Lamb Fattening Under Intensive Pasture-Based Systems: A Review

SIMPLE SUMMARY: The use of fresh high-quality pastures in intensive lamb production systems is considered worldwide as economically advantageous, environmentally friendly, and a promoter of animal welfare. Moreover, it generates a desirable meat composition. However, it is known that the availability of pastures in grazing regions is variable throughout the year, and this makes the maintenance of a stable offer of feeds and production difficult. The combination of high-quality pastures and other feedstuffs is very common in dairy cow grazing systems while, for sheep, there is less information available. The objective of the current review is to discuss this topic in light of published information about intake, digestion, rumen environment and health, performance, and carcass quality and composition. ABSTRACT: The benefits of pasture-based systems on the fatty acid composition of sheep meat appear to be achievable despite variability in the quality of the pastures. Lambs fed high levels of temperate pastures have an excess of N-ammonia derived from protein degradation. Furthermore, animal performance is highly variable depending on the quality of the pasture at the time of grazing, and high animal performance in these systems appears to be linked to the use of high-quality pastures with high availability, and is possibly added to by the inclusion of concentrates that allow increasing energy intake and a better use of the N in the pasture. The combination of high-quality pastures and total mixed ration offers a good alternative to the inclusion of concentrates in the diet, improving the use of N, and avoiding acidosis problems. However, information to determine the effect of a number of nutritional strategies on meat quality, and the minimum level of pasture intake necessary to achieve the benefits of pastoral systems is still lacking.