Strategier och lönsamhet vid napplammsuppfödning på fyra gårdar i Västra Götaland

In the case of surplus lambs where adoption is not possible, lamb producers have the option either to put down the lamb or to raise it on milk replacer. The decision to rear surplus lambs with milk replacers is made when the there is an inability by the mother to provide all lambs with her milk or when a preventive decision from the breeder is made to avoid an impossible situation for the mother to manage too many lambs. A project on rearing lambs on milk replacers started in 2019 on four farms with pasturebased autumn lambing in southwestern Sweden. One aim was to gather the knowledge from the participating farms with extensive experience of rearing of lamb with milk replacers in commercial sheep production systems. Another purpose was to investigate the growth and slaughter results of artificially reared lambs and their siblings, consumption of milk replacers and concentrates, working hours and economy. The study included follow up on these farms until the spring and winter of 2021. No follow-up of roughage consumption or comparison between different brands of milk replacers or concentrates has been made. Prior to the 2020 lambing season, the researchers registered the lamb producers' strategies, routines and previous experiences in production of artificially reared lambs. The breeders recorded weights of the artificially reared lambs and their siblings at birth, during lambing and rearing, day 60 and day 110. Additional information, such as health, was recorded. During the follow-up, consumption of milk replacers and concentrates and labour time in the artificially reared lamb production were registered. The artificially reared lambs and their siblings were followed until slaughter or until they were sold for breeding or selected to become replacements in their own herds. The number of artificially reared lambs in the herds in 2020 varied between 13 and 30. The follow-up of the artificially reared lambs showed similar growths as siblings who stayed with their ewes. Growth rates of the artificially reared lambs until weaning were between 290 and 353 g per day. Growth rates for the artificially reared lambs to 110 days was between 256 and 281 g per day, the siblings' growths were between 229 and 307 g per day during the corresponding period. The slaughter results of the artificially reared lambs were generally good to very good and, in some cases, even surpassed the results of their siblings. The slaughter age of the artificially reared lambs were between 151 and 219 days, and the slaughter weights were between 18.9 and 21.3 kg. The siblings' slaughter age were between 159 and 193 days, and the slaughter weights were between 18.9 and 21.6 kg. Total consumption of milk replacers was between 13 kg and 23 kg of powder per lamb, total concentrate consumption was between 37 kg and 56 kg per lamb. Until weaning, the feed consumption was very low, 3 to 15 kg per lamb depending on weaning age. The producers emphasized the importance to start the lambs on concentrates during early weaning to maintain sufficient growth. However, the producers emphasized that the transition from milk replacer to concentrate is difficult, as the lambs prefer to consume the milk replacer before the concentrate. In all cases, the lambs were weaned abruptly if concentrate and water intake were satisfactory. Other positive experiences were to keep artificially reared lambs into several and even groups in order to wean off at optimal weight and age. During the grazing period, own groups of artificially reared lambs are required as the supplementation of concentrate at the transition is necessary between the milking period and grazing. Mortality and health problems among the artificial reared lambs were generally low. The producers were careful to ensure that the lambs received colostrum before they were moved 33 to the artificially reared group and that they remained healthy during rearing. In summary, factors to ensure a well-functioning production of artificially reared lambs were to start quickly on the milk replacer, feed plenty of milk replacer and concentrates of good quality. Also, the health of the artificially reared lamb is important and the knowledge and care of experienced producers. The farmers in the project reported between nearly 2 to 3 hours of working time per artificially reared lamb. It is very important for the economy and animal welfare to be careful with supervision and care and to maintain very good hygiene when feeding milk. Regardless of the choice of technology, the steps of mixing and feeding milk replacer and cleaning equipment were the most time-consuming. Reviewing the time required and rationalizing these steps can make the production more efficient. In this limited project, individual farm-related factors played a major role in the time required. An objective comparison between different feeding systems of the milk substitute requires follow-up of the labour time on more farms. Success factors from an economic point of view were low mortality, good health and acceptable growth, a short period with milk replacer and early adaptation to concentrates to avoid a slow growth rate. Economic calculations showed that the slaughter income paid the costs for milk replacer and concentrates, but in most cases did not leave surplus large enough to cover costs, such as working hours, equipment, buildings, the costs of the ewe, etc. If the income from the artificially reared lambs can be increased through the sale of fur or breeding animals, the income per artificially reared lambs could cover other expenses. In general, it was not considered a problem to allow healthy surplus lambs to be used for breeding. However, the farmers avoided putting artificially reared lambs in breeding whose mothers rejected them at birth. Lamb producers who reduced litter sizes emphasized that reduction of litter sizes meant less wear on the ewe and her udder, subsequently reducing the risk of complications, such as mastitis. Therefore, the remaining lambs reared by the ewe could grow better and more evenly and the risks for neglected lambs decreased and facilitated smoother and earlier deliveries of slaughter lambs. Another important aspect when production goes well is that the working hours decrease and job satisfaction increases. In the project, any positive economic effects could not be investigated regarding the durability of the ewe, the siblings' growth rates, health and slaughter results or total working time when reducing the number of lambs in large litters. On the other hand, other studies and trials support the producers' positive experiences of the health and production of the ewe and siblings. Important issues and suggestions for further studies: • Compare different milk feeding systems regarding working hours, feed efficiency, growth rates, health, slaughter results and economy, but with similar animal material and milk substitutes. • How does the number of lambs per nipple and the number of lambs per pen affect the animals' growth rates, health, slaughter results and economy? • Compare different weaning weights concerning the animals' growth rates, health, slaughter results and economy. • Test the impact of different milk replacers on concentrate consumption, animal growth rate, health, slaughter results and economy with similar animal material and technology. 34 • The impact of different care routines, equipment, feed types and feeding on the lambs' interest in getting started quickly with eating larger amounts of concentrate and silage. • Impact of reducing the number of lambs in large litters on the durability of the ewe, the litter siblings' growth rates, health and slaughter results, total working hours and finances.