Arnesson A.1, Carlsson A.2 and Helander C.1
1Dept of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden;
2County Administrative Board of Västra Götaland, Skara, Sweden; annika.arnesson@slu.se
Abstract
The aim was to observe grazing management and breeding of recruitment sheep by successful lamb producers, and to find ways to improve management by exchange of knowledge and experiences between farmers, advisors and researchers. Eight lamb producers from Western Sweden were included in the observational study that lasted from autumn 2012 to summer 2014. Detailed registrations including pasture nutritional composition, management and animal performance were made on farm level and key-points to successful pasture-based lamb production were summarized. Average herd lamb live weight gain (LWG) from birth to 110 days of age varied from 190 to 380 g day-1. Pasture management, breed and flock size varied and seem to have affected LWG of the lambs. Also, the body condition score of the replacement ewes at mating seemed to influence the LWG of the lambs from birth to 110 days of age (R2 = 0.36). Lamb producers who set targets and had a strategy with a well-designed work plan met their goals even under varying weather conditions. Regular weighing of lambs is necessary in order to follow up on goals. Key-points for successful pasture-based lamb production, from a specific farm with exceptionally good results, are presented and discussed.
Keywords: grazing, management, replacements, sheep
Introduction
Pasture-based lamb production is the dominant lamb production system both in Sweden and world-wide.
There are, however, many different ways of raising lambs on pasture. In Sweden, most farmers let their sheep graze on both semi-natural pastures and on leys from early spring until late autumn. The growth rate of lambs in pasture-based lamb production varies depending on numerous variables. A too low daily live weight gain (LWG) leads to increased costs of production and may lead to lower slaughter income, but also the future production of the replacement ewe lambs are affected by the LWG until mating. One practical measure used in Europe is the weight of the ewe lamb at first mating, which is recommended to be 60% of her adult weight (HCC, 2010). In this on-farm study, which included eight farms with pasture-based lamb production with a range of differences in genetic and environmental differences, the aim was to find key-points in the production used by successful lamb producers. The data was collected by on-farm observations and included planning and execution of plans in the areas of grazing management and replacement-ewe management.
Materials and methods
Eight farms were included in the study that lasted from autumn 2012 to summer 2014. The project noted what the producers had aimed for in their production and what they thought they could improve. Also, data were collected giving background information from all farms. In addition to individual farm visits, the whole group gathered on farmers’ farms to exchange experiences and plan activities and to discuss the results that came up during the project. The ewes were weighed and body condition was assessed before mating, after lambing and at weaning, according to Thomson and Meyer (1994). The lambs were weighed at birth, at turnout and at weaning as well as continuously the weeks before slaughter. The replacement ewes were followed up until they lambed for the first time. During the grazing period, the pasture height was measured once per month in the field from where the sheep were turned out. Samples were cut in
the same field for analysis of nutrient and mineral contents. Farmers kept grazing diaries with details of grazing type, field area, sward type etc. Lambing took place in March to May depending on breed, and ewes and lambs on all farms were turned out on pasture as soon as possible. A grazing plan was made on each farm where farmers set their goals for their grazing strategy for the summer. On most of the farms where the farmers reached their targets, they worked actively with grazing management including rotational grazing, trimming of paddocks, supplementary feeding when necessary and allowing different categories of animals to graze on different pastures (grouping) etc. Also, the most successful farmers did not suffer from any parasitic problems, as the faeces were analysed and the sheep were treated based on parasitic species. Results from one of the most successful farmers are presented and discussed.
Results and discussion
One of the most successful farmers (No. 3) reached an average of 1.8 weaned lambs per replacement ewe (n=22) put to the ram. All the older ewes were also pregnant and had an average of 2.3 weaned lambs per ewe (n=70). All lambs were either sold, slaughtered or pregnant when the grazing period ended. Also, the ewe lambs from this farm reached, but did not exceed, the optimum BCS of the ewes at mating (Figure 1).
Furthermore, the average BW was 63% of the adult weight at mating and the sheep grazed only leys (Figure 1). The first ley grazed had not been used for sheep the year before and the replacement ewes were grouped and kept in one group after weaning until next year’s grazing period started. The weather varied between years, with 2013 being generally warmer and drier than 2012 in this part of Sweden. Averaged over farms, the protein content of the grass seemed to be linked to the LWG of the lambs, and the protein content of semi-natural pastures declined more rapidly than that of cropped leys during the summer.
Identified key-points for successful pasture-based lamb production:
• Weighing and condition scoring of ewes at mating, at end of grazing period and at start of grazing period.
• Strategic grouping when indoors, both during pregnancy and lactation.
• Feeding grass/clover silage with high feed value supplemented with pelleted concentrate.
• Parasitic control through analyse and treatment of specific species.
Figure. 1. Live weight and BCS of replacement ewes at mating in 2012 and 2013.
• Grazing plan with rotational grazing, trimming of pastures and supplementary feeding when needed.
• Adjusted grazing area by grouping and mobile fences.
• Regular weighing of lambs on pasture.
• Active selection of replacement ewes meeting criteria.
• Keeping replacement ewes in a separate group from weaning until next grazing season.
• Using cross-bred ewes from fertile breeds (e.g. Fine wool/Dorset) mated with a meat-breed (e.g. Texel).
Conclusions
Lamb producers who set targets and build strategies with a well-designed work plan generally meet their goals quite well even under varying weather conditions. The key-points presented in this paper highlight the importance of weighing, condition scoring, grouping, silage quality, parasite control, grazing management and active selection of replacement ewes. As the protein content of the pasture seemed to be linked to the LWG of the lambs, semi-natural pastures are most suitable for use early in the spring, as the content of protein and metabolizable energy declines more rapidly on these pastures than on leys.
References
HCC (2010) Feeding the ewe for lifetime production.
Thomson, J and Meyer, H. (1994) Body condition scoring of sheep. Oregon State University Extension Service, EC 1433.