Effects of temporary intensive feed restriction on performance,nutrient digestibility and carcass criteria of growing male Californian rabbits

The aim of the study was to evaluate the effect of a temporary quantitative feed restriction on growth performance, nutrient digestibility and carcass criteria of rabbits. A total of 80 weaned male Californian rabbits (30 d of age) were randomly assigned to four treatments of 20 rabbits each. The Control group was fed ad libitum during the whole experimental period (days 30–72 of age). For the three restricted fed groups the feed intake was reduced by 15%, 30% and 45% compared to the Control group, respectively. The feed restriction was applied after weaning and lasted for 21 d. Thereafter, at 51 d of age, in all treatments the feed supply returned to ad libitum intake till 72 d of age (AL period). The feed restriction decreased the body weight gain of rabbits (during the restriction period and the whole experimental period, p < 0.001) and improved feed conversion ratio during all tested periods (p < 0.001). In the AL period, the daily body weight gain of all groups was similar. After the AL period, the digestibility of all measured nutrients was significantly higher for animals fed restrictively. Furthermore, feed restrictions significantly decreased the proportion of perirenal and scapular fat and increased relative weight and length of the gastrointestinal tract. Therefore, it can be concluded that the applied feed restriction improved feed conversion, nutrient digestibility and reduced fat at the slaughter age of Californian rabbits, but the reduced body weight gain could not be compensated by a subsequent ad libitum feeding for 3 weeks.     

Dried artichoke bracts in rabbits nutrition: effects on the carcass characteristics,meat quality and fatty-acid composition

In this study, the effects of the inclusion of artichoke bracts (AB) in rabbit diets on the carcass characteristics and rabbit meat quality were studied. A total of 120 rabbits aged 38 days were used and divided into three groups that were fed with different isonitrogenous and isocaloric diets supplemented with AB at 0%, 5% and 10%. The animals were single housed in wire cages at a temperature of 22±2°C and had free access to clean drinking water. At 96 days of age, 12 rabbits/group were slaughtered in an experimental slaughterhouse without fasting. The carcass was weighed and the weights of the skin and full gastrointestinal tract were recorded. Carcasses were chilled at +4°C for 24 h in a refrigerated room. The chilled carcass weight (CCW), dressing out percentage (CCW as percentage of slaughter weight), and the ratio of the head and liver were determined as a percentage of CCW. The reference carcass weight was also calculated. Carcasses were halved and the two longissimus dorsi (LD) muscles were excised. The left LD muscle was divided into two parts. The fore part was used to measure pH, colour and cooking losses. The hind part of the left LD was vacuum-packed, frozen at –20°C and then freeze-dried. Proximate composition, fatty-acid profile and thiobarbituric acid-reactive substances values were determined on freeze-dried samples. Results showed that carcass characteristics, LD muscle traits and its oxidative status were not affected by the AB supplementation, except for the meat ether extract content that increased from 0.68% to 0.94% on fresh matter basis with the increase of the AB supplementation (P<0.01). The α-linolenic acid proportion decreased with the increase of the AB supplementation from 3.58% to 2.59% in the LD muscle and from 4.74% to 3.62% in the perirenal fat, whereas the n-6/n-3 ratio increased significantly with increasing AB inclusion from 7.15 to 10.20 in the LD muscle and from 6.68 to 9.35 in the perirenal fat (P<0.01). Furthermore, no significant difference was found in preference among meat samples from each group. The enrichment of the rabbit’s diet with AB allows the production of rabbit meat with a good degree of unsaturation and low saturation, even if the n-6/n-3 ratio was slightly worse.     

Effect of sire breed on carcass characteristics and meat and fat quality of heavy pigs reared outdoor and intended for dry-cured meat production

A trial was conducted to study the effect of sire line (Duroc (DU) and Pietrain (PI)) on carcass, meat and fat quality of pigs reared outdoor and destined to dry-cured meat production. No differences between sire genotypes were detected in carcass fat thickness (P > 0.10) but carcasses from DU-sired pigs were longer (P < 0.05) and tended to have a higher yield of trimmed shoulders (P = 0.07) and hams (P = 0.06) than carcasses from PI-sired pigs. Loins from DU-sired genotype showed higher (P < 0.05) L* value and lower (P < 0.01) a* value than loins from PI-sired genotype. Pork from DU-sired offspring tended to have higher (P = 0.09) intramuscular fat (IMF) percentage and lower (P < 0.05) moisture proportion than meat from PI-sired offspring. Also, loins from DU-sired pigs had lower (P < 0.001) thawing losses than loins from PI-sired pigs. The subcutaneous fat from the DU-sired line tended to show lower (P = 0.08) percentage of total polyunsaturated fatty acids (PUFAs) than that from the PI-sire line, mostly due to the higher proportion of C18:2 (P = 0.09) and C20:3 (P < 0.01). However, no effect of crossbreed was detected on the total proportion of saturated, monounsaturated fatty acid (MUFAs) or PUFAs of IMF (P > 0.10). We conclude that both sire lines can be used successfully under outdoor conditions but DU boars are more adequate than PI boars for the production of heavy pigs intended for the dry-cured meat industry.     

Housing of growing rabbits in individual,bicellular and collective cages: growth performance,carcass traits and meat quality

During growth (from 27 to 75 days of age), 384 rabbits were kept in different types of wire-net cages: 72 individual cages (72 rabbits; 10 animals/m²), 48 bicellular cages (96 rabbits; 2 rabbits/cage; 18 animals/m²) and 24 collective cages (216 rabbits; 9 rabbits/cage; 18 animals/m²). The rabbits housed in individual cages showed higher daily weight gain both during the fattening period (from 52 to 75 days of age) and during the whole period of growth (43.0 v. 41.8 and 41.5 g/day; P < 0.05), and they had a higher final live weight at 75 days of age (2678 v. 2619 and 2602 g; P < 0.05) compared with the rabbits in the bicellular and collective cages, respectively. Rabbits in individual cages ingested more feed (133 v. 127 and 126 g/day; P < 0.01), but the feed conversion did not differ significantly among rabbits housed in the three types of cages. At slaughter, the carcass traits and meat quality were weakly affected by the housing system. The transport losses were higher in rabbits kept in individual and bicellular cages compared with those reared in collective cages (3.1% and 2.9% v. 2.2%; P < 0.01). In rabbits kept in individual cages, the hind leg muscle to bone ratio was higher (6.35 v. 6.19 and 5.91; P < 0.05) compared with the bicellular and collective cages, respectively. The pH and colour of the longissimus lumborum did not change with the housing system, while the b* index of the biceps femoris was lower (3.04 and 3.32 v. 4.26; P < 0.001) in the rabbits kept in individual and bicellular cages, respectively, than in those kept in collective cages. In conclusion, the rabbits housed in individual cages showed higher daily growth than rabbits kept in bicellular or collective cages, but they had a similar feed conversion and carcass quality. Differently, neither in vivo performance nor slaughter results differed among the rabbits kept in bicellular cages or in collective cages. The meat colour may be affected by the housing system, but to an extent that is hardly perceivable by the final consumer.     

Effect of purple loosestrife (Lythrum salicaria) diet supplementation in rabbit nutrition on performance,digestibility, health and meat quality

In this study, 160 Hycole weaned rabbits (35 days old) were randomly divided into four groups of 40. The rabbits were studied throughout a 54-day experimentation period in order to determine the impact of dietary supplementation from herbs composed of 0.2%, 0.4% dry ground Lythrum salicaria leaves (LS) and 0.3% Cunirel® (CR; a commercial herb mixture containing LS as the main ingredient) on performance, digestibility, health and meat quality. The basal diet was given to the control group. No significant differences were found in performance, 10 rabbits from each group were selected for evaluation regarding apparent digestibility. The rabbits fed the control diet and the diet with the low level of LS had a higher level of CP digestibility than did the animals that were supplemented with the high LS levels and CR (85.7% and 84.9% v. 84.0% and 84.0%, respectively; P<0.05). The ether extract digestibility was lower in the treatment group with 0.4%LS addition and CR as compared with the control group (52.2% and 54.5% v. 62.6%, respectively; P<0.05). The slaughter process was performed on 89-day-old rabbits to study the carcass characteristics, meat quality, blood parameters, caecal contents and gut histology. The total leukocyte counts in the control animals were lower than they were in the rabbits fed 0.2%, 0.4%LS and CR (4.06 v. 8.25, 8.63 and 8.21×10⁹/l, respectively; P<0.05). For caecal fermentation, the caecal contents of the rabbits fed 0.4% of LS, showed higher concentrations of total volatile fatty acid (VFA; 24.1 v. 18.9 mg/kg dry matter (DM); P<0.05) and acetic acid (18.3 v. 14.4 mg/kg DM; P<0.05), but lower ammonia levels (594 v. 892 mg/kg DM; P<0.05) as compared with the control group. PCR-denaturing gradient gel electrophoresis analyses were performed to evaluate the microbial community in hard faeces, collected at days 35, 42, 49, 56, 70 and 89, whereas the caecal contents were taken after slaughtering. The results demonstrated that between the treatment groups, the similarity of the microbial communities was higher as compared with the control group. Moreover, only age was shown to influence microbiota diversity. In conclusion, the results of this study indicated that supplementation of LS in rabbit diets leads to an increase in the total white blood cells, total VFA and acetic acid concentration, and a decrease in the ammonia levels, as well as the digestibility when CR and high level of LS were supplemented, without causing any adverse effects on other parameters.     

Influence of gestational maternal feed restriction on growth performance and meat quality of rabbit offsprings

The purpose of the present study was to evaluate the effect of feed restriction during pregnancy on reproductive performance of rabbit does and growth performance and meat quality of their offspring. A total of 26 primiparous non lactating does were equally divided into two treatment groups: the control group (C, n=13) that was fed ad libitum throughout gestation and the feed restricted group (R, n=13) that was fed to 75% of maintenance energy requirements from the 7^th to the 26^th day of gestation. Rabbit offsprings were weaned at 35 days of age and grown until the 72 days of age when they were slaughtered for meat quality assessment. Meat quality traits measured were pH₂₄, colour (L*, a*, b*), percentage of released water, cook loss, shear values and intramuscular fat. At kindling, R does produced smaller litter weights compared with those of does from group C, 447.8 and 591.4 g, respectively, and smaller individual kit birth weights, 56.2 and 71.5 g, respectively (P<0.05). Ratio of stillborn kits and mortality rate from parturition until weaning was higher (P<0.05) in the R group, 21.4% and 11.1%, respectively, in comparison with the C group, 8.1% and 3.5%, respectively. Litter size and gestation length were unaffected by maternal undernutrition. Kit birth weight treatment differences were eliminated at weaning because of compensatory growth (P>0.05). Performance and meat quality characteristics of fattening rabbits at 72 days of age were not influenced by gestational feed restriction of their mothers (P>0.05). Taking into consideration that, simultaneous gestation and lactation in rabbit does may be simulated by gestational feed restriction, results of the present study suggest that lactating does can support a simultaneous gestation without any adverse effect on the offsprings’ quantitative and qualitative performance at the expense of increased mortality rates at parturition and until weaning.     

Effects of replacing palm oil with maize oil and Curcuma longa supplementation on the performance, carcass characteristics, meat quality and fatty acid profile of the perirenal fat and muscle of growing rabbits

An experiment has been conducted to study the effects of the inclusion of plant oil in rabbit diets. This study was aimed at evaluating the beneficial effects of the inclusion of maize oil (MO), rich in unsaturated fatty acids (UFAs), compared to palm oil (PO) containing saturated fatty acids (SFAs), on the meat fatty acid (FA) profile. As UFAs are susceptible to rancidity, Curcuma longa (CL), which is known for its antioxidant properties, was also added (3 g/kg) to the diet with two plant oils. CL contains curcuminoids, volatile oils, sugars, proteins, resins and polyunsaturated fatty acids (PUFAs). We also evaluated the influence of CL inclusion in the diet on the FA profile of the meat. Furthermore, the possibility of using these oil-enriched diets and the ability to assimilate CL in rabbits was evaluated by analysing the performance, carcass characteristics and meat quality. At the end of the experiment, there were no significant differences between the groups concerning the live weight, live weight gain, feed consumption, feed efficiency, carcass yield or the percentages of edible organs. The hind legs, forelegs, loins and abdominal wall, breast and ribs, skin and limbs and head were not affected by the oil type or by the inclusion of CL. The chemical composition, pH and oxidative status of the Longissimus dorsi muscle of the rabbits fed the experimental diets were not affected by the oil source or by the CL supplementation. Conversely, it has been shown that it is possible to modify the FA profile of rabbit meat and fat by dietary means. The SFA/PUFA ratio significantly decreased from -18% to -16% in the meat and from -25% to -23% in the perirenal fat of the rabbits fed diets containing MO without or with CL supplementation, respectively, compared to same tissues of the rabbits fed diets containing PO without or with CL supplementation, respectively. Similar trends were found for the atherogenic index, which decreased from -20% to -17% in the meat and from -26% to -23% in the perirenal fat, respectively, and the thrombogenic index, which decreased from -19% to -24% in the meat and from -24% to -23% in the perirenal fat, respectively. CL increased the α-Linolenic acid and PUFA n-3 contents and reduced the vaccenic acid content and the n-6/n-3 ratio in the meat of the rabbits fed the PO or MO diets.     

Repercussions of growth path on carcass characteristics,meat colour and shear force in Alentejana bulls

The aim of this study was to evaluate the carcass and meat characteristics of eight muscles from bulls with distinct growth paths. A total of 40 Alentejana male calves were allocated to two distinct feeding regimes. In the continuous growth (CG) system, the animals were fed concentrates plus hay and were slaughtered at 18 months of age. On the other hand, in the discontinuous growth (DG) system, the animals were fed hay until 15 months of age; the cattle were then fed the same diet provided to the CG group from 15 to 24 months of age. The DG reduced hot carcass weight, fatness and dressing %, but the proportions of fat, bone and muscle tissues in the leg were not affected. In contrast, there was a positive impact of compensatory growth on supraspinatus, triceps brachii, semitendinosus, biceps femoris muscle tenderness, overcoming the negative effects of age at slaughter. The reasons for such improvement in meat tenderness were not related to intra-muscular fat content or myofibrillar protein degradation values. An association between tenderness and muscle collagen properties was not established. The results indicate that the compensatory growth has a muscle-dependent effect.     

Effect of age and gender on carcass traits and meat quality of farmed brown hares

A total of 48 sub-adult hares and adult reproducing farmed hares were used to characterize carcass and meat traits according to the age and gender of animals. With respect to carcass traits, when age increased, the carcass weight significantly increased (2022 to 3391 g; P<0.001), but dressing out percentages did not change. The dissectible fat (1.3% to 2.2%; P<0.05) and Longissimus lumborum (LL) proportions (13.5% to 14.5%; P<0.001) and muscle-to-bone ratio of hind legs (5.11 to 6.23; P<0.001) increased, whereas the hind leg proportions decreased (37.3% to 36.3%; P=0.01). As for the meat quality, the pH of hind leg (5.74 to 5.83; P<0.001) and LL (5.53 to 5.69; P<0.001) increased with age, while the L* index decreased in both cuts (42.9 to 34.4 in hind leg; 45.1 to 40.3 in LL; P<0.001). The redness index increased at the hind leg (4.07 to 5.76; P<0.001), while it decreased at LL (3.03 to 1.46; P<0.001). In the case of the hind leg, meat thawing losses decreased (1.58% to 1.02%), and shear force increased (2.97 to 4.02 kg/g). In the case of LL, thawing losses decreased (8.79% to 4.91%; P<0.001) in the adult hares compared with the sub-adult ones. Meat water and protein contents decreased in the hind leg and LL of the adult hares compared with the sub-adult ones, whereas ether extract increased in a restricted range in LL only (0.92% to 1.11%; P<0.001). In the case of the hind leg, the rate of the saturated fatty acids (SFA) decreased (41.0% to 26.7%), and the rate of the polyunsaturated fatty acids (PUFA) increased (34.0% to 45.3%) (P<0.001). In the case of LL, SFA (38.6% to 42.9%) and monounsaturated fatty acids (19.4% to 27.2%) increased, whereas PUFA decreased (42.0% to 30.1%) when the age increased (P<0.001). Gender affected only the slaughter results and carcass traits. In conclusion, farmed hares have favourable slaughter results (high dressing percentage), carcass traits (high hind legs and loins rates), and meat nutritional value (high-protein, low-fat meat). This fact would offer additional commercial opportunities, in addition to restocking, to hare farmers.     

兔黑素皮质素受体4(MC4R)基因多态性及其与体重及屠体性状的关联研究

以哈尔滨白兔、天府黑兔、比利时兔、齐卡巨型兔以及加利福尼亚兔5个肉兔品种共220个个体为研究对象, 采用PCR-SSCP技术和克隆测序技术进行SNPs检测和基因型的分析。结果发现兔MC4R基因237位发生转换突变(A→G), 5个品种内的AA基因型和A等位基因频率均分别高于AG基因型和G等位基因, 而哈尔滨白兔、比利时兔以及齐卡巨型兔3个品种兔的AG基因型频率和G等位基因频率明显高于天府黑兔和加利福尼亚兔。单位点基因型与屠体性状、饲料转化率以及熟肉率的最小二乘分析表明; AG基因型与兔的体重、全净膛重以及饲料转化率有显著的关系(P<0.05), 而与熟肉率的关系不显著(P>0.05)。结果表明, MC4R基因可以作为影响和控制兔体重及屠体性状的候选基因。     

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.     

Influence of rearing system,diet and gender on performance,carcass traits and meat quality of Polish Landrace pigs

Forty-eight Polish Landrace pigs (initially 32.43 ± 0.70 kg live weight) were assigned to a 2 × 2 × 2 factorial arrangement in order to assess the effects of the rearing system (outdoor v. indoor), diet (with corn grain silage v. without corn grain silage) and gender (barrows v. gilts) on performance, carcass traits, meat quality and intramuscular collagen (IMC) characteristics. During the trial period of 14 weeks, each group was housed in a pen of 12 m², and the outdoor-reared animals had access to a paddock of 24 m². Pigs were fed a diet computed according to standard requirements and supplied on a basis of 9% of metabolic weight (live weight^0.75). Pigs were slaughtered at 110.69 ± 0.85 kg. The rearing system did not significantly affect growth, hot and cold dressing, meat quality of m. longissimus lumborum or IMC. Outdoor pigs had less (P < 0.05) backfat thickness, slightly higher (P = 0.082) lean percent and a meat with lower pH and fat than the conventional system. In light of these results, alternative pig rearing systems with indoor space and free outdoor access could be an interesting production system for the pigs. Compared with the pigs fed diets with corn grain silage, those fed diets without corn had higher (P < 0.05) lean, ham percentage and IMC content, lower (P < 0.05) neck percentage but similar main tissue components of the ham and meat quality. Compared with the gilts, barrows were fatter and showed a meat with different physico-chemical traits, which was slightly more tender and had similar IMC properties.     

Using mixed silages of sweet sorghum and alfalfa in total mixed rations to improve growth performance,nutrient digestibility,carcass traits and meat quality of sheep

Combining sweet sorghum (SS) with alfalfa for ensiling has the potential to make a high-quality silage with relatively a better nutrient balance. However, the existing data are insufficient about how changes in ratios of SS to alfalfa in different silage mixtures affect animal performance and meat quality. Therefore, the objective of this study was to determine the effect of feeding total mixed rations containing mixed silages of SS and alfalfa on growth performance, nutrient digestibility, carcass traits and meat quality of Karakul sheep. Five total mixed rations were formulated with different SS proportions at 100%, 80%, 60%, 40%, and 20% on a fresh weight basis. Thirty 4-month old male Karakul sheep with 25.5 ± 1.4 kg BW were randomly allocated into five treatment groups, each with six lambs for this experiment. The results indicated that the Karakul sheep consuming total mixed rations containing SS-Alfalfa (SS-AF) silage mixtures with a lower proportion of SS tended to increase nutrient digestibility, growth performance, carcass traits, and meat quality. Feeding diets with SS at 40% and 20% inclusion rate showed a significant linear increase in the apparent digestibility of DM, CP and NDF, as well as subcutaneous fat thickness and water holding capacity (P < 0.5). Moreover, reduction in SS inclusion rate in these diets caused significant (P < 0.05) linear and quadratic increases in DM intake, final BW, average daily gain, carcass weight, and the amino acid contents of meat (P < 0.05). Conversely, feeding diet with lower SS inclusion rate led to decrease in feed conversion ratio and shear force significantly (P < 0.05) for these sheep. It appears that 40% inclusion of SS was the optimal rate in making the SS-AF silage mixture for lambs to achieve a superior production performance and high-quality meat products in Karakul sheep. However, further research is needed to investigate the effect of feeding SS-AF silage mixtures alongside contrasting ingredients on rumen function, ruminal microorganisms and digestive enzyme activity of sheep and other ruminant animals.     

Comparison between the three porcine RN genotypes for growth,carcass composition and meat quality traits

A three-step experimental design has been carried out to add evidence about the existence of the RN gene, with two segregating alleles RN^- and rn⁺, having major effects on meat quality in pigs, to estimate its effects on production traits and to map the RN locus. In the present article, the experimental population and sampling procedures are described and discussed, and effects of the three RN genotypes on growth and carcass traits are presented. The RN genotype had no major effect on growth performance and killing out percentage. Variables pertaining to carcass tissue composition showed that the RN^- allele is associated with leaner carcasses (about 1 s.d. effect without dominance for back fat thickness, 0.5 s.d. effect with dominance for weights of joints). Muscle glycolytic potential (GP) was considerably higher in RN^- carriers, with a maximum of a 6.85 s.d. effect for the live longissimus muscle GP. Physico-chemical characteristics of meat were also influenced by the RN genotype in a dominant way, ultimate pH differing by about 2 s.d. between homozygous genotypes and meat colour by about 1 s.d. Technological quality was also affected, with a 1 s.d. decrease in technological yield for RN^- carriers. The RN genotype had a more limited effect on eating quality. On the whole, the identity between the acid meat condition and the RN^- allele effect is clearly demonstrated (higher muscle GP, lower ultimate pH, paler meat and lower protein content), and the unfavourable relationship between GP and carcass lean to fat ratio is confirmed.     

Effects of time-based feed restriction on morbidity,mortality, performance and meat quality of growing rabbits housed in collective systems

In rabbit farms, quantitative feed restriction in the post-weaning period is widely used with the aim of reducing the impact of digestive diseases, whereas less information is available about feed restriction strategies based on the reduction of access time to feeders in different housing systems. This study compared morbidity, mortality, growth performance, carcass characteristics and meat quality of 368 crossbred rabbits fed ad libitum (L) or subjected to a time-based feed restriction programme (R) and housed from 31 to 73 days of age in cages or pens with different dimensions and group sizes, that is, eight conventional cages (0.33 m², six rabbits/cage), eight small open-top pens (0.50 m², eight rabbits/pen), eight medium open-top pens (1.00 m², 16 rabbits/pen) and four large open-top pens (2.00 m², 32 rabbits/pen). Feed restriction was attained by progressively reducing the access time to feeders in the 1st week from 14 to 8 h/day, maintaining 8 h in the 2nd week and then by increasing access time by 1 h/day during the 3rd and 4th week up to 24 h/day. In the first 2 weeks, R rabbits showed a lower (P ≤ 0.001) daily weight gain, feed intake and feed conversion as compared with L rabbits. During the 3rd and 4th weeks, R rabbits exhibited a greater daily weight gain and better feed conversion (P ≤ 0.001). In the last 2 weeks of trial, daily weight gain tended (P = 0.06) to be greater in the R than L rabbits. In the whole trial, R rabbits manifested a lower daily weight gain, feed intake and feed conversion, as well as lower final live weight and the carcass dressing percentage at slaughter (0.05 ≤ P ≤ 0.01). During feed restriction, R rabbits did not show digestive problems, which, however, appeared in the following 2 weeks of refeeding. Thus, R rabbits had a higher health risk index in the whole trial as compared with L rabbits (P ≤ 0.05). The housing system did not affect growth performance, characteristics at slaughter, and carcass and meat quality. Mortality tended to increase with group size (P = 0.06). In conclusion, the time-based feed restriction significantly improved feed efficiency of growing rabbits housed collectively but had somewhat negative effects on characteristics at slaughter and on morbidity and mortality rate.     

Effects of feeding and rearing systems on growth, carcass composition and meat quality in pigs

Animal growth performance and quality of pork depend on the interactive effects of pig genotype, rearing conditions, pre-slaughter handling, and carcass and meat processing. This paper focuses on the effects of feeding and rearing systems (feeding level and diet composition, housing, production system, etc.) on growth performance, carcass composition, and eating and technological qualities of pork. The feeding level and protein : energy ratio can be used to manipulate growth rate or composition of weight gain. Restricted feed allowance strongly reduces growth rate and carcass fatness and also intramuscular fat (IMF) level, resulting in decreased meat tenderness or juiciness. Expression of compensatory growth due to restricted followed by ad libitum feeding modifies the composition of weight gain at both carcass and muscle levels, and may improve meat tenderness due to higher in vivo protein turnover. Decreasing the protein : energy ratio of the diet actually increases IMF and improves eating quality, but gives fatter carcasses. In contrast, a progressive reduction in the protein : energy ratio leads to similar carcass composition at slaughter but with higher IMF. Technological meat traits (pH1, pHu, colour, drip loss) are generally not affected by the level or protein : energy in feed. Modification of fatty acid composition and antioxidant level in meat can be obtained through diet supplementations (e.g. vegetable sources with high n-3 fatty acids), thereby improving the nutritional quality of pork. Influences of pig rearing system on animal performance, carcass and meat traits result from interactive effects of housing (floor type, space allowance, ambient temperature, physical activity), feeding level and genotype in specific production systems. Indoor enrichment (more space, straw bedding) generally increases growth rate and carcass fatness, and may improve meat juiciness or flavour through higher IMF. Outdoor rearing and organic production system have various effects on growth rate and carcass fatness, depending on climatic conditions and feed allowance. Influence on meat quality is also controversial: higher drip and lower pHu and tenderness have been reported, whereas some studies show improved meat juiciness with outdoor rearing. Discrepancies are likely due to differences between studies in rearing conditions and physiological responses of pigs to pre-slaughter handling. Specific production systems of the Mediterranean area based on local breeds (low growth rate, high adiposity) and free-range finishing (pasture, forests), which allows pig to express their genetic potential for IMF deposition, clearly demonstrate the positive effects of genotype × rearing system interactions on the quality of pork and pork products.     

Effect of slaughter age on foal carcass traits and meat quality

Meat has played a crucial role in human evolution and is an important component of a healthy and well-balanced diet due to its nutritional richness. Recent studies have shown that horsemeat may be considered as an alternative to other meat (such as beef or pork), and it may have a positive effect on human health from a nutritional point of view. This research was conducted to characterize the carcass measurement, meat quality (chemical composition, colour characteristics and textural traits) and nutritional value (fatty acid and amino acid composition) of foals slaughtered at 8 and 11 months of age (8 and 11 m groups). For this study, a total of 21 foals (10 and 11 animals from the 8 and 11-m groups, respectively) were used. The results obtained showed a positive influence on carcass characteristics with an increase in slaughter age, because 11 m animals had slightly higher values of live (275 v. 247 kg) and carcass weights (148 v. 133 kg), length of leg (72.86 v. 69.85 cm) and carcass (100.41 v. 96.30 cm) and perimeter of leg (97.68 v. 89.22 cm) compared with animals from the 8-m group. Regarding meat quality, only Fe-haeme and cholesterol content in chemical composition and luminosity (L*) in colour parameters showed significant differences. Foals from the 8-m group had the highest content of cholesterol (0.47 v. 0.28 mg/100 g of meat) and luminosity values (39.66 v. 37.88) and the lowest content of ash (1.20% v. 1.40%). In fatty acids content, only five out of 23 fatty acids showed differences between the two groups. However, an interesting change in the fatty acid profile occurred with an increase in the slaughter age. Foals from the 8-m group had the highest values of α-linolenic acid and n-3 fatty acids and the lowest values of linoleic and n-6 fatty acids, which is an interesting fact from a health point of view. Finally, slaughter age had no statistical influence on textural properties or amino acid content. As a main conclusion, animals slaughtered at 8 months of age had higher nutritional quality meat (with higher content of n-3 fatty acids) than meat from foals slaughtered at 11 months of age. The slaughter of animals at 8 months of age also reduced production costs because they ate a smaller amount of commercial fodder.     

A 3-week feed restriction after weaning as an alternative to a medicated diet: effects on growth,health, carcass and meat traits of rabbits of two genotypes

Feed restriction after weaning is widely used in meat rabbit farms to promote health and reduce mortality, but this practice impacts negatively on rabbit growth and slaughter performance. This study compared a 3-week post-weaning feed restriction with ad libitum medicated feeding, evaluating effects on feed intake, growth, health, carcass and meat quality of rabbits of two genotypes: Italian White pure breed and Hycole hybrid×Italian White crossbred. A total of 512 rabbits at 36 days of age, of both sexes and two genotypes, were divided into four homogeneous groups assigned, from 36 to 57 days of age, to different feeding programmes (FP): restricted non-medicated (R-N), ad libitum non-medicated (L-N), restricted medicated (R-M) and ad libitum medicated (L-M). The diets were medicated with oxytetracycline (1540 mg/kg) and colistin sulphate (240 mg/kg). The restriction, performed by giving 70, 80 and 90 g/day of feed for the 1st, 2nd and 3rd week, was followed by ad libitum feeding in the successive 5 weeks, up to slaughter at 92 days of age. Restricted feeds were ingested at a level of 64% of the feed intake recorded in the ad libitum fed rabbits; it was significantly associated, regardless of medication and rabbit genotype, with a lower feed intake (−22 to −24 g dry matter/day) during the entire experiment, compensatory growth and a lower feed conversion ratio in the ad libitum period, and a lower final live weight (−150 g) than ad libitum feeding (P<0.001). During restriction, mortality was lower in the restricted rabbits (6.25%, 5.47% v. 12.5%, 14.8% for R-N, R-M, L-N and L-M; P<0.05), whereas in the ad libitum period mortality did not differ among the groups (9.23%, 9.90%, 11.0% and 4.59% for R-N, R-M, L-N and L-M). Dressing out percentage was not affected by FP or genotype; heavier carcasses were produced by rabbits fed ad libitum (+100 g; P<0.001) and crossbred rabbits (+122 g; P<0.001). Restriction did not alter meat quality, except for a tendency towards a higher cooking loss and less fat; crossbred meat was higher in L* (+1.3; P<0.01) and b* (+0.51; P<0.05) colour indexes and tenderness (−0.14 kg/cm²; P<0.05) than pure breed meat. Under the conditions of this study, a 3-week restricted feeding after weaning resulted to be a suitable alternative, also for high growth potential genotypes, to the antibiotics to preserve rabbit health. The production of lighter carcasses could be compensated partly by the lower feed conversion ratio showed by restricted rabbits.