Protein supplementation and grazing behavior for cows on differing late-season rangeland grazing systems

Authors: SPRINKLE, JAMES - University Of Idaho; SAGERS, JOSEPH - University Of Idaho; HALL, JOHN - University Of Idaho; ELLISON, MELINDA - University Of Idaho; YELICH, JOEL - University Of Idaho; BRENNAN, JAMESON - South Dakota State University; Taylor, Joshua - Bret; LAMB, JAMES - Furst-Mcness Company

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2021
Publication Date: 11/11/2021
Citation: Sprinkle, J., Sagers, J., Hall, J., Ellison, M., Yelich, J., Brennan, J., Taylor, J.B., Lamb, J. 2021. Protein supplementation and grazing behavior for cows on differing late-season rangeland grazing systems. Animals. 11(11). Article 3219. https://doi.org/10.3390/ani11113219.
DOI: https://doi.org/10.3390/ani11113219

Interpretive Summary: Cows maintained on late-season rangeland in the Pacific Northwest often experience declining forage quality, which often fails to provide sufficient protein for the cow. We have recently shown that in two-year-old cows grazing late-season rangeland, those that were classified as “efficient” experienced less body condition and weight loss than those classified as “inefficient.” Considering this evidence, we set out to determine if protein supplementation was beneficial to two different efficiency-types of cattle managed in either a continuous or rotational late-season grazing system. Based on the results, we determined that protein supplementation and the frequency of supplementation altered grazing behavior. Furthermore, rotational grazing management seemed to reduce the body weight loss normally associated with cows that are grazing late-season rangeland, without additional supplemental protein, and confined to continuous grazing management.

Technical Abstract: The objectives were to determine if Hereford x Angus cows on continuously or rotationally grazed rangeland differed in weight (BW) or body condition (BCS, all cows) or altered grazing behavior [2-yr-old cows; low- or high-residual feed intake (LRFI or HRFI)] when provided a protein supplement (3.17 kg/cow/wk) from mid-October to mid-December. Treatments included continuously grazed, control (CCON, n = 75); continuously grazed, supplemented (CTRT, n = 71); rotationally grazed, control (RCON, n = 73); and rotationally grazed, supplemented pastures (RTRT, n = 73). Three LRFI- and 3 HRFI-collared cows in each treatment carried accelerometers and global-positioning-system loggers to measure grazing time (GT), resting time (RT), walking time (WLK), and daily travel distance (DTD). Bite rate (BR) was also measured. The CCON group lost (P < 0.05) BW (-1.0 +/- 2.99 kg), while CTRT (23.5 +/- 3.05 kg), RCON (9.9 +/- 3.30 kg) and RTRT (16.7 +/- 2.89 kg) gained BW. All cows lost BCS, with CCON losing more BCS (P < 0.05) than RTRT. In 2017, CTRT cattle reduced (P < 0.05) WLK (2.3 +/- 0.32 vs 3.2 +/- 0.29 h·d-1) and increased (P < 0.05) RT (11.3 +/- 0.34 vs 10.3 +/- 0.30 h/d) when compared with CCON. Similarly, there was a tendency (P < 0.10) for LRFI cattle in 2017 to have less WLK (2.4 +/- 0.23 vs 3.0 +/- 0.20 h/d) and more RT (11.0 +/- 0.24 vs 10.4 +/- 0.22 h/d) than did HRFI. Time distributions of GT and RT differed by year (P < 0.05). The DTD differed by pasture (P < 0.0001) in 2016. The BR for control cattle was less (P < 0.05) in 2017. Cattle with greater nutritional requirements appeared to engage in more search grazing. Rotational grazing of late-season forage can assist in reducing weight loss of non-supplemented cattle.