Lammproduktion på nio ekologiska gårdar i västra Sverige
Abstract: The purpose with this study was to analyze the possibilities to produce organic lambs and to hihglight the most common difficulties in such a production system. A description of current organic and conventional lamb production systems was conducted, both from Sweden and from some other countries. The Department of Animal Environment and Health at SLU in Skara performed the project together with The County Board of Agriculture in Västra Götaland and Värmland and The Swedish Animal Health Service. The project lasted from 2002 to 2004. The student report contains the years 2002 and 2003. In the year of 2003 there were 210 000 adult sheep in Sweden, of which 16 400 adult sheep were certified by KRAV. Of the different countries in Sweden, Västra Götaland and Gotland had the largest number of sheep, 14 and 13 per cent of the total number. The total number and the number of certified sheep has increased whereas the total number and number of certified sheep producers have decreased during the last few years. In the year of 2003, the average herd size was 27,7 adult sheep while the average certified herd size was 57,6 adult sheep. Feeding strategies in organic and conventional lamb productions are quite similar to each ther. Legumes in mixture with grasses are used as forages in organic production because of the ability of legumes to fixate nitrogen. According to the rules of KRAV, a maximum of 40 per cent of the daily intake of dry matter can be provided as concentrate. However, during the first three months of lactation the maximum amount of concentrate in the ration is 50 per cent. Lambs are normally weaned when they are three months old, which means that the ewe can be fed with 50 % per cent of concentrate during their whole lactation. Hexane extracted feeds (meal) are prohibited to use as a source of protein in organic production. The feeding ration must thereby be completed by protein feed that are approved by KRAV, such as rapeseed, peas, field beans and lupine. Intestinal parasites occur in lungs, abomasum, gut and liver in sheep. Parasite infections are mostly a problem for the lambs, ewes has normally developed immunity. However, the barbers' worm can cause sickness in ewes, especially during lambing or at other times when the ewe's condition is low. The ewe's immunity does not, however, mean that they're free om parasites. They can carry parasites that through their manure pass on to the pasture where they can affect the lambs. By letting different animals, for example cattle and sheep, graze the same pasture simultaneously or by using rotational grazing the risks for parasite infections can be decreased. Parasites are in most cases specific to one species. Nine farms in western Sweden participated in the study. The herd size varied between 30 and 140 ewes. The breeds were mostly crosses with Fine wool or Texel but also pure bred Gotlandsheep was used. The farms used different lambing seasons. The ewes were lambing from January until May and in September. Five of the herds had the ewes lambing in the winter, three in the spring, two in the summer and two in the autumn. The farms were visited five times a year during the project. Lambing time, number of lambs per ewe, lamb weights and lamb age at weaning were registered. Slaughter data were collected from the abbatoir. Results from 2002 and 2003 are shown as birth weight, weight at 110 days of age, age at slaughter, body conformation and fat content of the carcass. Parasite status in the herds and methods that were used to reduce the risks for parasite infections were studied. The frequency of parasites where registered with assistance from the Swedish Animal Health Association. Several farms let the sheep graze together with cattle or horses and/or rotate sheep and cattle for grazing. Despite this, six of the farms had sheep affected by the barbers' worm. Intestinal parasites are thereby a large problem in organic lamb production. To reduce the risks for infections that cause production losses it is important to take faecal samples from the ewes before the grazing period to find out the status of parasites in the herd. Except for the barbers worm, there also were some problems with lung worm, large liver fluke and giardia. It is important to have control over the lambs and weigh them once in a while during the grazing period. By weighing the lambs you can discover if the growth rate of the lambs has been reduced, which can be a sign of a parasite infection. In the last years, forages that contain condensed tannins, for example birdsfoot trefoil, been noticed as feed for ruminants. Condensed tannins reduce the risk for parasite infections. However, studies at Röbäcksdalen, The Swedish University of Agricultural Sciences, Umeå, have not shown any effects of tannins on prevalence of parasite infections under Swedish conditions. Feeding rations for lactating ewes in 2003 were made for five herds in the study. The feeding rations were based on nutrient analyses of the forages and concentrates. Random bales of thilage that were used as feed were weighed to estimate the amount of silage offered to the animals. Feeding rations were compared to the nutrient requirements of lactating ewes. It was shown that the ewes on most of the farms had sufficient provisions of protein and energy. The most common concentrates were grain mixtures combined with a protein mixture. Today lambs are produced almost the whole year round. What production model that should be used should be based on the condition of the farm. In a production system with lambs born in the winter the lambs are raised intensively and the aim is to have them slaughtered before the grazing period starts. The ewes can then be used as nature conservators on semi-natural grasslands. Large amounts of pasture, both for ewes and lambs are needed, in a production model with spring born lambs. In a production system with summer born lambs the ewes can e grazing semi-natural grasslands in spring whereas they during summer and autumn during their late pregnancy and lactation have a demand for a high quality pasture. A production witlambs born in the autumn is based on the idea to let ewes graze regrowth pastures in the autumn during late pregnancy and lactation. After the grazing period the aim is to feed ewes and lambs with forages (silage) only. The lambs are raised extensively and are slaughtered inthe spring. Carcasses of lambs are judged after weight, form and content of fat in the body. The form is judged according to the five main classes of the EUROP-system, E, U, R, O and P that is omplemented with + and -. The content of fat is judged in the same way, with 1, 2, 3, 4 and 5 and is complemented with + and -. The requirements to receive the extra KRAV supplement were in 2002 and 2003 a conformation class from E+ to O, fat content of 2-to 3 and a slaughter weight between 14 and 25,9 kg. In this study, results form lambs born 2002 and 2003 were presented. The results were presented separately for ewe and ram lambs, winter born, spring born and autumn born. Lambs that were born in autumn were only few in the study and it is hard to make any conclusions for that kind of production model. However, it is an interesting model that needs to be studied more extensively. To compare how the growth rate differed among farms growth rate was calculated from birth weight, slaughter weight and an expected dressing percentage oft 40 per cent. The daily growth rate varied between 145 and 339 g. The large difference is caused by the conditions on the farms and the aim of the production model. Low daily growth rates are also certainly caused by parasite infections. There are great opportunities to succeed with organic as well as conventional lamb production. The largest problem with lamb production is parasite infections of the lambs, even when methods have been used to reduce the risks for infections. You have to control the parasite status of the lambs by weighing and by taking faecal samples during the grazing periods. When choosing a model you should take into account the conditions of the farm including types of buildings and pastures.
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