Influence of Protein Supplementation Frequency on Cows Consuming Low-Quality Forage:

*Performance                 *Intake    

*Harvest Efficiency        *Pasture Utilization

Objectives of this research were to determine the influence of protein supplementation frequency on cow performance, grazing time, distance traveled, maximum distance from water, cow distribution, DMI, DM digestibility, harvest efficiency, percentage of supplementation events frequented, and CV for supplement intake for cows grazing low-quality forage.  One hundred-twenty pregnant (60 ± 45 d) Angus x Hereford cows (467 ± 4 kg BW) were used in a 3 x 3 Latin square for one 84-d period in each of three consecutive years.  Cows were stratified by age, BCS, and BW and assigned randomly to one of three 810-ha pastures.  Treatments included an unsupplemented control (CON) and supplementation every day (D; 0.91 kg; DM basis) or once every 6 d (6D; 5.46 kg; DM basis) with cottonseed meal (43% CP; DM basis).  Four cows from each treatment (each year) were fitted with global positioning system collars to estimate grazing time, distance traveled, maximum distance from water, cow distribution, and percentage of supplementation events frequented.  Collared cows were dosed with intraruminal n-alkane controlled-release devices on d 28 for estimation of DMI, DM digestibility, and harvest efficiency.  Additionally, Cr2O3 was incorporated into CSM on d 36 at 3% of DM for use as a digesta flow marker to estimate the CV for supplement intake.  Cow BW and BCS change were greater (P £ 0.03) for supplemented treatments compared with CON.  No BW or BCS differences (P ³ 0.14) occurred between D and 6D.  Grazing time was greater (P = 0.04) for CON compared with supplemented treatments, with no difference (P = 0.26) due to supplementation frequency.  Distance traveled, maximum distance from water, cow distribution, DMI, DM digestibility, and harvest efficiency were not affected (P ³ 0.16) by protein supplementatio n or supplementation frequency.  The percentage of supplementation events frequented and the CV for supplement intake were not affected (P ³ 0.22) by supplementation frequency.  Results suggest that providing protein daily or once every 6 d to cows grazing low-quality forage increases BW and BCS gain while decreasing grazing time.  Additionally, protein supplementation and supplementation frequency may have little to no affect on cow distribution, DMI, and harvest efficiency in the northern Great Basin.

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Schauer, C.S., Bohnert, D.W., D.C. Ganskopp. 2003. Influence of protein supplementation frequency on cows consuming low-quality forage: Performance, grazing time, distance traveled, distance from water, and distribution.  Proc. West. Sect. Amer. Soc. Anim. Sci. 54:72-76 (DWB PDF#17)