Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2008
Publication Date: 9/15/2008
Citation: Burns, J.C., Fisher, D.S. 2008. Coastal and tifton 44' bermudagrass availability on animal and pasture productivity. Agronomy Journal. 100:1280-1288.
Interpretive Summary: Both ‘Coastal’ and ‘Tifton 44’ (T44) bermudagrasses can be grown in the Piedmont Region across the Southern US. Extension agents and producers continue to inquire about these two cultivars and which would best serve their enterprises. The advantage of one over the other, in terms of animal and pasture productivity for the upper South is not known. A 4-yr study was conducted to address this issue. Both cultivars were evaluated over a range of three herbage mass (HM) levels consisting of short (mean HM=2.3 Mg/ha), medium (4.1 Mg/ha), and tall (5.3 Mg/ha) to obtain a fair comparison. Generally, no difference was noted between cultivars (Coastal vs. T44) in stocking rate (13.1 vs. 13.0 steer/ha), animal daily gain (0.51 vs. 0.58 kg/day), animal days (1360 vs. 1400 days/ha), animal gain (890 vs. 980 kg/ha) or in effective feed units (5190 vs. 5480 kg/ha). Major differences were noted, however, among HM levels. Stocking rate decreased linearly (from 16 to 11 steers/ha) as HM increased from short to tall. On the other hand, least daily gain occurred from the short HM averaging 0.39 kg and most on the medium HM averaging 0.65 kg with daily gains intermediate from the medium HM averaging 0.59 kg. The reduction in stocking rate was of sufficient scope to result in a linear decrease in animal days per hectare, weight gain per hectare and effective feed units per hectare. Canopy characteristics in terms of the proportion and nutritive value of leaf, stem, and dead fractions, as well as masticate characteristics in terms of the proportion and nutritive value of the large, medium and small particles were examined. Coastal tended to have a greater proportion of stem, but a lesser proportion of dead compared with T44. The nutritive values of these fractions were similar between cultivars and few differences occurred among HM levels. The masticate samples were generally similar in nutritive value between cultivars and among HM levels. The proportion of large particles increased and small particles decreased linearly as HM level increase from short to tall HM. Overall the data from this study indicates that the adaptation of the two cultivars relative to stand survival and daily growth rate may be more important than forage quality. This may be of importance because T44 is more winter hearty and can be grown farther North than Coastal.
Technical Abstract: Hybrid cultivars of bermudagrass are a major feed source for ruminants across the Southeastern USA. This 4-yr experiment compared animal and pasture performance of ‘Coastal’ and ‘Tifton 44’ Bermudagrasses [Cynodon dactylon (L.) Pers.] over three canopy heights designated as short (5.8 cm), medium (10.1 cm), and tall (13.6 cm). The relationship of canopy height to ingestive mastication and canopy characteristics was also studied. Soil was a Cecil clay loam. Pastures were continuously stocked using variable stocking to maintain the targeted canopy heights. Herbage mass (to soil surface) was similar between Coastal and Tifton 44 (T44) within each canopy height averaging 2.36, 4.08, and 5.25 Mg ha-1. No differences were noted between cultivars in either animal performance or pasture productivity. Increasing herbage mass resulted in a linear (P < 0.01) increase in steer daily gain (0.40 to 0.59 kg) but a linear (P < 0.01) reduction in stocking rate (16.1 to 11.2 steers ha-1) which influenced animal days (1810 to 1079 d ha-1), weight gain (1057 to 786 kg ha-1) and effective feed units (6392 to 4452 kg ha-1). Average daily gain showed a significant (P = 0.01) lack of fit and attributed to an increase from short to medium canopy height (0.40 to 0.64 kg) but little change between medium and tall canopy height (0.64 to 0.59 kg). The influence of increasing herbage mass on canopy and masticate characteristics are discussed relative to animal and pasture responses.