Duggin, J., Beef Extension Specialist, University Of Georgia
Lourenco, J., Assistant Professor, University of Georgia
Pringle, D, Professor of Animal Science , University of Georgia
Stewart, L., Professor of Animal Science , University of Georgia
Hammond, K. , Superintendent, Northwest GA Research & Education , University of Georgia
Ray, L., ANR Extension Agent , University of Georgia

ABSTRACT

The focus of this study is to gain a better understanding of the impact of feed efficiency traits on cow-calf managment and weaning stress.  The 22 days during which CowManager® recorded activity pre-weaning, heifers with genetics for High Residual Average Daily Gain (RADG) spent an average of 390 minutes eating, while Low RADG heifers spent an average eating time of 334 minutes per day (P=0.001). The CowManager® data recorded in this study suggests that selection for various carcass traits and performance traits such as RADG do impact an animal’s physiological behavior. Additionally, behavioral systems such as CowManager®, can serve as an excellent tool in Extension education programs to illustrate the impact of genetic selection and animal management on animal behavior and welfare.

 

Introduction

It is well known that feed efficiency in beef cattle plays a critical role in feedlot industry profitability. However, the impact of feed efficiency in a cow-calf setting has not been as well documented. As producers more progressively use selection tools to gain an economic advantage for weaned calf value, any potential negatives or benefits for selecting particular traits should be studied. Eearly research (Arthur et al., 2001) determined that feed efficiency tended to be moderately heritable. Likewise, selection pressure for marbling continues across the industry, and the subsequent affects on calf behavior and development should be further evaluated.

Cattle behavior during the weaning phase has long been studied as a critical management period. The impact of various genetic types may have a subsequent impact on cattle behavior during calfhood and weaning management. Thus, producers in the cow-calf segment may benefit from understanding the impact of feed efficiency trait selection in their herds. This type of research is often times difficult to assess in a normal production setting. However, with the advent of new tracking and accelerometer technologies, this is becoming more feasible and insightful.

The Department of Animal and Dairy Science at UGA and the Northwest Georgia Research and Education Center (Calhoun and Rome, Georgia) cooperatively use the CowManager® System for research and production management. This system is a tag-based sensor system that electronically records animal movement. This accelerometer system algorithmically calculates eating time, rumination time, and estrus activity. Mature cows and their calves wear the sensors over their electronic identification tag (EID). 

The use of the CowManager® System has understandably been used to gather information in dairy nutrition research (Jones et al., 2016) as it is a validated management tool for that industry. Still, systems such as these show hope for similar use in the beef industry once validated (Wolfger et al., 2015) and have already been used in research involving feeding trails for beef cattle (Deters et al., 2018).

 

Materials and Methods 

CowManager ® Application

CowManager® sensor accelerometers (Gerverscop 9, Harmenlen, Netherlands) were applied to heifer calves (n=63) 30 days prior to weaning and steers (n=27) at weaning.  Upon weaning, steers and heifers with sensors were block randomized by weight, sex and genetic type into treatment groups.  The CowManager® accelerometers recorded eating time, rumination, active time (normal activity), high activity and non-active times for each animal unit. 

Calf Genetics

All calves belong to one of four genetic types based on targeted matings in another ongoing research project.  The genetic types are: 1) Low RADG (Residual Average Daily Gain) x Average Marbling (LA); 2) Low RADG x High Marbling (LH); 3) High RADG x Average Marbling (HA); and 4) High RADG x High Marbling (HH). Heifers and steers wearing CowManager® sensors had known birth dates and sires. All calves were sired by 1 of 8 Angus bulls.

Calf Management

Total calves (n=219, project and non-project) were blocked by weight and randomized into two weaning management groups: barn weaned or pasture weaned.   Barn weaned (Barn) calves were fed a commodity mixed ration of pelleted soy hulls and corn gluten along with free choice hay.  Dams of Barn calves had access to nose-to-nose contact with calves on the perimeter of the barn (Figure 1). Pasture weaned calves (Pasture) were allowed access to 15 acres of pasture and fed the commodity ration inside the barn with free access to enter and exit.  Free choice hay was available. Dams of pasture calves had access to nose-to-nose contact along a woven wire pasture fence (Figure 1). Calves received booster vaccinations for Clostridial and respiratory disease seven days post weaning. 

             Figure 1. Barn Weaning and Fenceline Weaning

 

 

Statistical Analysis

Statistical analysis was conducted using the MIXED procedure of the software SAS (v. 9.4). Separate analysis were conducted for the pre-weaning and post-weaning periods. The statistical models included the effects of sex, genetics (RADG and marbling), and weaning group (Pasture or Barn). For the calf performance parameters, sire was used as a random effect. The activity counts were summarized as daily counts (minutes of each activity per day). The daily activity counts were analyzed as repeated measures (across days) within a randomized complete block, and treatments were arranged in a 2 x 2 x 2 factorial (RADG x marbling x weaning strategy). Two-way interactions between the main effects of RADG and marbling with day were also tested. Results were considered significant when P ≤ 0.05 and treated as trends when 0.20 > P > 0.05.

 

Results 

CowManager® Activity for Pre-Weaning Heifers 

CowManager activity for eating, ruminating and inactive time were shown to have significant variation (P <0.01) based on day (Figure 2). Natural variation in weather patterns and moving cattle from one pasture to another are possible reasons for this observation.

 

          Figure 2. Pre-Weaning Activity by Day

 

During the 22 days of CowManager® recorded activity pre-weaning, High RADG heifers spent an average of 390 minutes eating, while Low RADG heifers spent an average eating time of 334 minutes per day (P=0.001; Figure 3). In addition, there was a trend for High RADG heifers to spend more time ruminating with an average of 341 minutes a day versus 314 minutes for Low RADG heifers (P=0.17; Figure 4). There were no significant differences found between High or Low RADG heifers pre-weaning for inactive time (P=0.48). 

 

      Figure 3. Eating Time, High vs. Low RADG

 

 

  

 

 

 

 

 

 

Figure 4. Time heifers spent ruminating each day

 

When evaluating CowManager activity based on genetics for marbling, there were no significant differences found before weaning (P≥0.23). Still, high marbling calves recorded a numerically higher eating time (369 vs. 354 minutes; P=0.32), rumination times (339 vs. 316 minutes; P=0.23), and inactive time (391 vs. 385 minutes; P=0.65).

Weaning Management 

There was no significant difference found between growth performance in Barn versus Pasture calves. There was also no significant difference in growth performance relative to calf genetics or sex. 

CowManager® Activity During Post-Weaning

During the post weaning period, the CowManager® system recorded numerically higher eating times for high marbling calves, although not statistically significant (P=0.33). However, CowManager® reported rumination time was significantly higher (P=0.04) for high marbling versus low marbling calves (Figure 5). 

 

  Figure 5. Rumination Time, High vs Ave. Marbling

 

There was no significant difference between eating time (P=0.42) and rumination time (P=0.64) for High and Low RADG calves. CowManager® showed that inactive times tended to be higher (P=0.07) with High RADG calves, which recorded an average inactive time of 485 minutes, compared to 459 minutes for Low RADG calves (Figure 6). 

 

Figure 6. Inactive Time, High vs. Low RADG Post Weaning

 

 

Conclusions

Barn and Pasture calves exhibited no differences in performance or health. Instead, the genetic differences played a larger role in this study regardless of weaning management. The CowManager® data recorded in this study suggests that selection for various carcass traits and performance traits such as RADG do impact an animal’s physiological behavior.  Still, some observations did not carry over from pre-weaning to post weaning and visa-versa. High RADG heifers exhibited greater eating time pre-weaning, but this did not carry forward as statistically significant in the post weaning RADG group of combined steers and heifers.  Furthermore, inactive times for high RADG calves tended to be higher post weaning, but not pre-weaning. The CowManager® system is not yet fully validated for use in beef cattle research, but does show promise in the ability for technology to record animal behavior in a real time production setting. The CowManager® system and others like it show potential use for understanding behavioral and physiological differences in a production environment due to genetics, weather patterns, and management stress.

 

Literature Cited

Arthur, P. F., J. A. Archer, D. J. Johnston, R. M. Herd, E. C. Richardson, P. F. Parnell. (2001). Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other postweaning traits in Angus cattle. J. of Anim. Sci. 79:2805-2811. https://doi.org/10.2527/2001.79112805x

Deters, E. L., R. S. Stokes, O. N. Genther-Schroeder, S. L. Hansen. (2018). Effects of a Saccharomyces cerevisiae fermentation product in receiving diets of newly weaned beef steers. II. Digestibility and response to a vaccination challenge. J. of Anim.Sci. 96:3906-3915. https://doi.org/10.1093/jas/sky247

Jones, M. L., J. D. Clark, N. A. Michael, J. M. Bewley. (2016). 1380 Effects of supplementing lactating dairy cow ration with sodium sesquicarbonate on reticulorumen pH, rumination, and dry matter intake. J. of Anima. Sci. 94:667. https://doi.org/10.2527/jam2016-1380

Wolfger, B., E. Timsit, E. A. Pajor, N. Cook, H. W. Barkema, K. Orsel. (2015). Technical note: Accuracy of an ear tag-attached accelerometer to monitor rumination and feeding behavior in feedlot cattle. J. of Anim. Sci. 93:3164-3168. https://doi.org/10.2527/jas.2014-8802 

---