Carcass composition and meat characteristics of two rabbit breeds of different degrees of maturity

Effect of Silver Nanoparticle Administration on Productive Performance, Blood Parameters, Antioxidative Status, and Silver Residues in Growing Rabbits under Hot Climate

Simple Summary

Silver nanoparticles (AgNPs) were used for their antibacterial effects, which increase productive performance and immune response in poultry and rabbits. On the other hand, residues of silver in meat and the internal organs of treated animals may be toxic for human beings. The current results of using two doses of injecting AgNPs revealed that body weight significantly improved in rabbits given a low dose of AgNPs compared with control animals. For consumers’ health concerns, it is of interest to note that the amount of accumulated silver in blood plasma and meat increased dramatically with an increasing dose.

Abstract

The influence of subcutaneous injections of silver nanoparticles (AgNPs) on rabbit performance, hematological and biochemical parameters of blood, antioxidant status, and the residues of silver in meat and blood in two breeds (New Zealand White (NZW) and Jabali) of rabbits growing under high ambient temperature was evaluated. A total of 90 six-week-old rabbits (45 NZW and 45 Jabali) were randomly distributed into three equal treatment groups (control, 0.5 mg, and 1.0 mg AgNPs/kg body weight). The treated rabbits were injected twice a week for four consecutive weeks. The results revealed that AgNPs administration had no significant effect on average daily gain (ADG), feed intake, and feed conversion ratio (FCR). The NZW breed surpassed the Jabali breed in growth performance traits, carcass weight, dressing percentage, and cuts of mid parts and hind cuts. Administration of AgNPs had a significant effect on hematocrit (HCT) and platelet (PLT) values. Rabbits injected with AgNPs at a dose of 0.5 mg showed a lower plasma concentration of total cholesterol and triglycerides than that of control rabbits. The NZW breed had significantly low platelet, total cholesterol, and triglyceride values. Rabbits injected with 0.5 mg/kg BW had the lowest total antioxidant capacity and highest malondialdehyde (MDA) and glutathione peroxidase. The Ag residues were higher in blood than those in meat in treated rabbits. The local breed (Jabali) had significantly lower residues than the imported one (NZW) either in meat or in blood. However, the amount of accumulated silver in blood plasma and meat increased with increasing dose.

Technical note: Estimation of real rabbit meat consumption in Italy

As in other livestock species, the annual per capita consumption of rabbit meat is currently estimated as the ratio of the total weight of carcasses available for consumption to the number of inhabitants of a certain region. The aim of this work was to establish conversion coefficients from carcass to dible lean meat and estimate real rabbit meat consumption in Italy. Accordingly, a total of 24 rabbits were slaughtered at 2 different ages to obtain carcasses representative of the main market categories in Northern Italy: medium-size (carcass weight of about 1.4 kg) and heavy-size (carcass weight of about 1.8 kg). Chilled carcasses were used to determine offal, dissectible fat, bone and meat weights and yields. Experimentally obtained conversion factors from carcass to edible lean meat and estimated meat waste percentage at retail and consumption levels were subsequently used to estimate the real per capita amount of rabbit meat consumed in Italy. The finding of this study revealed that, if compared to the medium-size group, heavy-size carcasses had higher lean meat yield for both intermediate (92.9 vs. 92.4%; P<0.05) and hind parts (84.3 vs. 79.1%; P<0.001). On the contrary, the meat yield of fore part was higher in the medium-size group (66.2 vs. 65.5%; P<0.001) compared to heavy-size carcasses. Eventually, overall meat yield was higher in heavy-size carcasses compared to medium-size ones (64.4 vs. 63.2%; P<0.001). By using these conversion factors and estimated overall losses at retailing and home-consumption (15%), we estimated that real per capita annual rabbit meat consumption is 0.50 kg in Italy, which is only 54% compared to the estimated apparent consumption (0.90 kg).

The effect of age on the carcass composition, portion yield and proximate composition of two rabbit genetic types in South Africa

This study investigated the carcass component yields and meat proximate composition of 2 rabbit genetic types (Californian and hybrid New Zealand Red×Californian), with 5 rabbits per genetic type being slaughtered every 2 wk throughout the study period (9-17 wk) to evaluate the effect of age on these traits. Slaughter weight, reference yield, portion yield (hind leg, foreleg and fore part, as percentage of slaughter weight), meat yield, skin weight and the fat content of the meat (percentage of wet weight) increased significantly with age, while the full gastrointestinal tract, liver, head and feet decreased significantly. This is likely a reflection of the early-maturing nature of bone and viscera and later maturing nature of muscle and fat. These results indicate that delaying slaughter to 13 wk tends to improve yields for valuable carcass components. The Californian had a significantly higher total meat yield at 11 and 17 wk and higher portion meat yields at 9 (hind leg), 11 (hind leg and fore part) and 13 (foreleg) weeks than the hybrid. This was likely due to the later maturation of the hybrid and the influence of the New Zealand Red on carcass quality. It therefore appears that the Californian may be more favourable for meat production, from a carcass and meat quality perspective.

Comparison of productive and carcass traits and economic value of lines selected for different criteria, slaughtered at similar weights

<p>The aim of the experiment was to compare 3 genetic groups, slaughtered at similar weights, to examine their productive and carcass traits and economic value. Three lines of the Pannon Breeding Programme, selected for different criteria, were examined in the experiment. Pannon Ka (PKa, maternal line) does were inseminated with semen of PKa, Pannon White (PWhite) or Pannon Large (PLarge, terminal line) bucks. The kits (PKa×PKa, PWhite×PKa, PLarge×PKa; n=60 in each genetic group) were weaned at 35 d of age and reared until 88, 83 and 79, respectively, when they reached similar body weights for slaughtering (2.8 kg). The weight gain of PLarge×PKa was the largest (51.0 g/d) and that of PKa×PKa was the smallest (47.2 g/d), while PWhite×PKa (41.8 g/d) was intermediate (P&lt;0.001). Difference was found in feed conversion ratio between weaning and the age of slaughter  PKa×PKa: 3.03 respect to PWhite×PKa: 2.75 and PLarge×PKa: 2.66; , P&lt;0.05). Dressing out percentage and ratio of hind part to reference carcass of PWhite×PKa, PLarge×PKa and PKa×PKa were 62.4 and 37.7, 61.8 and 37.5, 61.3 and 36.8%, respectively (P&lt;0.01). Results show that PLarge×PKa rabbits were able to exceed the average economic indicators compared to other groups. It may be concluded that the production performance of growing rabbits was affected by the adult weight, but the carcass traits were influenced by the computer tomography (CT)-based selection.</p>

Comparison of Carcass and Meat Quality Traits among Three Rabbit Breeds

The objective of this study was to compare carcass composition and meat quality traits in the longissimus dorsi and biceps femoris muscles in the Hyla, Champagne and Tianfu Black rabbit breeds. Tianfu Black rabbits had the heaviest head, skin, thoracic viscera and commercial carcass percentage (p<0.05). In addition, Tianfu Black had the highest pH_{0 h} value, followed by the Champagne and Hyla breeds (p<0.01) in the longissimus dorsi and biceps femoris muscles. Tianfu Black had a higher a* (0 h and 24 h) than the other two breeds in both longissimus dorsi and biceps femoris muscles (p<0.05). The Hyla, Champagne, and Tianfu Black breeds showed a similar pattern of differences for meat quality traits (pH, L*, a* and b*) measured in fresh meat (0 h) and meat stored for 24 h. Hyla had the highest IMF values of the three breeds (p<0.01). The lower intramuscular fat of Tianfu Black and Champagne rabbits gives them an advantage over Hyla rabbits among most consumers seeking lean rabbit meat.

Comparison of degrees of maturity of rabbit lines selected for different traits

<p>The aim of this work was to study whether commercial nucleus lines of rabbits selected for different traits, and experimental lines having commercial purposes, have the same degree of maturity when compared at the same slaughter age. The study was carried out with 17897 rabbits from Universitat Politècnica de València. Rabbits came from the maternal lines A (3902 rabbits; 44^th generation), V (4238 rabbits; 39^th generation) and LP (6115 rabbits; 9^th generation), selected for litter size at weaning; the paternal line R (2023 rabbits; 25^th generation), selected for growth rate between 28 and 63 days of age; the maternal line OR (586 rabbits; 11^th generation) selected for ovulation rate; and the lines High (503 rabbits; 5^th generation) and Low (530 rabbits; 5^thgeneration) lines, from a divergent selection for high and low intramuscular fat, respectively. Rabbits were weighted at 28 (W28) and 63 (W63) days of age. Rabbit does (42, 25, 39, 94, 14, 32 and 22 from lines A, V, R, LP, OR, High and Low, respectively) were weighed between 30 and 80 wk of age to determine adult weight (AW). Line R had higher W28 and W63, growth rate between 28 and 63 d of age and AW than lines A, V and LP (5802 g vs. 4410, 4222, and 4391 g for AW, respectively). No relevant differences between lines in degrees of maturity at 28 and 63 d of age and time to reach 40% of degree of maturity (percentage of weight compared to AW) were found between lines A, V, R and LP, but the degree of maturity at 2000 g and the time taken to reach that weight were lower in line R (34.7% and 55.2 d) than in lines A (45.5% and 71.1 d), V (47.4% and 69.6 d), and LP (45.8% and 68.0 d). No relevant differences were found between lines OR, High and Low in the traits analysed. A robustness analysis showed that results can be extrapolated to other commercial lines and other slaughter weights. In conclusion, comparison of lines at similar slaughter age could be considered a valid approach for comparisons at the same maturity stage.</p>

Effect of electrical and mechanical stunning on bleeding, instrumental properties and sensory meat quality in rabbits

Different voltage and frequency (T-1=49V, 250Hz; T-2=130V, 172Hz; T-3=22V, 833Hz) combinations of electrical stunning and cervical dislocation (T-4) were studied in 101 commercial rabbits in an industrial abattoir. Electrical stunning accelerated the early muscular acidification, providing lower pH-45 and pH-2h values on Longissimus dorsi and Biceps femoris and higher pH-24h on Biceps femoris than cervical dislocation (P<0.02). Furthermore, meat from rabbits stunned with electrical methods showed more redness (a* with mean values 1.17-1.30 vs. 0.66, P<0.02), although this cannot be associated to low exsanguination levels because electrical methods tend to produce even higher bleeding percentage than mechanical stunning (P=0.063). Haematin content in muscle, water-holding capacity and cooking losses were similar in all treatments. Shear force did not change because of the stunning methods, but the members of experienced panel found the meat coming from electrical stunning T-1 (with intermediate voltages and frequencies) tougher and less juicy than the meat obtained with other electrical applications or with cervical dislocation (P<0.05).

Effect of diets on growth, digestibility, carcass and meat quality characteristics of four rabbit breeds

The current study was conducted to evaluate three diets using four rabbit breeds. A total of 320 male weaned rabbits representing four breeds named V-line, Saudi-1, Saudi-2 and Saudi-3 were randomly distributed into three comparable dietary treatments. Three levels of indigenous feedstuffs (IFS) of 42.5%, 65% or 87.5% (alfalfa hay, barley and wheat bran) were substituted for the same levels of non-indigenous feedstuffs in the diet (corn grain, soybean, molasses, and limestone) to form three diets named D1, D2 and D3, respectively. These dietary treatments were used to evaluate post-weaning growth performance, feed intake, feed conversion, carcass and lean composition, and nutrients digestibility in four rabbit breeds. Partial replacement of IFS with non-indigenous feedstuffs attained significant increase in growth performance. The diet containing 87.5% IFS led to significant increase in daily weight gains by 8.4, 4.0, 8.1, 6.2 and 6.7 g at age intervals of 5-6, 7-8, 9-10, 10-11 and 11-12 weeks compared to the control diet, respectively. The diet containing 87.5% IFS showed a significant reduction in feed conversion ratio compared to control diet during the experimental periods. The diet containing 65% IFS showed significant increases in pre-slaughter weight (112 g) and hot carcass weight (89 g), while dressing percent, offal weight and percent, and non-carcass weights and percentages (head, fur, legs + tail, viscera) were not significantly different. The diet containing 87.5% IFS gave an increase of 1.1%, 6.4%, 8.8%, 17.9%, 7.4%, and 19.6% in digestibility coefficients of organic matter (OM), crude protein (CP), neutral detergent fibre (NFD), acid detergent fiber (ADF), hemi-cellulose (HC) and cellulose (C) compared to control diet, respectively. Feed intakes were moderate and ranged from 69 to 124 g for V-line, 77 to 128 g for Saudi-1, 79 to 130 g for Saudi-2, and 76 to 119 g for Saudi-3 along with moderate ratios of feed conversion ranging from 2.65 to 3.80, 2.45 to 3.90, 2.46 to 3.79 and 2.63 to 3.65, respectively. Pre-slaughter weight, hot carcass weight, and offal weight were in favour of Saudi-2 rabbits compared to the other groups. Both Saudi-1 and Saudi-2 rabbits were slightly higher than Saudi-3 in weights and percentages of head, fur, viscera and legs + tail. Lean and bone weights and percentages and meat to bone ratio in Saudi-2 carcasses were slightly higher than those recorded in the other groups, while moisture, DM, CP, EE and ash contents in the lean have shown little differences between groups. Rabbits of Saudi-1 were ranked the first in digestibility coefficients of OM, CP, NDF, ADF, HC, C and cell count compared to other groups. Rabbits of Saudi-2 fed diet containing 87.5% IFS recorded the heaviest body weights and gains since this class showed considerable deviations in body weights of 345, 341, 269, 307, 321, 345 and 347 g at 6, 7, 8, 9, 10, 11 and 12 weeks of age, respectively, in comparison with the lightest class. Both Saudi-2 and Saudi-3 rabbits fed the diet containing 87.5% IFS had favourable estimates of feed conversions ranging from 2.1 to 3.4, while rabbits of Saudi-1 fed the diet containing 87.5% IFS recorded the best digestibility coefficients.

Carcass and meat quality traits of rabbits under heat stress

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 × 3 factorial arrangement (two genetic groups and three ambient temperatures: 18°C, 25°C and 30°C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.4°C and 63.9%, 24.4°C and 80.2% and 29.6°C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 30°C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group × ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.

Carcass and meat quality of rabbits given diets having a high level of vegetable or animal fat

Three groups of does were fed respectively with three experimental diets: control (C), vegetable fat enriched (V) and animal fat enriched (A). Also their offspring were given their respective diets from weaning to slaughter. C was a standard commercial diet, V had 99 g vegetable fat per kg, and A had 114 g animal fat per kg. Sixty animals in the live-weight range 1·75 to 2·25 kg from each group were slaughtered at 9 weeks of age. The rabbits came from a commercial three-way cross. Animals on diets A and V had a better food conversion efficiency ratio, a lower drip loss and a dressing yield substantially better than those given diet C. Males had higher food conversion rate and smaller dressing yield. Carcass colour was not affected by the diet but rabbits given diet V showed less pale meat. Differences in the three colour parameters were found for the three diets for hot and chilled carcass fat colour. Muscular pH measured in the longissimus dorsi and biceps femoris were slightly higher for diets A and V and were also higher for males than for females. Water-holding capacity of raw meat from rabbits given diets A and V was higher than from rabbits given the control diet. Protein and moisture content of the meat of a hind leg was almost the same for the three diets but fat content was much higher in animals given diets A and V than in the control group.

The value of in vivo real time ultrasonography in assessing loin muscularity and carcass composition of rabbits

Sixty nine growing rabbits were scanned over the lumbar region using a real time ultrasonography (RTU) machine to estimate loin muscularity and carcass composition. Longissimus thoracis et lumborum muscle (LM) depth, width and area were taken. Animals were weighed (LW), slaughtered and carcass composition was determined. Equivalent measurements to those taken by RTU in vivo were taken on the carcass and muscularity indices were calculated on carcass and in vivo. Simple correlations between the two types of measurements were determined and carcass composition was estimated by simple and multiple regressions. The LW varied from 1200 to 3410g. The simple correlations between carcass and in vivo RTU LM measurements were high (P<0.001) and the LM area was the trait with the highest correlation (r=0.92). Simple correlations between muscularity indices measured by RTU and in carcass were significant (P<0.001). In vivo RTU measurements explained a large amount of the variation of the carcass meat weight (MW) and bone weight (r(2) range from 0.49 to 0.77; P<0.001). Using multiple regression equations to estimate carcass composition, the best fit was obtained with the LW and one or more in vivo RTU measurement. The LW explained 90.6% of the variation of MW in the carcass. In vivo RTU is able to estimate loin muscularity and carcass composition of rabbits with accuracy. The usefulness of in vivo RTU and LW to predict carcass composition of rabbits using multiple regressions was also shown.