Effect of Genotype, Gender, and Feed Restriction on Slaughter Results and Meat Quality of Broiler Chickens

Slaughter results and meat quality were evaluated in 768 broilers according to genotype (standard breast yield vs. high breast yield), gender, and feeding systems (ad libitum vs. feed restriction from 13 to 21 d of age). Standard-yield chickens had higher carcass weights (2358 g vs. 2319 g; P < 0.001) and hind legs proportion (31.1% vs. 30.6%; P < 0.01), and lower dressing out percentage (73.6% vs. 74.0%; P < 0.01) compared to high-yield birds, besides lower meat L* index (45.3 vs. 46.2; P < 0.05), higher final pH (5.89 vs. 5.85; P < 0.05) and thawing losses (10.5% vs. 9.43%; P < 0.05). Males showed higher carcass weight (+24%), dressing percentage (+0.7%), and hind leg yield (+4%) (P < 0.001) than females. Restricted birds had lower carcass weight (\u20132%; P < 0.001) and dressing percentage (-0.3%) (P < 0.05) than those always fed ad libitum. As what concerns meat quality, gender and feeding system aff ected only meat final pH, lower in ad libitum group than in restricted one and in females than males. In conclusions, slaughter results and carcass traits changed especially with genotype and gender, coherently with slaughter weight whereas meat quality was mostly affected by genotype

Influence of group housing, lactation system and floor type on performance and injuries in rabbit does

To evaluate the effect of group housing, lactation system, and floor type, 40 crossbred multiparous pregnant rabbit does were transferred to individual pens (0.5 m x 1.0 m); 8 does were kept individually during all the trial (I; n=8); the other 32 does were kept in 8 collective pens (2.0 m x 1.0 m, by joining 4 individual pens) in stable groups of 4 individuals (G; n=8) from 8 d until 2 d before kindling and from 2 d until 33 d after kindling. Half pens had wire net floor covered with plastic mats (W; n=8) and the other half plastic slatted floor (P; n=8). Within G does, in half pens (n=4) each doe nursed its own litter (fixed lactation, F); in the remaining half, each doe randomly nursed the litters of the group (random lactation, R). Doe performance at kindling and during lactation, litter performance from standardization until weaning (33 d), and skin injuries on G does (5, 12, 19, 26 and 34 d after kindling) were controlled. The effect of the housing system on performance was tested by PROC GLM of SAS. Within G does, the effect of the lactation system and floor type was evaluated by PROC MIXED (pen as random effect); the injury frequency was analysed by PROC FREQ according to observation day, lactation system, and floor type. Housing system did not affect doe kindling or lactation performance; litter weight at standardization was higher for G than I does (680 vs 619 g, P<0.05), but differences disappeared at weaning. The lactation system showed some residual effects when controlled lactation finished, nests were opened, and kits free of moving. In fact, from 19 to 33 d after kindling, does and litters had higher feed intake (679 g/d vs 602 g/d; P<0.05) and, at 33 d, kits were heavier (775 vs 748 g, P<0.05) in R than in F pens. Floor type (W vs P pens) affected milk production (244 vs 225 g/d; P=0.06), and kit weight at the end of controlled lactation (301 vs 290 g; P<0.05), without residual effects at weaning. The injury frequency changed after the group formation: 34% at 5 d, 47% at 12 d, 13% at 19 and 26 d, and 10% at 34 d of lactation (P<0.05). In conclusion, under our conditions, group housing did not negatively affect doe performance; lactation system and floor type had minor effects; aggressiveness among does was evident after group formation during early lactation but decreased in the late lactation. Further recordings on more reproductive cycles would be necessary to confirm the present results

Effects of the feeding system on performance and myopathy occurrence in two broiler chicken genotypes

To evaluate whether performance and myopathy occurrence differed according to genotype (Cobb 500 vs. Ross 308) and feeding system (AL: ad libitum vs. ER: early restricted from 13 to 23 d of age, vs. LR: late restricted from 27 to 37 d; restriction rate: 80% of ad libitum), 828 day- old male chicks were assigned to 6 groups (2 x 3 arrangement), housed in 36 pens, and controlled for: individual live weight (weekly) and pen feed intake (daily) until slaughter (48 d); white striping and wooden breast occurrence at slaughter. Individual data were analysed by PROC MIXED of SAS (fixed effects: feeding system, genotype, and interaction; random effect: pen); pen feed intake and myopathy occurrence were analysed by PROC GLM and CATMOD, respectively. The feeding system affected performance: at the end of the first period (1-22 d), ER chickens showed lower weight gain (40.5 g/d vs. 47.8 g/d and 48.0 g/d), feed intake (50.8 g/d vs 61.0 g/d and 60.2 g/d) and weight (903 g vs 1056 g and 1059 g) than AL and LR broilers (P<0.001); at the end of the second period (23-48 d), ER chickens showed higher weight gain (98.3 g/d vs 93.6 g/d and 90.2 g/d) and feed intake (182 g/d vs. 177 g/d and 171 g/d) compared to AL and LR chickens (P<0.001). Final live weight was the highest in AL group, intermediate in ER group, and the lowest in the LR one (3482 g, 3454 g, and 3399 g; P<0.01). Feed conversion in the whole period did not change with the feeding system. At gross examination, white striping occurrence changed from 77.8% to 67.1%, and 81.7% in AL, ER and LR broilers (p<0.10). Differences between genotypes were evident from the first day and, at the end of the trial, weight gain (74.3 g/d vs 70.1 g/d), feed intake (126 g/d vs 114 g/d), feed conversion (1.69 vs 1.64), and live weight (3548 g vs. 3342 g) were higher in the Ross than in the Cobb chickens (P<0.001). At slaughter, the rate of white-striped breasts was similar (on average 75.5%), but the occurrence of severely white-striped breasts was higher in the Ross than in the Cobb chickens (25.9% vs. 7.41%; P<0.001). Wooden breast occurrence (on average 5.1%) did not change with the feeding system or the genotype. In conclusion, under our conditions, a late feed restriction did not permit to recover performance at the end of the trial nor to control white striping occurrence. Moreover, the genotype affected growth rate and white striping degree: the highest the growth rate, the highest the severity of white striping

A New Approach to Background Subtraction in Low-Energy Neutrino Experiments

We discuss a new method to extract neutrino signals in low energy experiments. In this scheme the symmetric nature of most backgrounds allows for direct cancellation from data. The application of this technique to the Palo Verde reactor neutrino oscillation experiment allowed us to reduce the measurement errors on the anti-neutrino flux from $\sim 20$% to $\sim 10$%. We expect this method to substantially improve the data quality in future low background experiments such as KamLAND and LENS.Comment: 7 pages, 2 figure

Results from the Palo Verde neutrino oscillation experiment

The ν̅e flux and spectrum have been measured at a distance of about 800 m from the reactors of the Palo Verde Nuclear Generating Station using a segmented Gd-loaded liquid scintillator detector. Correlated positron-neutron events from the reaction ν̅ep→e+n were recorded for a period of 200 d including 55 d with one of the three reactors off for refueling. Backgrounds were accounted for by making use of the reactor-on and reactor-off cycles, and also with a novel technique based on the difference between signal and background under reversal of the e+ and n portions of the events. A detailed description of the detector calibration, background subtraction, and data analysis is presented here. Results from the experiment show no evidence for neutrino oscillations. ν̅e→ν̅x oscillations were excluded at 90% C.L. for Δm2>1.12×10-3 eV2 for full mixing and sin22θ>0.21 for large Δm2. These results support the conclusion that the observed atmospheric neutrino oscillations do not involve νe

Final results from the Palo Verde Neutrino Oscillation Experiment

The analysis and results are presented from the complete data set recorded at Palo Verde between September 1998 and July 2000. In the experiment, the \nuebar interaction rate has been measured at a distance of 750 and 890 m from the reactors of the Palo Verde Nuclear Generating Station for a total of 350 days, including 108 days with one of the three reactors off for refueling. Backgrounds were determined by (a) the $swap$ technique based on the difference between signal and background under reversal of the positron and neutron parts of the correlated event and (b) making use of the conventional reactor-on and reactor-off cycles. There is no evidence for neutrino oscillation and the mode \nuebar\to\bar\nu_x was excluded at 90% CL for \dm>1.1\times10^{-3} eV$^2$ at full mixing, and \sinq>0.17 at large \dm.Comment: 11 pages, 8 figure

Predicting Neutron Production from Cosmic-ray Muons

Fast neutrons from cosmic-ray muons are an important background to underground low energy experiments. The estimate of such background is often hampered by the difficulty of measuring and calculating neutron production with sufficient accuracy. Indeed substantial disagreement exists between the different analytical calculations performed so far, while data reported by different experiments is not always consistent. We discuss a new unified approach to estimate the neutron yield, the energy spectrum, the multiplicity and the angular distribution from cosmic muons using the Monte Carlo simulation package FLUKA and show that it gives a good description of most of the existing measurements once the appropriate corrections have been applied.Comment: 8 pages, 7 figure