M. Bella

Lipid and colour stability of meat from lambs fed fresh herbage or concentrate

Fourteen male Comisana lambs were divided into two groups at 45days of age and were individually penned for 105days. Over this period, seven lambs were fed a concentrate-based diet (C), whereas the remaining animals received vetch (Vicia sativa; H) harvested daily and given fresh to the animals. Lipid oxidation was measured in both minced cooked meat (semimembranosus muscle, SM) over 4days of aerobic refrigerated storage and on minced raw meat stored over 14days in a high oxygen atmosphere. Colour descriptors, haem pigment concentration, and metmyoglobin percentages were also determined during storage duration on the minced raw meat. Lipid oxidation increased over time in cooked and raw meat (P<0.0005), but lower TBARS values were found in both cooked and minced meat from lambs fed vetch compared to those given concentrates (P=0.001; P=0.006, respectively). Higher a* values, lower b* values and lower hue angle values were observed in meat from H-fed animals as compared to meat from C-fed lambs (P=0.006; P=0.02; P=0.005, respectively). Metmyoglobin formation increased over time (P<0.0005), but the H diet resulted in lower metmyoglobin percentages than the C diet (P=0.006). Haem pigment concentration decreased over the 14days of storage (P<0.0005). We conclude that, under conditions that promote oxidative stress in meat, a herbage-based diet can improve the oxidative stability of meat compared to a concentrate-based diet.

Lamb meat quality as affected by a natural or artificial milk feeding regime

Fourteen Barbaresca lambs were divided into two groups of seven at 24h from birth and reared exclusively on natural milk (NR) or on artificial milk (AR). Lambs were slaughtered at 40 days of age. The NR group tended (P<0.10) to grow faster, thus resulting in a higher (P<0.10) carcass weight as compared to the AR group. AR meat was darker (P<0.05), leaner (P<0.001) and with a higher moisture (P<0.10) and ash (P<0.05) content than its counterpart. The proportion of polyunsaturated fatty acids was higher (P<0.01), while that of saturated lower (P<0.01) in meat from the AR group, resulting in a higher (P<0.01) polyunsaturated/saturated ratio. Linoleic acid content (P<0.001) and its n-6 series derivatives, except 9-12 trans C18:2 n-6 (P<0.001), increased more in the AR group meat than in the NR group. On the other hand, α-linolenic (P<0.001) and other n-3 series fatty acids were higher in meat from the NR group than in the AR group, leading to a lower (P<0.001) n-6/n-3 ratio. Furthermore, 9 cis 11 trans CLA was higher (P<0.001) in NR meat compared to AR meat. Finally, a milk-feeding regime exclusively based on artificial milk adversely affected the dietetic value of lamb meat compared to a natural rearing system, reducing the level of desirable fatty acids such as n-3 series and CLA.

Intramuscular fatty acid composition of lambs given a tanniniferous diet with or without polyethylene glycol supplementation

The aim of this trial was to investigate the effects that dietary tannins have on lamb intramuscular fatty acids. Twenty-seven lambs were divided into three homogeneous groups: control group, receiving commercial concentrate based on maize; tannin group, fed a diet based on carob pulp (45% as fed basis); PEG group, receiving the same diet as the latter with addition of 42g/kg of polyethylene glycol (PEG, a binding agent that eliminates the effects of condensed tannins). The duration of the trial was 45 d. Intramuscular fatty acids were measured in the longissimus dorsi muscle. The isomer cis-9 trans-11 of linoleic acid (conjugated linoleic acid or CLA) and linolenic acid were higher in the longissimus muscle fat from animals fed the control diet compared to the other groups (P<0.0005); these fatty acids were higher in the fat from animals fed the carob diet supplemented with PEG compared to those fed the same diet without PEG (P<0.05). trans-Vaccenic acid (C18:1 trans-11) was found at higher concentration in fat from control and PEG lambs compared to tannin lambs (P<0.01); the CLA/C18:1 trans-11 ratio was lower in lambs fed control and PEG diets than in tannin-fed animals (P<0.05).

Effect of ewe feeding system (grass v. concentrate) on intramuscular fatty acids of lambs raised exclusively on maternal milk

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.

Meat odour and flavour and indoles concentration in ruminal fluid and adipose tissue of lambs fed green herbage or concentrates with or without tannins.

A 2 × 2 factorial experiment was carried out to evaluate the effect of herbage or concentrate feeding system and tannin addition to diet on skatole and indole in ruminal fluid and adipose tissue and meat sensory properties. Twenty-eight male lambs aged 45 days were randomly assigned to one of two feeding systems (vetch green herbage or concentrates, n = 14) and within feeding system to one supplement (quebracho tannins added to the diet or none). Animals were kept in singular pens and slaughtered at the age of 105 days. Indole (P < 0.05) and skatole (P < 0.01) concentrations in ruminal fluid were higher in lambs fed herbage compared to those given concentrates. Skatole in ruminal fluid tended to be present at lower concentrations in animals that received the tannin supplementation (P = 0.07). Indole was also higher in the caudal fat of animals fed green vetch compared to those fed concentrate (P = 0.04). Skatole concentration was lower in the fat of lambs fed concentrates compared to those given herbage (P = 0.05) and was lower in the fat of animals supplemented with tannins compared to the animals not supplemented (P = 0.01). Sheep meat odour was lower in meat from animals supplemented with tannins compared to those not supplemented (P < 0.01). It is concluded that tannins are more effective in reducing skatole formation in ruminants when they are associated with concentrate diets than green herbages.

Citrus pulp as an ingredient in ostrich diet: effects on meat quality.

The purpose of this trial was to study the effects of citrus pulp inclusion in ostrich diets on meat quality, evaluated on iliofibularis and gastrocnemius muscles. M. iliofibularis had a lower ultimate pH (P<0.05) and was lighter in colour (P<0.05) than M. gastrocnemius. The latter had higher moisture (P<0.05) and lower crude protein contents (P<0.05) as compared to M. iliofibularis. M. gastrocnemius had a lower proportion of C14:0 (P<0.05), C16:0 (P<0.05) and C16:1 (P<0.05) and a higher percentage of C18:0 (P<0.05), C20:2ω6 (P<0.05), C20:4ω6 (P<0.05) and C20:5ω3 (P<0.05) than M. iliofibularis. Citrus pulp diet increased (P<0.05) meat ultimate pH and reduced cooking losses (P<0.05) as compared to the control diet. Meat from animals given citrus pulp had lower crude fat (P<0.05) and ash percentages (P<0.05) in comparison to that from the control group. The proportions of intramuscular saturated and monounsaturated fatty acids were lower (P<0.05) in the citrus pulp group as compared to the control one. Meat from the citrus pulp treatment group had a higher (P<0.05) percentage of polyunsaturated fatty acids than meat from the control treatment. In particular, meat from ostriches given citrus pulp diet exhibited higher C18:2ω6 (P<0.05) and C20:4ω6 (P<0.05) contents that accounted for a higher ω6/ω3 ratio (P<0.05) as compared to the control group. Overall, the use of a citrus pulp-included diet in ostrich feeding did not adversely affect meat quality and, therefore, citrus pulp seems to be a possible ingredient to reduce feeding costs.

Effect of dietary saponins from Quillaja saponaria L. on fatty acid composition and cholesterol content in muscle Longissimus dorsi of lambs

The purpose of this study was to evaluate the effects of increasing levels of saponins from Quillaja saponaria on fatty acid (FA) composition and cholesterol content in muscle Longissimus dorsi of lambs. A total of 24 Barbarine lambs were assigned to four dietary treatments: control diet (C) consisting of oat hay ad libitum and 400 g of concentrate (80% barley, 17.5% soybean meal and 2.5% vitamin and mineral supplement); C diet plus 30 ppm of Q. saponaria L. (QS30); C diet plus 60 ppm of Quillaja (QS60); C diet plus 90 ppm of Quillaja (QS90). Saponin supplementation reduced the concentration of C14:1 cis-9 (P = 0.001) and of its desaturation index (P = 0.002). None of the FA intermediates of ruminal biohydrogenation (BH) was affected by Quillaja saponin supplementation (P > 0.05). The concentration of C20:4n-6 was higher in the meat of animals receiving 60 ppm of Quillaja than C and QS30 groups. Supplementing 60 ppm of Quillaja reduced the ratio between α-linolenic and linoleic acids compared with the C group (P = 0.023). We did not find any significant effect of Quillaja saponins on muscle cholesterol level. Further investigations are necessary to assess the metabolic fate of saponins in the rumen and to understand whether there is an effect of saponin on Δ9-desaturase enzyme activity, ruminal BH and cholesterol metabolism in ruminants. Supplementing up to 90 ppm of Quillaja saponins did not produce detrimental effects on the overall meat FA profile.

Lamb meat quality and intramuscular fatty acid composition as affected by concentrates including different legume seeds

The aim of this experiment was to study the effect of concentrates including legume seeds (Vicia faba var. minor or Pisum sativum) on lamb performances and meat quality, emphasizing the intramuscular fatty acid composition. Thirty lambs (14.5±3.45 kg live weight) were randomly assigned to three dietary treatments: i) group fed on concentrate including 400 g/kg of peas (PEA); ii) group fed on concentrate including 380 g/kg of faba bean (FB); iii) group fed on concentrate including 180 g/kg of soybean meal (SBM). Growth and slaughter performances were not affected by treatments as well as physical and proximate chemical meat characteristics. FB and SBM meat showed higher (P<0.001) vaccenic acid levels compared to PEA meat. Oleic acid was higher (P<0.05) in PEA meat compared to SBM meat while its level in FB meat was similar to counterparts. Linoleic acid levels tended to increase (P<0.10) in SBM lambs compared with PEA animals. PEA group showed higher (P<0.001) α-linolenic acid proportions compared with FB and SBM groups and a tendentially higher (P<0.10) eicosapentaenoic acid content compared with SBM meat. As a result, total n-3 fatty acids were higher (P<0.05) in PEA meat compared to SBM one while the proportions in FB meat were at intermediate level. These findings accounted for a lower and more favourable (P<0.001) n-6/n-3 ratio in PEA group compared with counterparts. Peas based-concentrate seemed to be more effective than faba bean- or soybean meal-included concentrates to improve the acidic profile of meat leading to higher α-linolenic acid levels and a lower n-6/n-3 ratio.

Partially or totally replacing soybean meal and maize by chickpeas in lamb diets: intramuscular fatty acid composition

Twenty-six Barbaresca lambs were randomly divided into three groups at age 60 days (SBM, Chickpeas 20, or Chickpeas 42). The SBM lambs received a commercial pelletted diet. The Chickpeas 20 received a diet in which part of the maize and part of the soybean meal were replaced by 20% of chickpeas. The Chickpeas 42 lambs received a diet with 42% of chickpeas and with neither maize nor soybean meal. Animals were slaughtered at 132 days of age and fatty acid composition of intramuscular fat was determined in the longissimus dorsi muscle. The dominant fatty acid in the meat from animals of all the three groups was the C18:1 cis (n-9). The proportion of this fatty acid was lower in the Chickpeas 42 lambs compared to the SBM and to the Chickpeas 20 lambs (P<0.01). Meat from animals receiving 42% chickpeas had higher proportions of C18:3 (n-6) than SBM animals (P<0.01). The C18:2 9-cis, 11-trans (conjugated linoleic acid (CLA)) increased with the proportion of chickpeas and was higher in the Chickpeas 20 and in the Chickpeas 42 animals compared with the SBM animals (P<0.05). The total replacement of soybean meal and maize by chickpeas gave a meat with higher proportions of C22:5 (n-3). Finally, the sum of n-3 fatty acids tended to be higher in the diet with 42% chickpeas.

The quality of meat from sheep treated with tannin- and saponin-based remedies as a natural strategy for parasite control.

Lambs were assigned to four groups of seven and treated as follows for 12 days: control group (BP) was fed beet pulp; group T (tannin remedy) received the BP diet including 80 g/kg of quebracho extract; group S (saponin remedy) received the BP diet including 15 g/kg of quillaja extract; and group C had a free choice between T and S remedies. Lipid oxidation was lower in meat from S lambs compared to T lambs (P<0.05). Among the volatile compounds, lactate was lower in meat from S lambs compared to T animals (P=0.05). Metabolomic analysis showed that the T treatment increased ribose, fructose, glucose and sorbitol concentration in meat (P<0.05), while cholesterol was decreased by S and C treatments. The T treatment increased the concentration of C14:1 cis-9 (P<0.05). These findings indicate that treatments for parasite control containing tannins and saponins do not detrimentally affect sheep meat quality.