Effect of dietary protein level and quebracho tannin on consumption of pine needles (Pinus ponderosa) by beef cows

Authors: Pfister, James; VILLALBA, JUAN - Utah State University; Gardner, Dale

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2012
Publication Date: 10/1/2012
Publication URL: http://handle.nal.usda.gov/10113/5394138
Citation: Pfister, J.A., Villalba, J., Gardner, D.R. 2012. Effect of dietary protein level and quebracho tannin on consumption of pine needles (Pinus ponderosa) by beef cows. Professional Animal Scientist. 28(5):528-533. https://doi.org/10.15232/S1080-7446(15)30401-0.
DOI: https://doi.org/10.15232/S1080-7446(15)30401-0

Interpretive Summary: Ponderosa pine trees occupy over 40 million acres of rangeland in western North America. Pregnant cows often consume pine needles (PN), and subsequently abort. The protein-to-energy ratio may be important in the ability of cattle to tolerate dietary terpenes. Tannins often co-occur with terpenes and may also influence diet selection. The objective of this experiment was to determine if the protein-to-energy ratio or the addition of quebracho tannin to cattle diets would influence PN consumption. In trial 1, 15 cows in moderate body condition were assigned to high (15.4% Crude Protein), medium (10.2% CP), or low (4.9% CP) dietary protein treatments for 12 days. In trial 2, 15 cows were assigned to high (5%), medium (2.5%), or no (0%) quebracho tannin diets for 8 days. In both trials, green PN were offered at 0930 h for 90 min. Cattle on the high protein treatment consumed more PN than cattle on the medium and low protein diets for 4 and 6 days, respectively. Initially, treatments did not differ, but from days 3 to 9 cattle on the high protein treatment ate more PN than the other treatments. Cattle on the 2.5% tannin treatment consumed less PN than did animals on the other treatments. Cattle are apparently unable to tolerate high quantities of PN terpenes on a low-protein diet. Tannins may influence PN consumption, but the mechanism is unknown.

Technical Abstract: Ponderosa pine trees occupy over 15 million hectares of rangeland in western North America. Pregnant cows often consume pine needles (PN), and subsequently abort. The protein-to-energy ratio may be important in the ability of cattle to tolerate dietary terpenes. Tannins often co-occur with terpenes and may also influence diet selection. The objective of this experiment was to determine if the protein-to-energy ratio or the addition of quebracho tannin to cattle diets would influence PN consumption. In trial 1, 15 cows in moderate body condition were assigned to high (15.4% CP), medium (10.2% CP), or low (4.9% CP) dietary protein treatments for 12 d. In trial 2, 15 cows were assigned to high (5%), medium (2.5%), or no (0%) quebracho tannin diets for 8 d. In both trials, green PN were offered at 0930 h for 90 min. There was a treatment effect (P = 0.05) and a treatment × day interaction (P = 0.01) for PN consumption, as cattle on the high CP treatment consumed more PN than cattle on the medium and low CP diets for 4 and 6 d, respectively. Initially, treatments did not differ (P > 0.09), but from d 3 to 9 cattle on the high CP treatment ate more PN than the other treatments. There was a day × treatment interaction (P = 0.002) for PN consumption; cattle on the 2.5% tannin treatment consumed less PN than did animals on the other treatments. Cattle are apparently unable to tolerate high quantities of PN terpenes on a low-protein diet. Tannins may influence PN consumption, but the mechanism is unknown.