| Abstract: |
Fostering is a method used by shepherds that allows the successful rearing of abandoned lambs onto other ewes, or the ability to provide surplus lambs a new mother in the case of triplets. Past research has focused on the success rates of the varying methods available, however, more research is needed to increase the knowledge about commonly selected fostering methods and the behaviour, welfare and production implications of the different methods used. Questionnaires were distributed at national farming events targeting registered sheep farms around the UK to establish which foster methods were currently in use and to collate the farmers opinions of their usage in modern day sheep farming. An experimental study was carried out to assess the welfare and production implications of the use of these methods. 84 ewes were allocated to one of the three experimental foster methods or the control group (twin lambing). They were also classified according to their lambing experience (multiparous or primiparous). Behavioural observations were conducted post-foster on the ewes and their lambs. The ewes’ salivary cortisol concentration and heart rate frequency were also monitored at 0, 30, 60, 90 and 180 minutes post-foster. To assess the production implications of the different foster methods, lamb weights and body measurements were taken at 0, 7, 30, 90 and 180 days of age to asses growth rates. Lambs were weaned at 3 months of age and remained at pasture until slaughter, at approximately 6 months of age. The lambs’ carcass quality was assessed by means of weights, zoometric measurements and conformation scores and some meat quality parameters (ultimate pH, water holding capacity and colour) were also investigated. 93% of farmers used fostering, preferring to foster rather than artificially rear lambs. Almost two-thirds favoured birth fluids (64%) and 19% of farmers used restraint crates, The most popular combination of foster methods was cervical stimulation plus birth fluids (CSBF). Exploratory factor analysis showed two main components helping farmers to decide which foster method to use, the ewes’ health and welfare and the farmers previous knowledge and success of a foster method. Birth fluids, restraint and CSBF were methods selected for behavioural data, showing that negative behaviours were significantly higher for restrained ewes compared to other treatments. Restrained ewes also showed significantly higher heart rates and salivary cortisol concentrations. Production data showed that ewe reared lambs gained significantly more weight than artificially reared lambs up to 90 days of age. However, there was no difference from that time until slaughter. Conformation and chest roundness scores were significantly better for ewe reared lambs compared to artificially reared ones. Foster methods did not have any significant effect on the growth rates, carcass or meat quality measurements for the lambs studied. The majority of farmers selected to use birth fluids, seen as a welfare friendly and less-invasive method of fostering. However, some farmers selected the restraint method based on the urgency of the lambs to receive milk and to avoid artificial rearing. The restraint crates caused significant changes to the ewes’ behaviour and increased their heart rates and cortisol concentrations, indicating a higher level of distress that could be compromising the ewes welfare. Lamb growth rates, carcass and meat quality were not affected by the different foster methods, proved that successfully established foster methods of any kind have no differential implications for the farms productivity (under UK commercial practices). Artificially reared lambs did show worse carcass conformation, suggesting that ewe rearing, and therefore fostering, offers advantages for the productivity of sheep farmers.
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