77076 Performance of a Tetraploid Vs. a Diploid Cultivar of Annual Ryegrass Pastures Under Grazing.

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Monday, February 4, 2013: 9:30 AM
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Juan K. Solomon, Plant and Soil Sciences, Mississippi State Univesity, Starkville, MS and Bisoondat Macoon, 1320 Seven Springs Road, Mississippi State University, Raymond, MS
Tetraploid annual ryegrass (Lolium multiflorum Lam.) is expected to have greater digestibility and water soluble carbohydrates than diploids. A 2‑yr study was conducted at Raymond, MS to evaluate the potential of a tetraploid (‘Maximus’) vs. a diploid cultivar (‘Marshall’).  Three stocking rates (SR), 3.75, 5, or 7.5 animals ha-1, were imposed on the two cultivars in a 3 × 2 factorial of a completely randomized design experiment with two replications. Angus cross-bred heifers (initial BW = 240 kg) were used. In both years of the study, there was no cultivar effect or any interactions (P > 0.10) on ADG or herbage mass (HM).  In Year 1, both ADG (1.22 kg d-1 at low SR to 0.98 kg d-1 at high SR) and HM (3.8 Mg ha-1 at low SR to 2.5 Mg ha-1 at high SR) had a linear response (P = 0.001) to SR. There was no effect of cultivar (P > 0.10) or SR (P > 0.10) on WSC concentration (150 g kg-1) or IVTD (775 g kg‑1). In the second year, there was a trend for a linear response of ADG (1.31 kg d-1at low SR to 1.08 kg d-1 at high SR) to SR (P = 0.051). Also, HM (4.4 Mg ha-1 at low SR to 3.8 Mg ha-1 at high SR) showed a linear response to SR (P = 0.028).  Contrary to first year results, WSC was different (P = 0.012) between Marshall (117.0 g kg-1) and Maximus (139.0 g kg-1) annual ryegrass, but there was no SR effect (P = 0.378). Also, IVTD was different (P = 0.01) between Marshall (671.6 g kg-1) and Maximus (696.1 g kg‑1). The results of this study suggest that animal performance and HM were not different between the diploid and tetraploid cultivars but were influenced only by SR.
See more from this Division: Submissions
See more from this Session: Graduate Student Oral Crops