to dynamically changing nutrient supply levels.

Mulliniks et al. (2013b) illustrated that the ability of livestock to modify metabolically in response to changes in nutrient availability was correlated with the timing of conception. Cows with elevated blood ketone concentrations — manifested from metabolic imbalance — prior to the breeding season had a prolonged interval from calving to conception. Therefore, ketone concentrations may be a useful indicator of adaptive capacity during metabolically challenging physiological periods.

 

The Bottom Line

Livestock are expected to survive, grow, reproduce and cope in dynamic and unpredictable weather patterns that create diverse environmental challenges or a combination of challenges. However, if adaptive, flexible management is not utilized, static management in the face of a dynamic problem will not yield the most favorable long-term results.

With that being said, adaptive management is similar to the "bend but don't break" philosophy: A defined amount of stress is allowed to elicit an increased capacity to respond positively to the stress.

With dynamic swings in environmental conditions, exploiting the natural ability of livestock to adapt in response to periods of nutrient imbalances may be an alternative strategy to manipulating the production environment. Implementing this approach may subsequently enhance animals' adaptive capacity to environmental stresses while increasing economic and biological efficiency.

 

References

Freetly, H.C., J.A. Nienaber and T. Brown-Brandl. 2008. Partitioning of energy in pregnant beef cows during nutritionally induced bodyweight fluctuation. J. Anim. Sci. 86:370-377.

Mayfield, W.M. 2012. Evaluating the relationship between ultrasound-derived carcass characteristics and the production traits in Angus cattle. Master's degree thesis. University of Tennessee, Knoxville.

Mulliniks, J.T., S.H. Cox, M.E. Kemp, R.L. Endecott, R.C. Waterman, D.M. VanLeeuwen and M.K. Petersen. 2012. Relationship between body condition score at calving and reproductive performance in young postpartum cows grazing native range. J. Anim. Sci. 90:2811-2817.

Mulliniks, J.T., D.E. Hawkins, K.K. Kane, S.H. Cox, L.A. Torell, E.J. Scholljegerdes and M.K. Petersen. 2013a. Metabolizable protein supply while grazing dormant winter forage during heifer development alters pregnancy and subsequent in-herd retention rate. J. Anim. Sci. 91:1409-1416.

Mulliniks, J.T., M.E. Kemp, R.L. Endecott, S.H. Cox, A.J. Roberts, R.C. Waterman, T.W. Geary, E.J. Scholljegerdes and M.K. Petersen. 2013b. Does beta-hydroxybutyrate concentration influence conception date in young postpartum range beef cows? J. Anim. Sci. 91:2902-2909.

Mulliniks, J.T., A.G. Rius, M.A. Edwards, S.R. Edwards, J.D. Hobbs and R.L.G. Nave. 2015. Improving efficiency of production in pasture- and range-based beef and dairy systems. J. Anim. Sci. 93:2609-2615.

Petersen, M.K., C.J. Mueller, J.T. Mulliniks, A.J. Roberts, T. DelCurto and R.C. Waterman. 2014. Potential limitations of NRC in predicting energetic requirements of beef females with western U.S. grazing systems. J. Anim. Sci. 92:2800-2808.

Stott, G.H. 1981. What is animal stress and how is it measured? J. Anim. Sci. 52:150-153.

Volume:88 Issue:06

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