Dietary vitamin or mineral mix removal during the finisher period on broiler chicken performance

The effect of dietary vitamin (VS) and mineral (MS) mix withdrawal between 42 and 49 d of age on broiler chicken performance was evaluated. The diets were formulated based on corn and soybean meal, and the experiments were conducted in floor pens using wood shavings as litter. Trial I evaluated withdrawal of VS and MS mix at 42, 45, and 49 d. The results of this trial showed that VS and MS mix withdrawal at 42 d of age did not impair feed intake (FI) or weight gain (WG), but feed conversion (FC) was improved (P = 0.043) when both mixes were maintained in the diets until 49 d of age. Trial 2 assessed the withdrawal of VS or MS mix at 42 d of age. FI and WG were not affected by withdrawal, but FC was poorer (P = 0.035) for the broilers fed the diet without VS. The relative liver weight was reduced by VS or MS mix withdrawal (P = 0.014 and P = 0.001, respectively). Carcass, breast, and leg yields were not affected by VS or MS mix withdrawals in either trial. The findings of the study suggested that VS mix withdrawal during the final period of broiler chicken growth was more deleterious than the withdrawal of MS mix, because it affected FC ratio. VS or MS withdrawal during this period did not affect carcass yield.

Mapping QTLs on chicken chromosome 1 for performance and carcass traits in a broiler x layer cross

With the objective of mapping quantitative trait loci (QTLs) for performance and carcass traits, an F-2 chicken population was developed by crossing broiler and layer lines. A total of 2063 F-2 chicks in 21 full-sib families were reared as broilers and slaughtered at 42 days of age. Seventeen performance and carcass traits were measured. Parental (F-0) and F-1 individuals were genotyped with 80 microsatellites from chicken chromosome 1 to select informative markers. Thirty-three informative markers were used for selective genotyping of F-2 individuals with extreme phenotypes for body weight at 42 days of age (BW42). Based on the regions identified by selective genotyping, seven full-sib families (649 F-2 chicks) were genotyped with 26 markers. Quantitative trait loci affecting body weight, feed intake, carcass weight, drums and thighs weight and abdominal fat weight were mapped to regions already identified in other populations. Quantitative trait loci for weights of gizzard, liver, lungs, heart and feet, as well as length of intestine, not previously described in the literature were mapped on chromosome 1. This F-2 population can be used to identify novel QTLs and constitutes a new resource for studies of genes related to growth and carcass traits in poultry.

Cytogenetics of three breeds of river buffalo (Bubalus bubalis L.), with evidence of a fragile site on the X chromosome

The cytogenetic study of 182 river buffalo (Bubalus bubalis L., 2n=50) of Murrah, Mediterranean and Jaffarabadi breeds, from the State of São Paulo, was carried out to characterize their chromosomes and to detect possible chromosomal abnormalities. The karyotypes were indistinguishable with conventional staining as well as with C and replication R banding techniques. In about 44% of the sample (8 males and 72 females), an X marker chromosome due to a fragile site was shown. The frequency of metaphases expressing the fragility site on the X was highly variable, from 2.86 to 41.03%. In females, the fragile site, rarely appeared on both X chromosomes. Most of the metaphases showed only 1 marker chromosome. In R-banded metaphases using 5-bromodeoxyuridine (BrdU) treatment, it corresponded in general to the late replicating X chromosome. No correlation between the X fragile site and altered phenotype was found. Structural and numerical chromosome rearrangements were ruled out in the present sample of buffalo. (C) 1998 by Elsevier B.V.

Shelf-life of chicken loaves

This research was designed to study the elaboration of chicken loaf with ground meat. The products were elaborated in laboratory scale utilizing broiler meat bought at the market. The products were conditioned in vacuum-packages and stored for 133 days at 5 and 10 degrees C. Chemical, sensorial and microbiological analyses of the elaborated products were performed. The storage temperature affected the total bacterial counts, pH, characteristic aroma and rancid aroma. In both treatments (storage temperature: 5 and 10 degrees C), depletion of nitrites, reaching 24 ppm in 133 days of storage, and exudate formation after 77 days were observed. The storage of chicken leaves, vacuum-packaged, at 5 degrees C for a maximum of 77 days is recommended.

Effect of thermal stress on physiological parameters, feed intake and plasma thyroid hormones concentration in Alentejana, Mertolenga, Frisian and Limousine cattle breeds

The aim of the present study was to assess the heat tolerance of animals of two Portuguese (Alentejana and Mertolenga) and two exotic (Frisian and Limousine) cattle breeds, through the monitoring of physiological acclimatization reactions in different thermal situations characterized by alternate periods of thermoneutrality and heat stress simulated in climatic chambers. In the experiment, six heifers of the Alentejana, Frisian and Mertolenga breeds and four heifers of the Limousine breed were used. The increase in chamber temperatures had different consequences on the animals of each breed. When submitted to heat stress, the Frisian animals developed high thermal polypnea (more than 105 breath movements per minute), which did not prevent an increase in the rectal temperature (from 38.7 degrees C to 40.0 degrees C). However, only a slight depression in food intake and in blood thyroid hormone concentrations was observed under thermal stressful conditions. Under the thermal stressful conditions, Limousine animals decreased food intake by 11.4% and blood triiodothyronine (T3) hormone concentration decreased to 76% of the level observed in thermoneutral conditions. Alentejana animals had similar reactions. The Mertolenga cattle exhibited the highest capacity for maintaining homeothermy: under heat stressful conditions, the mean thermal polypnea increased twofold, but mean rectal temperature did not increase. Mean food intake decreased by only 2% and mean T3 blood concentration was lowered to 85,6% of the concentration observed under thermoneutral conditions. These results lead to the conclusion that the Frisian animals had more difficulty in tolerating high temperatures, the Limousine and Alentejana ones had an intermediate difficulty, and the Mertolenga animals were by far the most heat tolerant.

Predicting body and carcass characteristics of 2 broiler chicken strains using support vector regression and neural network models

As a new modeling method, support vector regression (SVR) has been regarded as the state-of-the-art technique for regression and approximation. In this study, the SVR models had been introduced and developed to predict body and carcass-related characteristics of 2 strains of broiler chicken. To evaluate the prediction ability of SVR models, we compared their performance with that of neural network (NN) models. Evaluation of the prediction accuracy of models was based on the R-2, MS error, and bias. The variables of interest as model output were BW, empty BW, carcass, breast, drumstick, thigh, and wing weight in 2 strains of Ross and Cobb chickens based on intake dietary nutrients, including ME (kcal/bird per week), CP, TSAA, and Lys, all as grams per bird per week. A data set composed of 64 measurements taken from each strain were used for this analysis, where 44 data lines were used for model training, whereas the remaining 20 lines were used to test the created models. The results of this study revealed that it is possible to satisfactorily estimate the BW and carcass parts of the broiler chickens via their dietary nutrient intake. Through statistical criteria used to evaluate the performance of the SVR and NN models, the overall results demonstrate that the discussed models can be effective for accurate prediction of the body and carcass-related characteristics investigated here. However, the SVR method achieved better accuracy and generalization than the NN method. This indicates that the new data mining technique (SVR model) can be used as an alternative modeling tool for NN models. However, further reevaluation of this algorithm in the future is suggested.

A description of the growth of the major body components of 2 broiler chicken strains

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of broiler breeder genetic, diet type, and feeding program on maternal antibody transfer and development of lymphoid tissues in chicken progeny

Maternal antibody (MatAb) transfer is important for early chicken survivability. Diet composition and the amount of feed given to breeder pullets during rearing may affect the development of immunity and the transfer of MatAb to progeny, and could affect progeny performance and resistance to disease. The effects of broiler breeder nutrition and feeding management practices were evaluated for the transfer of MatAb to progeny and for spleen and bursa development at hatching in 2 genetic strains (A and B). In this experiment, the levels of MatAb against Newcastle disease virus were assessed by enzyme-linked immunosorbent assays in serum samples taken of pedigreed chicken progeny from hatching to 13 d of age. Chickens were fed corn-and wheat-based diets, as were their parents. The breeder feeding program and diet type altered the Newcastle disease virus MatAb found in progeny at hatching and affected how long these antibodies were maintained in circulation. Bursal follicle size at hatching was influenced by an interaction among all factors evaluated. Percentage of white pulp in the spleen was affected mainly by genetic strain and diet type, but responses varied according to the breeder feeding program. It was concluded that breeder feeding programs influence MatAb transfer and half-life, and may also affect the early development of lymphoid tissues.