The Effect of Bermudagrass Hybrid on Forage Characteristics, Animal Performance and Grazing Behaviour of Beef Steers10 June 2014
Considerations should be made when choosing Bermudagrass variety, according to a new study in the Journal of Animal Science.
Alicia, Jiggs and Tifton-85 were the three varieties evaluated by Professor Guillermo Scaglia of Louisiana State University and Professor Holly Boland of Mississippi State Univeristy.
They learned that, in addition to bermudagrass hybrid, other variable, such as temperature and humidity affected grazing behaviour.
Bermudagrass is a major feed source for ruminants across the southeastern United States.
In four consecutive years, three different bermudagrass hybrids – Alicia, Jiggs and Tifton-85 – were evaluated under a low stocking rate as forage and hay sources.
The nutritive value, in situ dry matter digestibility and performance and grazing behavior of beef steers under similar management were evaluated.
• Sampling day had an effect on all forage variables.
• Percentages of crude protein and TDN decreased while concentrations of ADF, NDF, lignin and nonfiber carbohydrates increased as grazing season advanced. • Alicia had lower nutritive value, showing greater lignin (5.3 per cent ) and indigestible fraction (44.9 per cent ) compared to Jiggs (4.9 per cent and 35.6 per cent , respectively) and Tifton-85 (4.5 per cent and 40.1 per cent , respectively). • Tifton-85 contained the lowest concentration of nonfiber carbohydrates (11.8 per cent ).
• Steers grazing Jiggs and Tifton-85 had greater average daily gain (1.12 and 1.21 lb, respectively) and body weight gain per acre (252 and 272 lb, respectively) than those on Alicia (0.35 kg and 180 lb/acre, respectively) – results that are probably explained by the lower nutritive value characteristics of the latter.
• Most grazing behavior variables were affected by the time of day and grazing period. • Two major grazing events were observed at dawn and dusk. Grazing time (32 minutes) was lowest while standing (140 minutes) and lying (98 minutes) times were greater from 1100 to 1559 hour, probably as an effect of temperature and humidity at that time of day.
• During summer, the temperature humidity index was above 72 (mild heat load) for the entire season and above 79 (severe heat load) during most of the daylight hours from June to August. Heat load likely affected animal performance and grazing behavior; however, some characteristics associated with these bermudagrass hybrids, especially with Alicia, such as its percentages of lignin and indigestible fraction may also partially explain the poor animal performance.
In the conditions of the study, environmental variables (temperature and humidity) as well as the type of bermudagrass hybrid affected animal performance and grazing behavior of recently weaned beef steers.