The effect of increasing extruded linseed level on nutrient digestibility, growth, carcass characteristics, and non-carcass components of lambs from two genotypes.

This research aimed to study the effect of extruded linseed level on digestibility, growth, carcass, and non-carcass components of two genotypes' lambs. For this, 36 lambs, with an average body weight (BW) of 21.3 ± 3.4 for Queue Fine de l'Ouest (QF) and 17.8 ± 2.9 kg for the cross QF × D'man (QF × D), were randomly divided into three groups of 12 lambs each (six per genotype) in a 12-week experiment. Sheep in each group received individually oat hay ad libitum and one of three concentrates containing 0% (control), 15% (L15), and 30% (L30) of extruded linseed on a dry matter basis. All concentrates were isocaloric and iso-nitrogenic. In the last 2 weeks, digestibility was measured, and then all lambs were slaughtered. The increasing level of extruded linseed did not affect hay and total dry matter (DM) intake as well as nutrient digestibility, except the neutral detergent fiber (NDF) digestibility which was significantly (P < 0.05) reduced by the diet treatment (66.4, 57.8, and 53.0% for C, L15, and L30, respectively). In addition, the different linseed levels resulted in similar average daily gain, final BW, carcass traits, and non-carcass components except the rumen and liver weights which were significantly (P < 0.05) reduced by the increasing linseed level. However, the addition of extruded linseed improved (P < 0.05) the weight of the heart. The carcass tissular composition was not affected by the dietary treatment guarding a similar proportion of muscle, bone, and fat. However, the growth performance and carcass traits were higher for cross QF × D than QF lambs. In addition, the carcasses were leaner (less fat and more muscle) for the cross genotype (P < 0.05) than the pure QF breed. It was concluded that extruded linseed can be used in lamb diet without adverse effects on growth performance and carcass components. Furthermore, the cross could be planned given it resulted in higher growth and better carcass composition.

Reliability of visible reflectance spectroscopy in discriminating between pasture and stall-fed lambs from thin and fat-tailed sheep breeds in dry and hot environment.

Considering the additional market value of pasture meat, many authentication methods were developed to discriminate it from meat produced in conventional systems. The visible reflectance spectroscopy technique has proved its efficiency under European conditions and breeds. The present study tested the reliability of this method to discriminate between pasture-fed (P) and stall-fed (S) lambs under North African conditions and investigated the effect of feeding system (FS) (P v. S) and breed (Barbarine; Queue Fine de l'Ouest; and Noire de Thibar) on weight and colour of perirenal, subcutaneous and caudal fat. A total of 18 P and 18 S lambs were used with 6 P and 6 S lambs for each breed. The colour and the reflectance spectrum of different fat tissues were measured. The FS affected weights of all fat tissues and all colour parameters of perirenal and subcutaneous fat (P ≤ 0.01); it almost affected redness and yellowness of caudal fat (P ≤ 0.05; P ≤ 0.01). In all adipose tissues, lightness was higher and both redness and yellowness were lower for S lambs than P lambs. The breed affected weight, lightness and redness of perirenal fat and weight and redness of subcutaneous fat with significant interaction with FS for subcutaneous fat data. To discriminate P lambs from S lambs, the reflectance spectrum of perirenal, subcutaneous and caudal fat at wavelengths between 450 and 510 nm (Method 1, M1) or at wavelengths between 400 and 700 nm using partial least squares discriminative analysis as a classification method (Method 2, M2) were used. M2 yielded to a higher proportion of correctly classified lambs compared with M1 (P = 0.001). The proportion of correctly classified lambs using M2 was 76.4, 75.0 and 80.0% for perirenal, subcutaneous and caudal fat for P lambs and 83.3, 76.4 and 100.0% for S lambs. Despite lower reliability in comparisons to European researches, this study confirmed the efficiency of visible reflectance spectroscopy technique applied on perirenal fat in feeding systems authentication under North African conditions and spotted the caudal fat as a new support for better classification of fat-tailed breeds.

Growth performance, carcass and noncarcass traits and meat quality of Barbarine lambs fed rosemary distillation residues.

The aim of this experiment was to study the effect of total replacement of oat hay by rosemary distillation residues (RR) on growth, carcass characteristics and meat quality of Barbarine lambs. A total of 21 lambs were divided into three groups. The control group (C) was offered 600 g of oat hay; the RR87 and RR60 groups received 600 g of pellets containing 87% and 60% of RR, respectively. The CP content was 9% and 14% for RR87 and RR60, respectively. All animals were supplemented by 600 g of concentrate. After 77 days of fattening, lambs were slaughtered. The DM and CP intakes were significantly increased with RR diets. The average daily gain was higher (P<0.001), while the feed conversion rate was lower for RR60 and RR87 than C group. The dressing percentage was similar for all groups. The tissular (muscle, fat and bone) and the regional (leg, shoulder, etc.) carcass composition did not differ among groups. The bony organs and gut weights were similar among groups, while functional ones (skin, liver, kidney and testicles) were significantly heavier for both RR groups than control. The ultimate pH, water cooking loss and color variables were similar among groups and the chemical composition (protein, fat, myoglobin, collagen and iron) did not differ also among groups. These results revealed the opportunity of RR use in fattening lambs without adverse effects on carcass and meat characteristics. Moreover, 9% CP in RR pellets are enough given the same growth performance recorded as that of RR with 14% CP.

Rosemary distillation residues reduce lipid oxidation, increase alpha-tocopherol content and improve fatty acid profile of lamb meat.

The experiment studied the effects of rosemary distillation residues (RR) intake on lamb meat quality, oxidative stability and fatty acid (FA) profile. Barbarine lambs of Control group were fed 600g of hay, which was substituted by 600g of pellets containing 60 and 87% of RR for RR60 and RR87 groups; all animals received 600g of concentrate. Meat protein and fat content was similar for 3 treatments. Lipid oxidation was strongly reduced with RR diets. Both RR diets resulted in a higher α- tocopherol content in muscle. The metmyoglobin and deoxymyoglobin percentages were similar for all groups; however oxymyoglobin was higher for RR groups. The saturated (SFA) and unsaturated FAs (UFA) were unaffected by the diets. However, the PUFA, n-6 and n-3 were higher for RR groups. In conclusion, rosemary residues resulted in higher vitamin E content, so it enhanced the oxidative status and improved the fatty acid profile of lamb meat.

Use of spineless cactus (Opuntia ficus indica f. inermis) for dairy goats and growing kids: impacts on milk production, kid's growth, and meat quality.

The objective of this study was to determine the effect of spineless cactus incorporation in food of dairy goats and growing kids on milk production and composition and on kid's growth and meat characteristics. Two experiments were conducted on Tunisian local goats. In the first, 30 females were divided into two groups; goats of Control group were reared on grazing pasture receiving indoor 0.5 kg of hay and 0.4 kg of concentrate. Goats for the second group (Cac-FL) were kept in feedlot and fed cactus ad libitum more 0.5 kg of hay and 0.4 kg of concentrate. In the second experiment, 14 kids were divided into 2 groups receiving 600 g of hay. The Control group received ad libitum a concentrate containing 130 g crude protein (CP) per kg of dry matter. The second group received cactus ad-libitum plus the half concentrate quantity of control one with 260 g CP/kg DM (Cactus). The daily milk production averaged 485 ml for Control group and 407 ml for Cac-FL one. The milk fat content was significantly higher for Control than Cac-FL group. In the second experiment, animals in Control and Cactus groups had similar growth rate. Carcass fat was significantly lower in Cactus than in the Control group. Cactus in the diet was associated with more C18:2 and conjugated linoleic acid as well as a higher proportion of PUFA than Control ones.

Effects of feeding system and nitrogen source on lamb growth, meat characteristics and fatty acid composition.

For this study, 28 lambs were allocated to four groups: two groups were raised in stalls and fed a hay-concentrate ration. The two remaining groups were reared on dry pasture and received concentrate in stalls. In each feeding system, two iso-nitrogen concentrates were used, soya bean and soya plus faba bean. At the end of the growth trial (77 days), all lambs were slaughtered. Samples of longissimus dorsi muscle were used for muscle analysis and fatty acid (FA) composition determination. Average daily gain (134g) was similar for all treatments. Stall lambs deposited significantly (p<0.001) more fat per day (13 vs 5g) and slightly more muscle (41 vs 35g) than pasture grazing ones; the first had more fat tissue (5.2kg) than the later (4.6kg). All these parameters were not influenced by nitrogen source. FA profile and meat characteristics were similar for all dietary treatments. It could be concluded that dry pasture did not affect meat quality but lead to the leaner lambs.

The effect of spineless cactus (Opuntia ficus-indica f. inermis) supplementation on growth, carcass, meat quality and fatty acid composition of male goat kids.

The objective of this study was to determine the effects of grain compared to spineless cactus feeding on goat kids growth, carcass characteristics and FA profile. For this purpose, 21 kids were used and allocated to 3 groups receiving a low quantity (200g) of oat hay. The control group received ad libitum a concentrate containing 130g crude protein (CP) per kg of dry matter (C130). The second group received half of that contained consumed by the control one but its CP content was 260g/kg DM and spineless cactus ad libitum (C260-Cac). In the third group, concentrate intake was limited to soya bean at a quantity that provided the same CP quantity as the two other groups and also cached spineless cactus was distributed ad libitum (Soya-Cac). Animals of all groups had free access to water. At the end of the growth trial which lasted for 74 days, all kids were slaughtered. Samples of longissimus dorsi muscle were used for meat quality and FA composition study. Animals in the control group and those in the C260-Cac had higher growth rate than Soya-Cac diet animals. Muscle and adipose tissue mean weights were higher in the first groups while the bone weight was similar in all treatments. Animals given Soya-Cac diet had relatively less fat (10.5%) than those fed other diets (p<0.001). Carcass fat content tended to be lower (p=0.07) in C260-Cac goats (13.5%) than in those of the C130 group (15.8%). The ultimate pH ranged between 6.18 and 6.48; it was higher in meat from control goats (C130) than in animals receiving cactus. Dietary treatment had no significant effect (p>0.05) on meat moisture, ash, crude fat and protein contents. The intra muscular lipid composition in fatty acids showed differences between the control group and those receiving cactus. Cactus in the diet was associated with more C18:2 and conjugated linoleic acid (CLA) as well as a higher proportion of PUFA and PUFA:SFA ratio than control ones. In conclusion, this study showed that cactus feeding of goat kids maximises the proportion of CLA, PUFA and PUFA:SFA ratio.