Interpretive Summary: Test duration for water intake, ADG and DMI in beef cattle.
By: Jackie Walling
Developing efficient feeding programs to enhance beef cattle production relies on measuring Feed Intake (FI), Dry Matter Intake (DMI), and Average Daily Gain (ADG). These necessary factors often overshadow one last important factor: Water Intake (WI). Water availability is becoming a concern of competition among life forms and little work has been done on understanding its role in beef production. While guidelines exist for the collection of ADG, DMI, and FI, the goal of this research was to develop guidelines for collecting WI data and determine an appropriate length of test duration.
This was a three-year study performed at the Willard Sparks Beef Research Center located at Oklahoma State University. An Insentec System equipped with Roughage Intake Control software was employed to collect daily FI and WI data. 578 steers were divided into five seasonal groups further divided by BW into 1 of 4 pens. Details of the system, data point qualifications, and seasonal groups can be found in the full article.
Groups 1-3 were fed via slick bunk procedure while Groups 4 and 5 were fed ad lib. All groups were allowed ad lib water. Cattle underwent a 70d test and results were analyzed in forward and reverse directions. ADG and BW were collected every 14 days and average WI and DMI every seven days. Pearson and Spearman correlations assessed and determined test duration (when correlations exceeded .95) for WI phenotype evaluating the full 70 days as well as shortened test periods. Test duration was also determined for ADG and DMI.
For all animals (70d period), mean ADG peaked at 28d and then steadily decreased, but as test duration increased, variation in ADG decreased. DMI remained steady and WI minimally increased before leveling out.
Recommended ADG test duration was 70d indicated by increasing Spearman and Pearson correlations. Groups 2 and 5 showed decreasing BW gain. For Groups 3 and 4, ADG increased mid test and then decreased, while Group 1 varied in ADG throughout. The differing ADG measurements were likely due to temperature changes.
Recommended DMI test duration was 42 days with a possible shortened period of 35 days suggested by Pearson and Spearman correlations. For all groups except 4, DMI increased, but the variation within decreased. DMI in Group 4 decreased as a result of heat stress during the test period. In a study simultaneously collecting DMI and ADG, FI can be substituted to calculated ADG diminishing a 70d test period to 35-42 days.
Pearson and Spearman correlations slightly differed for WI. Pearson recommended 35 days for WI test duration with a possible shortened period of 21 days. Spearman recommended 42 days which would benefit a study simultaneously collecting FI for that period of time. Overall, consumption of water increased due to size and BW increases, but individual variation among groups existed as a result of fluctuating temperature.
This study concludes a test duration for ADG as 70 days, DMI as 42 days, and WI as 35 to 42 days. While ADG and DMI are consistent with previous literature published, WI lacks comparisons. More research in different locations and times of seasons need to be pursued to solidify the suggestion of 35 to 42 days.
For the full description of the study, visit the Journal of Animal Science.