Title: A preliminary assessment of year long relative loose mineral intake and range cow productivity in Northern Great Plains Authors
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 15, 2013
Publication Date: June 20, 2013
Citation: Petersen, M.K., Muscha, J.M., Mulliniks, J.T., Roberts, A.J., Waterman, R.C. 2013. A preliminary assessment of year long relative loose mineral intake and range cow productivity in Northern Great Plains. Western Section of Animal Science Proceedings. 64:258-260. Interpretive Summary: Herd mineral consumption during the winter and spring was 12% less and in summer 37% less than the target amount 0f 58 g per day. However, individual intake as shown by the range in fecal Ti concentration was nearly 3-fold different suggesting large animal to animal variation with some animals consuming in excess while others were short of target amount. If mineral in fact limited cow productivity we would have predicted lower productivity in those cows that were found to have the lowest concentration of marker in their feces. However, this study indicates that the relationship with fecal Ti and productivity was not consistent and demonstrated that in the year this study was conducted the least amount of mineral consumed was sufficient to meet the cows’ requirements.
Technical Abstract: ssessment of the effectiveness of supplementary mineral nutrition in range cattle to promote important economic traits is lacking due a paucity of methods to measure cause and effect relationships, dynamic dietary mineral concentrations, shifting requirements and a lack of mineral intake quantification . This study evaluated relative mineral intake and its association with calf BW at birth and weaning, cow BW change and calving interval (d). Cross-bred cows grazed native range with access to mineral tubs containing 34% salt, 57% macro/microminerals, 9% distillers grains and 1% titanium (Ti) from August 2010 to November 2011. Rectal fecal samples were collected at 1 or 2 mo intervals and were analyzed for Ti content. It was assumed that fecal Ti was positively related to mineral consumption. Cows were assigned to one of four fecal Ti groups 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) and a model including Ti groups and cow age (2 to 11 years) as a covariate. 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 and weaning, cow BW change (2010-2011) and 2011 to 2012 calving interval (35.9, 37.3, 38.6 and 35 ± 1.4 kg, P < 0.22; 232.7, 230.9, 226.4 and 230 ± 6.4 kg, P = 0.89; 14.5, 8.1, 0.5, 1.8 ± 9.5 kg, P = 0.71; and 365, 356, 366 and 365 ± 5 d, P = 0.85; respectively for low, mid-low, mid-high and high). 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. 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 ingestion was a primary production limitation in the year of this study, then greater differences would be expected for the production traits evaluated.