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This Article Full Text (PDF) All Versions of this Article: jas.2008-1000v1 86/12/3608    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pfister, J. A. Articles by Welch, K. D. Search for Related Content PubMed PubMed Citation Articles by Pfister, J. A. Articles by Welch, K. D.

Effect of body condition on consumption of pine needles (Pinus ponderosa) by beef cows¹

Poisonous Plant Research Laboratory, ARS, USDA, Logan UT 84341

Jim.Pfister{at}ars.usda.gov

Abstract

We determined if cows in low (LBC) or high body condition (HBC) would consume different amounts of green pine needles (Pinus ponderosa). Cows (mature; open Hereford and Hereford x Angus) were fed a maintenance basal diet (alfalfa pellets) for Exp. 1 and 2; during Exp. 3 and 4 cows were fed high protein and high energy diets, respectively. Experiment 5 was a grazing study on rangeland during winter in South Dakota; diets were determined using bite counts. Mean BCS (1 = emaciated, 9 = obese) was 7.5 for HBC and < 4.0 for LBC cows during the experiments. During Exp. 1, LBC cows consumed more (P = 0.001) pine needles than did HBC cows (5.5 ± 0.25 vs. 1.0 ± 0.14 g/kg BW daily, respectively). During Exp. 2, there was a day x treatment interaction (P = 0.001) as LBC cows consumed variable, but greater amounts of pine needles than did HBC cows (3.7 ± 0.19 vs. 1.3 ± 0.12 g/kg BW daily, respectively). When fed a high protein/low energy diet, LBC cows ate more (P = 0.04) pine needles than did HBC cows. When fed a low protein/high energy diet, there was a day x treatment interaction (P = 0.001) as LBC cows consumed more pine needles than HBC cows for the first 3 d of the study, and then consumption by LBC animals decreased during the last 4 d. These experiments suggest that the protein/energy ratio may be an important factor in the ability of cows to tolerate terpenes, and that cows were not able to sustain high levels of needle consumption on a low protein diet. During the 25-d grazing study, there was a day x treatment interaction (P = 0.001) as LBC animals selected more pine needles (up to 25% of daily bites) on some days compared to HBC cows. Weather influenced pine needle consumption as pine needle bites by LBC cows were related (r² = 0.60; P = 0.001) to days of greater snow depth, and lower minimum daily temperatures. Both LBC and HBC cows increased selection of pine needles from trees during cold, snowy weather, but the magnitude of the increase was greater for LBC cows. The LBC cows consumed more pine needles than HBC cows in all experiments, except when cows were fed a low protein diet. This study indicates that both body condition and protein intake are important factors in pine needle consumption.

Key Words: body condition • cattle • intake • pine needles • Pinus ponderosa • toxic plants