Parasitenbelastung und Milchqualität bei Schafen und Ziegen im Ökologischen Landbau

Kurzfassung

Effects of subclinical parasitism on productivity parameters like milk yield and fat have been described previously in cows. Until now only a few data were reported for goats and ewes. Two main topics of the institute’s research focus on milking of small ruminants and strategies to reduce anthelmintic treatments. In 2003 45 goats and 19 sheep were monitored during lactation. Milk yield and milk composition (fat, protein, lactose) were registered monthly. Every two weeks, samples for cytobacteriological analysis were gained of each half of the udder. At the end of April the grazing season started and individual faecal samples were collected monthly. In September a part of the goats showed signs of clinical parasitism and a deworming was carried out. The ewes were only low infected and had a very stable udder health. Thus, they were excluded from the analyses. A first data evaluation showed no significant relationship between the severity of the infection with gastro-intestinalnematodes (GIN), estimated by the number of eggs counted in the faeces (FEC), and milk yield and milk quality. In a second step, animals were grouped according to the course of infection in “mild” and “serious”. “Mild” means that an FEC over 300 Epg was only registered at the end of the investigation period in August. Compared with the “mild” group, the FEC of animals with “serious” infection courses immediately increased after the beginning of grazing. The new analyses revealed differences between these groups for the content of lactose and protein, even if they were not statistically significant. During mid of July and August, when the prevalence of GIN was highest, the group with the “mild” course of infection showed a lower decrease of milk production com-pared with the higher infected group. However, further research is needed to evaluate, and maybe confirm our observations that the course of infection with GIN might be an interesting parameter to express the resistance to parasitic diseases in goats and might be related to the parameters of milk production and composition.