Gilberto Silber Schmidt

Effect of storage period and egg weight on embryo development and incubation results

A total number of 300 females and 30 males of two experimental broiler lines, TT (male) and PP (female), with 39 and 36 weeks of age, respectively. Experiment 1 (TT) evaluated the effect of storage time (ST) on hatchability and embryo mortality (EM). Eggs were stored for 2 (ST1), 4 (ST2), 6 (ST3), 8 (ST4), 10 (ST5), 12 (ST6), and 24 (ST7) days and EM was assessed in the periods of 0 to 6 (EM1), 7 a 13 (EM2), 14 to 17 (EM3), 18 to 21 (EM4), and 0 to 21 (TEM) days. Experiment 2 (PP) evaluated the effect of egg weight (EW) on embryo development. Eggs were individually collected and weighed. Embryos were collected and weighed on days 9 (EW9), 11 (EW11), 13 (EW13), EW15, 17 (EW17) days of incubation and at hatching (EW21). ST linearly influenced hatchability and EM, with an estimated 1.17% reduction and a 1.15% increase, respectively for each 1.0 day of storage. Hatchability was reduced in 21% betweeb ST2 and ST7, resulting from a 462% increase in EM. The correlation between egg weight and embryo weight (EW) was significant after EW3 (0.25), reaching 0.72 for EW21, which corresponded to 70.92% of egg weight. The estimated increase in embryo weight for each 1.0g increase in egg weight was 0.71g for EW21.

Selection for reproductive traits in white egg stock using independent culling levels

The objective of this study was to report the response to selection for fertility and hatchability in white egg layers strains, based on sire and dam performance, and the effects of inbreeding on these traits. Two selected white egg strains (CC and DD) from Embrapa·s poultry program under multiple trait selection were compared to a control strain (CCc). The control strain was established by randomly mating one male from each sire family to a non-related female from each dam family and was used to monitor genetic change in the selected lines. CC and DD were selected using family and individual information on hen-day egg production up to 40 weeks of age, egg weight, sexual maturity and 16-week-old body weight over five generations. Independent culling levels (ICL) were also used during population expansion to eliminate sires and dams with low fertility (FERT) and hatchability (HATC). Initially, FERT and HATC were over 90.0% in both selected and control strains. FERT and HATC of the selected and the control strains were compared during the last generation. FERT averages were 93.8, 93.8 and 94.4%, and HATCH averages were 93.2, 91.6 and 93.1% for CC, DD and CCc respectively. FERT and HATCH means were not different among strains. Estimated inbreeding increased at a rate of 0.4% per generation in all strains. Selection using ICL was able to effectively maintain the high initial FERT and HATC levels, and provide potential for high selection intensity in other traits. Inbreeding depression was not observed for any trait, indicating that selection compensated for any negative effects of inbreeding.

Morphological Genetic Markers for Selection of Broiler Lines

Two paternal broiler lines (LL and LLc, originated from the same stock in 1998) of Embrapa Suinos e Aves genetic program were used. Line LL had been selected for eight generations for rapid growth while LLc had been mated randomly, without selection, as a control line. In the last generation, 30 males and 240 females were used in hierarchical matings with pedigree control to determine sire effect. The same number of birds were used, but matings were at random for LLc. Eggs of both lines were incubated and embryos were collected in different development stages (40, 45, 50, 55 and 60 hours after setting) in order to determine somite number (NOS). The number of evaluated embryos were 1,967 and 498 for LL and LLc, respectively. This study aimed to determine the changes in somite formation during embryonic development that resulted from artificial selection for heavier body weight. In the evaluated generation, the differences for body weight, feed conversion ratio, carcass and breast yields between LL and LLc were 546 g; 0.16 FC units, 2.20 and 2.19%, respectively. NOS was greater in the initial (40 h) and in the final (60 h) stages for LL and in the intermediary stages (45, 50 and 55 h) for LLc, indicating significant differences in the mechanisms of somite formation and development. Considering that both lines had the same genetic origin, such deviation indicates genetic changes due to artificial selection for body weight. The heritability estimates indicated low additive genetic effect for NOS in the different stages. Since the alterations were due to artificial selection for body weight, one could consider the hypothesis of using such genetic marker throughout family selection.

The effect of broiler market age on performance parameters and economics

In the present study, 35 farmers contracted by an integration company were selected. Each farmer owned an average of seven poultry houses, and housed six flocks per year, with a total of 4.0 million housed broilers. Birds were grouped into 5 market ages (MA1= 46 days), and the following parameters were measured: average flock body weight (AFW), feed conversion ratio (FCR), livability (L), production efficiency index (PEI), production cost, and farmers gross margin. MA significantly influenced all parameters, except production cost/kg broiler. The effects of farm and farm*MA interaction were not significant. Each day of MA increase resulted in increases of 68.43g and 0.039 units in AFW and FCR, respectively. PEI was 4.0% lower in MA5 as compared to MA1, thereby reducing farmers compensation in 11.89% per reared broilers. Production costs were not different among market ages, partially due to a reduction from 16.86 (MA1) to 14.62% (MA5) in the farmers participation in the total cost. The results show that a new farmers compensation index that included MA is necessary to calculate farmers margin.

Evaluation of the technical and economic impacts of high-density broiler production in an integrated system

This study included 35 farmers contracted by a broiler integrator company. Each farmer owned an average of seven poultry houses, housing six flocks per year per farmer, summing up 4.0 million broilers housed. Live performance was evaluated in flocks housed in three densities (D1 14 birds/m2), and included the following parameters: market age (MA), average flock weight (AFW), average daily gain (DWG), feed conversion ratio (FCR), livability (LB), production efficiency index (PEI) and carcass yield/m2 (CY). Production costs and gross margin were calculated with birds housed at two densities (11.5<D4<12.4 and 14.5<D5<15.5birds/m2), standardizing MA to 44 days. The economic evaluation included 15 farmers and 1.0 million broilers housed. The average densities obtained for D1, D2, D3, D4, and D5 were 11.80, 13.15, 15.00, 12.02, and 14.98 birds/m2, respectively. Density effect was significant on most parameters, with D1 producing the best results in AFW, DWG, FCR, LB, and PEI, whereas D2 and D3 produced different results only in FCR. Despite the reduction in animal performance, carcass yield/m2 linearly increased with density. The economic analyses showed higher production costs, despite the higher margin for D5. The greatest impact was the reduction in farmers compensation (19.68%) per bird housed. From the farmers perspective, the 5% increase in compensation should be enough to cover the investment required to supply the requirements of higher densities.

Mudanças genéticas em linhas puras de frango de corte

O objetivo deste trabalho foi avaliar as mudancas geneticas ocorridas no desempenho, na composicao da carcaca e no tamanho e resistencia dos ossos, em linhagens experimentais, apos seis geracoes de selecao. As aves pertenciam as linhas paternas LL, LLc (controle), ZZ e LC1 (comercial), e as maternas PP, PPc (controle), KK e LC2 (comercial). As mudancas geneticas foram obtidas a partir dos desvios entre cada linha selecionada e a respectiva linha controle (LL-LLc e PP-PPc). A selecao para peso corporal resultou em respostas correlacionadas na conversao alimentar, mas nao nas caracteristicas de carcaca. As mudancas geneticas no ganho de peso nao estao sendo acompanhadas por mudancas correlacionadas na resistencia dos ossos. A enfase de selecao diferenciada entre linhas puras paternas e maternas esta alterando o conteudo de Ca, agua e de gordura das carcacas de frango de corte.

Effect of selection for productive traits in broiler male lines on embryo development

This study used 300 females and 30 males with 36 weeks of age from the selected PP and control PPc maternal broiler lines. PP has been selected for heavy body weight (PC) and high egg production for eight generations. Fertile eggs were collected and weighed individually for 4 periods of 5 consecutive days at two-week intervals. In each period, a total of 960 eggs/line were identified and separated in groups of 240 eggs, and stored for later incubation. Embryo weight (PE) was evaluated at 9 (P9), 11 (P11), 13 (P13), 15 (P15), 17 (P17) and 21 (P21) days of incubation. The objective was to estimate the effect of selection on embryo development. Egg weight (PO) was similar between the two lines. The differences in PE were significant from P15 on, resulting in 1.9g of difference in the chick weight, indicating correlated genetic changes in the embryo development, which can be credited to the selection for PC. Changes in PE while PO was kept unaltered modified the correlations between these two traits. Differences were significant from P13 on and estimated correlations for P21 were 0.72 and 0.70 for PP and PPc, respectively. Chick weight corresponded to 70.91% (PP) and 68.48% (PPc) of egg weight. The estimated increase in P21 that resulted from the increase of 1.0g in PO was 0.71 in PP and 0.68g in PPc.

Characterization of selection effects on broiler lines using DNA fingerprinting

The objective of this study was to evaluate the effect of selection for body weight on the genetic variability and diversity in broiler lines. Two paternal broiler lines (LL and LLc) were used. LL line was selected for 12 generations for growth and carcass and reproduction characteristics. The LLc line was established from LL line in 1985 and mated at random. Blood samples from six chickens per line were collected and used for molecular analysis. Also, a DNA pool was made for each line to compare effects between lines. Data were analyzed considering the collected information on the presence or absence of DNA bands. Band sharing scores were calculated using the DICE coefficient. The pattern of the 21 most representative bands was used. DNA fingerprinting (DFP) showed 90.48 % of polymorphism bands for both lines. Difference between lines was not due to the presence or absence of bands, but to the frequency of such bands in each genotype. Considering that both lines had the same genetic background, changes on band frequency were probably due to selection. Selection for body weight had an effect on the band frequency as evaluated by DFP, and for this reason this technique could be used as a tool in the selection process. Results also suggest that bands 4, 5 and 19 were linked to body weight traits, and bands 9, 10, 12, 13 and 21 were linked to reproductive traits such as egg production.

Correlation between oviposition interval and productive traits in White Leghorn strains

The oviposition interval (OI) and the laying persistency are important traits for predicting total egg production. The OI varies between and within lines. Both the genetic and the environmental variation influence OI with heretability estimates being several times higher than for traditional egg production traits (Lillpers and Wilhelmson, 1993). One of the important factors for reducing the OI to less than 24 h is the time of 25 h and 6 min required for the egg to pass through the oviduct (Warren and Scott, 1934). If breeders intend to obtain additional gain on total egg production, the barrier of one egg per day must be surpassed. The mechanism responsible for the ovulation control is not completely understood, but it is known that ovulation followed by oviposition does not occur during the dark period. Also, birds with an OI greater than 25 h lay eggs later and later on successive days up to the dark period, when they then skip a day. The objective of this paper was to estimate heretability (h), genetic (rg) and phenotypic (rp) correlations for productive traits and OI in layer strains. Two experimental lines (CC and DD) and a control line (CCc) were used. The experimental lines were selected for five generations for egg production (EP50), egg weight (EW), age at first egg (AFE), body weight (BW40), fertility (F) and hatchability (H). In the last generation, 1318 (CC), 975 (DD) and 205 (CCc) females born from hierarchical matings and kept in individual wire cages were examined during four days in the 30th week of age for OI and from the 19th to the 50th week for EP50, AFE and BW40. The data analysis was done using Harvey’s (1990) method. The genetic changes were determined from the deviation between the selected and the control lines. The h estimates (main diagonal), the rg (above the main diagonal), the rp (below the main diagonal) and the means obtained for the evaluated traits are showed in the Table. The genetic gains obtained were –1 and –2 d for AFE, 87 and 105 g for BW40, 4·7% and 2·75% for EP50, for CC and DD lines respectively, and –0·2 h for OI for DD. Excepting rg (0·49±0·3), these estimates agree with literature results. There is a low genetic correlation between OI and EP50, confirming that the population consisted of birds of a high rate of lay and birds with OI less or greater than 24 h. The progeny of birds selected only by egg production (EP) will show OI smaller or greater than 24 h like their dams. It is possible that the inclusion of OI in selection indices could reduce the length of the ‘biological’ day to less than 24 h and it would then be possible to pass the barrier of 100% EP. However, from a practical point of view, an OI smaller than 24 h would only be advantageous for darkhouse systems. In Brazil, where the poultry houses are open-sided, there is no advantage in using lines selected for this trait. In conclusion, selection for productive traits (AFE and EP50) has not resulted in a correlated response in OI. Therefore, a reduction in OI can only be obtained by the inclusion of this trait in selection programmes. G. S. Schmidt was sponsored by CNPq.