Kokvigeproduktion baserad på köttraser : en fältstudie

Sammanfattning: Most of the beef production in Sweden has been integrated with milk production. Since the 1990:s, the number of dairy cows has decreased. A specialised beef production has developed in purpose to compensate for this decrease. The consumption of beef have increased in the last decade, but the Swedish production has no followed this trend. In 2004, the percentage of beef self-sufficiency in Sweden was 60 %. Sweden was earlier a net exporter but changed during the 1990:s to become a net importer of beef. The import increased dramatically when Sweden joined the EU and the control at the border disappeared. The oversupply of heifers that are not for any use are slaughtered in most cases. Instead these heifers can overcast and then become once-bred heifers. They get to calf one time before they go to slaughter in the autumn. They are then at the age of 30 months. Then they should have a higher slaughter weight, better classification and result in an extra income for the calf compared to have been slaughtered as a heifer. Production with once-bred heifers leads up to more calves and in this way number of beef cows increases and this compensate the decrease of dairy cows. Once-breed heifers in Sweden is usually not systematic and it is an unusual production. Once-bred heifers are not a new production system. There were research about it for more than 40 years ago and it started to practice when there was a market for it. In many countries this happened when the milk quota was enforced. There is a greater risk to loose animals when heifers calf one time before slaughter and it demands more surveillance than traditional suckle cow production. The age of the heifers at first calf should not be too high, this for good economy. There are a couple of different beef breeds in Sweden and their characteristics make them suitable for different types of production. Main reason for difficulty in heifers is the size of the calf compared to the size of the mother, for example space in the pelvis. There is a greater difference in percentage deathborn calves between cow and heifer than among breeds. The once-bred heifer's main production is no only growth as in heifers but also to produce a calf. The heifers must have energy for both the fetus and the milk, if the calf is with the mother during the summer before slaughter. Heifers are good in extensive production because they obsess fat at a low weight and are easy to have on pasture compared to bulls. Corn silage is a good energy source as a complement to pasture and it works well in mixed rations. It is important with secure feed supply to all animals, even the low grade. The body composition at a certain live weight depends on animals as breed and gender and intensity in breeding. Heifers get fat at a lower weight compared to steers. The amount of fat increases faster with dairy breeds compared to beef breeds. A comparison between heifers and once-bred heifers showed that once-breed heifers had less of inner and external bodyfat in the abdomen compared with heifers, but more contents of fat on the breech. Despite the higher slaughter weight on the once-bred heifers, they do not have much body fat and fat in the abdomen. A Canadian approach showed significant differences between once- bred heifers and conventional heifers. Once-bred heifers had a lower share of body fat in kidney, mesentery and omental and a bigger share of digestion texture. An investigation from The Rural Economy and Agricultural Society in Sjuhärad showed differences in average weights and categories among heifers. To get a high slaughter weight without too much body fat, a very slow breeding is demanded of heifers from light beef breeds. A study showed that a diet based on pasture rich in omega 3-fatty acid gave a healthy fat composition in the meat. Once-bred heifer system is biologically more effective than traditional suckle-cow production because the young, growing once-bred heifer uses a less share of the energy intake to maintenance. The lack of profitability is a huge problem in Swedish beef production; half of the cost consists of buildings and labour. Problems with calving and death are other factors of economical concern. The investments for facility, fence and water as well as labour get smaller per animal in bigger herds. But it is not only about reducing the costs; it is also about producing right quality at a certain time. An increased risk of difficulties in calving can result in death of cow and calf. A calculation was done on once-bred heifers slaughtered at an age of 30 months and heifers slaughtered at an age of 22 months. The big income is the extra calf at production with once bred heifers. Feed and pasture consumption is a cost that get bigger compared with the calculation with heifer. Labour is also a big part. The aim of this thesis was to find appropriate ways for a successful production of once-bred heifers by conducting a field study. Three farms were dissipated in this thesis: Gröna Gårdar, Risinge Hereford and Ölanda Säteri. Risinge Hereford has an age of 25-27 months of the heifers at first calving. The heifers overcast with Hereford. The farmer does not think that calving is a problem. The average birth weigth of the calves are 40 kg. The once-bred heifers are slaughtered at an age of 30 months and a slaughter weight of 270 kg. The conformation was then O to O+ and fatness 3. The calves at Ölanda Säteri had a birth weigth of 43 kg. The animals were Charolais, Limousine, Simmental and Blonde d´Aquitaine. The farmer had big problems with the calving. The once-bred heifers were 30 months at slaughter and had a weight of 304 kg. The conformation was then O+ and fatness 3. The mean weigth of the calves at Gröna gårdar was 36 kg. The animals consist of crossbeeds of Limousine, Charolais, Simmental, Hereford and Aberdeen Angus. Age at slaughter was 36 months. Gröna Gårdar has a profile as a farm that produces healthy meat with a large content of omega-3 fatty acids. The average gain for the heifers was 534 kg/day during her life. Slaughter weight of the once-bred heifers was 305 kg. The conformation was then R- and fatness 3+. The income was considerably higher in the calculation for once-bred heifers compared with the heifer, around 4000 SEK. The calf, which is generated at production with once-bred heifer is a major reason to this as well as the higher slaughter weight for the once-bred heifer. This shows that the calculation for once-bred heifer is sensitive for the lost of the calf. Furthermore, the expenses are bigger for the once-bred heifer when the production time is 8 month longer which gives a bigger total feed consumption and rate. The sum for the first costs are around 1200 SEK bigger than for the once-bred heifer. Both productions had a positive TB1, it was 4155 SEK for the once-bred heifer and 1473 SEK for the heifer. Labour plays an important role and the TB2 was negative of the heifers. Once-bred heifers costs for labour were around 1000 SEK more but the high TB1 gave a positive TB2. There were big differences between the farms in the field study. It can be hard to distinguish what makes the differences. With support from results of earlier conducted projects, both international and national, some important conclusions can be made. Choice of breed plays an important role to succeed with the production and the calf is the big extra income in once-bred heifer. Labour and feed are the biggest costs. Simple constructions are economically effective to use. An extensive production gives higher slaughter weight without fat reduction and despite the higher slaughter weight on the once-bred heifers do not have much body fat and fat in the abdomen. Working with added value concerning beef production can give a higher income.