Alternative forage crops for finishing lambs

Summary

Alternative forage crops offer a number of benefits for farmers including a cheap finishing system for lambs, benefits for soil condition, fertility building for rotations and providing a cover crop. Certain forages have also been demonstrated to have some anthelmintic benefits for lambs. A demonstration study was undertaken to investigate the potential of six crops used in the horticulture industry (fertility building crops) as forage crops for weaned growing lambs. The crops include white mustard, Nemat (form of Rocket), Crimson Clover, Sweet Clover , Caliente 119 and Caliente 99 (Cruciferae). The grazing field was split into three blocks and two crops were sown in solid strips in each block. Each block also had grass headlands. 10 ewe lambs were randomly allocated (balanced for liveweight) to each block. Lambs were introduced to the blocks 1 week after crop emergence. Lambs were weighed fortnightly for 8 weeks. Mob faecal samples were also taken from each group on a fortnightly basis. Grazing behaviour assessments were also undertaken. Lambs grazing the mustard treatment had the least liveweight gain of the three groups over the grazing period (average of 58g/day). Whereas lambs grazing the clover treatment had the greatest liveweight gain (average of 110g/day). Lambs grazing the Caliente treatment were intermediate (average of 92g/day). However, in the third grazing period lambs on the Caliente treatment had negative liveweight gains (-50 g/day). Although activity varied throughout the day, on average 75% of lambs were grazing at any given time. For the Caliente treatment group on average at anytime 33% of lambs were grazing the Caliente 99 variety compared to 23% grazing the Caliente 119 variety. Only 16% of lambs were on average grazing the grass areas at any one time. In the clover treatment group 45% of lambs were to be found grazing the Crimson clover sward at any one time on average, 22% were grazing the Sweet clover sward and only 3% grazing the grass areas. For the mustard treatment 33% of lambs on average were grazing the Nemat sward at any time, with 22% grazing the white mustard sward and the grass areas.
This study suggests that fertility building crops such as Caliente, clover and mustard can be utilised as a grazed forage crops. However, it may be more appropriate to sow the crops as a mixed crop for grazing rather than as monoculture. This would also increase any environmental benefits such as an increase in biodiversity.