Production performance and meat quality of grazing lambs finished on red clover, lucerne or perennial ryegrass swards

Abstract

Fraser, M. D., Speijers, M. H. M., Theobald, V. J., Fychan, A. R., Jones, R. (2004). Production performance and meat quality of grazing lambs finished on red clover, lucerne or perennial ryegrass swards. Grass and Forage Science, 59, (4), 345-356. Sponsorship: DEFRA / MLCThe combined benefits of a high crude protein concentration, and possible protein protection and growth-promoting properties, make forage legumes potentially attractive as a natural means of increasing liveweight gain and time to slaughter of lambs in lamb finishing systems. An experiment was conducted to compare the production performance and meat quality of grazing lambs finished on red clover (Trifolium pratense), lucerne (Medicago sativa) or perennial ryegrass (Lolium perenne) swards. Replicate (n = 2) swards of red clover, lucerne and perennial ryegrass were rotationally grazed by ten ram lambs and ten ewe lambs from weaning until selection for slaughter at UK fat class 3L. Lambs grazing the red clover sward had a significantly higher liveweight gain and required significantly fewer days to slaughter than lambs grazing the lucerne sward (305 g d?1 vs. 243 g d?1; 38 d vs. 50 d), which in turn had a higher liveweight gain and required fewer days to slaughter than lambs grazing the perennial ryegrass sward (184 g d?1; 66 d). Lambs grazing the red clover and lucerne swards had significantly higher herbage intakes than those grazing the perennial ryegrass sward (2?06, 1?72 and 1?16 kg DM d?1 respectively), but in vivo digestibility of herbage was similar. Lambs grazing the red clover and lucerne swards also had significantly higher serum urea concentrations than those grazing ryegrass (12?5, 11?1 and 6?2 mmol L?1 respectively). Killing-out percentage was significantly higher for lambs grazing the red clover sward than for lambs grazing the perennial ryegrass sward (48% vs. 46%). There were no significant effects of finishing system on meat flavour, but meat from lambs finished on the lucerne sward was oxidatively less stable than that from lambs finished on the perennial ryegrass sward. Grazing the forage legume swards significantly increased the proportion of linoleic and linolenic acid in muscle tissue, and therefore the proportion of unsaturated to saturated fatty acids (0?19, 0?16 and 0?12 for the red clover, lucerne and perennial ryegrass swards respectively). However, the n?6/n?3 ratio was significantly lower for the muscle of lambs grazing the perennial ryegrass sward compared with those grazing the forage legume swards (1?13, 1?08 and 0?98 for the red clover, lucerne and perennial ryegrass swards respectively). The results indicate that by grazing lambs on forage legume swards it is possible to increase individual lamb performance without compromising meat quality.Peer reviewe

Effect of whole-crop pea (Pisum sativum L.) silages differing in condensed tannin content as a substitute for grass silage and soybean meal on the performance, metabolism, and carcass characteristics of lambs

“…It would be expected that if the diets containing WGP silages had been formulated to maximize niicrobial protein supply, then improved N efficiency may have been observed. Fraser et al (2004) and Speijers et al (2004) reported a greater forage DMI when either grazed red clover or alfalfa was offered to lambs in comparison with grazed ryegrass with the same effect observed when these forages were ensiled (Speijers et al, 2005). Forage DMI was unaffected by dietary treatment in the current study.…”

“…The plasma urea concentrations were, however, increased in lambs offered WCP-silagecontaining diets, indicating a potential deficit of rumen fermentable energy and further suggesting that feeding WCP silage in combination with a cereal or a cerealbased forage instead of GS would be beneficial. Fraser et al (2004) and Speijers et al (2004) also reported increased plasma urea concentration in lambs consuming grazed legumes in comparison with ryegrass. A similar effect was observed when the forages were ensiled (Speijers et al, 2005).…”

“…Work by McGlure et al (1994) and Fraser et al (2004) has demonstrated that when lambs were offered grazed leguminous forages ad libitum they had a greater ADG than those offered grazed ryegrass. Additionally, Speijers et al (2004) reported increased ADG for lambs consuming red clover or lotus over those offered ryegrass, but there was no difference when alfalfa was offered.…”

Effect of feeding silages from different plant raw materials on the profile of fatty acids, cholesterol, and vitamins A and E in lamb meat

“…A key role in this respect may be ascribed to red clover which is likely to exhibit a strong capacity to stimulate changes in the fatty acid profile owing to, among other things, a high content of polyphenolic oxidase (PPO) that inhibits lipolysis (Dewhurst et al 2003). Studies have shown that inclusion of red clover into the lambs' diet in the form of both green forage (Fraser et al 2004) and silage (Lourenco et al 2007) had a beneficial effect on the fatty …”

“…A key role in this respect may be ascribed to red clover which is likely to exhibit a strong capacity to stimulate changes in the fatty acid profile owing to, among other things, a high content of polyphenolic oxidase (PPO) that inhibits lipolysis (Dewhurst et al 2003). Studies have shown that inclusion of red clover into the lambs' diet in the form of both green forage (Fraser et al 2004) and silage (Lourenco et al 2007) had a beneficial effect on the fatty acid profile in intramuscular fat, as it increased the contribution of polyunsaturated fatty acids (PUFA) in this fat, including that of conjugated linoleic acid (CLA) cis-9, trans-11 being of high importance in terms of health. Research done by Lourenço et al (2007) suggests that feeding lambs with different silages induces changes in fatty acids metabolism in the rumen that may derive from differences in the extent of PUFAs biohydrogenation.…”