AU Triumph, Johnstone and Kentucky 31 tall fescue pastures versus maize silage in diets for lactating dairy cattle

Abstract

The performance of lactating dairy cattle fed on a maize silage (S) dry-lot scheme was compared with that of lactating dairy cattle switched abruptly from a dry-lot regime to graze endophyte-free Johnstone (J), Kentucky 31 (K), or AU Triumph (T) tall fescue (Festuca arundinacea Schreb.) as components of dairy diets. Twenty-four mature Holsteins either grazed pasture or received maize silage in a dry-lot as the only forage in the diet during each of two autumn and spring studies. A grain mix was allotted at 1 kg per 2.75kg of 3.5%fat-corrected milk (FCM). Herbage present was estimated with a disc meter. More herbage dry matter was provided during both spring periods (P < 0.05) from T and K than from J pasture. Cows on S ate more (P < 0.05) grain mix supplement and tended to gain more mass (P < 0.10) during one autumn and one spring period than cows on pasture, but did not consistently produce more actual milk and 3.5% FCM than cows grazing fescue pastures. There was no consistent advantage in actual milk production for cows on any fescue cultivar throughout the study. Animals grazing T produced less (P < 0.05) actual milk than those grazing K during the spring of each year, and less than those grazing J in spring, 1991. Milk fat and protein concentrations did not differ (P > 0.05) for cows on different pasture treatments but the trend was for greater (P < 0.10) milk fat content for cows on S. The production of 3.5% FCM did not differ for cows grazing different fescue cultivars, except cows on J produced more milk than those on T during one spring period. Cows in early lactation (autumn periods) lost mass while those in mid-lactation (spring periods) gained or at least maintained their mass. Grazing fescue pastures can be a viable herbage substitute for maize silage when pastures are of high nutrient content.

Keywords: alabama; animal nutrition; cattle; cultivar; dairy cattle; disc meter; dry matter; fescue; festuca arundinacea; forage; forage quality; grazing; herbage; maize; maize silage; milk production; pastures; performance; protein; silage; tall fescue; treatments; united states of america

African Journal of Range & Forage Science, 13(1): pp. 9-14