Use of Italian ryegrass on seasonal dairy farms in northern New Zealand: 2. Milk production

Abstract

Milk production from cows grazing existing perennial ryegrass pastures or those direct-drilled with Italian ryegrass (Lolium multiflorum Lam. cv. Concord) or with new perennial ryegrasses (Lolium perenne L.) was measured over the 1991/ 92 and 1992/93 lactations (July-April), on intensively managed farmlets. This trial complemented large-plot grazing experiments, and incorporated similar renovation methods of direct-drilling (undersowing) and herbicide application before direct-drilling of grass seed. Twenty Friesian cows rotationally grazed each of the three treatment farmlets; they were milked from July/August until April/May. Average herbage accumulation in late winter/early spring on the Concord farmlet was only slightly greater (+100 kg DM/ha), but in summer/autumn was inferior (-350 kg DM/ha) to herbage accumulation on the unrenovated perennial ryegrass-based farmlet (Control). In winter/spring (July-December) 1991 and 1992, cows on the Concord farmlet produced similar milk yields (about 2800 kg/cow) as those grazing existing perennial ryegrass pastures and existing pastures direct-drilled with new perennial ryegrasses. Similarly, there were no differences in fat, protein, or lactose yields at 129, 98, and 135 kg/cow, respectively. However, in summer/autumn 1991 (January-April), cows on the Concord farmlet produced less milk (782 vs 1059 kg/cow), fat (37 vs 54 kg/cow), protein (27 vs 38 kg/cow), and lactose (37 vs 50 kg/cow) than those grazing the Control farmlet; there were no treatment differences during summer/autumn 1992. It was concluded that Concord ryegrass was unable to provide sufficient increases in feed to improve seasonal or total milk production from cows on intensively grazed farms. © 1996 Taylor & Francis Group, LLC.