Assessment of variability in yearlong relative loose mineral intake and range cow productivity in North American northern Great Plains

Authors: Petersen, Mark; Muscha, Jennifer - Boyle; Roberts, Andrew

Submitted to: Journal of Animal Research and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2019
Publication Date: 4/10/2019
Publication URL: https://handle.nal.usda.gov/10113/6477326
Citation: Petersen, M.K., Muscha, J.M., Roberts, A.J. 2019. Assessment of variability in yearlong relative loose mineral intake and range cow productivity in North American northern Great Plains. Journal of Animal Research and Nutrition. 4(2):4. https://doi.org/10.21767/2572-5459.100054.
DOI: https://doi.org/10.21767/2572-5459.100054

Interpretive Summary: Range cattle were found to regulate self fed mineral intake in conjunction with stage of plant growth. The cows in this study consumed more mineral in the winter and spring than in the summer. We also found a three fold difference in the amount cattle selected to consume. These two findings would lead a manager to expect better productivity in the cattle that eat more and in the winter and spring. However our results showed no impact on calf weaning weights, cow weight change from year to year or in the interval from calf to calf. This study suggests that under certain conditions such year, location and genetic type of cattle mineral requirements maybe much lower than predicted such that some cattle in a herd do not require additional mineral supplementation saving a producer as much as $15 per head per year with no change in productivity.

Technical Abstract: Background. Appraisal of the effectiveness of supplementary mineral nutrition in grazing range cattle to promote growth and reproduction is lacking due to an inability of methods to measure cause and effect relationships, record variability of grazed diet mineral concentrations, evaluation of cattle presence at mineral feeder, measurement of shifting requirements due to changes in physiological stage and a lack of accurate mineral supplement intake quantification. Methods and findings. This study evaluated cattle presence at mineral feeder, relative mineral intake and its association with calf body weight (BW) at birth and weaning, cow BW change and calving interval (d). Cross-bred cows grazed native range with access to mineral feeders containing 34% salt, 57% macro/microminerals, 9% distillers grains and 1% titanium (Ti) as titanium dioxide from August 2010 to November 2011. Motion activated cameras were used to record ear tags of 80 cross-bred cows as their heads approached the open range mineral tub. Mineral feeder tubs were placed near water sources to promote contact of cattle with mineral supply. Rectal fecal samples were collected at 1 or 2-month intervals and were analyzed for Ti content. Filtered samples were transferred to 15ml falcon tubes for Ti analysis using inductively-coupled plasma mass spectrometry analytical technique (USFS Bozeman Fish Technology Center, Bozeman, Montana, USA). It was assumed that fecal Ti was positively related to mineral consumption. Cows were assigned to one of four fecal Ti concentration clusters based on their mean Ti concentration: (1) low (3 to 5 ppm, n = 23), (2) mid-low (5 to 6 ppm, n = 36), (3) mid-high (6 to 7 ppm, n = 26) and (4) high (7 to 11 ppm, n = 21). Data were analyzed using Proc Mixed SAS (SAS Inst., Inc., Cary, NC) and a model including Ti cluster and cow age (2 to 11 years) as a covariate. The percent of cows at mineral tub each day differed (P<0.01) by season. In late growing season (July-October), 48±3.9% of herd visited the tub daily compared to 31±3.4% in fall and winter dormancy (November-March) and 27±4.1% during spring growth (April-June). Average consumption based on amount of mineral fed was greatest (P<0.01) during forage dormancy and spring growth (53 g hd-1 d-1) and lowest during late growing season (38 g hd-1 d-1). Regardless of fecal Ti, all groups had similar 2011 calf BW at birth (P < 0.22) and weaning (P = 0.89), cow BW change (2010-2011) P = 0.71 and 2011 to 2012 calving interval (P = 0.85). In addition, mean fecal Ti in 18 non-pregnant and 88 pregnant cows were 6.22 ppm and 5.95 ppm (P = 0.68), indicating no differences in mineral consumption. Conclusion. During the late growing season, cow activity at a mineral tub should not be linked to high rates of consumption. Range in mean fecal Ti of individual cows represented a 3-fold divergence in Ti dilution indicating a magnitude difference in mineral consumption. If mineral consumption was a primary production limitation in the year of this study, then greater differences would be expected for the production traits evaluated. Keywords: mineral, intake, range cattle, titanium