ARS | Publication request: RUSSIAN KNAPWEED AS A PROTEIN SUPPLEMENT FOR BEEF COWS CONSUMING LOW-QUALITY FORAGE

Submitted to: Western Section of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2006
Publication Date: June 21, 2006
Citation: Bohnert, D.W., Sheley, R.L., Falck, S.J., Nyman, A.A. 2006. Russian knapweed as a protein supplement for beef cows consuming low-quality forage. Western Section of Animal Science Proceedings. Vol. 57:235-237.

Technical Abstract: Russian knapweed (Centaurea repens) is a perennial noxious weed. Controlling Russian knapweed has proven very difficult and expensive. Sustainable invasive weed strategies may require that weeds are used in livestock production systems. Russian knapweed has protein values similar to alfalfa and may have potential as a protein supplement for beef cattle consuming low-quality forages. Therefore, we compared Russian knapweed and alfalfa (13 and 21% CP, respectively; DM basis) as protein supplements using 48 Hereford × Angus, mid-gestation, beef cows (530 ± 5 kg) offered ad libitum hard fescue straw (4% CP; DM basis) in an 84-d study. Treatments included an unsupplemented control (CON) and alfalfa (ALF) or knapweed (KNAP) provided on an iso-nitrogenous basis (approximately 0.50 kg CP/d). Cows were stratified by weight and BCS and allotted to treatments in a randomized complete block design using 12 pens (4 cows/pen; 16 cows/treatment). Means were compared using orthogonal contrasts (CON vs ALF and KNAP; ALF vs KNAP). Protein supplementation increased (P < 0.01) cow weight gain and BCS compared to CON with no difference between ALF and KNAP (P > 0.27). There was no difference (P = 0.60) in the quantity of straw offered between CON and supplemented groups but ALF cows were offered approximately 11% more (P = 0.03) than KNAP cows. Total DM offered to cows was greater (P < 0.01) for supplemented compared with CON cows with no difference noted between ALF and KNAP (P = 0.79). Russian knapweed can be used as a protein supplement for beef cows consuming low-quality forage. Thus, haying Russian knapweed in the spring and feeding in the winter may provide an alternative to control of large scale infestations.