Naziha Atti

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.

Polyethylene glycol in concentrate or feedblocks to deactivate condensed tannins in Acacia cyanophylla Lindl. foliage 1. Effects on intake, digestion and growth by Barbarine lambs

Thirty young male sheep were given air-dried foliage of Acacia cyanophylla Lindl. ad libitum and 400 g oat hay. Animals were divided into five equal groups each of which was supplemented with either 300 g concentrate with (C PEG ) or without (C) 20 g polyethylene glycol 4000 (PEG) or urea-containing feedblocks with (BU PEG ) or without (BU) PEG. One other treatment was PEG-containing feedblock without urea (B PEG ). PEG was used to preferentially bind A. cyanophylla condensed tannins (CT). Feedblocks (BU, B PEG and BU PEG respectively) were made from olive cake (395, 376 and 353), wheat bran (263, 250 and 235), wheatfeeds (132, 125 and 118), quicklime (88, 83 and 78), salt (44, 42 and 39), mineral and vitamin supplement (12, 10 and 10), urea (66, 0 and 59) and PEG (0, 114 and 107 g/kg). These diets were used in growth (60 days) and metabolism (7 days) studies. Ureacontaining feedblocks, as compared with concentrate, were higher in crude protein (CP; 235 v. 116 g/kg DM) and lower in metabolizable energy (6 v. 10 MJ/kg DM). The type of supplement (i.e. concentrate v. feedblocks) had no effect ( P > 0·05) on A. cyanophylla DM intake, CP and neutral-detergent fibre (NDF) digestibilities and nitrogen (N) retention. However, concentrate-containing diets exhibited higher DM and organic matter (OM) digestibilities ( P < 0·05), urinary excretion of allantoin ( P < 0·05), microbial N supply ( P < 0·001) and average daily gain ( P < 0·001). PEG supply increased DM intake of A. cyanophylla , CP digestibility, N retention, allantoin voided in urine, microbial N supply and lamb growth. PEG-containing feedblocks enriched (BU PEG ) or not (B PEG ) with urea had similar effect on A. cyanophylla intake, DM, OM and NDF digestibilities, allantoin in urine, microbial N supply and average daily gain. These findings suggested that urea inclusion in feedblocks are not necessary and thus the feeding cost may be reduced. The higher amount of microbial N and daily gain in lambs given concentrate as compared with those on feedblock-supplemented diets was ascribed to the level of energy which was low in the latter diets. Enrichment of feedblocks with energy-rich ingredients such as molasses or cactus fruits could be a solution. This work confirmed that tannins depressed the nutritive value of this shrub species and lamb growth. However, the reduction was not drastic in the absence of PEG in the diet. Feedblock diet (BU) matched maintenance requirements of lambs while lambs on concentrate-supplemented diet (C) grew at a rate of 78 g/day. The choice between these two supplements will depend upon farm conditions and objectives.

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.

Polyethylene glycol in concentrate or feedblocks to deactivate condensed tannins in Acacia cyanophylla Lindl. foliage 2. Effects on meat quality of Barbarine lambs

Twenty-five male Barbarine lambs aged approximately 150 days were divided into five groups. All the animals received 400 g/day of oat hay and Acacia cyanophylla Lindl. foliage ad libitum . Two groups also received 300 g/ day of a mixture (70 : 30) of processed barley and wheat bran, with or without 20 g polyethylene glycol 4000 (PEG), groups C PEG and C respectively. The three other groups had free access to feedblocks based on olive cake, and containing urea, urea and PEG, or PEG, groups BU, BU PEG and B PEG respectively. Lambs were slaughtered at age 230 days and meat quality was determined in the longissimus thoracis et lumborum muscle. Lean colour was significantly affected by dietary condensed tannins. Lightness (L*) was higher in those animals that did not receive PEG ( P < 0·001) indicating that condensed tannins can cause lighter meat colour. This difference was not due to the ultimate pH, which was not affected by the inclusion of PEG in the diet. Meat from groups that received supplementation of concentrate had lower values of resistance to the Warner-Bratzler shear device compared with those that received feedblocks. This result was confirmed by a taste panel, that found samples from groups C and C PEG more tender than samples from groups BU, BU PEG and B PEG . Inclusion of PEG in the diet increased intensity of flavour ( P < 0·05) but had no effect on overall acceptability. Meat from animals that had received the concentrate had higher overall acceptability ( P < 0·05) than meat from animals that received the feedblocks. No differences were found in meat chemical composition.

Effects of restricted feeding and re-feeding of Barbarine lambs: carcass composition and fatty acid composition

Fifty intact male Barbarine lambs were used to assess the effects of restricted feeding and re-alimentation on carcass composition and fatty acid (FA) composition of intramuscular fat. Five lambs were slaughtered at the start of the trial; the remainder were randomly allocated to three groups. One group was offered only stubble grazing (low : L), another, also on stubble, received, indoors, an average of 80 g dry matter (DM) of soya-bean meal per day (medium : M); the third group was kept indoor and had free access to hay and 450 g of concentrate (high : H). At the end of this restriction period (70 days), five lambs per group were slaughtered. The 10 remaining animals in each group were divided into two groups receiving concentrate and hay ad libitum. The crude protein (CP) content of the concentrate was 160 and 210 g/kg DM in the two treatments, respectively. At the end of the trial all animals were slaughtered at 37·61 ± 2·05 kg live weight. In the restriction period, bone tissue was similar in terms of mass for all diet treatments. The absolute weight of muscle and fat in carcasses was higher for unrestricted sheep ( H) than for restricted ones, but L and M lambs had proportionately less fat and more muscle than those given food indoors. Intramuscular fat composition was similar for all the treatments. During this period, the carcass gain of M lambs had the highest proportion of muscle and the lowest fat concentration, which is the better composition. At the end of the compensating period, all carcasses contained the same quantity of bone and muscle, but unrestricted sheep had significantly more fat than compensating ones. So, carcasses of compensating animals contained relatively less fat (240 v. 310 g/kg) and more muscle (550 v. 500 g/kg) than unrestricted ones. The carcass gain of lambs with an earlier nutritional history on L had the highest muscle and the lowest fat concentration. The intramuscular lipid composition in terms of fatty acids showed differences between treatments. Unrestricted animals contained more C14 : 0 and C16 : 0 and compensating animals more C18 : 2 and a higher proportion of polyunsaturated fatty acids ( PUFA) and PUFA : saturated FA ratio. There were no significant differences associated with CP level during the re-alimentation period