ChileanJAR

Milk production in southern Chile is based on mixed swards of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). Recently, new ryegrass cultivars infected with endophyte have been introduced to improve persistency through enhanced resistance to insects. In a trial designed to measure intake, two groups of eight Holstein cows were randomly assigned to treatments T1: grazing group and T2: soiling group. Perennial ryegrass cultivars Santa Elvira and Embassy was the only feed supplied. The two cow groups grazed both cultivars during 4 days since 01.15.93. From 01.19.93,cows in group T2 were individually fed indoors with cultivar Santa Elvira until 24.01.93. The average initial milk production in T1 was 21.3 kg and 21.2 kg in T2, with intakes in T2 of 13.7 kg D.M. at dciy 1 and 15.9 kg on day six. On day 7, cultivar Embassy was offered to cows in both groups. In group T2 the íntake declined to 12.3 kg D.M. and the milk production dropped to 17.1 kg. In the grazing group the milk reduction was lower, 18.4 kg. On day 8, the clínical symptoms of ryegrass staggers becameevident in both groups. In T2 the intake declined to 8.6 kg D.M. and the milk productíon to 13 kg. In T1 milk produccion dropped to 17 kg. The clinical symptoms were more severe in the indoor fed group, with two downer cows. After changing the forrage supply to a mixture of ryegrass cv. Nui and white clover cv. Huía, the intake and production returned within 12 days to former levels. The experience described points out the need to test with animals every new cultivar before it is released to be marketed.