Twenty pregnant Comisana ewes were divided into two groups of 10. One group was allowed to graze a vetch pasture (grass). The second group of animals was housed collectively in a pen and was given hay and concentrates (concentrate). After lambing, all the ewes were allowed to stay with the respective lambs between 18:00 h and 07:00 h of the following day in two different pens. Therefore all the lambs were raised exclusively on maternal milk. The lambs were slaughtered at 38 days of age. Milk and lamb meat ( longissimus dorsi muscle) fatty acids were analysed. Ewes on grass produced milk with a lower ( P < 0·001) proportion of saturated fatty acids and with a higher proportion of both monounsaturated ( P < 0·05) and polyunsaturated fatty acids ( P < 0·01) than ewes given concentrates. Trans-vaccenic acid was significantly higher ( P < 0·001) in milk from grass-fed animals compared with ewes given concentrates. Linoleic acid (C18 : 2 n-6) tended to be higher ( P = 0·06) in milk from ewes on concentrates while linolenic acid (C18 : 3 n-3) was significantly higher ( P < 0·001) in milk from animals grazing pasture. Conjugated linoleic acid (cis-9, trans-11 C18 : 2) was almost double in milk from grass-fed ewes compared with animals given concentrates ( P < 0·001). Regarding lamb tissue, trans-vaccenic acid (C18 : 1 trans-11) was higher ( P = 0·01) in the fat from lambs raised by grazing ewes. Linoleic acid (C18 : 2 n-6) was at higher concentration ( P < 0·001) in the fat from lambs raised by ewes given concentrates. Linolenic acid (C18 : 3 n-3) was increased three-fold ( P < 0·001) in the fat of lambs from the grass group compared with lambs suckled by ewes given concentrates. The isomer cis-9, trans-11 of conjugated linoleic acid was present at double concentration ( P < 0·001) in the fat from animals raised by grazing ewes. Eicosapentaenoic (C20 : 5 n-3; EPA) and docosaesaenoic (C22 : 6 n-3; DHA) acids were higher (respectively P < 0·001 and P = 0·01) in the intramuscular fat from lambs from the grass group compared with animals from the concentrate group. The n-6/n-3 ratio was lower ( P < 0·001) in the meat from lambs raised by grazing ewes. Overall this trial showed that ewe feeding system strongly affects intramuscular fatty acids even in lambs raised exclusively on maternal milk.
|Titolo:||Effect of ewe feeding system (grass v. concentrate) on intramuscular fatty acids of lambs raised exclusively on maternal milk|
|Data di pubblicazione:||2005|
|Appare nelle tipologie:||1.1 Articolo in rivista|